yubikey v0.9.0-pre.0 (#666 )

This prerelease includes crates from the new RustCrypto release series including prereleases for crates which haven't yet received a new stable release. It also includes preliminary Curve25519/Ed25519 support.
Upgrade dependencies; bump version to v0.9.0-pre (#665 )
2026-04-02 13:59:53 -06:00 · 2026-04-02 13:35:37 -06:00 · 2026-02-18 17:27:43 -07:00 · 2025-12-15 19:59:48 +01:00 · 2025-12-15 19:59:04 +01:00 · 2025-12-15 18:08:36 +01:00
45 changed files with 5503 additions and 3287 deletions
@@ -0,0 +1,6 @@
+[advisories]
+ignore = [
+    "RUSTSEC-2020-0071", # chrono
+    "RUSTSEC-2021-0145", # atty
+    "RUSTSEC-2023-0071", # rsa: Marvin Attack: potential key recovery
+] # advisory IDs to ignore e.g. ["RUSTSEC-2019-0001", ...]
@@ -1,8 +1,19 @@
 version: 2
 updates:
  - package-ecosystem: cargo
+    versioning-strategy: lockfile-only
+    directory: "/"
+    allow:
+      - dependency-type: "all"
+    groups:
+      all-deps:
+        patterns:
+          - "*"
+    schedule:
+      interval: weekly
+    open-pull-requests-limit: 10
+  - package-ecosystem: github-actions
    directory: "/"
    schedule:
      interval: weekly
-    time: '13:00'
    open-pull-requests-limit: 10
@@ -13,7 +13,7 @@ jobs:
  check:
    runs-on: ubuntu-latest
    steps:
-      - uses: actions/checkout@v1
+      - uses: actions/checkout@v6
      - uses: actions-rs/toolchain@v1
        with:
          profile: minimal
@@ -36,17 +36,17 @@ jobs:
            toolchain: stable
            deps: true
          - platform: ubuntu-latest
-            toolchain: 1.46.0 # MSRV
+            toolchain: 1.85.0 # MSRV
            deps: sudo apt-get install libpcsclite-dev
          - platform: windows-latest
-            toolchain: 1.46.0 # MSRV
+            toolchain: 1.85.0 # MSRV
            deps: true
          - platform: macos-latest
-            toolchain: 1.46.0 # MSRV
+            toolchain: 1.85.0 # MSRV
            deps: true
    runs-on: ${{ matrix.platform }}
    steps:
-      - uses: actions/checkout@v1
+      - uses: actions/checkout@v6
      - uses: actions-rs/toolchain@v1
        with:
          profile: minimal
@@ -60,7 +60,7 @@ jobs:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout sources
-        uses: actions/checkout@v1
+        uses: actions/checkout@v6

      - name: Install stable toolchain
        uses: actions-rs/toolchain@v1
@@ -78,11 +78,12 @@ jobs:
  clippy:
    runs-on: ubuntu-latest
    steps:
-      - uses: actions/checkout@v1
+      - uses: actions/checkout@v6
      - uses: actions-rs/toolchain@v1
        with:
          profile: minimal
-          toolchain: 1.46.0 # MSRV
+          toolchain: 1.85.0 # MSRV
          components: clippy
+          override: true
      - run: sudo apt-get install libpcsclite-dev
-      - run: cargo clippy --all --exclude crypto_box --all-features -- -D warnings
+      - run: cargo clippy --all --all-features -- -D warnings
@@ -15,16 +15,16 @@ jobs:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout sources
-        uses: actions/checkout@v1
+        uses: actions/checkout@v6

      - name: Cache cargo registry
-        uses: actions/cache@v1
+        uses: actions/cache@v5
        with:
          path: ~/.cargo/registry
          key: ${{ runner.os }}-cargo-registry-${{ hashFiles('Cargo.lock') }}

      - name: Cache cargo index
-        uses: actions/cache@v1
+        uses: actions/cache@v5
        with:
          path: ~/.cargo/git
          key: ${{ runner.os }}-cargo-index-${{ hashFiles('Cargo.lock') }}
@@ -42,4 +42,4 @@ jobs:
        uses: actions-rs/cargo@v1
        with:
          command: audit
-          args: --deny-warnings --ignore RUSTSEC-2019-0031 # spin
+          args: --deny warnings
@@ -4,7 +4,226 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).

-## 0.2.0 (2021-01-30)
+## Unreleased
+### Added
+- `yubikey::certificate::SelfSigned`
+- `yubikey::Error::CertificateBuilder`
+- `yubikey::MgmAlgorithmId`
+- `yubikey::mgm`:
+  - `MgmKey::generate_for`
+  - `MgmKey::get_default`
+  - `impl AsRef<[u8]> for MgmKey`
+
+### Changed
+- MSRV is now 1.81.
+- Migrated the public API to the following (pre-release) dependencies:
+  - `der 0.8.0-rc.1`
+  - `ecdsa 0.17.0-pre.9`
+  - `p256 0.14.0-pre.2`
+  - `p384 0.14.0-pre.2`
+  - `rsa 0.10.0-pre.3`
+  - `sha2 0.11.0-pre.4`
+  - `x509-cert 0.3.0-pre.0`
+- `yubikey::mgm`:
+  - `MgmKey::generate` now takes a `rand::TryCryptoRng` argument.
+  - `MgmKey::generate` now requires the caller to specify the key algorithm via
+    an `MgmAlgorithmId` parameter.
+    - Use `MgmKey::generate_for` if you want to generate a key using the
+      preferred algorithm for a given Yubikey's firmware version.
+  - `MgmKey::from_bytes` now takes an `Option<MgmAlgorithmId>` argument, to
+    disambiguate algorithms with the same key length.
+- `yubikey::piv`:
+  - `ManagementAlgorithmId` has been renamed to `SlotAlgorithmId`, and its
+    `ThreeDes` variant has been replaced by `SlotAlgorithmId::Management`
+    containing a `yubikey::MgmAlgorithmId`.
+- Metadata command returns `Error:NotFound` instead of `Error::GenericError` when the object doesn't exist ([#558]).
+
+### Removed
+- `yubikey::mgm`:
+  - `MgmKey::new` (use `MgmKey::from_bytes(_, Some(MgmAlgorithmId::ThreeDes))`
+    instead).
+  - `impl AsRef<[u8; DES_LEN_3DES]> for MgmKey` (use
+    `impl AsRef<[u8]> for MgmKey` instead).
+  - `impl Default for MgmKey` (use `MgmKey::get_default` instead).
+  - `impl TryFrom<&[u8]> for MgmKey` (use `MgmKey::from_bytes` instead).
+
+## 0.8.0 (2023-08-15)
+### Added
+- `impl Debug for {Context, YubiKey}` ([#457])
+- `YubiKey::disconnect` ([#462])
+- `Error::AppletNotFound` ([#476])
+
+### Changed
+- `Reader::open` now returns `Error::AppletNotFound` instead of `Error::Generic`
+  if the PIV applet is not present on the device. This is returned by non-PIV
+  virtual smart cards like Windows Hello for Business, as well as some smart
+  card readers when no card is present.
+- `Reader::open` now avoids resetting the card if an error occurs (equivalent to
+  calling `YubiKey::disconnect(pcsc::Disposition::LeaveCard)` if `Reader::open`
+  succeeds).
+- Raise minimum `pcsc` version to 2.3.1 and remove workaround ([#478])
+- Bump asymmetric crypto dependencies; MSRV 1.65 ([#490])
+  - `elliptic-curve` v0.13
+  - `k256` v0.13
+  - `p256` v0.13
+  - `p384` v0.13
+  - `pbkdf2` v0.12
+  - `rsa` v0.9 ([#502])
+  - `signature` v2
+- Use `x509-cert` certificate builder ([#495])
+- Make `RsaKeyData::new` fallible ([#517])
+
+### Fixed
+- `StatusWords::code` now returns the correct code (including embedded `tries`
+  count) for `StatusWords::VerifyFailError`. Previously the returned code lost
+  information and was not round-trip compatible with `StatusWords::from(u16)`.
+- Parsing of serial numbers ([#466])
+- Make `YubiKey::open()` more robust ([#504])
+
+[#457]: https://github.com/iqlusioninc/yubikey.rs/pull/457
+[#462]: https://github.com/iqlusioninc/yubikey.rs/pull/462
+[#466]: https://github.com/iqlusioninc/yubikey.rs/pull/466
+[#476]: https://github.com/iqlusioninc/yubikey.rs/pull/476
+[#478]: https://github.com/iqlusioninc/yubikey.rs/pull/478
+[#490]: https://github.com/iqlusioninc/yubikey.rs/pull/490
+[#495]: https://github.com/iqlusioninc/yubikey.rs/pull/495
+[#502]: https://github.com/iqlusioninc/yubikey.rs/pull/502
+[#504]: https://github.com/iqlusioninc/yubikey.rs/pull/504
+[#517]: https://github.com/iqlusioninc/yubikey.rs/pull/517
+
+## 0.7.0 (2022-11-14)
+### Added
+- Display inner PC/SC errors ([#420])
+- Support for metadata command ([#371])
+- Better `certificate::Serial` inspection ([#437])
+
+### Changed
+- MSRV 1.60.0 ([#423])
+- Bump `rsa` to v0.7.1 ([#440])
+- Switch from `lazy_static` to `once_cell` ([#442])
+- Switch from `subtle-encoding` to `base16ct` ([#443])
+
+### Fixed
+- Use `chrono` v0.4.23 or newer ([#436])
+- `Certificate::issuer` was returning the subject instead ([#437])
+
+[#371]: https://github.com/iqlusioninc/yubikey.rs/pull/371
+[#420]: https://github.com/iqlusioninc/yubikey.rs/pull/420
+[#423]: https://github.com/iqlusioninc/yubikey.rs/pull/423
+[#436]: https://github.com/iqlusioninc/yubikey.rs/pull/436
+[#437]: https://github.com/iqlusioninc/yubikey.rs/pull/437
+[#440]: https://github.com/iqlusioninc/yubikey.rs/pull/440
+[#442]: https://github.com/iqlusioninc/yubikey.rs/pull/442
+[#443]: https://github.com/iqlusioninc/yubikey.rs/pull/443
+
+## 0.6.0 (2022-08-10)
+### Changed
+- 2021 edition upgrade ([#343])
+- RustCrypto crate upgrades; MSRV 1.57 ([#378])
+  - `des` v0.8
+  - `elliptic-curve` v0.12
+  - `hmac` v0.12
+  - `num-bigint-dig` v0.8
+  - `pbkdf2` v0.11
+  - `p256` v0.11
+  - `p384` v0.11
+  - `rsa` v0.6
+  - `sha1` v0.10 (replacing `sha-1`)
+  - `sha2` v0.10
+- Bump `uuid` to v1.0 ([#376])
+- Bump `der-parser` to v8.0 ([#402])
+- Bump `x509-parser` to v0.14 ([#402])
+
+[#343]: https://github.com/iqlusioninc/yubikey.rs/pull/343
+[#376]: https://github.com/iqlusioninc/yubikey.rs/pull/376
+[#378]: https://github.com/iqlusioninc/yubikey.rs/pull/378
+[#402]: https://github.com/iqlusioninc/yubikey.rs/pull/402
+
+## 0.5.0 (2021-11-21)
+### Changed
+- Update `rsa` dependency to 0.5 ([#315])
+- Update `pbkdf2` dependency to 0.9 ([#315])
+- Update `x509-parser` dependency to 0.12 ([#315], [#322])
+- Update `nom` to v7.0 ([#322])
+
+[#315]: https://github.com/iqlusioninc/yubikey.rs/pull/315
+[#322]: https://github.com/iqlusioninc/yubikey.rs/pull/322
+
+## 0.4.2 (2021-07-13)
+### Added
+- Make `yubikey::Buffer` a pub type ([#290])
+
+### Changed
+- Have `YubiKey::block_puk` take `&mut self` as argument ([#289])
+
+[#289]: https://github.com/iqlusioninc/yubikey.rs/pull/289
+[#290]: https://github.com/iqlusioninc/yubikey.rs/pull/290
+
+## 0.4.1 (2021-07-12)
+### Changed
+- Rename `SettingValue` to `Setting` ([#286])
+- Rename `Ccc` to `CccId` ([#287])
+
+[#286]: https://github.com/iqlusioninc/yubikey.rs/pull/286
+[#287]: https://github.com/iqlusioninc/yubikey.rs/pull/287
+
+## 0.4.0 (2021-07-12) [YANKED]
+### Added
+- `Result` alias ([#271])
+
+### Changed
+- Renamed crate from `yubikey-piv` => `yubikey` ([#267])
+- Renamed the following:
+    - `APDU` => `Apdu` ([#269])
+    - `CCC` => `Ccc` ([#269])
+    - `CHUID` => `ChuId` ([#269])
+    - `Ccc::cccid` => `Ccc::card_id` ([#270])
+    - `key` => `piv` ([#277])
+    - `readers` => `reader` ([#278])
+    - `readers::Readers` => `reader::Context` ([#278])
+- Bumped the following dependencies:
+  - `rsa` => v0.4 ([#246])
+  - `des` => v0.7 ([#251])
+  - `elliptic-curve` => v0.10 ([#268])
+  - `hmac` => v0.11 ([#251])
+  - `pbkdf2` => v0.8 ([#251])
+  - `p256` => v0.9 ([#268])
+  - `p384` => v0.8 ([#268])
+- MSRV 1.51+ ([#268])
+- Flatten API ([#274])
+- Replace `getrandom` with `rand_core` ([#276])
+
+### Fixed
+- Potential local DoS in TLV parser ([#279])
+
+[#246]: https://github.com/iqlusioninc/yubikey.rs/pull/246
+[#251]: https://github.com/iqlusioninc/yubikey.rs/pull/251
+[#267]: https://github.com/iqlusioninc/yubikey.rs/pull/267
+[#268]: https://github.com/iqlusioninc/yubikey.rs/pull/268
+[#269]: https://github.com/iqlusioninc/yubikey.rs/pull/269
+[#270]: https://github.com/iqlusioninc/yubikey.rs/pull/270
+[#271]: https://github.com/iqlusioninc/yubikey.rs/pull/271
+[#274]: https://github.com/iqlusioninc/yubikey.rs/pull/274
+[#276]: https://github.com/iqlusioninc/yubikey.rs/pull/276
+[#277]: https://github.com/iqlusioninc/yubikey.rs/pull/277
+[#278]: https://github.com/iqlusioninc/yubikey.rs/pull/278
+[#279]: https://github.com/iqlusioninc/yubikey.rs/pull/279
+
+## yubikey-piv 0.3.0 (2021-03-22)
+### Added
+- Typed structs for PIN-protected and admin metadata ([#223])
+- `MgmKey::set_default`/`MgmKey::set_manual` methods ([#224])
+
+### Changed
+- Have `Transaction::set_mgm_key` take touch requirement as bool ([#224])
+
+### Removed
+- `MgmKey::set` method ([#224])
+
+[#223]: https://github.com/iqlusioninc/yubikey.rs/pull/223
+[#224]: https://github.com/iqlusioninc/yubikey.rs/pull/224
+
+## yubikey-piv 0.2.0 (2021-01-30)
 ### Changed
 - Bump `der-parser` to v5.0 ([#194])
 - Improve self-signed certificates ([#207])
@@ -13,12 +232,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Bump MSRV to 1.46+ ([#208])
 - Bump `pbkdf2` dependency to v0.7 ([#219])

-[#194]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/194
-[#207]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/207
-[#208]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/208
-[#219]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/219
+[#194]: https://github.com/iqlusioninc/yubikey.rs/pull/194
+[#207]: https://github.com/iqlusioninc/yubikey.rs/pull/207
+[#208]: https://github.com/iqlusioninc/yubikey.rs/pull/208
+[#219]: https://github.com/iqlusioninc/yubikey.rs/pull/219

-## 0.1.0 (2020-10-19)
+## yubikey-piv 0.1.0 (2020-10-19)
 ### Added
 - `Certificate::generate_self_signed` ([#80])
 - `YubiKey::open_by_serial` ([#69])
@@ -43,24 +262,24 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Removed
 - YubiKey NEO support ([#63])

-[#177]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/177
-[#175]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/175
-[#128]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/128
-[#82]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/82
-[#73]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/73
-[#88]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/88
-[#80]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/80
-[#69]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/69
-[#68]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/68
-[#67]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/67
-[#65]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/65
-[#64]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/64
-[#63]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/63
-[#62]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/62
-[#61]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/61
-[#60]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/60
+[#177]: https://github.com/iqlusioninc/yubikey.rs/pull/177
+[#175]: https://github.com/iqlusioninc/yubikey.rs/pull/175
+[#128]: https://github.com/iqlusioninc/yubikey.rs/pull/128
+[#82]: https://github.com/iqlusioninc/yubikey.rs/pull/82
+[#73]: https://github.com/iqlusioninc/yubikey.rs/pull/73
+[#88]: https://github.com/iqlusioninc/yubikey.rs/pull/88
+[#80]: https://github.com/iqlusioninc/yubikey.rs/pull/80
+[#69]: https://github.com/iqlusioninc/yubikey.rs/pull/69
+[#68]: https://github.com/iqlusioninc/yubikey.rs/pull/68
+[#67]: https://github.com/iqlusioninc/yubikey.rs/pull/67
+[#65]: https://github.com/iqlusioninc/yubikey.rs/pull/65
+[#64]: https://github.com/iqlusioninc/yubikey.rs/pull/64
+[#63]: https://github.com/iqlusioninc/yubikey.rs/pull/63
+[#62]: https://github.com/iqlusioninc/yubikey.rs/pull/62
+[#61]: https://github.com/iqlusioninc/yubikey.rs/pull/61
+[#60]: https://github.com/iqlusioninc/yubikey.rs/pull/60

-## 0.0.3 (2019-12-02)
+## yubikey-piv 0.0.3 (2019-12-02)
 ### Added
 - Initial `Readers` enumerator for detecting YubiKeys ([#51])
 - Certificate parsing ([#45])
@@ -76,19 +295,19 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - `Ins` (APDU instruction codes) enum ([#33])
 - Factor `Response` into `apdu` module; improved debugging ([#32])

-[#51]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/51
-[#45]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/45
-[#44]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/44
-[#43]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/43
-[#42]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/42
-[#39]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/39
-[#37]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/37
-[#36]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/36
-[#34]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/34
-[#33]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/33
-[#32]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/32
+[#51]: https://github.com/iqlusioninc/yubikey.rs/pull/51
+[#45]: https://github.com/iqlusioninc/yubikey.rs/pull/45
+[#44]: https://github.com/iqlusioninc/yubikey.rs/pull/44
+[#43]: https://github.com/iqlusioninc/yubikey.rs/pull/43
+[#42]: https://github.com/iqlusioninc/yubikey.rs/pull/42
+[#39]: https://github.com/iqlusioninc/yubikey.rs/pull/39
+[#37]: https://github.com/iqlusioninc/yubikey.rs/pull/37
+[#36]: https://github.com/iqlusioninc/yubikey.rs/pull/36
+[#34]: https://github.com/iqlusioninc/yubikey.rs/pull/34
+[#33]: https://github.com/iqlusioninc/yubikey.rs/pull/33
+[#32]: https://github.com/iqlusioninc/yubikey.rs/pull/32

-## 0.0.2 (2019-11-25)
+## yubikey-piv 0.0.2 (2019-11-25)
 ### Added
 - `untested` Cargo feature to mark untested functionality ([#30])
 - Initial connect test and docs ([#19])
@@ -103,16 +322,16 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Use `log` crate for logging ([#7])
 - Replace `ErrorKind::Ok` with `Result` ([#6])

-[#30]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/30
-[#19]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/19
-[#17]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/17
-[#15]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/15
-[#13]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/13
-[#10]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/10
-[#9]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/9
-[#8]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/8
-[#7]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/7
-[#6]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/6
+[#30]: https://github.com/iqlusioninc/yubikey.rs/pull/30
+[#19]: https://github.com/iqlusioninc/yubikey.rs/pull/19
+[#17]: https://github.com/iqlusioninc/yubikey.rs/pull/17
+[#15]: https://github.com/iqlusioninc/yubikey.rs/pull/15
+[#13]: https://github.com/iqlusioninc/yubikey.rs/pull/13
+[#10]: https://github.com/iqlusioninc/yubikey.rs/pull/10
+[#9]: https://github.com/iqlusioninc/yubikey.rs/pull/9
+[#8]: https://github.com/iqlusioninc/yubikey.rs/pull/8
+[#7]: https://github.com/iqlusioninc/yubikey.rs/pull/7
+[#6]: https://github.com/iqlusioninc/yubikey.rs/pull/6

-## 0.0.1 (2019-11-18)
+## yubikey-piv 0.0.1 (2019-11-18)
 - Initial release
@@ -1,4 +1,4 @@
-Copyright (c) 2014-2019 Yubico AB, Tony Arcieri
+Copyright (c) 2014-2021 Yubico AB, Tony Arcieri
 All rights reserved.

 Redistribution and use in source and binary forms, with or without
@@ -1,60 +1,68 @@
 [package]
-name    = "yubikey-piv"
-version = "0.2.0" # Also update html_root_url in lib.rs when bumping this
+name = "yubikey"
+version = "0.9.0-pre.0"
 description = """
-Pure Rust host-side driver for the YubiKey Personal Identity Verification (PIV)
-application providing general-purpose public-key signing and encryption
-with hardware-backed private keys for RSA (2048/1024) and ECC (P-256/P-384)
-algorithms (e.g, PKCS#1v1.5, ECDSA)
+Pure Rust cross-platform host-side driver for YubiKey devices from Yubico with
+support for hardware-backed public-key decryption and digital signatures using
+the Personal Identity Verification (PIV) application. Supports RSA (1024/2048/3072/4096)
+or ECC (NIST P-256/P-384) algorithms e.g, PKCS#1v1.5, ECDSA
 """
 authors = ["Tony Arcieri <tony@iqlusion.io>", "Yubico AB"]
-edition    = "2018"
 license = "BSD-2-Clause"
-repository = "https://github.com/iqlusioninc/yubikey-piv.rs"
+repository = "https://github.com/iqlusioninc/yubikey.rs"
 readme = "README.md"
-categories = ["api-bindings", "cryptography", "hardware-support"]
-keywords   = ["ecdsa", "rsa", "piv", "pcsc", "yubikey"]
+categories = ["api-bindings", "authentication", "cryptography", "hardware-support"]
+keywords = ["ecdsa", "encryption", "rsa", "piv", "signature"]
+edition = "2021"
+rust-version = "1.85"

 [workspace]
 members = [".", "cli"]

-[badges]
-maintenance = { status = "experimental" }
+[workspace.dependencies]
+sha2 = "0.11"
+x509-cert = { version = "0.3.0-rc.4", features = ["builder", "hazmat"] }

 [dependencies]
-chrono = "0.4"
-cookie-factory = "0.3"
-der-parser = "5"
-des = "0.6"
-elliptic-curve = "0.8"
-getrandom = "0.1"
-hmac = "0.10"
+aes = { version = "0.9.0-rc.4", features = ["zeroize"] }
+bitflags = "2.5.0"
+cipher = { version = "0.5", features = ["getrandom", "rand_core"] }
+curve25519-dalek = "5.0.0-pre.6"
+der = "0.8"
+des = "0.9.0-rc.3"
+ecdsa = { version = "0.17.0-rc.16", features = ["digest", "pem"] }
+ed25519-dalek = { version = "3.0.0-pre.6", features = ["alloc", "pkcs8"] }
+elliptic-curve = "0.14.0-rc.29"
+hex = { package = "base16ct", version = "0.2", features = ["alloc"] }
 log = "0.4"
-nom = "6"
-num-bigint = { version = "0.6", features = ["rand"], package = "num-bigint-dig" }
-num-traits = "0.2"
-num-integer = "0.1"
-pbkdf2 = { version = "0.7", default-features = false }
-p256 = "0.7"
-p384 = "0.6"
-pcsc = "2"
-rsa = "0.3"
-secrecy = "0.7"
-sha-1 = "0.9"
-sha2 = "0.9"
+nom = "8"
+p256 = "0.14.0-rc.8"
+p384 = "0.14.0-rc.8"
+pbkdf2 = { version = "0.13.0-rc.10", default-features = false, features = ["hmac"] }
+pcsc = "2.3.1"
+rand = "0.10"
+rand_core = "0.10"
+rsa = { version = "0.10.0-rc.17", features = ["sha2"] }
+sha1 = { version = "0.11", features = ["oid"] }
+sha2 = { workspace = true, features = ["oid"] }
+signature = "3.0.0-rc.10"
 subtle = "2"
-subtle-encoding = "0.5"
-x509 = "0.2"
-x509-parser = "0.9"
+uuid = { version = "1.2", features = ["v4"] }
+x25519-dalek = "3.0.0-pre.6"
+x509-cert.workspace = true
 zeroize = "1"

 [dev-dependencies]
-env_logger = "0.8"
-ring = "0.16.18"
-lazy_static = "1"
+env_logger = "0.11"
+once_cell = "1"

 [features]
 untested = []

+[[example]]
+name = "change-mode"
+required-features = ["untested"]
+
 [package.metadata.docs.rs]
 all-features = true
+rustdoc-args = ["--cfg", "docsrs"]
@@ -1,50 +1,89 @@
-<img src="https://raw.githubusercontent.com/iqlusioninc/yubikey-piv.rs/main/img/logo.png" width="150" height="110">
+<img src="https://raw.githubusercontent.com/iqlusioninc/yubikey.rs/main/img/logo.png" width="150" height="110">

-# yubikey-piv.rs
+# yubikey.rs

 [![crate][crate-image]][crate-link]
 [![Docs][docs-image]][docs-link]
-[![2-Clause BSD Licensed][license-image]][license-link]
-![Rust Version][rustc-image]
-![Maintenance Status: Experimental][maintenance-image]
-[![Safety Dance][safety-image]][safety-link]
 [![Build Status][build-image]][build-link]
-[![Gitter Chat][gitter-image]][gitter-link]
+[![Safety Dance][safety-image]][safety-link]
+[![Dependency Status][deps-image]][deps-link]
+[![2-Clause BSD Licensed][license-image]][license-link]
+![MSRV][msrv-image]

-Pure Rust host-side YubiKey [Personal Identity Verification (PIV)][PIV] driver
-with general-purpose public-key encryption and signing support.
+Pure Rust cross-platform host-side driver for [YubiKey] devices from [Yubico]
+with support for public-key encryption and digital signatures using the
+[Personal Identity Verification (PIV)][PIV] application.
+
+Uses the Personal Computer/Smart Card ([PC/SC]) interface with cross-platform
+access provided by the [`pcsc` crate].

 [Documentation][docs-link]

 ## About

 YubiKeys are versatile devices and through their PIV support, you can use them
-to store a number of RSA (2048/1024) and ECC (NIST P-256/P-384) private keys
+to store a number of RSA (1024/2048/3072/4096) and ECC (NIST P-256/P-384) private keys
 with configurable access control policies. Both the signing (RSASSA/ECDSA) and
 encryption (PKCS#1v1.5/ECIES) use cases are supported for either key type.

 See [Yubico's guide to PIV-enabled YubiKeys][yk-guide] for more information
 on which devices support PIV and the available functionality.

-If you've been wanting to use Rust to sign and/or encrypt stuff using a
-private key generated and stored on a Yubikey (with option PIN-based access),
+If you've been wanting to use Rust to sign and/or encrypt data using a
+private key generated and stored on a YubiKey (with option PIN-based access),
 this is the crate you've been after!

 Note that while this project started as a fork of a [Yubico] project,
 this fork is **NOT** an official Yubico project and is in no way supported or
 endorsed by Yubico.

+## Features
+
+### Personal Identity Verification (PIV)
+
+[PIV] is a [NIST] standard for both *signing* and *encryption*
+using SmartCards and SmartCard-based hardware tokens like YubiKeys.
+
+PIV-related functionality can be found in the [`piv`] module.
+
+This library natively implements the protocol used to manage and
+utilize PIV encryption and signing keys which can be generated, imported,
+and stored on YubiKey devices.
+
+See [Yubico's guide to PIV-enabled YubiKeys][yk-guide] for more information
+on which devices support PIV and the available functionality.
+
+### Supported Algorithms
+
+- **Authentication**: `3DES`
+- **Encryption**:
+    - RSA: `RSA1024`, `RSA2048`, `RSA3072`, `RSA4096`
+    - ECC: `ECCP256`, `ECCP384` (NIST curves: P-256, P-384)
+- **Signatures**:
+    - RSASSA-PKCS#1v1.5: `RSA1024`, `RSA2048`, `RSA3072`, `RSA4096`
+    - ECDSA: `ECCP256`, `ECCP384` (NIST curves: P-256, P-384)
+
+NOTE:
+
+- RSASSA-PSS signatures and RSA-OAEP encryption may be supportable (TBD)
+- `RSA3072` and `RSA4096` require a YubiKey with firmware 5.7 or newer.
+
 ## Minimum Supported Rust Version

- Rust **1.46** or newer
+Rust **1.60** or newer.

 ## Supported YubiKeys

 - [YubiKey 4] series
 - [YubiKey 5] series

-NOTE: Nano and USB-C variants of the above are also supported.
-      Pre-YK4 [YubiKey NEO] series is **NOT** supported (see [#18]).
+NOTE: Nano and USB-C variants of the above are also supported. NEO series is NOT supported.
+
+## Supported Operating Systems
+
+- Linux
+- macOS
+- Windows

 ## Security Warning

@@ -55,49 +94,25 @@ USE AT YOUR OWN RISK!

 ## Status

-This project is a largely incomplete work-in-progress. So far the only
-functionality which has actually been tested is connecting to Yubikeys.
+Functionality which has been successfully tested is available by default.

-If you're interested helping test functionality, the table below documents
-the current status of the project and relevant GitHub issues for various
-functions of the YubiKey:
+Any functionality which is gated on the `untested` feature has not been
+properly tested and is not known to function correctly.

-|    | Module        | Issue | Description |
-|----|---------------|-------|-------------|
-| 🚧 | `yubikey`     | [#20] | Core functionality: auth, keys, PIN/PUK, encrypt, sign, attest |
-| 🚧 | `cccid`       | [#21] | Cardholder Capability Container (CCC) IDs |
-| 🚧️ | `certificate` | [#22] | Certificates for stored keys |
-| 🚧 | `chuid`       | [#23] | Cardholder Unique Identifier (CHUID) |
-| ✅️ | `config`      | [#24] | Support for reading on-key configuration |
-| 🚧 | `key`         | [#26] | Crypto key management: list, generate, import |
-| 🚧 | `mgm`         | [#26] | Management Key (MGM) support: set, get, derive |
-| ⚠️ | `mscmap`      | [#25] | MS Container Map Records |
-| ⚠️ | `msroots`     | [#28] | `msroots` file: PKCS#7 formatted certificate store for enterprise trusted roots |
-
-Legend:
-
-|    | Description                        |
-|----|------------------------------------|
-| ✅ | Working                            |
-| 🚧 | Testing and validation in progress |
-| ⚠️ | Untested support                   |
-
-NOTE: Commands marked ⚠️ are disabled by default as they have have not been properly tested and may contain bugs or
-not work at all. USE AT YOUR OWN RISK!
-
-Enable the `untested` feature in your `Cargo.toml` to enable features marked ⚠️
-above.
+Please see the [`untested` functionality tracking issue] for current status.
+We would appreciate any help testing this functionality and removing the
+`untested` gating as well as writing more automated tests.

 ## Testing

-To run the full test suite, you'll need a connected YubiKey NEO/4/5 device in
-the default state (i.e. default PIN/PUK).
+To run the full test suite, you'll need a supported YubiKey device connected
+which is in the default state (i.e. default PIN/PUK).

 Tests which run live against a YubiKey device are marked as `#[ignore]` by
 default in order to pass when running in a CI environment. To run these
 tests locally, invoke the following command:

-```
+```shell
 cargo test -- --ignored
 ```

@@ -106,26 +121,26 @@ information about what is happening. If you'd like to print this logging
 information while running the tests, set the `RUST_LOG` environment variable
 to a relevant loglevel (e.g. `error`, `warn`, `info`, `debug`, `trace`):

-```
+```shell
 RUST_LOG=info cargo test -- --ignored
 ```

 To trace every message sent to/from the card i.e. the raw
 Application Protocol Data Unit (APDU) messages, use the `trace` log level:

-```
+```text
 running 1 test
-[INFO  yubikey_piv::yubikey] trying to connect to reader 'Yubico YubiKey OTP+FIDO+CCID'
-[INFO  yubikey_piv::yubikey] connected to 'Yubico YubiKey OTP+FIDO+CCID' successfully
-[TRACE yubikey_piv::apdu] >>> APDU { cla: 0, ins: SelectApplication, p1: 4, p2: 0, data: [160, 0, 0, 3, 8] }
-[TRACE yubikey_piv::transaction] >>> [0, 164, 4, 0, 5, 160, 0, 0, 3, 8]
-[TRACE yubikey_piv::apdu] <<< Response { status_words: Success, data: [97, 17, 79, 6, 0, 0, 16, 0, 1, 0, 121, 7, 79, 5, 160, 0, 0, 3, 8] }
-[TRACE yubikey_piv::apdu] >>> APDU { cla: 0, ins: GetVersion, p1: 0, p2: 0, data: [] }
-[TRACE yubikey_piv::transaction] >>> [0, 253, 0, 0, 0]
-[TRACE yubikey_piv::apdu] <<< Response { status_words: Success, data: [5, 1, 2] }
-[TRACE yubikey_piv::apdu] >>> APDU { cla: 0, ins: GetSerial, p1: 0, p2: 0, data: [] }
-[TRACE yubikey_piv::transaction] >>> [0, 248, 0, 0, 0]
-[TRACE yubikey_piv::apdu] <<< Response { status_words: Success, data: [0, 115, 0, 178] }
+[INFO  yubikey::yubikey] trying to connect to reader 'Yubico YubiKey OTP+FIDO+CCID'
+[INFO  yubikey::yubikey] connected to 'Yubico YubiKey OTP+FIDO+CCID' successfully
+[TRACE yubikey::apdu] >>> Apdu { cla: 0, ins: SelectApplication, p1: 4, p2: 0, data: [160, 0, 0, 3, 8] }
+[TRACE yubikey::transaction] >>> [0, 164, 4, 0, 5, 160, 0, 0, 3, 8]
+[TRACE yubikey::apdu] <<< Response { status_words: Success, data: [97, 17, 79, 6, 0, 0, 16, 0, 1, 0, 121, 7, 79, 5, 160, 0, 0, 3, 8] }
+[TRACE yubikey::apdu] >>> Apdu { cla: 0, ins: GetVersion, p1: 0, p2: 0, data: [] }
+[TRACE yubikey::transaction] >>> [0, 253, 0, 0, 0]
+[TRACE yubikey::apdu] <<< Response { status_words: Success, data: [5, 1, 2] }
+[TRACE yubikey::apdu] >>> Apdu { cla: 0, ins: GetSerial, p1: 0, p2: 0, data: [] }
+[TRACE yubikey::transaction] >>> [0, 248, 0, 0, 0]
+[TRACE yubikey::apdu] <<< Response { status_words: Success, data: [0, 115, 0, 178] }
 test connect ... ok
 ```

@@ -139,6 +154,14 @@ Yubico, which was originally written in C. It was mechanically translated
 from C into Rust using [Corrode], and then subsequently heavily
 refactored into safer, more idiomatic Rust.

+For more information on [yubico-piv-tool] and background information on how
+the YubiKey implementation of PIV works in general, see the
+[Yubico PIV Tool Command Line Guide][piv-tool-guide].
+
+## ⚠️ Security Warning
+
+No security audits of this crate have ever been performed.
+
 ## Code of Conduct

 We abide by the [Contributor Covenant][cc-md] and ask that you do as well.
@@ -147,12 +170,12 @@ For more information, please see [CODE_OF_CONDUCT.md][cc-md].

 ## License

-**yubikey-piv.rs** is a fork of and originally a mechanical translation from
+**yubikey.rs** is a fork of and originally a mechanical translation from
 Yubico's [yubico-piv-tool], a C library/CLI program. The original library
 was licensed under a [2-Clause BSD License][BSDL], which this library inherits
 as a derived work.

-Copyright (c) 2014-2020 Yubico AB, Tony Arcieri
+Copyright (c) 2014-2025 Yubico AB, Tony Arcieri
 All rights reserved.

 Redistribution and use in source and binary forms, with or without
@@ -188,44 +211,48 @@ or conditions.

 [//]: # (badges)

-[crate-image]: https://img.shields.io/crates/v/yubikey-piv.svg
-[crate-link]: https://crates.io/crates/yubikey-piv
-[docs-image]: https://docs.rs/yubikey-piv/badge.svg
-[docs-link]: https://docs.rs/yubikey-piv/
+[crate-image]: https://img.shields.io/crates/v/yubikey?logo=rust
+[crate-link]: https://crates.io/crates/yubikey
+[docs-image]: https://docs.rs/yubikey/badge.svg
+[docs-link]: https://docs.rs/yubikey/
 [license-image]: https://img.shields.io/badge/license-BSD-blue.svg
-[license-link]: https://github.com/iqlusioninc/yubikey-piv.rs/blob/main/COPYING
-[rustc-image]: https://img.shields.io/badge/rustc-1.46+-blue.svg
-[maintenance-image]: https://img.shields.io/badge/maintenance-experimental-blue.svg
+[license-link]: https://github.com/iqlusioninc/yubikey.rs/blob/main/COPYING
+[msrv-image]: https://img.shields.io/badge/rustc-1.85+-blue.svg
 [safety-image]: https://img.shields.io/badge/unsafe-forbidden-success.svg
 [safety-link]: https://github.com/rust-secure-code/safety-dance/
-[build-image]: https://github.com/iqlusioninc/yubikey-piv.rs/workflows/CI/badge.svg?branch=main&event=push
-[build-link]: https://github.com/iqlusioninc/yubikey-piv.rs/actions
-[gitter-image]: https://badges.gitter.im/badge.svg
-[gitter-link]: https://gitter.im/iqlusioninc/community
+[build-image]: https://github.com/iqlusioninc/yubikey.rs/actions/workflows/ci.yml/badge.svg
+[build-link]: https://github.com/iqlusioninc/yubikey.rs/actions
+[deps-image]: https://deps.rs/repo/github/iqlusioninc/yubikey.rs/status.svg
+[deps-link]: https://deps.rs/repo/github/iqlusioninc/yubikey.rs

 [//]: # (general links)

-[PIV]: https://piv.idmanagement.gov/
-[yk-guide]: https://developers.yubico.com/PIV/Introduction/YubiKey_and_PIV.html
+[YubiKey]: https://www.yubico.com/products/yubikey-hardware/
 [Yubico]: https://www.yubico.com/
-[YubiKey NEO]: https://support.yubico.com/support/solutions/articles/15000006494-yubikey-neo
+[PIV]: https://piv.idmanagement.gov/
+[NIST]: https://www.nist.gov/
+[PC/SC]: https://en.wikipedia.org/wiki/PC/SC
+[`pcsc` crate]: https://github.com/bluetech/pcsc-rust
+[yk-guide]: https://developers.yubico.com/PIV/Introduction/YubiKey_and_PIV.html
 [YubiKey 4]: https://support.yubico.com/support/solutions/articles/15000006486-yubikey-4
 [YubiKey 5]: https://www.yubico.com/products/yubikey-5-overview/
 [yubico-piv-tool]: https://github.com/Yubico/yubico-piv-tool/
+[piv-tool-guide]: https://docs.yubico.com/software/yubikey/tools/pivtool/Introduction.html
 [Corrode]: https://github.com/jameysharp/corrode
 [cc-web]: https://contributor-covenant.org/
-[cc-md]: https://github.com/iqlusioninc/yubikey-piv.rs/blob/main/CODE_OF_CONDUCT.md
+[cc-md]: https://github.com/iqlusioninc/yubikey.rs/blob/main/CODE_OF_CONDUCT.md
 [BSDL]: https://opensource.org/licenses/BSD-2-Clause
+[`untested` functionality tracking issue]: https://github.com/iqlusioninc/yubikey.rs/issues/280

 [//]: # (github issues)

-[#18]: https://github.com/iqlusioninc/yubikey-piv.rs/issues/18
-[#20]: https://github.com/iqlusioninc/yubikey-piv.rs/issues/20
-[#21]: https://github.com/iqlusioninc/yubikey-piv.rs/issues/21
-[#22]: https://github.com/iqlusioninc/yubikey-piv.rs/issues/22
-[#23]: https://github.com/iqlusioninc/yubikey-piv.rs/issues/23
-[#24]: https://github.com/iqlusioninc/yubikey-piv.rs/issues/24
-[#25]: https://github.com/iqlusioninc/yubikey-piv.rs/issues/25
-[#26]: https://github.com/iqlusioninc/yubikey-piv.rs/issues/26
-[#27]: https://github.com/iqlusioninc/yubikey-piv.rs/issues/27
-[#28]: https://github.com/iqlusioninc/yubikey-piv.rs/issues/28
+[#18]: https://github.com/iqlusioninc/yubikey.rs/issues/18
+[#20]: https://github.com/iqlusioninc/yubikey.rs/issues/20
+[#21]: https://github.com/iqlusioninc/yubikey.rs/issues/21
+[#22]: https://github.com/iqlusioninc/yubikey.rs/issues/22
+[#23]: https://github.com/iqlusioninc/yubikey.rs/issues/23
+[#24]: https://github.com/iqlusioninc/yubikey.rs/issues/24
+[#25]: https://github.com/iqlusioninc/yubikey.rs/issues/25
+[#26]: https://github.com/iqlusioninc/yubikey.rs/issues/26
+[#27]: https://github.com/iqlusioninc/yubikey.rs/issues/27
+[#28]: https://github.com/iqlusioninc/yubikey.rs/issues/28
@@ -4,30 +4,77 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).

+## Unreleased
+### Changed
+- MSRV is now 1.81.
+
+## 0.7.0 (2022-11-14)
+### Changed
+- Bump `clap` to v4.0 ([#438])
+- Bump `x509-parser` to v0.14 ([#441])
+- Switch from `lazy_static` to `once_cell` ([#442])
+- Switch from `subtle-encoding` to `base16ct` ([#443])
+- Bump `yubikey` dependency to v0.7 ([#444])
+
+[#438]: https://github.com/iqlusioninc/yubikey.rs/pull/438
+[#441]: https://github.com/iqlusioninc/yubikey.rs/pull/441
+[#442]: https://github.com/iqlusioninc/yubikey.rs/pull/442
+[#443]: https://github.com/iqlusioninc/yubikey.rs/pull/443
+[#444]: https://github.com/iqlusioninc/yubikey.rs/pull/444
+
+## 0.6.0 (2022-08-10)
+### Changed
+- 2021 edition upgrade; MSRV 1.57 ([#343])
+- Migrate from `gumdrop` to `clap` v3 ([#379])
+- Bump `yubikey` dependency to v0.6 ([#403])
+
+[#343]: https://github.com/iqlusioninc/yubikey.rs/pull/343
+[#379]: https://github.com/iqlusioninc/yubikey.rs/pull/379
+[#403]: https://github.com/iqlusioninc/yubikey.rs/pull/403
+
+## 0.5.0 (2021-11-21)
+### Changed
+- Bump `yubikey` dependency to v0.5 ([#327])
+
+[#327]: https://github.com/iqlusioninc/yubikey.rs/pull/327
+ 
+## 0.4.0 (2021-07-12)
+### Changed
+- Switch to renamed `yubikey` crate ([#283])
+- Bump MSRV to 1.51+ ([#283])
+
+[#283]: https://github.com/iqlusioninc/yubikey.rs/pull/283
+
+## 0.3.0 (2021-03-22)
+### Changed
+- Bump `yubikey-piv` dependency to v0.3 ([#240])
+
+[#240]: https://github.com/iqlusioninc/yubikey.rs/pull/240
+
 ## 0.2.0 (2021-01-30)
 ### Changed
 - Bump MSRV to 1.46+ ([#208])
- Bump `yubikey-piv` dependency to v0.2.0 ([#220])
+- Bump `yubikey-piv` dependency to v0.2 ([#220])

-[#208]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/208
-[#220]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/220
+[#208]: https://github.com/iqlusioninc/yubikey.rs/pull/208
+[#220]: https://github.com/iqlusioninc/yubikey.rs/pull/220

 ## 0.1.0 (2020-10-19)
 ### Added
 - `status` command ([#72], [#74])

 ### Changed
- Bump `yubikey-piv` to v0.1.0 ([#180])
+- Bump `yubikey-piv` to v0.1 ([#180])
 - Bump `x509-parser` to v0.8 ([#181])
 - Bump `sha2` to v0.9 ([#182])
 - Rename `list` command to `readers`; improve usage ([#71])

-[#182]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/182
-[#181]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/181
-[#180]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/180
-[#74]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/74
-[#72]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/72
-[#71]: https://github.com/iqlusioninc/yubikey-piv.rs/pull/71
+[#182]: https://github.com/iqlusioninc/yubikey.rs/pull/182
+[#181]: https://github.com/iqlusioninc/yubikey.rs/pull/181
+[#180]: https://github.com/iqlusioninc/yubikey.rs/pull/180
+[#74]: https://github.com/iqlusioninc/yubikey.rs/pull/74
+[#72]: https://github.com/iqlusioninc/yubikey.rs/pull/72
+[#71]: https://github.com/iqlusioninc/yubikey.rs/pull/71

 ## 0.0.1 (2019-12-02)
 - Initial release
@@ -1,25 +1,26 @@
 [package]
 name = "yubikey-cli"
-version = "0.2.0"
+version = "0.9.0-pre"
 description = """
 Command-line interface for performing encryption and signing using RSA/ECC keys
 stored on YubiKey devices.
 """
 authors = ["Tony Arcieri <tony@iqlusion.io>"]
-edition    = "2018"
 license = "BSD-2-Clause"
-repository = "https://github.com/iqlusioninc/yubikey-piv.rs"
+repository = "https://github.com/iqlusioninc/yubikey.rs"
 readme = "README.md"
 categories = ["command-line-utilities", "cryptography", "hardware-support"]
 keywords = ["ecdsa", "rsa", "piv", "pcsc", "yubikey"]
+edition = "2021"
+rust-version = "1.85"

 [dependencies]
-gumdrop = "0.8"
-env_logger = "0.8"
-lazy_static = "1"
+clap = { version = "4", features = ["derive"] }
+env_logger = "0.11"
+hex = { package = "base16ct", version = "0.2", features = ["alloc"] }
 log = "0.4"
-sha2 = "0.9"
-subtle-encoding = "0.5"
+once_cell = "1"
+sha2.workspace = true
 termcolor = "1"
-x509-parser = "0.9"
-yubikey-piv = { version = "0.2", path = ".." }
+x509-cert.workspace = true
+yubikey = { version = "=0.9.0-pre.0", path = ".." }
@@ -1,4 +1,4 @@
-<img src="https://raw.githubusercontent.com/iqlusioninc/yubikey-piv.rs/main/img/logo.png" width="150" height="110">
+<img src="https://raw.githubusercontent.com/iqlusioninc/yubikey.rs/main/img/logo.png" width="150" height="110">

 # yubikey-cli.rs

@@ -18,15 +18,14 @@ utility with general-purpose public-key encryption and signing support.

 ## Minimum Supported Rust Version

- Rust **1.39+**
+Rust **1.60** or newer.

 ## Supported YubiKeys

 - [YubiKey 4] series
 - [YubiKey 5] series

-NOTE: Nano and USB-C variants of the above are also supported.
-      Pre-YK4 [YubiKey NEO] series is **NOT** supported (see [#18]).
+NOTE: Nano and USB-C variants of the above are also supported. NEO series is NOT supported.

 ## Security Warning

@@ -35,10 +34,6 @@ an experimental stage and may still contain high-severity issues.

 USE AT YOUR OWN RISK!

-## Status
-
-WIP. Check back later.
-
 ## Code of Conduct

 We abide by the [Contributor Covenant][cc-md] and ask that you do as well.
@@ -47,7 +42,7 @@ For more information, please see [CODE_OF_CONDUCT.md][cc-md].

 ## License

-Copyright (c) 2014-2019 Yubico AB, Tony Arcieri
+Copyright (c) 2014-2023 Yubico AB, Tony Arcieri
 All rights reserved.

 Redistribution and use in source and binary forms, with or without
@@ -88,12 +83,12 @@ or conditions.
 [docs-image]: https://docs.rs/yubikey-cli/badge.svg
 [docs-link]: https://docs.rs/yubikey-cli/
 [license-image]: https://img.shields.io/badge/license-BSD-blue.svg
-[rustc-image]: https://img.shields.io/badge/rustc-1.39+-blue.svg
+[rustc-image]: https://img.shields.io/badge/rustc-1.85+-blue.svg
 [maintenance-image]: https://img.shields.io/badge/maintenance-experimental-blue.svg
 [safety-image]: https://img.shields.io/badge/unsafe-forbidden-success.svg
 [safety-link]: https://github.com/rust-secure-code/safety-dance/
-[build-image]: https://github.com/iqlusioninc/yubikey-piv.rs/workflows/CI/badge.svg?branch=main&event=push
-[build-link]: https://github.com/iqlusioninc/yubikey-piv.rs/actions
+[build-image]: https://github.com/iqlusioninc/yubikey.rs/workflows/CI/badge.svg?branch=main&event=push
+[build-link]: https://github.com/iqlusioninc/yubikey.rs/actions
 [gitter-image]: https://badges.gitter.im/badge.svg
 [gitter-link]: https://gitter.im/iqlusioninc/community

@@ -102,7 +97,6 @@ or conditions.
 [PIV]: https://piv.idmanagement.gov/
 [yk-guide]: https://developers.yubico.com/PIV/Introduction/YubiKey_and_PIV.html
 [Yubico]: https://www.yubico.com/
-[YubiKey NEO]: https://support.yubico.com/support/solutions/articles/15000006494-yubikey-neo
 [YubiKey 4]: https://support.yubico.com/support/solutions/articles/15000006486-yubikey-4
 [YubiKey 5]: https://www.yubico.com/products/yubikey-5-overview/
 [yubico-piv-tool]: https://github.com/Yubico/yubico-piv-tool/
@@ -8,9 +8,9 @@
    unused_qualifications
 )]

-use gumdrop::Options;
+use clap::Parser;
 use yubikey_cli::commands::YubiKeyCli;

 fn main() {
-    YubiKeyCli::parse_args_default_or_exit().run();
+    YubiKeyCli::parse().run()
 }
@@ -4,62 +4,25 @@ pub mod readers;
 pub mod status;

 use self::{readers::ReadersCmd, status::StatusCmd};
-use crate::terminal::{self, STDOUT};
-use gumdrop::Options;
-use std::{
-    env,
-    io::{self, Write},
-    process::exit,
-};
-use termcolor::{ColorChoice, ColorSpec, WriteColor};
-use yubikey_piv::{Serial, YubiKey};
+use crate::terminal;
+use clap::Parser;
+use std::{env, process::exit};
+use termcolor::ColorChoice;
+use yubikey::{Serial, YubiKey};

 /// The `yubikey` CLI utility
-#[derive(Debug, Options)]
+#[derive(Debug, Parser)]
 pub struct YubiKeyCli {
-    /// Obtain help about the current command
-    #[options(short = "h", help = "print help message")]
-    pub help: bool,
-
-    /// Specify the serial number of the YubiKey to connect to
-    #[options(
-        short = "s",
-        long = "serial",
-        help = "serial number of the YubiKey to connect to"
-    )]
+    /// Serial number of the YubiKey to connect to
+    #[clap(short = 's', long = "serial")]
    pub serial: Option<Serial>,

    /// Subcommand to execute.
-    #[options(command)]
-    pub command: Option<Commands>,
+    #[clap(subcommand)]
+    pub command: Commands,
 }

 impl YubiKeyCli {
-    /// Print usage information
-    pub fn print_usage() -> Result<(), io::Error> {
-        let mut stdout = STDOUT.lock();
-        stdout.reset()?;
-
-        let mut bold = ColorSpec::new();
-        bold.set_bold(true);
-
-        stdout.set_color(&bold)?;
-        writeln!(
-            stdout,
-            "{} {}",
-            env!("CARGO_PKG_NAME"),
-            env!("CARGO_PKG_VERSION")
-        )?;
-        stdout.reset()?;
-
-        writeln!(stdout, "{}", env!("CARGO_PKG_AUTHORS"))?;
-        writeln!(stdout, "{}", env!("CARGO_PKG_DESCRIPTION").trim())?;
-        writeln!(stdout)?;
-        writeln!(stdout, "{}", Commands::usage())?;
-
-        Ok(())
-    }
-
    /// Run the underlying command type or print usage info and exit
    pub fn run(&self) {
        // TODO(tarcieri): make this more configurable
@@ -70,10 +33,7 @@ impl YubiKeyCli {
            env_logger::builder().format_timestamp(None).init();
        }

-        match &self.command {
-            Some(cmd) => cmd.run(self.yubikey_init()),
-            None => Self::print_usage().unwrap(),
-        }
+        self.command.run(self.yubikey_init())
    }

    /// Initialize the YubiKey client driver
@@ -92,22 +52,18 @@ impl YubiKeyCli {
 }

 /// Subcommands of this application
-#[derive(Debug, Options)]
+#[derive(Debug, Parser)]
 pub enum Commands {
-    /// `help` subcommand
-    #[options(help = "show help for a command")]
-    Help(HelpOpts),
-
    /// `version` subcommand
-    #[options(help = "display version information")]
+    #[clap(about = "display version information")]
    Version(VersionOpts),

    /// `readers` subcommand
-    #[options(help = "list detected readers")]
+    #[clap(about = "list detected readers")]
    Readers(ReadersCmd),

    /// `status` subcommand
-    #[options(help = "show yubikey status")]
+    #[clap(about = "show yubikey status")]
    Status(StatusCmd),
 }

@@ -115,7 +71,6 @@ impl Commands {
    /// Run the given command
    pub fn run(&self, yubikey: YubiKey) {
        match self {
-            Commands::Help(help) => help.run(),
            Commands::Version(version) => version.run(),
            Commands::Readers(list) => list.run(),
            Commands::Status(status) => status.run(yubikey),
@@ -123,28 +78,8 @@ impl Commands {
    }
 }

-/// Help options
-#[derive(Debug, Options)]
-pub struct HelpOpts {
-    #[options(free, help = "subcommand to get help for")]
-    free: Vec<String>,
-}
-
-impl HelpOpts {
-    fn run(&self) {
-        if let Some(command) = self.free.first() {
-            if let Some(usage) = Commands::command_usage(command) {
-                println!("{}", usage);
-                exit(1);
-            }
-        }
-
-        println!("{}", Commands::usage());
-    }
-}
-
 /// Version options
-#[derive(Debug, Options)]
+#[derive(Debug, Parser)]
 pub struct VersionOpts {}

 impl VersionOpts {
@@ -1,22 +1,22 @@
 //! List detected readers

 use crate::terminal::STDOUT;
-use gumdrop::Options;
+use clap::Parser;
 use std::{
    io::{self, Write},
    process::exit,
 };
 use termcolor::{ColorSpec, StandardStreamLock, WriteColor};
-use yubikey_piv::{Readers, Serial};
+use yubikey::{Context, Serial};

 /// The `readers` subcommand
-#[derive(Debug, Options)]
+#[derive(Debug, Parser)]
 pub struct ReadersCmd {}

 impl ReadersCmd {
    /// Run the `readers` subcommand
    pub fn run(&self) {
-        let mut readers = Readers::open().unwrap_or_else(|e| {
+        let mut readers = Context::open().unwrap_or_else(|e| {
            status_err!("couldn't open PC/SC context: {}", e);
            exit(1);
        });
@@ -53,7 +53,7 @@ impl ReadersCmd {
        index: usize,
        name: &str,
        serial: Serial,
-    ) -> Result<(), io::Error> {
+    ) -> io::Result<()> {
        stream.set_color(ColorSpec::new().set_bold(true))?;
        write!(stream, "{:>3}:", index)?;
        stream.reset()?;
@@ -1,18 +1,16 @@
 //! Print device status

-use crate::terminal::STDOUT;
-use gumdrop::Options;
+use crate::terminal::{print_cert_info, STDOUT};
+use clap::Parser;
 use std::io::{self, Write};
 use termcolor::{ColorSpec, StandardStreamLock, WriteColor};
-use yubikey_piv::{key::*, YubiKey};
-
-use crate::print_cert_info;
+use yubikey::{piv::*, YubiKey};

 // String to use for `None`
 const NONE_STR: &str = "<none>";

 /// The `status` subcommand
-#[derive(Debug, Options)]
+#[derive(Debug, Parser)]
 pub struct StatusCmd {}

 impl StatusCmd {
@@ -51,7 +49,7 @@ impl StatusCmd {
        stream: &mut StandardStreamLock<'_>,
        name: &str,
        value: impl ToString,
-    ) -> Result<(), io::Error> {
+    ) -> io::Result<()> {
        stream.set_color(ColorSpec::new().set_bold(true))?;
        write!(stream, "{:>12}:", name)?;
        stream.reset()?;
@@ -1,92 +1,13 @@
-//! `yubikey` command-line utility
+//! `yubikey` command-line utility.
+//!
+//! The goal of this tool is to provide functionality similar to `yubico-piv-tool`
+//! but implemented in pure Rust.
+//!
+//! It also serves as a demonstration/example of how to use the `yubikey` crate.

 #![forbid(unsafe_code)]
-#![warn(
-    missing_docs,
-    rust_2018_idioms,
-    unused_lifetimes,
-    unused_qualifications
-)]
+#![warn(missing_docs, rust_2018_idioms, unused_qualifications)]

 #[macro_use]
 pub mod terminal;
-
 pub mod commands;
-
-use log::debug;
-use sha2::{Digest, Sha256};
-use std::io::{self, Write};
-use std::str;
-use subtle_encoding::hex;
-use termcolor::{ColorSpec, StandardStreamLock, WriteColor};
-use x509_parser::parse_x509_certificate;
-use yubikey_piv::{certificate::Certificate, key::*, YubiKey};
-
-///Write information about certificate found in slot a la yubico-piv-tool output.
-pub fn print_cert_info(
-    yubikey: &mut YubiKey,
-    slot: SlotId,
-    stream: &mut StandardStreamLock<'_>,
-) -> Result<(), io::Error> {
-    let cert = match Certificate::read(yubikey, slot) {
-        Ok(c) => c,
-        Err(e) => {
-            debug!("error reading certificate in slot {:?}: {}", slot, e);
-            return Ok(());
-        }
-    };
-    let buf = cert.into_buffer();
-
-    if !buf.is_empty() {
-        let fingerprint = Sha256::digest(&buf);
-        let slot_id: u8 = slot.into();
-        print_cert_attr(stream, "Slot", format!("{:x}", slot_id))?;
-        match parse_x509_certificate(&buf) {
-            Ok((_rem, cert)) => {
-                print_cert_attr(
-                    stream,
-                    "Algorithm",
-                    cert.tbs_certificate.subject_pki.algorithm.algorithm,
-                )?;
-
-                print_cert_attr(stream, "Subject", cert.tbs_certificate.subject)?;
-                print_cert_attr(stream, "Issuer", cert.tbs_certificate.issuer)?;
-                print_cert_attr(
-                    stream,
-                    "Fingerprint",
-                    str::from_utf8(hex::encode(fingerprint).as_slice()).unwrap(),
-                )?;
-                print_cert_attr(
-                    stream,
-                    "Not Before",
-                    cert.tbs_certificate.validity.not_before.to_rfc2822(),
-                )?;
-                print_cert_attr(
-                    stream,
-                    "Not After",
-                    cert.tbs_certificate.validity.not_after.to_rfc2822(),
-                )?;
-            }
-            _ => {
-                println!("Failed to parse certificate");
-                return Ok(());
-            }
-        };
-    }
-
-    Ok(())
-}
-
-/// Print a status attribute
-fn print_cert_attr(
-    stream: &mut StandardStreamLock<'_>,
-    name: &str,
-    value: impl ToString,
-) -> Result<(), io::Error> {
-    stream.set_color(ColorSpec::new().set_bold(true))?;
-    write!(stream, "{:>12}:", name)?;
-    stream.reset()?;
-    writeln!(stream, " {}", value.to_string())?;
-    stream.flush()?;
-    Ok(())
-}
@@ -1,9 +1,16 @@
 //! Status messages

-use lazy_static::lazy_static;
-use std::io::{self, Write};
-use std::sync::Mutex;
-use termcolor::{Color, ColorChoice, ColorSpec, StandardStream, WriteColor};
+use log::debug;
+use once_cell::sync::Lazy;
+use sha2::{Digest, Sha256};
+use std::{
+    io::{self, Write},
+    str,
+    sync::Mutex,
+};
+use termcolor::{Color, ColorChoice, ColorSpec, StandardStream, StandardStreamLock, WriteColor};
+use x509_cert::der::Encode;
+use yubikey::{certificate::Certificate, piv::*, YubiKey};

 /// Print a success status message (in green if colors are enabled)
 #[macro_export]
@@ -51,16 +58,14 @@ macro_rules! status_err {
    };
 }

-lazy_static! {
 /// Color configuration
-    static ref COLOR_CHOICE: Mutex<Option<ColorChoice>> = Mutex::new(None);
+static COLOR_CHOICE: Lazy<Mutex<Option<ColorChoice>>> = Lazy::new(|| Mutex::new(None));

 /// Standard output
-    pub static ref STDOUT: StandardStream = StandardStream::stdout(get_color_choice());
+pub static STDOUT: Lazy<StandardStream> = Lazy::new(|| StandardStream::stdout(get_color_choice()));

 /// Standard error
-    pub static ref STDERR: StandardStream = StandardStream::stderr(get_color_choice());
-}
+pub static STDERR: Lazy<StandardStream> = Lazy::new(|| StandardStream::stderr(get_color_choice()));

 /// Obtain the color configuration.
 ///
@@ -132,18 +137,16 @@ impl Status {

    /// Print the given message to stdout
    pub fn print_stdout(self, msg: impl AsRef<str>) {
-        self.print(&*STDOUT, msg)
-            .expect("error printing to stdout!")
+        self.print(&STDOUT, msg).expect("error printing to stdout!")
    }

    /// Print the given message to stderr
    pub fn print_stderr(self, msg: impl AsRef<str>) {
-        self.print(&*STDERR, msg)
-            .expect("error printing to stderr!")
+        self.print(&STDERR, msg).expect("error printing to stderr!")
    }

    /// Print the given message
-    fn print(self, stream: &StandardStream, msg: impl AsRef<str>) -> Result<(), io::Error> {
+    fn print(self, stream: &StandardStream, msg: impl AsRef<str>) -> io::Result<()> {
        let mut s = stream.lock();
        s.reset()?;
        s.set_color(ColorSpec::new().set_fg(self.color).set_bold(self.bold))?;
@@ -163,3 +166,65 @@ impl Status {
        Ok(())
    }
 }
+
+/// Write information about certificate found in slot a la yubico-piv-tool output.
+pub fn print_cert_info(
+    yubikey: &mut YubiKey,
+    slot: SlotId,
+    stream: &mut StandardStreamLock<'_>,
+) -> io::Result<()> {
+    let cert = match Certificate::read(yubikey, slot) {
+        Ok(c) => c,
+        Err(e) => {
+            debug!("error reading certificate in slot {:?}: {}", slot, e);
+            return Ok(());
+        }
+    };
+    let cert = &cert.cert;
+
+    let fingerprint = Sha256::digest(cert.to_der().unwrap());
+    let slot_id: u8 = slot.into();
+    print_cert_attr(stream, "Slot", format!("{:x}", slot_id))?;
+    print_cert_attr(
+        stream,
+        "Algorithm",
+        cert.tbs_certificate()
+            .subject_public_key_info()
+            .algorithm
+            .oid,
+    )?;
+
+    print_cert_attr(stream, "Subject", cert.tbs_certificate().subject())?;
+    print_cert_attr(stream, "Issuer", cert.tbs_certificate().issuer())?;
+    print_cert_attr(
+        stream,
+        "Fingerprint",
+        hex::upper::encode_string(&fingerprint),
+    )?;
+    print_cert_attr(
+        stream,
+        "Not Before",
+        cert.tbs_certificate().validity().not_before,
+    )?;
+    print_cert_attr(
+        stream,
+        "Not After",
+        cert.tbs_certificate().validity().not_after,
+    )?;
+
+    Ok(())
+}
+
+/// Print a status attribute
+fn print_cert_attr(
+    stream: &mut StandardStreamLock<'_>,
+    name: &str,
+    value: impl ToString,
+) -> io::Result<()> {
+    stream.set_color(ColorSpec::new().set_bold(true))?;
+    write!(stream, "{:>12}:", name)?;
+    stream.reset()?;
+    writeln!(stream, " {}", value.to_string())?;
+    stream.flush()?;
+    Ok(())
+}
@@ -0,0 +1,10 @@
+#![cfg(feature = "untested")]
+
+use yubikey::{mgm, YubiKey};
+
+fn main() {
+    let yubikey = YubiKey::open().unwrap();
+
+    let mut mgmt = mgm::Manager::new(yubikey).unwrap();
+    mgmt.enable_yubihsm().unwrap();
+}
@@ -30,7 +30,7 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

-use crate::{error::Error, transaction::Transaction, Buffer};
+use crate::{transaction::Transaction, Buffer, Result};
 use log::trace;
 use zeroize::{Zeroize, Zeroizing};

@@ -41,7 +41,7 @@ const APDU_DATA_MAX: usize = 0xFF;
 ///
 /// These messages are packets used to communicate with the YubiKey.
 #[derive(Clone, Debug, Eq, PartialEq)]
-pub(crate) struct APDU {
+pub(crate) struct Apdu {
    /// Instruction class: indicates the type of command (e.g. inter-industry or proprietary)
    cla: u8,

@@ -58,7 +58,7 @@ pub(crate) struct APDU {
    data: Vec<u8>,
 }

-impl APDU {
+impl Apdu {
    /// Create a new APDU with the given instruction code
    pub fn new(ins: impl Into<Ins>) -> Self {
        Self {
@@ -82,6 +82,12 @@ impl APDU {
        self
    }

+    /// Set this APDU's second parameter only
+    pub(crate) fn p2(&mut self, value: u8) -> &mut Self {
+        self.p2 = value;
+        self
+    }
+
    /// Set both parameters for this APDU
    pub fn params(&mut self, p1: u8, p2: u8) -> &mut Self {
        self.p1 = p1;
@@ -109,7 +115,7 @@ impl APDU {
    }

    /// Transmit this APDU using the given card transaction
-    pub fn transmit(&self, txn: &Transaction<'_>, recv_len: usize) -> Result<Response, Error> {
+    pub fn transmit(&self, txn: &Transaction<'_>, recv_len: usize) -> Result<Response> {
        trace!(">>> {:?}", self);
        let response = Response::from(txn.transmit(&self.to_bytes(), recv_len)?);
        trace!("<<< {:?}", &response);
@@ -129,13 +135,13 @@ impl APDU {
    }
 }

-impl Drop for APDU {
+impl Drop for Apdu {
    fn drop(&mut self) {
        self.zeroize();
    }
 }

-impl Zeroize for APDU {
+impl Zeroize for Apdu {
    fn zeroize(&mut self) {
        // Only `data` may contain secrets
        self.data.zeroize();
@@ -195,6 +201,18 @@ pub enum Ins {
    /// Get device serial
    GetSerial,

+    /// Get slot metadata
+    GetMetadata,
+
+    /// Management // Read Config
+    ReadConfig,
+
+    /// Management // Write Config
+    WriteConfig,
+
+    /// Management // DeviceReset
+    DeviceReset,
+
    /// Other/unrecognized instruction codes
    Other(u8),
 }
@@ -219,6 +237,13 @@ impl Ins {
            Ins::SetPinRetries => 0xfa,
            Ins::Attest => 0xf9,
            Ins::GetSerial => 0xf8,
+            Ins::GetMetadata => 0xf7,
+
+            // Management
+            Ins::ReadConfig => 0x1d,
+            Ins::WriteConfig => 0x1c,
+            Ins::DeviceReset => 0x1f,
+
            Ins::Other(code) => code,
        }
    }
@@ -227,6 +252,11 @@ impl Ins {
 impl From<u8> for Ins {
    fn from(code: u8) -> Self {
        match code {
+            // Management
+            0x1d => Ins::ReadConfig,
+            0x1c => Ins::WriteConfig,
+            0x1f => Ins::DeviceReset,
+
            0x20 => Ins::Verify,
            0x24 => Ins::ChangeReference,
            0x2c => Ins::ResetRetry,
@@ -243,6 +273,7 @@ impl From<u8> for Ins {
            0xfa => Ins::SetPinRetries,
            0xf9 => Ins::Attest,
            0xf8 => Ins::GetSerial,
+            0xf7 => Ins::GetMetadata,
            code => Ins::Other(code),
        }
    }
@@ -313,7 +344,7 @@ impl From<Vec<u8>> for Response {
        }

        let sw = StatusWords::from(
-            (bytes[bytes.len() - 2] as u16) << 8 | (bytes[bytes.len() - 1] as u16),
+            ((bytes[bytes.len() - 2] as u16) << 8) | (bytes[bytes.len() - 1] as u16),
        );

        let len = bytes.len() - 2;
@@ -348,6 +379,12 @@ pub(crate) enum StatusWords {
    /// Successful execution
    Success,

+    /// The requested data was too large for the response, and there is data remaining.
+    BytesRemaining {
+        /// The number of bytes remaining, as indicated in the response.
+        len: u8,
+    },
+
    /// https://github.com/Yubico/yubikey-manager/blob/1f22620b623c6b345dd9f9193ec765a542dddc80/ykman/driver_ccid.py#L53
    NoInputDataError,

@@ -384,6 +421,9 @@ pub(crate) enum StatusWords {
    /// Not enough memory
    NoSpaceError,

+    /// Referenced data or reference data not found
+    ReferenceDataNotFoundError,
+
    //
    // Custom Yubico Status Word extensions
    //
@@ -405,8 +445,9 @@ impl StatusWords {
    pub fn code(self) -> u16 {
        match self {
            StatusWords::None => 0,
+            StatusWords::BytesRemaining { len } => 0x6100 | len as u16,
            StatusWords::NoInputDataError => 0x6285,
-            StatusWords::VerifyFailError { tries } => 0x63c0 & tries as u16,
+            StatusWords::VerifyFailError { tries } => 0x63c0 | tries as u16,
            StatusWords::WrongLengthError => 0x6700,
            StatusWords::SecurityStatusError => 0x6982,
            StatusWords::AuthBlockedError => 0x6983,
@@ -416,6 +457,7 @@ impl StatusWords {
            StatusWords::IncorrectParamError => 0x6a80,
            StatusWords::NotFoundError => 0x6a82,
            StatusWords::NoSpaceError => 0x6a84,
+            StatusWords::ReferenceDataNotFoundError => 0x6a88,
            StatusWords::IncorrectSlotError => 0x6b00,
            StatusWords::NotSupportedError => 0x6d00,
            StatusWords::CommandAbortedError => 0x6f00,
@@ -434,6 +476,9 @@ impl From<u16> for StatusWords {
    fn from(sw: u16) -> Self {
        match sw {
            0x0000 => StatusWords::None,
+            sw if sw & 0xff00 == 0x6100 => Self::BytesRemaining {
+                len: (sw & 0x00ff) as u8,
+            },
            0x6285 => StatusWords::NoInputDataError,
            sw if sw & 0xfff0 == 0x63c0 => StatusWords::VerifyFailError {
                tries: (sw & 0x000f) as u8,
@@ -447,6 +492,7 @@ impl From<u16> for StatusWords {
            0x6a80 => StatusWords::IncorrectParamError,
            0x6a82 => StatusWords::NotFoundError,
            0x6a84 => StatusWords::NoSpaceError,
+            0x6a88 => StatusWords::ReferenceDataNotFoundError,
            0x6b00 => StatusWords::IncorrectSlotError,
            0x6d00 => StatusWords::NotSupportedError,
            0x6f00 => StatusWords::CommandAbortedError,
@@ -461,3 +507,40 @@ impl From<StatusWords> for u16 {
        sw.code()
    }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::StatusWords;
+
+    #[test]
+    fn status_words_round_trip() {
+        let round_trip = |sw: StatusWords| {
+            assert_eq!(StatusWords::from(sw.code()), sw);
+        };
+
+        round_trip(StatusWords::None);
+        round_trip(StatusWords::BytesRemaining { len: 1 });
+        round_trip(StatusWords::BytesRemaining { len: 10 });
+        round_trip(StatusWords::BytesRemaining { len: 0xFF });
+        round_trip(StatusWords::Success);
+        round_trip(StatusWords::NoInputDataError);
+        round_trip(StatusWords::VerifyFailError { tries: 0x0F });
+        round_trip(StatusWords::VerifyFailError { tries: 3 });
+        round_trip(StatusWords::VerifyFailError { tries: 2 });
+        round_trip(StatusWords::VerifyFailError { tries: 1 });
+        round_trip(StatusWords::VerifyFailError { tries: 0 });
+        round_trip(StatusWords::WrongLengthError);
+        round_trip(StatusWords::SecurityStatusError);
+        round_trip(StatusWords::AuthBlockedError);
+        round_trip(StatusWords::DataInvalidError);
+        round_trip(StatusWords::ConditionsNotSatisfiedError);
+        round_trip(StatusWords::CommandNotAllowedError);
+        round_trip(StatusWords::IncorrectParamError);
+        round_trip(StatusWords::NotFoundError);
+        round_trip(StatusWords::NoSpaceError);
+        round_trip(StatusWords::IncorrectSlotError);
+        round_trip(StatusWords::NotSupportedError);
+        round_trip(StatusWords::CommandAbortedError);
+        round_trip(StatusWords::Other(0x1337));
+    }
+}
@@ -30,16 +30,10 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

-use crate::{error::Error, yubikey::YubiKey};
-use getrandom::getrandom;
+use crate::{Result, YubiKey};
+use cipher::common::Generate;
+use rand_core::CryptoRng;
 use std::fmt::{self, Debug, Display};
-use subtle_encoding::hex;
-
-/// CCCID size
-pub const CCCID_SIZE: usize = 14;
-
-/// CCC size
-pub const CCC_SIZE: usize = 51;

 /// CCCID offset
 const CCC_ID_OFFS: usize = 9;
@@ -55,6 +49,7 @@ const OBJ_CAPABILITY: u32 = 0x005f_c107;
 ///  - 0xff == Manufacturer ID (dummy)
 ///  - 0x02 == Card type (javaCard)
 ///  - next 14 bytes: card ID
+#[allow(dead_code)]
 const CCC_TMPL: &[u8] = &[
    0xf0, 0x15, 0xa0, 0x00, 0x00, 0x01, 0x16, 0xff, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xf1, 0x01, 0x21, 0xf2, 0x01, 0x21, 0xf3, 0x00, 0xf4,
@@ -62,48 +57,50 @@ const CCC_TMPL: &[u8] = &[
    0x00, 0xfe, 0x00,
 ];

-/// Cardholder Capability Container (CCC) Identifier Card ID
-#[derive(Copy, Clone, Debug, Eq, PartialEq)]
-pub struct CardId(pub [u8; CCCID_SIZE]);
+/// Cardholder Capability Container (CCC) Identifier Card ID.
+#[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord)]
+pub struct CardId(pub [u8; Self::BYTE_SIZE]);

 impl CardId {
+    /// CCCID size in bytes
+    pub const BYTE_SIZE: usize = 14;
+
    /// Generate a random CCC Card ID
-    pub fn generate() -> Result<Self, Error> {
-        let mut id = [0u8; CCCID_SIZE];
-        getrandom(&mut id).map_err(|_| Error::RandomnessError)?;
-        Ok(Self(id))
+    pub fn generate() -> Self {
+        Self(Generate::generate())
+    }
+
+    /// Generate a random CCC Card ID from an [`Rng`]
+    pub fn generate_from_rng<R: CryptoRng + ?Sized>(rng: &mut R) -> Self {
+        Self(Generate::generate_from_rng(rng))
    }
 }

-/// Cardholder Capability Container (CCC) Identifier
-#[derive(Copy, Clone)]
-pub struct CCC(pub [u8; CCC_SIZE]);
+/// Cardholder Capability Container (CCC) Identifier.
+#[derive(Copy, Clone, Debug, Eq, PartialEq)]
+pub struct CccId(pub [u8; Self::BYTE_SIZE]);
+
+impl CccId {
+    /// CCC size in bytes
+    pub const BYTE_SIZE: usize = 51;

-impl CCC {
    /// Return CardId component of CCC
-    pub fn cccid(&self) -> Result<CardId, Error> {
-        let mut cccid = [0u8; CCCID_SIZE];
-        cccid.copy_from_slice(&self.0[CCC_ID_OFFS..(CCC_ID_OFFS + CCCID_SIZE)]);
+    pub fn card_id(&self) -> Result<CardId> {
+        let mut cccid = [0u8; CardId::BYTE_SIZE];
+        cccid.copy_from_slice(&self.0[CCC_ID_OFFS..(CCC_ID_OFFS + CardId::BYTE_SIZE)]);
        Ok(CardId(cccid))
    }

    /// Get Cardholder Capability Container (CCC) ID
-    pub fn get(yubikey: &mut YubiKey) -> Result<Self, Error> {
+    pub fn get(yubikey: &mut YubiKey) -> Result<Self> {
        let txn = yubikey.begin_transaction()?;
        let response = txn.fetch_object(OBJ_CAPABILITY)?;
-
-        if response.len() != CCC_TMPL.len() {
-            return Err(Error::GenericError);
+        Ok(response[..Self::BYTE_SIZE].try_into().map(Self)?)
    }

-        let mut ccc = [0u8; CCC_SIZE];
-        ccc.copy_from_slice(&response[0..CCC_SIZE]);
-        Ok(Self(ccc))
-    }
-
-    /// Get Cardholder Capability Container (CCC) ID
+    /// Set Cardholder Capability Container (CCC) ID
    #[cfg(feature = "untested")]
-    pub fn set(&self, yubikey: &mut YubiKey) -> Result<(), Error> {
+    pub fn set(&self, yubikey: &mut YubiKey) -> Result<()> {
        let mut buf = CCC_TMPL.to_vec();
        buf[0..self.0.len()].copy_from_slice(&self.0);

@@ -112,18 +109,14 @@ impl CCC {
    }
 }

-impl Debug for CCC {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "CCC({:?})", &self.0[..])
+impl AsRef<[u8]> for CccId {
+    fn as_ref(&self) -> &[u8] {
+        &self.0
    }
 }

-impl Display for CCC {
+impl Display for CccId {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(
-            f,
-            "{}",
-            String::from_utf8(hex::encode(&self.0[..])).unwrap()
-        )
+        f.write_str(&hex::upper::encode_string(self.as_ref()))
    }
 }
@@ -1,4 +1,4 @@
-//! YubiKey Certificates
+//! X.509 certificate support.

 // Adapted from yubico-piv-tool:
 // <https://github.com/Yubico/yubico-piv-tool/>
@@ -31,76 +31,31 @@
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 use crate::{
-    error::Error,
-    key::{sign_data, AlgorithmId, SlotId},
+    consts::CB_OBJ_MAX,
+    error::{Error, Result},
+    piv::SlotId,
    serialization::*,
    transaction::Transaction,
    yubikey::YubiKey,
    Buffer,
 };
-use chrono::{DateTime, Utc};
-use elliptic_curve::sec1::EncodedPoint as EcPublicKey;
 use log::error;
-use num_bigint::BigUint;
-use p256::NistP256;
-use p384::NistP384;
-use rsa::{PublicKeyParts, RSAPublicKey};
-use sha2::{Digest, Sha256};
-use std::convert::TryFrom;
-use std::fmt;
-use std::ops::DerefMut;
-use x509::{der::Oid, RelativeDistinguishedName};
-use x509_parser::{parse_x509_certificate, x509::SubjectPublicKeyInfo};
+use x509_cert::{
+    builder::{profile::BuilderProfile, Builder, CertificateBuilder},
+    der::{referenced::OwnedToRef, Decode, Encode},
+    name::Name,
+    serial_number::SerialNumber,
+    spki::{SubjectPublicKeyInfoOwned, SubjectPublicKeyInfoRef},
+    time::Validity,
+};
 use zeroize::Zeroizing;

-use crate::CB_OBJ_MAX;
-
-// TODO: Make these der_parser::oid::Oid constants when it has const fn support.
-const OID_RSA_ENCRYPTION: &str = "1.2.840.113549.1.1.1";
-const OID_EC_PUBLIC_KEY: &str = "1.2.840.10045.2.1";
-const OID_NIST_P256: &str = "1.2.840.10045.3.1.7";
-const OID_NIST_P384: &str = "1.3.132.0.34";
-
 const TAG_CERT: u8 = 0x70;
 const TAG_CERT_COMPRESS: u8 = 0x71;
 const TAG_CERT_LRC: u8 = 0xFE;

-/// A serial number for a [`Certificate`].
-#[derive(Clone, Debug)]
-pub struct Serial(BigUint);
-
-impl From<BigUint> for Serial {
-    fn from(num: BigUint) -> Serial {
-        Serial(num)
-    }
-}
-
-impl From<[u8; 20]> for Serial {
-    fn from(bytes: [u8; 20]) -> Serial {
-        Serial(BigUint::from_bytes_be(&bytes))
-    }
-}
-
-impl TryFrom<&[u8]> for Serial {
-    type Error = ();
-
-    fn try_from(bytes: &[u8]) -> Result<Serial, ()> {
-        if bytes.len() <= 20 {
-            Ok(Serial(BigUint::from_bytes_be(&bytes)))
-        } else {
-            Err(())
-        }
-    }
-}
-
-impl Serial {
-    fn to_bytes(&self) -> Vec<u8> {
-        self.0.to_bytes_be()
-    }
-}
-
 /// Information about how a [`Certificate`] is stored within a YubiKey.
-#[derive(Clone, Copy, Debug, PartialEq)]
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
 pub enum CertInfo {
    /// The certificate is uncompressed.
    Uncompressed,
@@ -112,7 +67,7 @@ pub enum CertInfo {
 impl TryFrom<u8> for CertInfo {
    type Error = Error;

-    fn try_from(value: u8) -> Result<Self, Self::Error> {
+    fn try_from(value: u8) -> Result<Self> {
        match value {
            0x00 => Ok(CertInfo::Uncompressed),
            0x01 => Ok(CertInfo::Gzip),
@@ -130,209 +85,11 @@ impl From<CertInfo> for u8 {
    }
 }

-impl x509::AlgorithmIdentifier for AlgorithmId {
-    type AlgorithmOid = &'static [u64];
-
-    fn algorithm(&self) -> Self::AlgorithmOid {
-        match self {
-            // RSA encryption
-            AlgorithmId::Rsa1024 | AlgorithmId::Rsa2048 => &[1, 2, 840, 113_549, 1, 1, 1],
-            // EC Public Key
-            AlgorithmId::EccP256 | AlgorithmId::EccP384 => &[1, 2, 840, 10045, 2, 1],
-        }
-    }
-
-    fn parameters<W: std::io::Write>(
-        &self,
-        w: cookie_factory::WriteContext<W>,
-    ) -> cookie_factory::GenResult<W> {
-        use x509::der::write::der_oid;
-
-        // From [RFC 5480](https://tools.ietf.org/html/rfc5480#section-2.1.1):
-        // ```text
-        // ECParameters ::= CHOICE {
-        //   namedCurve         OBJECT IDENTIFIER
-        //   -- implicitCurve   NULL
-        //   -- specifiedCurve  SpecifiedECDomain
-        // }
-        // ```
-        match self {
-            AlgorithmId::EccP256 => der_oid(&[1, 2, 840, 10045, 3, 1, 7][..])(w),
-            AlgorithmId::EccP384 => der_oid(&[1, 3, 132, 0, 34][..])(w),
-            _ => Ok(w),
-        }
-    }
-}
-
-/// Information about a public key within a [`Certificate`].
-#[derive(Clone, Eq, PartialEq)]
-pub enum PublicKeyInfo {
-    /// RSA keys
-    Rsa {
-        /// RSA algorithm
-        algorithm: AlgorithmId,
-
-        /// Public key
-        pubkey: RSAPublicKey,
-    },
-
-    /// EC P-256 keys
-    EcP256(EcPublicKey<NistP256>),
-
-    /// EC P-384 keys
-    EcP384(EcPublicKey<NistP384>),
-}
-
-impl fmt::Debug for PublicKeyInfo {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "PublicKeyInfo({:?})", self.algorithm())
-    }
-}
-
-impl PublicKeyInfo {
-    fn parse(subject_pki: &SubjectPublicKeyInfo<'_>) -> Result<Self, Error> {
-        match subject_pki.algorithm.algorithm.to_string().as_str() {
-            OID_RSA_ENCRYPTION => {
-                let pubkey = read_pki::rsa_pubkey(subject_pki.subject_public_key.data)?;
-
-                Ok(PublicKeyInfo::Rsa {
-                    algorithm: match pubkey.n().bits() {
-                        1024 => AlgorithmId::Rsa1024,
-                        2048 => AlgorithmId::Rsa2048,
-                        _ => return Err(Error::AlgorithmError),
-                    },
-                    pubkey,
-                })
-            }
-            OID_EC_PUBLIC_KEY => {
-                let key_bytes = &subject_pki.subject_public_key.data;
-                let algorithm_parameters = subject_pki
-                    .algorithm
-                    .parameters
-                    .as_ref()
-                    .ok_or(Error::InvalidObject)?;
-
-                match read_pki::ec_parameters(algorithm_parameters)? {
-                    AlgorithmId::EccP256 => EcPublicKey::from_bytes(key_bytes)
-                        .map(PublicKeyInfo::EcP256)
-                        .map_err(|_| Error::InvalidObject),
-                    AlgorithmId::EccP384 => EcPublicKey::from_bytes(key_bytes)
-                        .map(PublicKeyInfo::EcP384)
-                        .map_err(|_| Error::InvalidObject),
-                    _ => Err(Error::AlgorithmError),
-                }
-            }
-            _ => Err(Error::InvalidObject),
-        }
-    }
-
-    /// Returns the algorithm that this public key can be used with.
-    pub fn algorithm(&self) -> AlgorithmId {
-        match self {
-            PublicKeyInfo::Rsa { algorithm, .. } => *algorithm,
-            PublicKeyInfo::EcP256(_) => AlgorithmId::EccP256,
-            PublicKeyInfo::EcP384(_) => AlgorithmId::EccP384,
-        }
-    }
-}
-
-impl x509::SubjectPublicKeyInfo for PublicKeyInfo {
-    type AlgorithmId = AlgorithmId;
-    type SubjectPublicKey = Vec<u8>;
-
-    fn algorithm_id(&self) -> AlgorithmId {
-        self.algorithm()
-    }
-
-    fn public_key(&self) -> Vec<u8> {
-        match self {
-            PublicKeyInfo::Rsa { pubkey, .. } => {
-                cookie_factory::gen_simple(write_pki::rsa_pubkey(pubkey), vec![])
-                    .expect("can write to Vec")
-            }
-            PublicKeyInfo::EcP256(pubkey) => pubkey.as_bytes().to_vec(),
-            PublicKeyInfo::EcP384(pubkey) => pubkey.as_bytes().to_vec(),
-        }
-    }
-}
-
-/// Digest algorithms.
-///
-/// See RFC 4055 and RFC 8017.
-enum DigestId {
-    /// Secure Hash Algorithm 256 (SHA256)
-    Sha256,
-}
-
-impl x509::AlgorithmIdentifier for DigestId {
-    type AlgorithmOid = &'static [u64];
-
-    fn algorithm(&self) -> Self::AlgorithmOid {
-        match self {
-            // See https://tools.ietf.org/html/rfc4055#section-2.1
-            DigestId::Sha256 => &[2, 16, 840, 1, 101, 3, 4, 2, 1],
-        }
-    }
-
-    fn parameters<W: std::io::Write>(
-        &self,
-        w: cookie_factory::WriteContext<W>,
-    ) -> cookie_factory::GenResult<W> {
-        // Parameters are an explicit NULL
-        // See https://tools.ietf.org/html/rfc8017#appendix-A.2.4
-        x509::der::write::der_null()(w)
-    }
-}
-
-enum SignatureId {
-    /// Public-Key Cryptography Standards (PKCS) #1 version 1.5 signature algorithm with
-    /// Secure Hash Algorithm 256 (SHA256) and Rivest, Shamir and Adleman (RSA) encryption
-    ///
-    /// See RFC 4055 and RFC 8017.
-    Sha256WithRsaEncryption,
-
-    /// Elliptic Curve Digital Signature Algorithm (DSA) coupled with the Secure Hash
-    /// Algorithm 256 (SHA256) algorithm
-    ///
-    /// See RFC 5758.
-    EcdsaWithSha256,
-}
-
-impl x509::AlgorithmIdentifier for SignatureId {
-    type AlgorithmOid = &'static [u64];
-
-    fn algorithm(&self) -> Self::AlgorithmOid {
-        match self {
-            SignatureId::Sha256WithRsaEncryption => &[1, 2, 840, 113_549, 1, 1, 11],
-            SignatureId::EcdsaWithSha256 => &[1, 2, 840, 10045, 4, 3, 2],
-        }
-    }
-
-    fn parameters<W: std::io::Write>(
-        &self,
-        w: cookie_factory::WriteContext<W>,
-    ) -> cookie_factory::GenResult<W> {
-        // No parameters for any SignatureId
-        Ok(w)
-    }
-}
-
 /// Certificates
 #[derive(Clone, Debug)]
 pub struct Certificate {
-    serial: Serial,
-    issuer: String,
-    subject: String,
-    subject_pki: PublicKeyInfo,
-    data: Buffer,
-}
-
-impl<'a> TryFrom<&'a [u8]> for Certificate {
-    type Error = Error;
-
-    fn try_from(bytes: &'a [u8]) -> Result<Self, Error> {
-        Self::from_bytes(bytes.to_vec())
-    }
+    /// Inner certificate
+    pub cert: x509_cert::Certificate,
 }

 impl Certificate {
@@ -341,119 +98,37 @@ impl Certificate {
    ///
    /// `extensions` is optional; if empty, no extensions will be included. Due to the
    /// need for an `O: Oid` type parameter, users who do not have any extensions should
-    /// use the workaround `let extensions: &[x509::Extension<'_, &[u64]>] = &[];`.
-    pub fn generate_self_signed<O: Oid>(
+    /// use the workaround `let extensions: &[x509_cert::Extension<'_, &[u64]>] = &[];`.
+    pub fn generate_self_signed<F, KT: yubikey_signer::KeyType>(
        yubikey: &mut YubiKey,
        key: SlotId,
-        serial: impl Into<Serial>,
-        not_after: Option<DateTime<Utc>>,
-        subject: &[RelativeDistinguishedName<'_>],
-        subject_pki: PublicKeyInfo,
-        extensions: &[x509::Extension<'_, O>],
-    ) -> Result<Self, Error> {
-        let serial = serial.into();
+        serial: SerialNumber,
+        validity: Validity,
+        subject: Name,
+        subject_pki: SubjectPublicKeyInfoOwned,
+        extensions: F,
+    ) -> Result<Self>
+    where
+        F: FnOnce(&mut CertificateBuilder<SelfSigned>) -> der::Result<()>,
+    {
+        let signer =
+            yubikey_signer::Signer::<'_, KT>::new(yubikey, key, subject_pki.owned_to_ref())?;
+        let mut builder =
+            CertificateBuilder::new(SelfSigned { subject }, serial, validity, subject_pki)
+                .map_err(|_| Error::KeyError)?;

-        let mut tbs_cert = Buffer::new(Vec::with_capacity(CB_OBJ_MAX));
-
-        let signature_algorithm = match subject_pki.algorithm() {
-            AlgorithmId::Rsa1024 | AlgorithmId::Rsa2048 => SignatureId::Sha256WithRsaEncryption,
-            AlgorithmId::EccP256 | AlgorithmId::EccP384 => SignatureId::EcdsaWithSha256,
-        };
-
-        cookie_factory::gen(
-            x509::write::tbs_certificate(
-                &serial.to_bytes(),
-                &signature_algorithm,
-                // Issuer and subject are the same in self-signed certificates.
-                &subject,
-                Utc::now(),
-                not_after,
-                &subject,
-                &subject_pki,
-                &extensions,
-            ),
-            tbs_cert.deref_mut(),
-        )
-        .expect("can serialize to Vec");
-
-        let signature = match signature_algorithm {
-            SignatureId::Sha256WithRsaEncryption => {
-                use cookie_factory::{combinator::slice, sequence::tuple};
-                use x509::{
-                    der::write::{der_octet_string, der_sequence},
-                    write::algorithm_identifier,
-                };
-
-                let em_len = if let AlgorithmId::Rsa1024 = subject_pki.algorithm() {
-                    128
-                } else {
-                    256
-                };
-
-                let h = Sha256::digest(&tbs_cert);
-
-                let t = cookie_factory::gen_simple(
-                    der_sequence((
-                        algorithm_identifier(&DigestId::Sha256),
-                        der_octet_string(&h),
-                    )),
-                    vec![],
-                )
-                .expect("can serialize into Vec");
-
-                let em = cookie_factory::gen_simple(
-                    tuple((
-                        slice(&[0x00, 0x01]),
-                        slice(&vec![0xff; em_len - t.len() - 3]),
-                        slice(&[0x00]),
-                        slice(t),
-                    )),
-                    vec![],
-                )
-                .expect("can serialize to Vec");
-
-                sign_data(yubikey, &em, subject_pki.algorithm(), key)
-            }
-            SignatureId::EcdsaWithSha256 => sign_data(
-                yubikey,
-                &Sha256::digest(&tbs_cert),
-                subject_pki.algorithm(),
-                key,
-            ),
-        }?;
-
-        let mut data = Buffer::new(Vec::with_capacity(CB_OBJ_MAX));
-
-        cookie_factory::gen(
-            x509::write::certificate(&tbs_cert, &signature_algorithm, &signature),
-            data.deref_mut(),
-        )
-        .expect("can serialize to Vec");
-
-        let (issuer, subject) = parse_x509_certificate(&data)
-            .map(|(_, cert)| {
-                (
-                    cert.tbs_certificate.issuer.to_string(),
-                    cert.tbs_certificate.subject.to_string(),
-                )
-            })
-            .expect("We just serialized this correctly");
-
-        let cert = Certificate {
-            serial,
-            issuer,
-            subject,
-            subject_pki,
-            data,
-        };
+        // Add custom extensions
+        extensions(&mut builder)?;

+        let cert = builder.build(&signer).map_err(|_| Error::KeyError)?;
+        let cert = Self { cert };
        cert.write(yubikey, key, CertInfo::Uncompressed)?;

        Ok(cert)
    }

    /// Read a certificate from the given slot in the YubiKey
-    pub fn read(yubikey: &mut YubiKey, slot: SlotId) -> Result<Self, Error> {
+    pub fn read(yubikey: &mut YubiKey, slot: SlotId) -> Result<Self> {
        let txn = yubikey.begin_transaction()?;
        let buf = read_certificate(&txn, slot)?;

@@ -461,29 +136,25 @@ impl Certificate {
            return Err(Error::InvalidObject);
        }

-        Certificate::from_bytes(buf)
+        Self::from_bytes(buf)
    }

    /// Write this certificate into the YubiKey in the given slot
-    pub fn write(
-        &self,
-        yubikey: &mut YubiKey,
-        slot: SlotId,
-        certinfo: CertInfo,
-    ) -> Result<(), Error> {
+    pub fn write(&self, yubikey: &mut YubiKey, slot: SlotId, certinfo: CertInfo) -> Result<()> {
        let txn = yubikey.begin_transaction()?;
-        write_certificate(&txn, slot, Some(&self.data), certinfo)
+        let data = self.cert.to_der().map_err(|_| Error::InvalidObject)?;
+        write_certificate(&txn, slot, Some(&data), certinfo)
    }

    /// Delete a certificate located at the given slot of the given YubiKey
    #[cfg(feature = "untested")]
-    pub fn delete(yubikey: &mut YubiKey, slot: SlotId) -> Result<(), Error> {
+    pub fn delete(yubikey: &mut YubiKey, slot: SlotId) -> Result<()> {
        let txn = yubikey.begin_transaction()?;
        write_certificate(&txn, slot, None, CertInfo::Uncompressed)
    }

    /// Initialize a local certificate struct from the given bytebuffer
-    pub fn from_bytes(cert: impl Into<Buffer>) -> Result<Self, Error> {
+    pub fn from_bytes(cert: impl Into<Buffer>) -> Result<Self> {
        let cert = cert.into();

        if cert.is_empty() {
@@ -491,60 +162,64 @@ impl Certificate {
            return Err(Error::SizeError);
        }

-        let parsed_cert = match parse_x509_certificate(&cert) {
-            Ok((_, cert)) => cert,
-            _ => return Err(Error::InvalidObject),
-        };
-
-        let serial = Serial::try_from(parsed_cert.tbs_certificate.serial.to_bytes_be().as_slice())
-            .map_err(|_| Error::InvalidObject)?;
-        let issuer = parsed_cert.tbs_certificate.issuer.to_string();
-        let subject = parsed_cert.tbs_certificate.subject.to_string();
-        let subject_pki = PublicKeyInfo::parse(&parsed_cert.tbs_certificate.subject_pki)?;
-
-        Ok(Certificate {
-            serial,
-            issuer,
-            subject,
-            subject_pki,
-            data: cert,
-        })
-    }
-
-    /// Returns the serial number of the certificate.
-    pub fn serial(&self) -> &Serial {
-        &self.serial
+        x509_cert::Certificate::from_der(&cert)
+            .map(|cert| Self { cert })
+            .map_err(|_| Error::InvalidObject)
    }

    /// Returns the Issuer field of the certificate.
-    pub fn issuer(&self) -> &str {
-        &self.subject
+    pub fn issuer(&self) -> String {
+        self.cert.tbs_certificate().issuer().to_string()
    }

    /// Returns the SubjectName field of the certificate.
-    pub fn subject(&self) -> &str {
-        &self.subject
+    pub fn subject(&self) -> String {
+        self.cert.tbs_certificate().subject().to_string()
    }

    /// Returns the SubjectPublicKeyInfo field of the certificate.
-    pub fn subject_pki(&self) -> &PublicKeyInfo {
-        &self.subject_pki
-    }
-
-    /// Extract the inner buffer
-    pub fn into_buffer(self) -> Buffer {
-        self.data
+    pub fn subject_pki(&self) -> SubjectPublicKeyInfoRef<'_> {
+        self.cert
+            .tbs_certificate()
+            .subject_public_key_info()
+            .owned_to_ref()
    }
 }

-impl AsRef<[u8]> for Certificate {
-    fn as_ref(&self) -> &[u8] {
-        self.data.as_ref()
+/// A [`BuilderProfile`] for self-signed certificates.
+///
+/// This profile has no default extensions.
+pub struct SelfSigned {
+    subject: Name,
+}
+
+impl BuilderProfile for SelfSigned {
+    fn get_issuer(&self, subject: &Name) -> Name {
+        // RFC 5280 Section 3.2:
+        //
+        // > Self-issued certificates are CA certificates in which the issuer and subject
+        // > are the same entity. [..] Self-signed certificates are self-issued
+        // > certificates where the digital signature may be verified by the public key
+        // > bound into the certificate.
+        subject.clone()
+    }
+
+    fn get_subject(&self) -> Name {
+        self.subject.clone()
+    }
+
+    fn build_extensions(
+        &self,
+        _spk: SubjectPublicKeyInfoRef<'_>,
+        _issuer_spk: SubjectPublicKeyInfoRef<'_>,
+        _tbs: &x509_cert::TbsCertificate,
+    ) -> x509_cert::builder::Result<Vec<x509_cert::ext::Extension>> {
+        Ok(vec![])
    }
 }

 /// Read certificate
-pub(crate) fn read_certificate(txn: &Transaction<'_>, slot: SlotId) -> Result<Buffer, Error> {
+pub(crate) fn read_certificate(txn: &Transaction<'_>, slot: SlotId) -> Result<Buffer> {
    let object_id = slot.object_id();

    let buf = match txn.fetch_object(object_id) {
@@ -572,15 +247,10 @@ pub(crate) fn write_certificate(
    slot: SlotId,
    data: Option<&[u8]>,
    certinfo: CertInfo,
-) -> Result<(), Error> {
+) -> Result<()> {
    let object_id = slot.object_id();

-    if data.is_none() {
-        return txn.save_object(object_id, &[]);
-    }
-
-    let data = data.unwrap();
-
+    if let Some(data) = data {
        let mut buf = [0u8; CB_OBJ_MAX];
        let mut offset = Tlv::write(&mut buf, TAG_CERT, data)?;

@@ -589,102 +259,260 @@ pub(crate) fn write_certificate(
        offset += Tlv::write(&mut buf[offset..], TAG_CERT_LRC, &[])?;

        txn.save_object(object_id, &buf[..offset])
+    } else {
+        txn.save_object(object_id, &[])
+    }
 }

-mod read_pki {
-    use der_parser::{
-        ber::BerObjectContent,
-        der::{parse_der_integer, DerObject},
-        error::BerError,
-        *,
+pub mod yubikey_signer {
+    //! Signer implementation for yubikey
+
+    use crate::{
+        error::{Error, Result},
+        piv::AlgorithmId,
+        piv::{sign_data, SlotId},
+        YubiKey,
    };
-    use nom::{combinator, IResult};
-    use rsa::{BigUint, RSAPublicKey};
-
-    use super::{OID_NIST_P256, OID_NIST_P384};
-    use crate::{error::Error, key::AlgorithmId};
-
-    /// From [RFC 8017](https://tools.ietf.org/html/rfc8017#appendix-A.1.1):
-    /// ```text
-    /// RSAPublicKey ::= SEQUENCE {
-    ///     modulus           INTEGER,  -- n
-    ///     publicExponent    INTEGER   -- e
-    /// }
-    /// ```
-    pub(super) fn rsa_pubkey(encoded: &[u8]) -> Result<RSAPublicKey, Error> {
-        fn parse_rsa_pubkey(i: &[u8]) -> IResult<&[u8], DerObject<'_>, BerError> {
-            parse_der_sequence_defined!(i, parse_der_integer >> parse_der_integer)
-        }
-
-        fn rsa_pubkey_parts(i: &[u8]) -> IResult<&[u8], (BigUint, BigUint), BerError> {
-            combinator::map(parse_rsa_pubkey, |object| {
-                let seq = object.as_sequence().expect("is DER sequence");
-                assert_eq!(seq.len(), 2);
-
-                let n = match seq[0].content {
-                    BerObjectContent::Integer(s) => BigUint::from_bytes_be(s),
-                    _ => panic!("expected DER integer"),
+    use der::{
+        asn1::{Any, OctetString},
+        oid::db::rfc5912,
+        Encode, Sequence,
    };
-                let e = match seq[1].content {
-                    BerObjectContent::Integer(s) => BigUint::from_bytes_be(s),
-                    _ => panic!("expected DER integer"),
+    use sha2::{Digest, Sha256, Sha384, Sha512};
+    use signature::Keypair;
+    use std::{cell::RefCell, fmt, io::Write, marker::PhantomData};
+    use x509_cert::spki::{
+        self, AlgorithmIdentifierOwned, DynSignatureAlgorithmIdentifier, EncodePublicKey,
+        SignatureBitStringEncoding, SubjectPublicKeyInfoRef,
    };

-                (n, e)
-            })(i)
+    type SigResult<T> = core::result::Result<T, signature::Error>;
+
+    /// Key to be used to sign certificates
+    pub trait KeyType {
+        /// Error returned when working with signature
+        type Error: Into<signature::Error> + fmt::Debug;
+        /// The signature type returned by the signer
+        type Signature: SignatureBitStringEncoding
+            + for<'s> TryFrom<&'s [u8], Error = Self::Error>
+            + fmt::Debug;
+        /// The public key used to verify signature
+        type VerifyingKey: EncodePublicKey
+            + DynSignatureAlgorithmIdentifier
+            + Clone
+            + From<Self::PublicKey>;
+        /// Public key type used to load the SPKI formatted key
+        type PublicKey: for<'a> TryFrom<SubjectPublicKeyInfoRef<'a>, Error = spki::Error>;
+
+        /// The algorithm used when talking with the yubikey
+        const ALGORITHM: AlgorithmId;
+
+        /// Prepare buffer before submitting it for signature
+        fn prepare(input: &[u8]) -> SigResult<Vec<u8>>;
+        /// Read back the signature from the device
+        fn read_signature(input: &[u8]) -> SigResult<Self::Signature>;
    }

-        let (n, e) = match rsa_pubkey_parts(encoded) {
-            Ok((_, res)) => res,
-            _ => return Err(Error::InvalidObject),
+    impl KeyType for ed25519_dalek::SigningKey {
+        const ALGORITHM: AlgorithmId = AlgorithmId::Ed25519;
+        type Error = ed25519_dalek::SignatureError;
+        type Signature = ed25519_dalek::Signature;
+        type VerifyingKey = ed25519_dalek::VerifyingKey;
+        type PublicKey = ed25519_dalek::VerifyingKey;
+
+        fn prepare(input: &[u8]) -> SigResult<Vec<u8>> {
+            Ok(Sha512::digest(input).to_vec())
+        }
+
+        fn read_signature(input: &[u8]) -> SigResult<Self::Signature> {
+            Self::Signature::try_from(input)
+        }
+    }
+
+    impl KeyType for p256::NistP256 {
+        const ALGORITHM: AlgorithmId = AlgorithmId::EccP256;
+        type Error = ecdsa::Error;
+        type Signature = p256::ecdsa::DerSignature;
+        type VerifyingKey = p256::ecdsa::VerifyingKey;
+        type PublicKey = p256::ecdsa::VerifyingKey;
+
+        fn prepare(input: &[u8]) -> SigResult<Vec<u8>> {
+            Ok(Sha256::digest(input).to_vec())
+        }
+
+        fn read_signature(input: &[u8]) -> SigResult<Self::Signature> {
+            Self::Signature::from_bytes(input)
+        }
+    }
+
+    impl KeyType for p384::NistP384 {
+        const ALGORITHM: AlgorithmId = AlgorithmId::EccP384;
+        type Error = ecdsa::Error;
+        type Signature = p384::ecdsa::DerSignature;
+        type VerifyingKey = p384::ecdsa::VerifyingKey;
+        type PublicKey = p384::ecdsa::VerifyingKey;
+
+        fn prepare(input: &[u8]) -> SigResult<Vec<u8>> {
+            Ok(Sha384::digest(input).to_vec())
+        }
+
+        fn read_signature(input: &[u8]) -> SigResult<Self::Signature> {
+            Self::Signature::from_bytes(input)
+        }
+    }
+
+    /// Trait used to handle subtypes of RSA keys
+    pub trait RsaLength {
+        /// The length of the RSA key in bits
+        const BIT_LENGTH: usize;
+        /// The algorithm to use when talking with the Yubikey.
+        const ALGORITHM: AlgorithmId;
+    }
+
+    /// RSA 1024 bits key
+    pub struct Rsa1024;
+
+    impl RsaLength for Rsa1024 {
+        const BIT_LENGTH: usize = 1024;
+        const ALGORITHM: AlgorithmId = AlgorithmId::Rsa1024;
+    }
+
+    /// RSA 2048 bits key
+    pub struct Rsa2048;
+
+    impl RsaLength for Rsa2048 {
+        const BIT_LENGTH: usize = 2048;
+        const ALGORITHM: AlgorithmId = AlgorithmId::Rsa2048;
+    }
+
+    /// RSA 3072 bits key
+    pub struct Rsa3072;
+
+    impl RsaLength for Rsa3072 {
+        const BIT_LENGTH: usize = 3072;
+        const ALGORITHM: AlgorithmId = AlgorithmId::Rsa3072;
+    }
+
+    /// RSA 4096 bits key
+    pub struct Rsa4096;
+
+    impl RsaLength for Rsa4096 {
+        const BIT_LENGTH: usize = 4096;
+        const ALGORITHM: AlgorithmId = AlgorithmId::Rsa4096;
+    }
+
+    /// RSA keys used to sign certificates
+    pub struct YubiRsa<N: RsaLength> {
+        _len: PhantomData<N>,
+    }
+
+    impl<N: RsaLength> KeyType for YubiRsa<N> {
+        type Error = signature::Error;
+        type Signature = rsa::pkcs1v15::Signature;
+        type VerifyingKey = rsa::pkcs1v15::VerifyingKey<Sha256>;
+        type PublicKey = rsa::RsaPublicKey;
+        const ALGORITHM: AlgorithmId = N::ALGORITHM;
+
+        fn prepare(input: &[u8]) -> SigResult<Vec<u8>> {
+            let hashed = Sha256::digest(input).to_vec();
+
+            OctetString::new(hashed)
+                .map_err(|e| e.into())
+                .and_then(Self::emsa_pkcs1_1_5)
+                .map_err(signature::Error::from_source)
+        }
+
+        fn read_signature(input: &[u8]) -> SigResult<Self::Signature> {
+            Self::Signature::try_from(input)
+        }
+    }
+
+    impl<N: RsaLength> YubiRsa<N> {
+        /// https://www.rfc-editor.org/rfc/rfc8017#section-9.2
+        fn emsa_pkcs1_1_5(digest: OctetString) -> Result<Vec<u8>> {
+            /// https://www.rfc-editor.org/rfc/rfc8017#appendix-A.2.4
+            #[derive(Debug, Sequence)]
+            struct DigestInfo {
+                digest_algorithm: AlgorithmIdentifierOwned,
+                digest: OctetString,
+            }
+
+            let em_len = N::BIT_LENGTH / 8;
+
+            let null = Any::null();
+
+            let t = DigestInfo {
+                digest_algorithm: AlgorithmIdentifierOwned {
+                    oid: rfc5912::ID_SHA_256,
+                    parameters: Some(null),
+                },
+                digest,
            };
+            let t = t.to_der()?;

-        RSAPublicKey::new(n, e).map_err(|_| Error::InvalidObject)
-    }
+            let ps = vec![0xff; em_len - t.len() - 3];
+            assert!(ps.len() >= 8, "spec violation");

-    /// From [RFC 5480](https://tools.ietf.org/html/rfc5480#section-2.1.1):
-    /// ```text
-    /// ECParameters ::= CHOICE {
-    ///   namedCurve         OBJECT IDENTIFIER
-    ///   -- implicitCurve   NULL
-    ///   -- specifiedCurve  SpecifiedECDomain
-    /// }
-    /// ```
-    pub(super) fn ec_parameters(parameters: &DerObject<'_>) -> Result<AlgorithmId, Error> {
-        let curve_oid = parameters.as_oid_val().map_err(|_| Error::InvalidObject)?;
-
-        match curve_oid.to_string().as_str() {
-            OID_NIST_P256 => Ok(AlgorithmId::EccP256),
-            OID_NIST_P384 => Ok(AlgorithmId::EccP384),
-            _ => Err(Error::AlgorithmError),
-        }
+            let mut out = Vec::with_capacity(em_len);
+            out.write(&[0x00, 0x01]).map_err(|_| Error::MemoryError)?;
+            out.write(&ps).map_err(|_| Error::MemoryError)?;
+            out.write(&[0x00]).map_err(|_| Error::MemoryError)?;
+            out.write(&t).map_err(|_| Error::MemoryError)?;
+            Ok(out)
        }
    }

-mod write_pki {
-    use cookie_factory::{SerializeFn, WriteContext};
-    use rsa::{BigUint, PublicKeyParts, RSAPublicKey};
-    use std::io::Write;
-    use x509::der::write::{der_integer, der_sequence};
-
-    /// Encodes a usize as an ASN.1 integer using DER.
-    fn der_integer_biguint<'a, W: Write + 'a>(num: &'a BigUint) -> impl SerializeFn<W> + 'a {
-        move |w: WriteContext<W>| der_integer(&num.to_bytes_be())(w)
+    /// The entrypoint to sign data with the yubikey.
+    pub struct Signer<'y, KT: KeyType> {
+        yubikey: RefCell<&'y mut YubiKey>,
+        key: SlotId,
+        public_key: KT::VerifyingKey,
    }

-    /// From [RFC 8017](https://tools.ietf.org/html/rfc8017#appendix-A.1.1):
-    /// ```text
-    /// RSAPublicKey ::= SEQUENCE {
-    ///     modulus           INTEGER,  -- n
-    ///     publicExponent    INTEGER   -- e
-    /// }
-    /// ```
-    pub(super) fn rsa_pubkey<'a, W: Write + 'a>(
-        pubkey: &'a RSAPublicKey,
-    ) -> impl SerializeFn<W> + 'a {
-        der_sequence((
-            der_integer_biguint(pubkey.n()),
-            der_integer_biguint(pubkey.e()),
-        ))
+    impl<'y, KT: KeyType> Signer<'y, KT> {
+        /// Create new Signer
+        pub fn new(
+            yubikey: &'y mut YubiKey,
+            key: SlotId,
+            subject_pki: SubjectPublicKeyInfoRef<'_>,
+        ) -> Result<Self> {
+            let public_key = KT::PublicKey::try_from(subject_pki).map_err(|_| Error::ParseError)?;
+            let public_key = public_key.into();
+
+            Ok(Self {
+                yubikey: RefCell::new(yubikey),
+                key,
+                public_key,
+            })
+        }
+    }
+
+    impl<KT: KeyType> Keypair for Signer<'_, KT> {
+        type VerifyingKey = KT::VerifyingKey;
+        fn verifying_key(&self) -> <Self as Keypair>::VerifyingKey {
+            self.public_key.clone()
+        }
+    }
+
+    impl<KT: KeyType> DynSignatureAlgorithmIdentifier for Signer<'_, KT> {
+        fn signature_algorithm_identifier(&self) -> spki::Result<AlgorithmIdentifierOwned> {
+            self.verifying_key().signature_algorithm_identifier()
+        }
+    }
+
+    impl<KT: KeyType> signature::Signer<KT::Signature> for Signer<'_, KT> {
+        fn try_sign(&self, msg: &[u8]) -> SigResult<KT::Signature> {
+            let data = KT::prepare(msg)?;
+
+            let out = sign_data(
+                &mut self.yubikey.borrow_mut(),
+                &data,
+                KT::ALGORITHM,
+                self.key,
+            )
+            .map_err(signature::Error::from_source)?;
+            let out = KT::read_signature(&out)?;
+            Ok(out)
+        }
    }
 }
@@ -30,22 +30,9 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

-use crate::{error::Error, yubikey::YubiKey};
-use getrandom::getrandom;
+use crate::{Result, YubiKey};
 use std::fmt::{self, Debug, Display};
-use subtle_encoding::hex;
-
-/// CHUID size
-pub const CHUID_SIZE: usize = 59;
-
-/// CARDID size
-pub const CARDID_SIZE: usize = 16;
-
-/// FASC-N component size
-pub const FASCN_SIZE: usize = 25;
-
-/// Expiration size
-pub const EXPIRATION_SIZE: usize = 8;
+use uuid::Uuid;

 /// FASC-N offset
 const CHUID_FASCN_OFFS: usize = 2;
@@ -74,6 +61,7 @@ const OBJ_CHUID: u32 = 0x005f_c102;
 /// - 0x35: Exp. Date (hard-coded)
 /// - 0x3e: Signature (hard-coded, empty)
 /// - 0xfe: Error Detection Code (hard-coded)
+#[allow(dead_code)]
 const CHUID_TMPL: &[u8] = &[
    0x30, 0x19, 0xd4, 0xe7, 0x39, 0xda, 0x73, 0x9c, 0xed, 0x39, 0xce, 0x73, 0x9d, 0x83, 0x68, 0x58,
    0x21, 0x08, 0x42, 0x10, 0x84, 0x21, 0xc8, 0x42, 0x10, 0xc3, 0xeb, 0x34, 0x10, 0x00, 0x00, 0x00,
@@ -81,87 +69,67 @@ const CHUID_TMPL: &[u8] = &[
    0x30, 0x33, 0x30, 0x30, 0x31, 0x30, 0x31, 0x3e, 0x00, 0xfe, 0x00,
 ];

-/// Cardholder Unique Identifier (CHUID) Card UUID/GUID value
+/// Cardholder Unique Identifier (CHUID).
 #[derive(Copy, Clone, Debug)]
-pub struct Uuid(pub [u8; CARDID_SIZE]);
+pub struct ChuId(pub [u8; Self::BYTE_SIZE]);

-impl Uuid {
-    /// Generate a random Cardholder Unique Identifier (CHUID) UUID
-    pub fn generate() -> Result<Self, Error> {
-        let mut id = [0u8; CARDID_SIZE];
-        getrandom(&mut id).map_err(|_| Error::RandomnessError)?;
-        Ok(Self(id))
-    }
-}
+impl ChuId {
+    /// CHUID size in bytes
+    pub const BYTE_SIZE: usize = 59;

-/// Cardholder Unique Identifier (CHUID)
-#[derive(Copy, Clone)]
-pub struct CHUID(pub [u8; CHUID_SIZE]);
+    /// FASC-N component size
+    pub const FASCN_SIZE: usize = 25;
+
+    /// Expiration size
+    pub const EXPIRATION_SIZE: usize = 8;

-impl CHUID {
    /// Return FASC-N component of CHUID
-    pub fn fascn(&self) -> Result<[u8; FASCN_SIZE], Error> {
-        let mut fascn = [0u8; FASCN_SIZE];
-        fascn.copy_from_slice(&self.0[CHUID_FASCN_OFFS..(CHUID_FASCN_OFFS + FASCN_SIZE)]);
-        Ok(fascn)
+    pub fn fascn(&self) -> [u8; Self::FASCN_SIZE] {
+        self.0[CHUID_FASCN_OFFS..(CHUID_FASCN_OFFS + Self::FASCN_SIZE)]
+            .try_into()
+            .expect("should be FASCN_SIZE")
    }

    /// Return Card UUID/GUID component of CHUID
-    pub fn uuid(&self) -> Result<[u8; CARDID_SIZE], Error> {
-        let mut uuid = [0u8; CARDID_SIZE];
-        uuid.copy_from_slice(&self.0[CHUID_GUID_OFFS..(CHUID_GUID_OFFS + CARDID_SIZE)]);
-        Ok(uuid)
+    pub fn uuid(&self) -> Uuid {
+        Uuid::from_slice(&self.0[CHUID_GUID_OFFS..(CHUID_GUID_OFFS + 16)])
+            .expect("should be UUID-sized")
    }

    /// Return expiration date component of CHUID
    // TODO(tarcieri): parse expiration?
-    pub fn expiration(&self) -> Result<[u8; EXPIRATION_SIZE], Error> {
-        let mut expiration = [0u8; EXPIRATION_SIZE];
-        expiration.copy_from_slice(
-            &self.0[CHUID_EXPIRATION_OFFS..(CHUID_EXPIRATION_OFFS + EXPIRATION_SIZE)],
-        );
-        Ok(expiration)
+    pub fn expiration(&self) -> [u8; Self::EXPIRATION_SIZE] {
+        self.0[CHUID_EXPIRATION_OFFS..(CHUID_EXPIRATION_OFFS + Self::EXPIRATION_SIZE)]
+            .try_into()
+            .expect("should be EXPIRATION_SIZE")
    }

    /// Get Cardholder Unique Identifier (CHUID)
-    pub fn get(yubikey: &mut YubiKey) -> Result<CHUID, Error> {
+    pub fn get(yubikey: &mut YubiKey) -> Result<ChuId> {
        let txn = yubikey.begin_transaction()?;
        let response = txn.fetch_object(OBJ_CHUID)?;
-
-        if response.len() != CHUID_TMPL.len() {
-            return Err(Error::GenericError);
-        }
-
-        let mut chuid = [0u8; CHUID_SIZE];
-        chuid.copy_from_slice(&response[0..CHUID_SIZE]);
-        let retval = CHUID { 0: chuid };
-        Ok(retval)
+        Ok(response[..Self::BYTE_SIZE].try_into().map(Self)?)
    }

    /// Set Cardholder Unique Identifier (CHUID)
    #[cfg(feature = "untested")]
-
-    pub fn set(&self, yubikey: &mut YubiKey) -> Result<(), Error> {
+    pub fn set(&self, yubikey: &mut YubiKey) -> Result<()> {
        let mut buf = CHUID_TMPL.to_vec();
-        buf[0..self.0.len()].copy_from_slice(&self.0);
+        buf[..Self::BYTE_SIZE].copy_from_slice(&self.0);

        let txn = yubikey.begin_transaction()?;
        txn.save_object(OBJ_CHUID, &buf)
    }
 }

-impl Display for CHUID {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(
-            f,
-            "{}",
-            String::from_utf8(hex::encode(&self.0[..])).unwrap()
-        )
+impl AsRef<[u8]> for ChuId {
+    fn as_ref(&self) -> &[u8] {
+        &self.0
    }
 }

-impl Debug for CHUID {
+impl Display for ChuId {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "CHUID({:?})", &self.0[..])
+        f.write_str(&hex::upper::encode_string(self.as_ref()))
    }
 }
@@ -31,56 +31,60 @@
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 use crate::{
-    error::Error,
-    metadata,
+    consts::{
+        TAG_ADMIN_FLAGS_1, TAG_ADMIN_SALT, TAG_ADMIN_TIMESTAMP, TAG_PROTECTED_FLAGS_1,
+        TAG_PROTECTED_MGM,
+    },
+    metadata::{AdminData, ProtectedData},
    mgm::{MgmType, ADMIN_FLAGS_1_PROTECTED_MGM},
    yubikey::{YubiKey, ADMIN_FLAGS_1_PUK_BLOCKED},
-    TAG_ADMIN, TAG_ADMIN_FLAGS_1, TAG_ADMIN_SALT, TAG_ADMIN_TIMESTAMP, TAG_PROTECTED,
-    TAG_PROTECTED_FLAGS_1, TAG_PROTECTED_MGM,
+    Result,
 };
 use log::error;
-use std::{
-    convert::TryInto,
-    time::{Duration, SystemTime, UNIX_EPOCH},
-};
+use std::time::{Duration, SystemTime, UNIX_EPOCH};

 const CB_ADMIN_TIMESTAMP: usize = 0x04;
 const PROTECTED_FLAGS_1_PUK_NOBLOCK: u8 = 0x01;

-/// Config
+/// YubiKey configuration.
 #[derive(Copy, Clone, Debug)]
 pub struct Config {
    /// Protected data available
-    protected_data_available: bool,
+    pub protected_data_available: bool,

    /// PUK blocked
-    puk_blocked: bool,
+    pub puk_blocked: bool,

    /// No block on upgrade
-    puk_noblock_on_upgrade: bool,
+    pub puk_noblock_on_upgrade: bool,

    /// PIN last changed
-    pin_last_changed: Option<SystemTime>,
+    pub pin_last_changed: Option<SystemTime>,

    /// MGM type
-    mgm_type: MgmType,
+    pub mgm_type: MgmType,
 }

-impl Config {
-    /// Get YubiKey config
-    pub fn get(yubikey: &mut YubiKey) -> Result<Config, Error> {
-        let mut config = Config {
+impl Default for Config {
+    fn default() -> Config {
+        Config {
            protected_data_available: false,
            puk_blocked: false,
            puk_noblock_on_upgrade: false,
            pin_last_changed: None,
            mgm_type: MgmType::Manual,
-        };
+        }
+    }
+}

+impl Config {
+    /// Get YubiKey config.
+    pub(crate) fn get(yubikey: &mut YubiKey) -> Result<Config> {
+        let mut config = Self::default();
        let txn = yubikey.begin_transaction()?;

-        if let Ok(data) = metadata::read(&txn, TAG_ADMIN) {
-            if let Ok(item) = metadata::get_item(&data, TAG_ADMIN_FLAGS_1) {
+        if let Ok(admin_data) = AdminData::read(&txn) {
+            if let Ok(item) = admin_data.get_item(TAG_ADMIN_FLAGS_1) {
                if item.is_empty() {
                    error!("empty response for admin flags metadata item! ignoring");
                } else {
@@ -94,7 +98,7 @@ impl Config {
                }
            }

-            if metadata::get_item(&data, TAG_ADMIN_SALT).is_ok() {
+            if admin_data.get_item(TAG_ADMIN_SALT).is_ok() {
                if config.mgm_type != MgmType::Manual {
                    error!("conflicting types of MGM key administration configured");
                } else {
@@ -102,12 +106,12 @@ impl Config {
                }
            }

-            if let Ok(item) = metadata::get_item(&data, TAG_ADMIN_TIMESTAMP) {
+            if let Ok(item) = admin_data.get_item(TAG_ADMIN_TIMESTAMP) {
                if item.len() != CB_ADMIN_TIMESTAMP {
                    error!("pin timestamp in admin metadata is an invalid size");
                } else {
                    // TODO(tarcieri): double-check endianness is correct
-                    let pin_last_changed = u32::from_le_bytes(item.try_into().unwrap());
+                    let pin_last_changed = u32::from_le_bytes([item[0], item[1], item[2], item[3]]);

                    if pin_last_changed != 0 {
                        config.pin_last_changed =
@@ -117,10 +121,10 @@ impl Config {
            }
        }

-        if let Ok(data) = metadata::read(&txn, TAG_PROTECTED) {
+        if let Ok(protected_data) = ProtectedData::read(&txn) {
            config.protected_data_available = true;

-            if let Ok(item) = metadata::get_item(&data, TAG_PROTECTED_FLAGS_1) {
+            if let Ok(item) = protected_data.get_item(TAG_PROTECTED_FLAGS_1) {
                if item.is_empty() {
                    error!("empty response for protected flags metadata item! ignoring");
                } else if item[0] & PROTECTED_FLAGS_1_PUK_NOBLOCK != 0 {
@@ -128,11 +132,9 @@ impl Config {
                }
            }

-            if metadata::get_item(&data, TAG_PROTECTED_MGM).is_ok() {
+            if protected_data.get_item(TAG_PROTECTED_MGM).is_ok() {
                if config.mgm_type != MgmType::Protected {
-                    error!(
-                        "conflicting types of mgm key administration configured: protected MGM exists"
-                    );
+                    error!("conflicting MGM key types: protected MGM exists");
                }

                // Always favor protected MGM
@@ -0,0 +1,37 @@
+//! Miscellaneous constant values
+
+#![allow(dead_code)]
+
+/// YubiKey max buffer size
+pub(crate) const CB_BUF_MAX: usize = 3072;
+
+/// YubiKey max object size
+pub(crate) const CB_OBJ_MAX: usize = CB_BUF_MAX - 9;
+
+pub(crate) const CB_OBJ_TAG_MIN: usize = 2; // 1 byte tag + 1 byte len
+pub(crate) const CB_OBJ_TAG_MAX: usize = CB_OBJ_TAG_MIN + 2; // 1 byte tag + 3 bytes len
+
+// Admin tags
+pub(crate) const TAG_ADMIN_FLAGS_1: u8 = 0x81;
+pub(crate) const TAG_ADMIN_SALT: u8 = 0x82;
+pub(crate) const TAG_ADMIN_TIMESTAMP: u8 = 0x83;
+
+// Protected tags
+pub(crate) const TAG_PROTECTED_FLAGS_1: u8 = 0x81;
+pub(crate) const TAG_PROTECTED_MGM: u8 = 0x89;
+
+// Management
+pub(crate) const TAG_USB_SUPPORTED: u8 = 0x01;
+pub(crate) const TAG_SERIAL: u8 = 0x02;
+pub(crate) const TAG_USB_ENABLED: u8 = 0x03;
+pub(crate) const TAG_FORM_FACTOR: u8 = 0x04;
+pub(crate) const TAG_VERSION: u8 = 0x05;
+pub(crate) const TAG_AUTO_EJECT_TIMEOUT: u8 = 0x06;
+pub(crate) const TAG_CHALRESP_TIMEOUT: u8 = 0x07;
+pub(crate) const TAG_DEVICE_FLAGS: u8 = 0x08;
+pub(crate) const TAG_APP_VERSIONS: u8 = 0x09;
+pub(crate) const TAG_CONFIG_LOCK: u8 = 0x0A;
+pub(crate) const TAG_UNLOCK: u8 = 0x0B;
+pub(crate) const TAG_REBOOT: u8 = 0x0C;
+pub(crate) const TAG_NFC_SUPPORTED: u8 = 0x0D;
+pub(crate) const TAG_NFC_ENABLED: u8 = 0x0E;
@@ -32,65 +32,75 @@

 use std::fmt::{self, Display};

-/// Kinds of errors
+/// Result type with [`Error`].
+pub type Result<T> = core::result::Result<T, Error>;
+
+/// Kinds of errors.
 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
+#[non_exhaustive]
 pub enum Error {
+    /// Algorithm error
+    AlgorithmError,
+
+    /// Applet error
+    AppletError,
+
+    /// We tried to select an applet that could not be found.
+    AppletNotFound {
+        /// Human-readable name of the applet.
+        applet_name: &'static str,
+    },
+
+    /// Argument error
+    ArgumentError,
+
+    /// Authentication error
+    AuthenticationError,
+
+    /// Error while building a certificate
+    CertificateBuilder,
+
+    /// Generic error
+    GenericError,
+
+    /// Invalid object
+    InvalidObject,
+
+    /// Key error
+    KeyError,
+
    /// Memory error
    MemoryError,

+    /// Not supported
+    NotSupported,
+
+    /// Not found
+    NotFound,
+
+    /// Parse error
+    ParseError,
+
    /// PCSC error
    PcscError {
        /// Original PC/SC error
        inner: Option<pcsc::Error>,
    },

+    /// PIN locked
+    PinLocked,
+
+    /// Range error
+    RangeError,
+
    /// Size error
    SizeError,

-    /// Applet error
-    AppletError,
-
-    /// Authentication error
-    AuthenticationError,
-
-    /// Randomness error
-    RandomnessError,
-
-    /// Generic error
-    GenericError,
-
-    /// Key error
-    KeyError,
-
-    /// Parse error
-    ParseError,
-
    /// Wrong PIN
    WrongPin {
        /// Number of tries remaining
        tries: u8,
    },
-
-    /// Invalid object
-    InvalidObject,
-
-    /// Algorithm error
-    AlgorithmError,
-
-    /// PIN locked
-    PinLocked,
-
-    /// Argument error
-    ArgumentError,
-
-    /// Range error
-    RangeError,
-
-    /// Not supported
-    NotSupported,
-
-    /// Not found
-    NotFound,
 }

 impl Error {
@@ -98,55 +108,75 @@ impl Error {
    ///
    /// These names map to the legacy names from the Yubico C library, to
    /// assist in web searches for relevant information for these errors.
-    pub fn name(self) -> &'static str {
-        match self {
-            Error::MemoryError => "YKPIV_MEMORY_ERROR",
-            Error::PcscError { .. } => "YKPIV_PCSC_ERROR",
-            Error::SizeError => "YKPIV_SIZE_ERROR",
-            Error::AppletError => "YKPIV_APPLET_ERROR",
-            Error::AuthenticationError => "YKPIV_AUTHENTICATION_ERROR",
-            Error::RandomnessError => "YKPIV_RANDOMNESS_ERROR",
-            Error::GenericError => "YKPIV_GENERIC_ERROR",
-            Error::KeyError => "YKPIV_KEY_ERROR",
-            Error::ParseError => "YKPIV_PARSE_ERROR",
-            Error::WrongPin { .. } => "YKPIV_WRONG_PIN",
-            Error::InvalidObject => "YKPIV_INVALID_OBJECT",
+    pub fn name(self) -> Option<&'static str> {
+        Some(match self {
            Error::AlgorithmError => "YKPIV_ALGORITHM_ERROR",
-            Error::PinLocked => "YKPIV_PIN_LOCKED",
+            Error::AppletError => "YKPIV_APPLET_ERROR",
            Error::ArgumentError => "YKPIV_ARGUMENT_ERROR",
-            Error::RangeError => "YKPIV_RANGE_ERROR",
+            Error::AuthenticationError => "YKPIV_AUTHENTICATION_ERROR",
+            Error::GenericError => "YKPIV_GENERIC_ERROR",
+            Error::InvalidObject => "YKPIV_INVALID_OBJECT",
+            Error::KeyError => "YKPIV_KEY_ERROR",
+            Error::MemoryError => "YKPIV_MEMORY_ERROR",
            Error::NotSupported => "YKPIV_NOT_SUPPORTED",
-            Error::NotFound => "<not found>",
-        }
+            Error::ParseError => "YKPIV_PARSE_ERROR",
+            Error::PcscError { .. } => "YKPIV_PCSC_ERROR",
+            Error::PinLocked => "YKPIV_PIN_LOCKED",
+            Error::RangeError => "YKPIV_RANGE_ERROR",
+            Error::SizeError => "YKPIV_SIZE_ERROR",
+            Error::WrongPin { .. } => "YKPIV_WRONG_PIN",
+            _ => return None,
+        })
    }

    /// Error message
-    pub fn msg(self) -> &'static str {
+    pub fn msg(self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
-            Error::MemoryError => "memory error",
-            Error::PcscError { .. } => "PCSC error",
-            Error::SizeError => "size error",
-            Error::AppletError => "applet error",
-            Error::AuthenticationError => "authentication error",
-            Error::RandomnessError => "randomness error",
-            Error::GenericError => "generic error",
-            Error::KeyError => "key error",
-            Error::ParseError => "parse error",
-            Error::WrongPin { .. } => "wrong pin",
-            Error::InvalidObject => "invalid object",
-            Error::AlgorithmError => "algorithm error",
-            Error::PinLocked => "PIN locked",
-            Error::ArgumentError => "argument error",
-            Error::RangeError => "range error",
-            Error::NotSupported => "not supported",
-            Error::NotFound => "not found",
+            Error::AlgorithmError => f.write_str("algorithm error"),
+            Error::AppletError => f.write_str("applet error"),
+            Error::AppletNotFound { applet_name } => {
+                f.write_str(&format!("{applet_name} applet not found"))
+            }
+            Error::ArgumentError => f.write_str("argument error"),
+            Error::AuthenticationError => f.write_str("authentication error"),
+            Error::CertificateBuilder => f.write_str("certificate builder error"),
+            Error::GenericError => f.write_str("generic error"),
+            Error::InvalidObject => f.write_str("invalid object"),
+            Error::KeyError => f.write_str("key error"),
+            Error::MemoryError => f.write_str("memory error"),
+            Error::NotSupported => f.write_str("not supported"),
+            Error::NotFound => f.write_str("not found"),
+            Error::ParseError => f.write_str("parse error"),
+
+            Error::PcscError {
+                inner: Some(pcsc_error),
+            } => f.write_fmt(format_args!("PC/SC error: {pcsc_error}")),
+
+            Error::PcscError { .. } => f.write_str("PC/SC error"),
+
+            Error::PinLocked => f.write_str("PIN locked"),
+            Error::RangeError => f.write_str("range error"),
+            Error::SizeError => f.write_str("size error"),
+            Error::WrongPin { .. } => f.write_str("wrong pin"),
        }
    }
 }

 impl Display for Error {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.write_str(self.msg())
+        self.msg(f)
+    }
+}
+
+impl From<std::array::TryFromSliceError> for Error {
+    fn from(_: std::array::TryFromSliceError) -> Error {
+        Error::SizeError
+    }
+}
+
+impl From<std::time::SystemTimeError> for Error {
+    fn from(_: std::time::SystemTimeError) -> Error {
+        Error::GenericError
    }
 }

@@ -159,11 +189,21 @@ impl From<pcsc::Error> for Error {
 impl std::error::Error for Error {
    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
        match self {
-            #[allow(trivial_casts)] // why doesn't this work without the cast???
-            Error::PcscError { inner } => inner
-                .as_ref()
-                .map(|err| err as &(dyn std::error::Error + 'static)),
+            #[allow(trivial_casts)]
+            Error::PcscError { inner } => inner.as_ref().map(|err| err as &_),
            _ => None,
        }
    }
 }
+
+impl From<der::Error> for Error {
+    fn from(_err: der::Error) -> Error {
+        Error::ParseError
+    }
+}
+
+impl From<x509_cert::builder::Error> for Error {
+    fn from(_err: x509_cert::builder::Error) -> Error {
+        Error::CertificateBuilder
+    }
+}
@@ -1,95 +1,17 @@
-//! [YubiKey] PIV: [Personal Identity Verification][PIV] support for
-//! [Yubico] devices using the Personal Computer/Smart Card ([PC/SC])
-//! interface as provided by the [`pcsc` crate].
-//!
-//! **PIV** is a [NIST] standard for both *signing* and *encryption*
-//! using SmartCards and SmartCard-based hardware tokens like YubiKeys.
-//!
-//! This library natively implements the protocol used to manage and
-//! utilize PIV encryption and signing keys which can be generated, imported,
-//! and stored on YubiKey devices.
-//!
-//! See [Yubico's guide to PIV-enabled YubiKeys][yk-guide] for more information
-//! on which devices support PIV and the available functionality.
-//!
-//! ## Minimum Supported Rust Version
-//!
-//! Rust 1.44+
-//!
-//! ## Supported YubiKeys
-//!
-//! - [YubiKey 4] series
-//! - [YubiKey 5] series
-//!
-//! NOTE: Nano and USB-C variants of the above are also supported.
-//!       Pre-YK4 [YubiKey NEO] series is **NOT** supported.
-//!
-//! ## Supported Algorithms
-//!
-//! - **Authentication**: `3DES`
-//! - **Encryption**: `RSA1024`, `RSA2048`, `ECCP256`, `ECCP384`
-//! - **Signatures**:
-//!   - RSASSA-PKCS#1v1.5: `RSA1024`, `RSA2048`
-//!   - ECDSA: `ECCP256`, `ECCP384`
-//!
-//! NOTE: RSASSA-PSS signatures and RSA-OAEP encryption may be supportable (TBD)
-//!
-//! ## Status
-//!
-//! This is a work-in-progress effort, and while much of the library-level
-//! code from upstream [yubico-piv-tool] has been translated into Rust
-//! presenting a safe interface, much of it is still untested.
-//!
-//! Please see the [project's README.md for a complete status][status].
-//!
-//! ## History
-//!
-//! This library is a Rust translation of the [yubico-piv-tool] utility by
-//! Yubico, which was originally written in C. It was mechanically translated
-//! from C into Rust using [Corrode], and then subsequently heavily
-//! refactored into safer, more idiomatic Rust.
-//!
-//! For more information on [yubico-piv-tool] and background information on how
-//! the YubiKey implementation of PIV works in general, see the
-//! [Yubico PIV Tool Command Line Guide][piv-tool-guide].
-//!
-//! ## Security Warning
-//!
-//! No security audits of this crate have ever been performed. Presently it is in
-//! an experimental stage and may still contain high-severity issues.
-//!
-//! USE AT YOUR OWN RISK!
-//!
-//! ## Code of Conduct
-//!
-//! We abide by the [Contributor Covenant][cc-md] and ask that you do as well.
-//!
-//! For more information, please see [CODE_OF_CONDUCT.md][cc-md].
-//!
-//! ## License
-//!
-//! **yubikey-piv.rs** is a fork of and originally a mechanical translation from
-//! Yubico's [yubico-piv-tool], a C library/CLI program. The original library
-//! was licensed under a [2-Clause BSD License][BSDL], which this library inherits
-//! as a derived work.
-//!
-//! [YubiKey]: https://www.yubico.com/products/yubikey-hardware/
-//! [PIV]: https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-73-4.pdf
-//! [Yubico]: https://www.yubico.com/
-//! [PC/SC]: https://en.wikipedia.org/wiki/PC/SC
-//! [`pcsc` crate]: https://github.com/bluetech/pcsc-rust
-//! [NIST]: https://www.nist.gov/
-//! [yk-guide]: https://developers.yubico.com/PIV/Introduction/YubiKey_and_PIV.html
-//! [YubiKey NEO]: https://support.yubico.com/support/solutions/articles/15000006494-yubikey-neo
-//! [YubiKey 4]: https://support.yubico.com/support/solutions/articles/15000006486-yubikey-4
-//! [YubiKey 5]: https://www.yubico.com/products/yubikey-5-overview/
-//! [status]: https://github.com/iqlusioninc/yubikey-piv.rs#status
-//! [yubico-piv-tool]: https://github.com/Yubico/yubico-piv-tool/
-//! [Corrode]: https://github.com/jameysharp/corrode
-//! [piv-tool-guide]: https://www.yubico.com/wp-content/uploads/2016/05/Yubico_PIV_Tool_Command_Line_Guide_en.pdf
-//! [cc-web]: https://contributor-covenant.org/
-//! [cc-md]: https://github.com/iqlusioninc/yubikey-piv.rs/blob/main/CODE_OF_CONDUCT.md
-//! [BSDL]: https://opensource.org/licenses/BSD-2-Clause
+#![doc = include_str!("../README.md")]
+#![doc(
+    html_logo_url = "https://raw.githubusercontent.com/iqlusioninc/yubikey.rs/main/img/logo-sq.png"
+)]
+#![cfg_attr(docsrs, feature(doc_auto_cfg))]
+#![forbid(unsafe_code)]
+#![warn(
+    clippy::mod_module_files,
+    clippy::unwrap_used,
+    missing_docs,
+    rust_2018_idioms,
+    unused_lifetimes,
+    unused_qualifications
+)]

 // Adapted from yubico-piv-tool:
 // <https://github.com/Yubico/yubico-piv-tool/>
@@ -121,78 +43,49 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

-#![doc(
-    html_logo_url = "https://raw.githubusercontent.com/iqlusioninc/yubikey-piv.rs/main/img/logo.png",
-    html_root_url = "https://docs.rs/yubikey-piv/0.1.0"
-)]
-#![forbid(unsafe_code)]
-#![warn(
-    missing_docs,
-    rust_2018_idioms,
-    trivial_casts,
-    trivial_numeric_casts,
-    unused_lifetimes,
-    unused_qualifications
-)]
-
 mod apdu;
-pub mod cccid;
+mod cccid;
 pub mod certificate;
-pub mod chuid;
-pub mod config;
-pub mod error;
-pub mod key;
+mod chuid;
+mod config;
+mod consts;
+mod error;
 mod metadata;
 pub mod mgm;
 #[cfg(feature = "untested")]
-pub mod mscmap;
+mod mscmap;
 #[cfg(feature = "untested")]
-pub mod msroots;
-pub mod policy;
-pub mod readers;
+mod msroots;
+mod otp;
+pub mod piv;
+mod policy;
+pub mod reader;
 mod serialization;
-pub mod settings;
+mod setting;
 mod transaction;
-pub mod yubikey;
+mod yubikey;

-pub use self::{
-    error::Error,
-    key::Key,
-    mgm::MgmKey,
-    readers::Readers,
-    yubikey::{Serial, YubiKey},
+pub use crate::{
+    cccid::{CardId, CccId},
+    certificate::Certificate,
+    chuid::ChuId,
+    config::Config,
+    error::{Error, Result},
+    mgm::{MgmAlgorithmId, MgmKey, MgmType},
+    piv::Key,
+    policy::{PinPolicy, TouchPolicy},
+    reader::Context,
+    setting::{Setting, SettingSource},
+    yubikey::{CachedPin, Serial, Version, YubiKey},
 };

-/// Object identifiers
+#[cfg(feature = "untested")]
+pub use crate::{mscmap::MsContainer, msroots::MsRoots};
+
+pub use uuid::Uuid;
+
+/// Object identifiers: handles to particular objects stored on a YubiKey.
 pub type ObjectId = u32;

 /// Buffer type (self-zeroizing byte vector)
-pub(crate) type Buffer = zeroize::Zeroizing<Vec<u8>>;
-
-/// YubiKey max buffer size
-pub(crate) const CB_BUF_MAX: usize = 3072;
-
-/// YubiKey max object size
-pub(crate) const CB_OBJ_MAX: usize = CB_BUF_MAX - 9;
-pub(crate) const CB_OBJ_TAG_MIN: usize = 2; // 1 byte tag + 1 byte len
-#[cfg(feature = "untested")]
-pub(crate) const CB_OBJ_TAG_MAX: usize = CB_OBJ_TAG_MIN + 2; // 1 byte tag + 3 bytes len
-
-pub(crate) const TAG_ADMIN: u8 = 0x80;
-pub(crate) const TAG_ADMIN_FLAGS_1: u8 = 0x81;
-pub(crate) const TAG_ADMIN_SALT: u8 = 0x82;
-pub(crate) const TAG_ADMIN_TIMESTAMP: u8 = 0x83;
-pub(crate) const TAG_PROTECTED: u8 = 0x88;
-pub(crate) const TAG_PROTECTED_FLAGS_1: u8 = 0x81;
-pub(crate) const TAG_PROTECTED_MGM: u8 = 0x89;
-
-/// PIV Applet ID
-pub(crate) const PIV_AID: [u8; 5] = [0xa0, 0x00, 0x00, 0x03, 0x08];
-
-/// MGMT Applet ID.
-/// <https://developers.yubico.com/PIV/Introduction/Admin_access.html>
-#[cfg(feature = "untested")]
-pub(crate) const MGMT_AID: [u8; 8] = [0xa0, 0x00, 0x00, 0x05, 0x27, 0x47, 0x11, 0x17];
-
-/// YubiKey OTP Applet ID. Needed to query serial on YK4.
-pub(crate) const YK_AID: [u8; 8] = [0xa0, 0x00, 0x00, 0x05, 0x27, 0x20, 0x01, 0x01];
+pub type Buffer = zeroize::Zeroizing<Vec<u8>>;
@@ -30,21 +30,86 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

-use crate::{
-    error::Error, serialization::*, transaction::Transaction, Buffer, TAG_ADMIN, TAG_PROTECTED,
-};
-
-#[cfg(feature = "untested")]
-use crate::{CB_OBJ_MAX, CB_OBJ_TAG_MAX};
-
-#[cfg(feature = "untested")]
+use std::{iter, marker::PhantomData};
 use zeroize::Zeroizing;

+use crate::{
+    consts::{CB_OBJ_MAX, CB_OBJ_TAG_MAX},
+    serialization::*,
+    transaction::Transaction,
+    Buffer, Error, Result,
+};
+
+const TAG_ADMIN: u8 = 0x80;
+const TAG_PROTECTED: u8 = 0x88;
 pub const OBJ_ADMIN_DATA: u32 = 0x005f_ff00;
 pub const OBJ_PRINTED: u32 = 0x005f_c109;

+pub(crate) trait MetadataType: private::Sealed {}
+
+/// A type variable corresponding to PIN-protected metadata.
+pub(crate) enum Protected {}
+impl MetadataType for Protected {}
+
+/// A type variable corresponding to administrative metadata.
+pub(crate) enum Admin {}
+impl MetadataType for Admin {}
+
+/// Metadata stored in a YubiKey.
+pub(crate) struct Metadata<T: MetadataType> {
+    inner: Buffer,
+    _marker: PhantomData<T>,
+}
+
+/// PIN-protected metadata stored in a YubiKey.
+pub(crate) type ProtectedData = Metadata<Protected>;
+/// Administrative metadata stored in a YubiKey.
+pub(crate) type AdminData = Metadata<Admin>;
+
+impl<T: MetadataType> Default for Metadata<T> {
+    fn default() -> Self {
+        Metadata {
+            inner: Zeroizing::new(vec![]),
+            _marker: PhantomData,
+        }
+    }
+}
+
+impl<T: MetadataType> Metadata<T> {
+    /// Read metadata
+    pub(crate) fn read(txn: &Transaction<'_>) -> Result<Self> {
+        let data = txn.fetch_object(T::obj_id())?;
+        Ok(Metadata {
+            inner: Tlv::parse_single(data, T::tag())?,
+            _marker: PhantomData,
+        })
+    }
+
+    /// Write metadata
+    pub(crate) fn write(&self, txn: &Transaction<'_>) -> Result<()> {
+        if self.inner.len() > CB_OBJ_MAX - CB_OBJ_TAG_MAX {
+            return Err(Error::GenericError);
+        }
+
+        if self.inner.is_empty() {
+            return Self::delete(txn);
+        }
+
+        let mut buf = Zeroizing::new(vec![0u8; CB_OBJ_MAX]);
+        let len = Tlv::write(&mut buf, T::tag(), &self.inner)?;
+
+        txn.save_object(T::obj_id(), &buf[..len])
+    }
+
+    /// Delete metadata
+    pub(crate) fn delete(txn: &Transaction<'_>) -> Result<()> {
+        txn.save_object(T::obj_id(), &[])
+    }
+
    /// Get metadata item
-pub(crate) fn get_item(mut data: &[u8], tag: u8) -> Result<&[u8], Error> {
+    pub(crate) fn get_item(&self, tag: u8) -> Result<&[u8]> {
+        let mut data = &self.inner[..];
+
        while !data.is_empty() {
            let (remaining, tlv) = Tlv::parse(data)?;
            data = remaining;
@@ -59,26 +124,18 @@ pub(crate) fn get_item(mut data: &[u8], tag: u8) -> Result<&[u8], Error> {
    }

    /// Set metadata item
-#[cfg(feature = "untested")]
-pub(crate) fn set_item(
-    data: &mut [u8],
-    pcb_data: &mut usize,
-    cb_data_max: usize,
-    tag: u8,
-    p_item: &[u8],
-) -> Result<(), Error> {
+    pub(crate) fn set_item(&mut self, tag: u8, item: &[u8]) -> Result<()> {
        let mut cb_temp: usize = 0;
        let mut tag_temp: u8 = 0;
        let mut cb_len: usize = 0;
-    let cb_item = p_item.len();

        let mut offset = 0;

-    while offset < *pcb_data {
-        tag_temp = data[offset];
+        while offset < self.inner.len() {
+            tag_temp = self.inner[offset];
            offset += 1;

-        cb_len = get_length(&data[offset..], &mut cb_temp);
+            cb_len = get_length(&self.inner[offset..], &mut cb_temp);
            offset += cb_len;

            if tag_temp == tag {
@@ -89,13 +146,18 @@ pub(crate) fn set_item(
        }

        if tag_temp != tag {
-        if cb_item == 0 {
+            if item.is_empty() {
                // We've been asked to delete an existing item that isn't in the blob
                return Ok(());
            }

            // We did not find an existing tag, append
-        *pcb_data += Tlv::write(&mut data[*pcb_data..], tag, p_item)?;
+            assert_eq!(offset, self.inner.len());
+            self.inner.extend(iter::repeat_n(
+                0,
+                1 + get_length_size(item.len()) + item.len(),
+            ));
+            Tlv::write(&mut self.inner[offset..], tag, item)?;

            return Ok(());
        }
@@ -103,84 +165,53 @@ pub(crate) fn set_item(
        // Found tag

        // Check length, if it matches, overwrite
-    if cb_temp == cb_item {
-        data[offset..offset + cb_item].copy_from_slice(p_item);
+        if cb_temp == item.len() {
+            self.inner[offset..offset + item.len()].copy_from_slice(item);
            return Ok(());
        }

        // Length doesn't match, expand/shrink to fit
        let next_offset = offset + cb_temp;
        // Must be signed to have negative offsets
-    let cb_moved: isize = (cb_item as isize - cb_temp as isize)
-        + if cb_item != 0 {
-            get_length_size(cb_item) as isize
-        } else {
+        let cb_moved: isize = (item.len() as isize - cb_temp as isize)
+            + if item.is_empty() {
                // For tag, if deleting
                -1
+            } else {
+                get_length_size(item.len()) as isize
            }
            // Accounts for different length encoding
            - cb_len as isize;

        // If length would cause buffer overflow, return error
-    if (*pcb_data as isize + cb_moved) as usize > cb_data_max {
+        if (self.inner.len() as isize + cb_moved) as usize > CB_OBJ_MAX {
            return Err(Error::GenericError);
        }

        // Move remaining data
-    data.copy_within(
-        next_offset..*pcb_data,
+        let orig_len = self.inner.len();
+        if cb_moved > 0 {
+            self.inner.extend(iter::repeat_n(0, cb_moved as usize));
+        }
+        self.inner.copy_within(
+            next_offset..orig_len,
            (next_offset as isize + cb_moved) as usize,
        );
-    *pcb_data = (*pcb_data as isize + cb_moved) as usize;
+        self.inner
+            .resize((orig_len as isize + cb_moved) as usize, 0);

        // Re-encode item and insert
-    if cb_item != 0 {
+        if !item.is_empty() {
            offset -= cb_len;
-        offset += set_length(&mut data[offset..], cb_item)?;
-        data[offset..offset + cb_item].copy_from_slice(p_item);
+            offset += set_length(&mut self.inner[offset..], item.len())?;
+            self.inner[offset..offset + item.len()].copy_from_slice(item);
        }

        Ok(())
    }
-
-/// Read metadata
-pub(crate) fn read(txn: &Transaction<'_>, tag: u8) -> Result<Buffer, Error> {
-    let obj_id = match tag {
-        TAG_ADMIN => OBJ_ADMIN_DATA,
-        TAG_PROTECTED => OBJ_PRINTED,
-        _ => return Err(Error::InvalidObject),
-    };
-
-    let data = txn.fetch_object(obj_id)?;
-    Tlv::parse_single(data, tag)
-}
-
-/// Write metadata
-#[cfg(feature = "untested")]
-pub(crate) fn write(txn: &Transaction<'_>, tag: u8, data: &[u8]) -> Result<(), Error> {
-    if data.len() > CB_OBJ_MAX - CB_OBJ_TAG_MAX {
-        return Err(Error::GenericError);
-    }
-
-    let obj_id = match tag {
-        TAG_ADMIN => OBJ_ADMIN_DATA,
-        TAG_PROTECTED => OBJ_PRINTED,
-        _ => return Err(Error::InvalidObject),
-    };
-
-    if data.is_empty() {
-        // Deleting metadata
-        return txn.save_object(obj_id, &[]);
-    }
-
-    let mut buf = Zeroizing::new(vec![0u8; CB_OBJ_MAX]);
-    let len = Tlv::write(&mut buf, tag, data)?;
-
-    txn.save_object(obj_id, &buf[..len])
 }

 /// Get the size of a length tag for the given length
-#[cfg(feature = "untested")]
 fn get_length_size(length: usize) -> usize {
    if length < 0x80 {
        1
@@ -190,3 +221,27 @@ fn get_length_size(length: usize) -> usize {
        3
    }
 }
+
+mod private {
+    use super::*;
+    pub trait Sealed {
+        fn tag() -> u8;
+        fn obj_id() -> u32;
+    }
+    impl Sealed for Protected {
+        fn tag() -> u8 {
+            TAG_PROTECTED
+        }
+        fn obj_id() -> u32 {
+            OBJ_PRINTED
+        }
+    }
+    impl Sealed for Admin {
+        fn tag() -> u8 {
+            TAG_ADMIN
+        }
+        fn obj_id() -> u32 {
+            OBJ_ADMIN_DATA
+        }
+    }
+}
@@ -1,7 +1,4 @@
-//! MS Container Map Records
-//!
-//! These appear(?) to be defined in Microsoft's Smart Card Minidriver Specification:
-//! <https://docs.microsoft.com/en-us/previous-versions/windows/hardware/design/dn631754(v=vs.85)>
+//! MS Container Map Records.

 // Adapted from yubico-piv-tool:
 // <https://github.com/Yubico/yubico-piv-tool/>
@@ -33,54 +30,56 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

-use crate::{error::Error, key::SlotId, serialization::*, yubikey::YubiKey, CB_OBJ_MAX};
+use crate::{consts::CB_OBJ_MAX, piv::SlotId, serialization::*, Error, Result, YubiKey};
 use log::error;
-use std::{
-    convert::{TryFrom, TryInto},
-    fmt::{self, Debug},
-};
-
-/// Container name length
-const CONTAINER_NAME_LEN: usize = 40;
-
-/// Container record length: 27 = 80 + 1 + 1 + 2 + 1 + 1 + 1 + 20
-const CONTAINER_REC_LEN: usize = (2 * CONTAINER_NAME_LEN) + 27;

 const OBJ_MSCMAP: u32 = 0x005f_ff10;

 const TAG_MSCMAP: u8 = 0x81;

-/// MS Container Map(?) Records
-#[derive(Copy, Clone)]
-pub struct Container {
-    /// Container name
-    pub name: [u16; CONTAINER_NAME_LEN],
+/// MS Container Map records.
+///
+/// Defined in Microsoft's Smart Card Minidriver Specification:
+/// <https://docs.microsoft.com/en-us/previous-versions/windows/hardware/design/dn631754(v=vs.85)>
+#[derive(Clone, Debug)]
+pub struct MsContainer {
+    /// Container name.
+    pub name: [u16; Self::NAME_LEN],

-    /// Card slot
+    /// Card slot.
    pub slot: SlotId,

-    /// Key spec
+    /// Key spec.
    pub key_spec: u8,

-    /// Key size in bits
+    /// Key size in bits.
    pub key_size_bits: u16,

-    /// Flags
+    /// Flags.
    pub flags: u8,

-    /// PIN ID
+    /// PIN ID.
    pub pin_id: u8,

-    /// Associated ECHD(?) container (typo of "ecdh" perhaps?)
+    /// Associated ECHD container.
    pub associated_echd_container: u8,

-    /// Cert fingerprint
-    pub cert_fingerprint: [u8; 20],
+    /// Cert fingerprint.
+    pub cert_fingerprint: [u8; Self::CERT_FINGERPRINT_LEN],
 }

-impl Container {
-    /// Read MS Container Map records
-    pub fn read_mscmap(yubikey: &mut YubiKey) -> Result<Vec<Self>, Error> {
+impl MsContainer {
+    /// Container name length in UTF-16 chars.
+    const NAME_LEN: usize = 40;
+
+    /// Container record length: 27 = 80 + 1 + 1 + 2 + 1 + 1 + 1 + 20
+    const REC_LEN: usize = (2 * Self::NAME_LEN) + 27;
+
+    /// Length of a certificate fingerprint.
+    const CERT_FINGERPRINT_LEN: usize = 20;
+
+    /// Read MS Container Map records.
+    pub fn read_mscmap(yubikey: &mut YubiKey) -> Result<Vec<Self>> {
        let txn = yubikey.begin_transaction()?;
        let response = txn.fetch_object(OBJ_MSCMAP)?;
        let mut containers = vec![];
@@ -98,17 +97,17 @@ impl Container {
            return Err(Error::InvalidObject);
        }

-        for chunk in tlv.value.chunks_exact(CONTAINER_REC_LEN) {
-            containers.push(Container::new(chunk)?);
+        for chunk in tlv.value.chunks_exact(Self::REC_LEN) {
+            containers.push(MsContainer::new(chunk)?);
        }

        Ok(containers)
    }

    /// Write MS Container Map records.
-    pub fn write_mscmap(yubikey: &mut YubiKey, containers: &[Self]) -> Result<(), Error> {
+    pub fn write_mscmap(yubikey: &mut YubiKey, containers: &[Self]) -> Result<()> {
        let n_containers = containers.len();
-        let data_len = n_containers * CONTAINER_REC_LEN;
+        let data_len = n_containers * Self::REC_LEN;

        let txn = yubikey.begin_transaction()?;

@@ -118,7 +117,7 @@ impl Container {

        let mut buf = [0u8; CB_OBJ_MAX];
        let offset = Tlv::write_as(&mut buf, TAG_MSCMAP, data_len, |buf| {
-            for (i, chunk) in buf.chunks_exact_mut(CONTAINER_REC_LEN).enumerate() {
+            for (i, chunk) in buf.chunks_exact_mut(Self::REC_LEN).enumerate() {
                chunk.copy_from_slice(&containers[i].to_bytes());
            }
        })?;
@@ -126,36 +125,35 @@ impl Container {
        txn.save_object(OBJ_MSCMAP, &buf[..offset])
    }

-    /// Parse a container record from a byte slice
-    pub fn new(bytes: &[u8]) -> Result<Self, Error> {
-        if bytes.len() != CONTAINER_REC_LEN {
+    /// Parse a container record from a byte slice.
+    pub fn new(bytes: &[u8]) -> Result<Self> {
+        if bytes.len() != Self::REC_LEN {
            error!(
                "couldn't parse PIV container: expected {}-bytes, got {}-bytes",
-                CONTAINER_REC_LEN,
+                Self::REC_LEN,
                bytes.len()
            );
            return Err(Error::ParseError);
        }

-        let mut name = [0u16; CONTAINER_NAME_LEN];
-        let name_bytes_len = CONTAINER_NAME_LEN * 2;
+        let mut name = [0u16; Self::NAME_LEN];
+        let name_bytes_len = Self::NAME_LEN * 2;

        for (i, chunk) in bytes[..name_bytes_len].chunks_exact(2).enumerate() {
-            name[i] = u16::from_le_bytes(chunk.try_into().unwrap());
+            name[i] = u16::from_le_bytes([chunk[0], chunk[1]]);
        }

        let mut cert_fingerprint = [0u8; 20];
        cert_fingerprint.copy_from_slice(&bytes[(bytes.len() - 20)..]);

-        Ok(Container {
+        Ok(Self {
            name,
            slot: bytes[name_bytes_len].try_into()?,
            key_spec: bytes[name_bytes_len + 1],
-            key_size_bits: u16::from_le_bytes(
-                bytes[(name_bytes_len + 2)..(name_bytes_len + 4)]
-                    .try_into()
-                    .unwrap(),
-            ),
+            key_size_bits: u16::from_le_bytes([
+                bytes[name_bytes_len + 2],
+                bytes[name_bytes_len + 3],
+            ]),
            flags: bytes[name_bytes_len + 4],
            pin_id: bytes[name_bytes_len + 5],
            associated_echd_container: bytes[name_bytes_len + 6],
@@ -163,16 +161,17 @@ impl Container {
        })
    }

-    /// Parse the container name as a UTF-16 string
-    pub fn parse_name(&self) -> Result<String, Error> {
+    /// Parse the container name as a UTF-16 string.
+    pub fn parse_name(&self) -> Result<String> {
        String::from_utf16(&self.name).map_err(|_| Error::ParseError)
    }

-    /// Serialize a container record as a byte size
-    pub fn to_bytes(&self) -> [u8; CONTAINER_REC_LEN] {
-        let mut bytes = Vec::with_capacity(CONTAINER_REC_LEN);
+    /// Serialize a container record as a byte size.
+    pub fn to_bytes(&self) -> [u8; Self::REC_LEN] {
+        // TODO(tarcieri): use array instead of `Vec`
+        let mut bytes = Vec::with_capacity(Self::REC_LEN);

-        for i in 0..CONTAINER_NAME_LEN {
+        for i in 0..Self::NAME_LEN {
            bytes.extend_from_slice(&self.name[i].to_le_bytes());
        }

@@ -183,36 +182,17 @@ impl Container {
        bytes.push(self.pin_id);
        bytes.push(self.associated_echd_container);
        bytes.extend_from_slice(&self.cert_fingerprint);
-
-        // TODO(tarcieri): use TryInto here when const generics are available
-        let mut result = [0u8; CONTAINER_REC_LEN];
-        result.copy_from_slice(&bytes);
-        result
+        bytes
+            .as_slice()
+            .try_into()
+            .expect("should be REC_LEN-sized")
    }
 }

-impl Debug for Container {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(
-            f,
-            "PivContainer {{ name: {:?}, slot: {:?}, key_spec: {}, key_size_bits: {}, \
-             flags: {}, pin_id: {}, associated_echd_container: {}, cert_fingerprint: {:?} }}",
-            &self.name[..],
-            self.slot,
-            self.key_spec,
-            self.key_size_bits,
-            self.flags,
-            self.pin_id,
-            self.associated_echd_container,
-            &self.cert_fingerprint[..]
-        )
-    }
-}
-
-impl<'a> TryFrom<&'a [u8]> for Container {
+impl<'a> TryFrom<&'a [u8]> for MsContainer {
    type Error = Error;

-    fn try_from(bytes: &'a [u8]) -> Result<Self, Error> {
+    fn try_from(bytes: &'a [u8]) -> Result<Self> {
        Self::new(bytes)
    }
 }
@@ -1,11 +1,4 @@
-//! `msroots`: PKCS#7 formatted certificate store for enterprise trusted roots.
-//!
-//! This `msroots` file contains a bag of certificates with empty content and
-//! an empty signature, allowing an enterprise root certificate truststore to
-//! be written to and read from a YubiKey.
-//!
-//! For more information, see:
-//! <https://docs.microsoft.com/en-us/windows-hardware/drivers/smartcard/developer-guidelines#-interoperability-with-msroots>
+//! PKCS#7 formatted certificate store for enterprise trusted roots.

 // Adapted from yubico-piv-tool:
 // <https://github.com/Yubico/yubico-piv-tool/>
@@ -37,8 +30,11 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

-use crate::{error::Error, serialization::*, yubikey::YubiKey};
-use crate::{CB_OBJ_MAX, CB_OBJ_TAG_MAX};
+use crate::{
+    consts::{CB_OBJ_MAX, CB_OBJ_TAG_MAX},
+    serialization::*,
+    Error, Result, YubiKey,
+};
 use log::error;

 const OBJ_MSROOTS1: u32 = 0x005f_ff11;
@@ -53,17 +49,24 @@ const OBJ_MSROOTS5: u32 = 0x005f_ff15;
 const TAG_MSROOTS_END: u8 = 0x82;
 const TAG_MSROOTS_MID: u8 = 0x83;

-/// `msroots` file: PKCS#7-formatted certificate store for enterprise trust roots
+/// PKCS#7-formatted certificate store for enterprise trust roots.
+///
+/// The `msroots` file contains a bag of certificates with empty content and
+/// an empty signature, allowing an enterprise root certificate truststore to
+/// be written to and read from a YubiKey.
+///
+/// For more information, see:
+/// <https://docs.microsoft.com/en-us/windows-hardware/drivers/smartcard/developer-guidelines#-interoperability-with-msroots>
 pub struct MsRoots(Vec<u8>);

 impl MsRoots {
    /// Initialize a local certificate struct from the given bytebuffer
-    pub fn new(msroots: impl AsRef<[u8]>) -> Result<Self, Error> {
+    pub fn new(msroots: impl AsRef<[u8]>) -> Result<Self> {
        Ok(MsRoots(msroots.as_ref().into()))
    }

    /// Read `msroots` file from YubiKey
-    pub fn read(yubikey: &mut YubiKey) -> Result<Option<Self>, Error> {
+    pub fn read(yubikey: &mut YubiKey) -> Result<Option<Self>> {
        let txn = yubikey.begin_transaction()?;

        // allocate first page
@@ -93,21 +96,20 @@ impl MsRoots {
            }
        }

-        MsRoots::new(&data).map(Some).map_err(|e| {
-            error!("error parsing msroots: {:?}", e);
-            e
-        })
+        MsRoots::new(&data)
+            .map(Some)
+            .inspect_err(|e| error!("error parsing msroots: {:?}", e))
    }

    /// Write `msroots` file to YubiKey
-    pub fn write(&self, yubikey: &mut YubiKey) -> Result<(), Error> {
+    pub fn write(&self, yubikey: &mut YubiKey) -> Result<()> {
        let mut buf = [0u8; CB_OBJ_MAX];
        let mut offset: usize;
        let mut data_offset: usize = 0;
        let mut data_chunk: usize;
        let data = &self.0;
        let data_len = data.len();
-        let n_objs: usize;
+
        let txn = yubikey.begin_transaction()?;

        if data_len == 0 {
@@ -115,7 +117,7 @@ impl MsRoots {
        }

        // Calculate number of objects required to store blob
-        n_objs = (data_len / (CB_OBJ_MAX - CB_OBJ_TAG_MAX)) + 1;
+        let n_objs: usize = (data_len / (CB_OBJ_MAX - CB_OBJ_TAG_MAX)) + 1;

        if n_objs > 5 {
            return Err(Error::SizeError);
@@ -0,0 +1,5 @@
+/// YubiKey OTP Applet Name
+pub(crate) const APPLET_NAME: &str = "YubiKey OTP";
+
+/// YubiKey OTP Applet ID. Needed to query serial on YK4.
+pub(crate) const APPLET_ID: &[u8] = &[0xa0, 0x00, 0x00, 0x05, 0x27, 0x20, 0x01, 0x01];
@@ -1,11 +1,12 @@
 //! Enums representing key policies.

-use crate::{error::Error, serialization::Tlv};
+use crate::{serialization::Tlv, Error, Result};

 /// Specifies how often the PIN needs to be entered for access to the credential in a
-/// given slot. This policy must be set upon key generation or importation, and cannot be
-/// changed later.
-#[derive(Clone, Copy, Debug, PartialEq)]
+/// given slot.
+///
+/// This policy must be set when keys are generated or imported, and cannot be changed later.
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
 pub enum PinPolicy {
    /// Use the default PIN policy for the slot. See the slot's documentation for details.
    Default,
@@ -34,10 +35,24 @@ impl From<PinPolicy> for u8 {
    }
 }

+impl TryFrom<u8> for PinPolicy {
+    type Error = Error;
+
+    fn try_from(value: u8) -> Result<Self> {
+        match value {
+            0 => Ok(PinPolicy::Default),
+            1 => Ok(PinPolicy::Never),
+            2 => Ok(PinPolicy::Once),
+            3 => Ok(PinPolicy::Always),
+            _ => Err(Error::GenericError),
+        }
+    }
+}
+
 impl PinPolicy {
    /// Writes the `PinPolicy` in the format the YubiKey expects during key generation or
    /// importation.
-    pub(crate) fn write(self, buf: &mut [u8]) -> Result<usize, Error> {
+    pub(crate) fn write(self, buf: &mut [u8]) -> Result<usize> {
        match self {
            PinPolicy::Default => Ok(0),
            _ => Tlv::write(buf, 0xaa, &[self.into()]),
@@ -46,9 +61,10 @@ impl PinPolicy {
 }

 /// Specifies under what conditions a physical touch on the metal contact is required, in
-/// addition to the [`PinPolicy`]. This policy must be set upon key generation or
-/// importation, and cannot be changed later.
-#[derive(Clone, Copy, Debug, PartialEq)]
+/// addition to the [`PinPolicy`].
+///
+/// This policy must be set when keys are generated or imported, and cannot be changed later.
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
 pub enum TouchPolicy {
    /// Use the default touch policy for the slot.
    Default,
@@ -81,10 +97,24 @@ impl From<TouchPolicy> for u8 {
 impl TouchPolicy {
    /// Writes the `TouchPolicy` in the format the YubiKey expects during key generation
    /// or importation.
-    pub(crate) fn write(self, buf: &mut [u8]) -> Result<usize, Error> {
+    pub(crate) fn write(self, buf: &mut [u8]) -> Result<usize> {
        match self {
            TouchPolicy::Default => Ok(0),
            _ => Tlv::write(buf, 0xab, &[self.into()]),
        }
    }
 }
+
+impl TryFrom<u8> for TouchPolicy {
+    type Error = Error;
+
+    fn try_from(value: u8) -> Result<Self> {
+        match value {
+            0 => Ok(TouchPolicy::Default),
+            1 => Ok(TouchPolicy::Never),
+            2 => Ok(TouchPolicy::Always),
+            3 => Ok(TouchPolicy::Cached),
+            _ => Err(Error::GenericError),
+        }
+    }
+}
@@ -1,18 +1,18 @@
-//! Support for enumerating available readers
+//! Support for enumerating available PC/SC card readers.

-use crate::{error::Error, yubikey::YubiKey};
+use crate::{Error, Result, YubiKey};
 use std::{
    borrow::Cow,
-    convert::TryInto,
    ffi::CStr,
+    fmt,
    sync::{Arc, Mutex},
 };

 /// Iterator over connected readers
 pub type Iter<'ctx> = std::vec::IntoIter<Reader<'ctx>>;

-/// Enumeration support for available readers
-pub struct Readers {
+/// PC/SC reader context: used to enumerate available PC/SC [`Reader`]s.
+pub struct Context {
    /// PC/SC context
    ctx: Arc<Mutex<pcsc::Context>>,

@@ -20,10 +20,16 @@ pub struct Readers {
    reader_names: Vec<u8>,
 }

-impl Readers {
+impl fmt::Debug for Context {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("Context").finish_non_exhaustive()
+    }
+}
+
+impl Context {
    /// Open a PC/SC context, which can be used to enumerate available PC/SC
    /// readers (which can be used to connect to YubiKeys).
-    pub fn open() -> Result<Self, Error> {
+    pub fn open() -> Result<Self> {
        let ctx = pcsc::Context::establish(pcsc::Scope::System)?;
        let reader_names = vec![0u8; ctx.list_readers_len()?];
        Ok(Self {
@@ -32,12 +38,13 @@ impl Readers {
        })
    }

-    /// Iterate over the available readers
-    pub fn iter(&mut self) -> Result<Iter<'_>, Error> {
+    /// Iterate over the available readers.
+    pub fn iter(&mut self) -> Result<Iter<'_>> {
        let Self { ctx, reader_names } = self;

        let reader_cstrs: Vec<_> = {
-            let c = ctx.lock().unwrap();
+            // TODO(tarcieri): better error?
+            let c = ctx.lock().map_err(|_| Error::GenericError)?;

            // ensure PC/SC context is valid
            c.is_valid()?;
@@ -45,6 +52,7 @@ impl Readers {
            c.list_readers(reader_names)?.collect()
        };

+        #[allow(clippy::needless_collect)]
        let readers: Vec<_> = reader_cstrs
            .iter()
            .map(|name| Reader::new(name, Arc::clone(ctx)))
@@ -54,7 +62,7 @@ impl Readers {
    }
 }

-/// An individual connected reader
+/// An individual connected PC/SC card reader.
 pub struct Reader<'ctx> {
    /// Name of this reader
    name: &'ctx CStr,
@@ -64,26 +72,27 @@ pub struct Reader<'ctx> {
 }

 impl<'ctx> Reader<'ctx> {
-    /// Create a new reader from its name and context
+    /// Create a new reader from its name and context.
    fn new(name: &'ctx CStr, ctx: Arc<Mutex<pcsc::Context>>) -> Self {
        // TODO(tarcieri): open devices, determine they're YubiKeys, get serial?
        Self { name, ctx }
    }

-    /// Get this reader's name
+    /// Get this reader's name.
    pub fn name(&self) -> Cow<'_, str> {
        // TODO(tarcieri): is lossy ok here? try to avoid lossiness?
        self.name.to_string_lossy()
    }

-    /// Open a connection to this reader, returning a `YubiKey` if successful
-    pub fn open(&self) -> Result<YubiKey, Error> {
+    /// Open a connection to this reader, returning a `YubiKey` if successful.
+    pub fn open(&self) -> Result<YubiKey> {
        self.try_into()
    }

-    /// Connect to this reader, returning its `pcsc::Card`
-    pub(crate) fn connect(&self) -> Result<pcsc::Card, Error> {
-        let ctx = self.ctx.lock().unwrap();
+    /// Connect to this reader, returning its `pcsc::Card`.
+    pub(crate) fn connect(&self) -> Result<pcsc::Card> {
+        // TODO(tarcieri): better error?
+        let ctx = self.ctx.lock().map_err(|_| Error::GenericError)?;
        Ok(ctx.connect(self.name, pcsc::ShareMode::Shared, pcsc::Protocols::T1)?)
    }
 }
@@ -30,7 +30,7 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

-use crate::{error::Error, Buffer, ObjectId, CB_OBJ_TAG_MIN};
+use crate::{consts::CB_OBJ_TAG_MIN, Buffer, Error, ObjectId, Result};

 pub const OBJ_DISCOVERY: u32 = 0x7e;

@@ -44,24 +44,27 @@ pub(crate) struct Tlv<'a> {

 impl<'a> Tlv<'a> {
    /// Parses a `Tlv` from a buffer, returning the remainder of the buffer.
-    pub(crate) fn parse(buffer: &'a [u8]) -> Result<(&'a [u8], Self), Error> {
+    pub(crate) fn parse(buffer: &'a [u8]) -> Result<(&'a [u8], Self)> {
        if buffer.len() < CB_OBJ_TAG_MIN || !has_valid_length(&buffer[1..], buffer.len() - 1) {
            return Err(Error::SizeError);
        }

        let tag = buffer[0];
-
        let mut len = 0;
        let offset = 1 + get_length(&buffer[1..], &mut len);
+        let buffer = buffer.get(offset..).ok_or(Error::SizeError)?;

-        let (value, buffer) = buffer[offset..].split_at(len);
-
+        if buffer.len() >= len {
+            let (value, buffer) = buffer.split_at(len);
            Ok((buffer, Tlv { tag, value }))
+        } else {
+            Err(Error::SizeError)
+        }
    }

    /// Takes a [`Buffer`] containing a single `Tlv` with the given tag, and returns a
    /// `Buffer` containing only the value part of the `Tlv`.
-    pub(crate) fn parse_single(mut buffer: Buffer, tag: u8) -> Result<Buffer, Error> {
+    pub(crate) fn parse_single(mut buffer: Buffer, tag: u8) -> Result<Buffer> {
        if buffer.len() < CB_OBJ_TAG_MIN || !has_valid_length(&buffer[1..], buffer.len() - 1) {
            return Err(Error::SizeError);
        }
@@ -79,7 +82,7 @@ impl<'a> Tlv<'a> {
    }

    /// Writes a TLV to the given buffer.
-    pub(crate) fn write(buffer: &mut [u8], tag: u8, value: &[u8]) -> Result<usize, Error> {
+    pub(crate) fn write(buffer: &mut [u8], tag: u8, value: &[u8]) -> Result<usize> {
        if buffer.len() < CB_OBJ_TAG_MIN {
            return Err(Error::SizeError);
        }
@@ -103,7 +106,7 @@ impl<'a> Tlv<'a> {
        tag: u8,
        length: usize,
        value: Gen,
-    ) -> Result<usize, Error>
+    ) -> Result<usize>
    where
        Gen: FnOnce(&mut [u8]),
    {
@@ -124,7 +127,7 @@ impl<'a> Tlv<'a> {
 }

 /// Set length
-pub(crate) fn set_length(buffer: &mut [u8], length: usize) -> Result<usize, Error> {
+pub(crate) fn set_length(buffer: &mut [u8], length: usize) -> Result<usize> {
    if length < 0x80 {
        if buffer.is_empty() {
            Err(Error::SizeError)
@@ -0,0 +1,127 @@
+//! Configuration setting values parsed from the environment and config file:
+//! `/etc/yubico/yubikeypiv.conf`
+
+// Adapted from yubico-piv-tool:
+// <https://github.com/Yubico/yubico-piv-tool/>
+//
+// Copyright (c) 2014-2016 Yubico AB
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//   * Redistributions of source code must retain the above copyright
+//     notice, this list of conditions and the following disclaimer.
+//
+//   * Redistributions in binary form must reproduce the above
+//     copyright notice, this list of conditions and the following
+//     disclaimer in the documentation and/or other materials provided
+//     with the distribution.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+/// Default location of the YubiKey PIV configuration file
+pub const DEFAULT_CONFIG_FILE: &str = "/etc/yubico/yubikeypiv.conf";
+
+use std::{
+    env,
+    fs::File,
+    io::{BufRead, BufReader},
+};
+
+/// Source of how a setting was configured.
+#[derive(Clone, Copy, Debug, Default, Eq, PartialEq)]
+pub enum SettingSource {
+    /// User-specified setting: sourced via `YUBIKEY_PIV_*` environment vars.
+    User,
+
+    /// Admin-specified setting: sourced via the `/etc/yubico/yubikeypiv.conf`
+    /// configuration file.
+    Admin,
+
+    /// Default setting.
+    #[default]
+    Default,
+}
+
+/// Setting booleans: configuration values sourced from a file or the environment.
+///
+/// These can be configured globally in `/etc/yubico/yubikeypiv.conf` by a
+/// system administrator, or by the local user via `YUBIKEY_PIV_*` environment
+/// variables.
+#[derive(Copy, Clone, Debug, Default)]
+pub struct Setting {
+    /// Boolean value
+    pub value: bool,
+
+    /// Source of the configuration setting (user, admin, or default)
+    pub source: SettingSource,
+}
+
+impl Setting {
+    /// Get a setting by name.
+    pub fn get(key: &str, default: bool) -> Self {
+        Self::from_file(key)
+            .or_else(|| Self::from_env(key))
+            .unwrap_or(Self {
+                value: default,
+                source: SettingSource::Default,
+            })
+    }
+
+    /// Get a boolean config value from the provided config file
+    fn from_file(key: &str) -> Option<Self> {
+        if let Ok(file) = File::open(DEFAULT_CONFIG_FILE) {
+            for line in BufReader::new(file).lines() {
+                let line = match line {
+                    Ok(line) => line,
+                    _ => continue,
+                };
+
+                if line.starts_with('#') || line.starts_with('\r') || line.starts_with('\n') {
+                    continue;
+                }
+
+                let (name, value) = {
+                    let mut parts = line.splitn(2, '=');
+                    let name = parts.next();
+                    let value = parts.next();
+                    match (name, value, parts.next()) {
+                        (Some(name), Some(value), None) => (name.trim(), value.trim()),
+                        _ => continue,
+                    }
+                };
+
+                if name == key {
+                    return Some(Setting {
+                        source: SettingSource::Admin,
+                        value: value == "1" || value == "true",
+                    });
+                }
+            }
+        }
+
+        None
+    }
+
+    /// Get a setting boolean from an environment variable
+    fn from_env(key: &str) -> Option<Self> {
+        env::var(format!("YUBIKEY_PIV_{key}"))
+            .ok()
+            .map(|value| Setting {
+                source: SettingSource::User,
+                value: value == "1" || value == "true",
+            })
+    }
+}
@@ -1,138 +0,0 @@
-//! Configuration setting values parsed from the environment and config file:
-//! `/etc/yubico/yubikeypiv.conf`
-
-// Adapted from yubico-piv-tool:
-// <https://github.com/Yubico/yubico-piv-tool/>
-//
-// Copyright (c) 2014-2016 Yubico AB
-// All rights reserved.
-//
-// Redistribution and use in source and binary forms, with or without
-// modification, are permitted provided that the following conditions are
-// met:
-//
-//   * Redistributions of source code must retain the above copyright
-//     notice, this list of conditions and the following disclaimer.
-//
-//   * Redistributions in binary form must reproduce the above
-//     copyright notice, this list of conditions and the following
-//     disclaimer in the documentation and/or other materials provided
-//     with the distribution.
-//
-// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-/// Default location of the YubiKey PIV configuration file
-pub const DEFAULT_CONFIG_FILE: &str = "/etc/yubico/yubikeypiv.conf";
-
-use std::{
-    env,
-    fs::File,
-    io::{BufRead, BufReader},
-};
-
-/// Source of how a setting was configured
-#[derive(Clone, Copy, Debug, Eq, PartialEq)]
-pub enum Source {
-    /// User-specified setting
-    User,
-
-    /// Admin-specified setting
-    Admin,
-
-    /// Default setting
-    Default,
-}
-
-/// Setting booleans
-#[derive(Copy, Clone, Debug)]
-pub struct BoolValue {
-    /// Boolean value
-    pub value: bool,
-
-    /// Source of the configuration setting (user/admin/default)
-    pub source: Source,
-}
-
-impl BoolValue {
-    /// Get a [`BoolValue`] value
-    pub fn get(key: &str, def: bool) -> Self {
-        let mut setting = get_setting_from_file(key);
-
-        if setting.source == Source::Default {
-            setting = get_setting_from_env(key);
-        }
-
-        if setting.source == Source::Default {
-            setting.value = def;
-        }
-
-        setting
-    }
-}
-
-/// Get a boolean config value
-fn get_setting_from_file(key: &str) -> BoolValue {
-    let mut setting: BoolValue = BoolValue {
-        value: false,
-        source: Source::Default,
-    };
-
-    let file = match File::open(DEFAULT_CONFIG_FILE) {
-        Ok(f) => f,
-        Err(_) => return setting,
-    };
-
-    for line in BufReader::new(file).lines() {
-        let line = match line {
-            Ok(line) => line,
-            _ => continue,
-        };
-
-        if line.starts_with('#') || line.starts_with('\r') || line.starts_with('\n') {
-            continue;
-        }
-
-        let (name, value) = {
-            let mut parts = line.splitn(1, '=');
-            let name = parts.next();
-            let value = parts.next();
-            match (name, value, parts.next()) {
-                (Some(name), Some(value), None) => (name.trim(), value.trim()),
-                _ => continue,
-            }
-        };
-
-        if name == key {
-            setting.source = Source::Admin;
-            setting.value = value == "1" || value == "true";
-            break;
-        }
-    }
-
-    setting
-}
-
-/// Get a setting boolean from an environment variable
-fn get_setting_from_env(key: &str) -> BoolValue {
-    let mut setting: BoolValue = BoolValue {
-        value: false,
-        source: Source::Default,
-    };
-
-    if let Ok(value) = env::var(format!("YUBIKEY_PIV_{}", key)) {
-        setting.source = Source::User;
-        setting.value = value == "1" || value == "true";
-    }
-
-    setting
-}
@@ -2,19 +2,21 @@

 use crate::{
    apdu::Response,
-    apdu::{Ins, StatusWords, APDU},
-    error::Error,
-    key::{AlgorithmId, SlotId},
+    apdu::{Apdu, Ins, StatusWords},
+    consts::{CB_BUF_MAX, CB_OBJ_MAX},
+    error::{Error, Result},
+    mgm::MgmKey,
+    otp,
+    piv::{self, AlgorithmId, SlotId},
    serialization::*,
    yubikey::*,
-    Buffer, ObjectId, CB_BUF_MAX, CB_OBJ_MAX, PIV_AID, YK_AID,
+    Buffer, ObjectId,
 };
 use log::{error, trace};
-use std::convert::TryInto;
 use zeroize::Zeroizing;

 #[cfg(feature = "untested")]
-use crate::mgm::{MgmKey, DES_LEN_3DES};
+use crate::mgm::{DeviceConfig, DeviceInfo, Lock};

 const CB_PIN_MAX: usize = 8;

@@ -32,7 +34,7 @@ pub(crate) struct Transaction<'tx> {

 impl<'tx> Transaction<'tx> {
    /// Create a new transaction with the given card.
-    pub fn new(card: &'tx mut pcsc::Card) -> Result<Self, Error> {
+    pub fn new(card: &'tx mut pcsc::Card) -> Result<Self> {
        Ok(Transaction {
            inner: card.transaction()?,
        })
@@ -45,7 +47,7 @@ impl<'tx> Transaction<'tx> {
    /// single APDU messages at a time. For larger messages that need to be
    /// split into multiple APDUs, use the [`Transaction::transfer_data`]
    /// method instead.
-    pub fn transmit(&self, send_buffer: &[u8], recv_len: usize) -> Result<Vec<u8>, Error> {
+    pub fn transmit(&self, send_buffer: &[u8], recv_len: usize) -> Result<Vec<u8>> {
        trace!(">>> {:?}", send_buffer);

        let mut recv_buffer = vec![0u8; recv_len];
@@ -59,110 +61,128 @@ impl<'tx> Transaction<'tx> {
        Ok(recv_buffer)
    }

+    /// Select PIV application.
+    pub fn select_piv_application(&self) -> Result<()> {
+        self.select_application(
+            piv::APPLET_ID,
+            piv::APPLET_NAME,
+            "failed selecting application",
+        )
+    }
+
    /// Select application.
-    pub fn select_application(&self) -> Result<(), Error> {
-        let response = APDU::new(Ins::SelectApplication)
+    pub fn select_application(
+        &self,
+        applet: &[u8],
+        applet_name: &'static str,
+        error: &'static str,
+    ) -> Result<()> {
+        let response = Apdu::new(Ins::SelectApplication)
            .p1(0x04)
-            .data(&PIV_AID)
+            .data(applet)
            .transmit(self, 0xFF)
-            .map_err(|e| {
-                error!("failed communicating with card: '{}'", e);
-                e
-            })?;
+            .inspect_err(|e| error!("failed communicating with card: '{}'", e))?;

        if !response.is_success() {
-            error!(
-                "failed selecting application: {:04x}",
-                response.status_words().code()
-            );
-            return Err(Error::GenericError);
+            error!("{}: {:04x}", error, response.status_words().code());
+            return Err(match response.status_words() {
+                StatusWords::NotFoundError => Error::AppletNotFound { applet_name },
+                _ => Error::GenericError,
+            });
        }

        Ok(())
    }

    /// Get the version of the PIV application installed on the YubiKey.
-    pub fn get_version(&self) -> Result<Version, Error> {
+    pub fn get_version(&self) -> Result<Version> {
        // get version from device
-        let response = APDU::new(Ins::GetVersion).transmit(self, 261)?;
+        let response = Apdu::new(Ins::GetVersion).transmit(self, 261)?;

-        if !response.is_success() {
+        if !response.is_success() || response.data().is_empty() {
            return Err(Error::GenericError);
        }

-        if response.data().len() < 3 {
-            return Err(Error::SizeError);
-        }
-
-        Ok(Version::new(response.data()[..3].try_into().unwrap()))
+        Ok(response.data()[..3].try_into().map(Version::new)?)
    }

    /// Get YubiKey device serial number.
-    pub fn get_serial(&self, version: Version) -> Result<Serial, Error> {
-        let response = if version.major < 5 {
-            // YK4 requires switching to the yk applet to retrieve the serial
-            let sw = APDU::new(Ins::SelectApplication)
-                .p1(0x04)
-                .data(&YK_AID)
-                .transmit(self, 0xFF)?
-                .status_words();
+    pub fn get_serial(&self, version: Version) -> Result<Serial> {
+        match version.major {
+            // YK4 requires switching to the YK applet to retrieve the serial
+            4 => {
+                self.select_application(
+                    otp::APPLET_ID,
+                    otp::APPLET_NAME,
+                    "failed selecting yk application",
+                )?;

-            if !sw.is_success() {
-                error!("failed selecting yk application: {:04x}", sw.code());
-                return Err(Error::GenericError);
-            }
+                let response = Apdu::new(0x01).p1(0x10).transmit(self, 0xFF)?;

-            let resp = APDU::new(0x01).p1(0x10).transmit(self, 0xFF)?;
-
-            if !resp.is_success() {
+                if !response.is_success() {
+                    // TODO(tarcieri): still reselect the PIV applet in this case?
                    error!(
                        "failed retrieving serial number: {:04x}",
-                    resp.status_words().code()
+                        response.status_words().code()
                    );
                    return Err(Error::GenericError);
                }

                // reselect the PIV applet
-            let sw = APDU::new(Ins::SelectApplication)
-                .p1(0x04)
-                .data(&PIV_AID)
-                .transmit(self, 0xFF)?
-                .status_words();
+                self.select_application(
+                    piv::APPLET_ID,
+                    piv::APPLET_NAME,
+                    "failed selecting application",
+                )?;

-            if !sw.is_success() {
-                error!("failed selecting application: {:04x}", sw.code());
-                return Err(Error::GenericError);
+                response.data().try_into()
            }

-            resp
-        } else {
            // YK5 implements getting the serial as a PIV applet command (0xf8)
-            let resp = APDU::new(Ins::GetSerial).transmit(self, 0xFF)?;
+            5 => {
+                let response = Apdu::new(Ins::GetSerial).transmit(self, 0xFF)?;

-            if !resp.is_success() {
+                if !response.is_success() {
                    error!(
                        "failed retrieving serial number: {:04x}",
-                    resp.status_words().code()
+                        response.status_words().code()
                    );
                    return Err(Error::GenericError);
                }

-            resp
-        };
+                response.data().try_into()
+            }

-        response.data()[..4]
-            .try_into()
-            .map(|serial| Serial::from(u32::from_be_bytes(serial)))
-            .map_err(|_| Error::SizeError)
+            // Other versions unsupported
+            _ => Err(Error::NotSupported),
+        }
+    }
+
+    /// Read metadata
+    pub(crate) fn get_metadata(&self, slot: SlotId) -> Result<piv::SlotMetadata> {
+        let response = Apdu::new(Ins::GetMetadata)
+            .p2(slot.into())
+            .transmit(self, CB_OBJ_MAX)?;
+
+        match response.status_words() {
+            StatusWords::Success => {
+                let buf = Buffer::new(response.data().into());
+                piv::SlotMetadata::try_from(buf)
+            }
+            StatusWords::ReferenceDataNotFoundError => Err(Error::NotFound),
+            // Requires firmware 5.2.3
+            StatusWords::NotSupportedError => Err(Error::NotSupported),
+            _ => Err(Error::GenericError),
+        }
    }

    /// Verify device PIN.
-    pub fn verify_pin(&self, pin: &[u8]) -> Result<(), Error> {
+    pub fn verify_pin(&self, pin: &[u8]) -> Result<()> {
        if pin.len() > CB_PIN_MAX {
            return Err(Error::SizeError);
        }

-        let mut query = APDU::new(Ins::Verify);
+        let mut query = Apdu::new(Ins::Verify);
        query.params(0x00, 0x80);

        // Empty pin means we are querying the number of retries. We set no data in this
@@ -171,7 +191,7 @@ impl<'tx> Transaction<'tx> {
        if !pin.is_empty() {
            let mut data = Zeroizing::new([0xff; CB_PIN_MAX]);
            data[0..pin.len()].copy_from_slice(pin);
-            query.data(data.as_ref());
+            query.data(data.as_slice());
        }

        let response = query.transmit(self, 261)?;
@@ -191,7 +211,7 @@ impl<'tx> Transaction<'tx> {
        action: ChangeRefAction,
        current_pin: &[u8],
        new_pin: &[u8],
-    ) -> Result<(), Error> {
+    ) -> Result<()> {
        if current_pin.len() > CB_PIN_MAX || new_pin.len() > CB_PIN_MAX {
            return Err(Error::SizeError);
        }
@@ -228,25 +248,18 @@ impl<'tx> Transaction<'tx> {
    }

    /// Set the management key (MGM).
-    #[cfg(feature = "untested")]
-    pub fn set_mgm_key(&self, new_key: &MgmKey, touch: Option<u8>) -> Result<(), Error> {
-        let p2 = match touch.unwrap_or_default() {
-            0 => 0xff,
-            1 => 0xfe,
-            _ => {
-                return Err(Error::GenericError);
-            }
-        };
+    pub fn set_mgm_key(&self, new_key: &MgmKey, require_touch: bool) -> Result<()> {
+        let p2 = if require_touch { 0xfe } else { 0xff };

-        let mut data = [0u8; DES_LEN_3DES + 3];
-        data[0] = ALGO_3DES;
-        data[1] = KEY_CARDMGM;
-        data[2] = DES_LEN_3DES as u8;
-        data[3..3 + DES_LEN_3DES].copy_from_slice(new_key.as_ref());
+        let mut data = Vec::with_capacity(usize::from(new_key.key_size()) + 3);
+        data.push(new_key.algorithm_id().into());
+        data.push(KEY_CARDMGM);
+        data.push(new_key.key_size());
+        data.extend_from_slice(new_key.as_ref());

-        let status_words = APDU::new(Ins::SetMgmKey)
+        let status_words = Apdu::new(Ins::SetMgmKey)
            .params(0xff, p2)
-            .data(&data)
+            .data(data)
            .transmit(self, 261)?
            .status_words();

@@ -269,20 +282,29 @@ impl<'tx> Transaction<'tx> {
        algorithm: AlgorithmId,
        key: SlotId,
        decipher: bool,
-    ) -> Result<Buffer, Error> {
+    ) -> Result<Buffer> {
        let in_len = sign_in.len();
        let mut indata = [0u8; 1024];
        let templ = [0, Ins::Authenticate.code(), algorithm.into(), key.into()];

        match algorithm {
-            AlgorithmId::Rsa1024 | AlgorithmId::Rsa2048 => {
-                let key_len = if let AlgorithmId::Rsa1024 = algorithm {
-                    128
-                } else {
-                    256
-                };
-
-                if in_len != key_len {
+            AlgorithmId::Rsa1024 => {
+                if in_len != 128 {
+                    return Err(Error::SizeError);
+                }
+            }
+            AlgorithmId::Rsa2048 => {
+                if in_len != 256 {
+                    return Err(Error::SizeError);
+                }
+            }
+            AlgorithmId::Rsa3072 => {
+                if in_len != 384 {
+                    return Err(Error::SizeError);
+                }
+            }
+            AlgorithmId::Rsa4096 => {
+                if in_len != 512 {
                    return Err(Error::SizeError);
                }
            }
@@ -298,6 +320,19 @@ impl<'tx> Transaction<'tx> {
                    return Err(Error::SizeError);
                }
            }
+            AlgorithmId::X25519 => {
+                if !decipher {
+                    return Err(Error::NotSupported);
+                }
+                if in_len != 32 {
+                    return Err(Error::SizeError);
+                }
+            }
+            AlgorithmId::Ed25519 => {
+                if decipher {
+                    return Err(Error::NotSupported);
+                }
+            }
        }

        let bytes = if in_len < 0x80 {
@@ -314,7 +349,9 @@ impl<'tx> Transaction<'tx> {
                Tlv::write(
                    &mut buf[2..],
                    match (algorithm, decipher) {
-                        (AlgorithmId::EccP256, true) | (AlgorithmId::EccP384, true) => 0x85,
+                        (AlgorithmId::EccP256, true)
+                        | (AlgorithmId::EccP384, true)
+                        | (AlgorithmId::X25519, true) => 0x85,
                        _ => 0x81,
                    },
                    sign_in
@@ -326,10 +363,7 @@ impl<'tx> Transaction<'tx> {

        let response = self
            .transfer_data(&templ, &indata[..offset], 1024)
-            .map_err(|e| {
-                error!("sign command failed to communicate: {}", e);
-                e
-            })?;
+            .inspect_err(|e| error!("sign command failed to communicate: {}", e))?;

        if !response.is_success() {
            error!("failed sign command with code {:x}", response.code());
@@ -364,12 +398,7 @@ impl<'tx> Transaction<'tx> {
    /// messages into smaller APDU-sized messages (using the provided APDU
    /// template to construct them), and then sending those via
    /// [`Transaction::transmit`].
-    pub fn transfer_data(
-        &self,
-        templ: &[u8],
-        in_data: &[u8],
-        max_out: usize,
-    ) -> Result<Response, Error> {
+    pub fn transfer_data(&self, templ: &[u8], in_data: &[u8], max_out: usize) -> Result<Response> {
        let mut in_offset = 0;
        let mut out_data = vec![];
        let mut sw;
@@ -386,17 +415,18 @@ impl<'tx> Transaction<'tx> {

            trace!("going to send {} bytes in this go", this_size);

-            let response = APDU::new(templ[1])
+            let response = Apdu::new(templ[1])
                .cla(cla)
                .params(templ[2], templ[3])
                .data(&in_data[in_offset..(in_offset + this_size)])
                .transmit(self, 261)?;

-            sw = response.status_words().code();
+            sw = response.status_words();

-            if !response.is_success() && (sw >> 8 != 0x61) {
+            match sw {
+                StatusWords::Success | StatusWords::BytesRemaining { .. } => (),
                // TODO(tarcieri): is this really OK?
-                return Ok(Response::new(sw.into(), out_data));
+                _ => return Ok(Response::new(sw, out_data)),
            }

            if !out_data.is_empty() && (out_data.len() - response.data().len() > max_out) {
@@ -417,17 +447,15 @@ impl<'tx> Transaction<'tx> {
            }
        }

-        while sw >> 8 == 0x61 {
-            trace!(
-                "The card indicates there is {} bytes more data for us",
-                sw & 0xff
-            );
+        while let StatusWords::BytesRemaining { len } = sw {
+            trace!("The card indicates there is {} bytes more data for us", len);

-            let response = APDU::new(Ins::GetResponseApdu).transmit(self, 261)?;
-            sw = response.status_words().code();
+            let response = Apdu::new(Ins::GetResponseApdu).transmit(self, 261)?;
+            sw = response.status_words();

-            if sw != StatusWords::Success.code() && (sw >> 8 != 0x61) {
-                return Ok(Response::new(sw.into(), vec![]));
+            match sw {
+                StatusWords::Success | StatusWords::BytesRemaining { .. } => (),
+                _ => return Ok(Response::new(sw, vec![])),
            }

            if out_data.len() + response.data().len() > max_out {
@@ -443,11 +471,11 @@ impl<'tx> Transaction<'tx> {
            out_data.extend_from_slice(&response.data()[..response.data().len()]);
        }

-        Ok(Response::new(sw.into(), out_data))
+        Ok(Response::new(sw, out_data))
    }

    /// Fetch an object.
-    pub fn fetch_object(&self, object_id: ObjectId) -> Result<Buffer, Error> {
+    pub fn fetch_object(&self, object_id: ObjectId) -> Result<Buffer> {
        let mut indata = [0u8; 5];
        let templ = [0, Ins::GetData.code(), 0x3f, 0xff];

@@ -481,7 +509,7 @@ impl<'tx> Transaction<'tx> {
    }

    /// Save an object.
-    pub fn save_object(&self, object_id: ObjectId, indata: &[u8]) -> Result<(), Error> {
+    pub fn save_object(&self, object_id: ObjectId, indata: &[u8]) -> Result<()> {
        let templ = [0, Ins::PutData.code(), 0x3f, 0xff];

        // TODO(tarcieri): replace with vector
@@ -508,4 +536,66 @@ impl<'tx> Transaction<'tx> {
            _ => Err(Error::GenericError),
        }
    }
+
+    /// Write configuration to the YubiKey
+    #[cfg(feature = "untested")]
+    pub fn write_config(
+        &mut self,
+        version: Version,
+        config: DeviceConfig,
+        current_lock: Option<Lock>,
+        new_lock: Option<Lock>,
+    ) -> Result<()> {
+        if version
+            < (Version {
+                major: 5,
+                minor: 0,
+                patch: 0,
+            })
+        {
+            return Err(Error::NotSupported);
+        }
+
+        let data = config.as_tlv(true, current_lock, new_lock)?;
+
+        let response = Apdu::new(Ins::WriteConfig)
+            .params(0x00, 0x00)
+            .data(&data)
+            .transmit(self, 2)?;
+
+        if !response.is_success() {
+            error!(
+                "Unable to write_config: {:04x}",
+                response.status_words().code()
+            );
+            return Err(Error::GenericError);
+        }
+
+        Ok(())
+    }
+
+    /// Write configuration to the YubiKey
+    #[cfg(feature = "untested")]
+    pub fn read_config(&mut self) -> Result<DeviceInfo> {
+        let mut data = [0u8; CB_BUF_MAX];
+        let mut len = data.len();
+        let data_remaining = &mut data[..];
+
+        len -= data_remaining.len();
+        let response = Apdu::new(Ins::ReadConfig)
+            .params(0x00, 0x00)
+            .data(&data[..len])
+            .transmit(self, CB_BUF_MAX + 2)?;
+
+        if !response.is_success() {
+            error!(
+                "Unable to read configuration: {:04x}",
+                response.status_words().code()
+            );
+            return Err(Error::GenericError);
+        }
+
+        let data = response.data();
+        DeviceInfo::parse(data)
+    }
 }
@@ -31,38 +31,44 @@
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 use crate::{
-    apdu::{Ins, APDU},
-    cccid::CCC,
-    chuid::CHUID,
+    apdu::{Apdu, Ins},
+    cccid::CccId,
+    chuid::ChuId,
    config::Config,
-    error::Error,
+    error::{Error, Result},
    mgm::MgmKey,
-    readers::{Reader, Readers},
+    piv,
+    reader::{Context, Reader},
    transaction::Transaction,
 };
+use cipher::common::getrandom::SysRng;
 use log::{error, info};
 use pcsc::Card;
+use rand_core::TryRng;
 use std::{
-    convert::{TryFrom, TryInto},
+    cmp::{Ord, Ordering},
    fmt::{self, Display},
    str::FromStr,
 };

 #[cfg(feature = "untested")]
-use crate::{
-    apdu::StatusWords, metadata, transaction::ChangeRefAction, Buffer, ObjectId, CB_BUF_MAX,
-    CB_OBJ_MAX, MGMT_AID, TAG_ADMIN, TAG_ADMIN_FLAGS_1, TAG_ADMIN_TIMESTAMP,
+use {
+    crate::{
+        apdu::StatusWords,
+        consts::{TAG_ADMIN_FLAGS_1, TAG_ADMIN_TIMESTAMP},
+        metadata::AdminData,
+        mgm,
+        transaction::ChangeRefAction,
+        Buffer, ObjectId,
+    },
+    std::time::{SystemTime, UNIX_EPOCH},
 };
-use getrandom::getrandom;
-#[cfg(feature = "untested")]
-use secrecy::ExposeSecret;
-#[cfg(feature = "untested")]
-use std::time::{SystemTime, UNIX_EPOCH};

 /// Flag for PUK blocked
 pub(crate) const ADMIN_FLAGS_1_PUK_BLOCKED: u8 = 0x01;

 /// 3DES authentication
+#[cfg(feature = "untested")]
 pub(crate) const ALGO_3DES: u8 = 0x03;

 /// Card management key
@@ -70,11 +76,12 @@ pub(crate) const KEY_CARDMGM: u8 = 0x9b;

 const TAG_DYN_AUTH: u8 = 0x7c;

-/// Cached YubiKey PIN
-pub type CachedPin = secrecy::SecretVec<u8>;
+/// Cached YubiKey PIN.
+// TODO(tarcieri): add a newtype for this with a zeroize impl
+pub type CachedPin = Vec<u8>;

-/// YubiKey Serial Number
-#[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord)]
+/// YubiKey serial number.
+#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash, PartialOrd, Ord)]
 pub struct Serial(pub u32);

 impl From<u32> for Serial {
@@ -89,11 +96,25 @@ impl From<Serial> for u32 {
    }
 }

+impl TryFrom<&[u8]> for Serial {
+    type Error = Error;
+
+    fn try_from(bytes: &[u8]) -> Result<Self> {
+        if bytes.len() > 4 {
+            return Err(Error::SizeError);
+        }
+
+        let mut arr = [0u8; 4];
+        arr[(4 - bytes.len())..].copy_from_slice(bytes);
+        Ok(Self(u32::from_be_bytes(arr)))
+    }
+}
+
 impl FromStr for Serial {
    type Err = Error;

-    fn from_str(s: &str) -> Result<Self, Error> {
-        u32::from_str(s).map(Serial).map_err(|_| Error::ParseError)
+    fn from_str(s: &str) -> Result<Self> {
+        s.parse().map(Serial).map_err(|_| Error::ParseError)
    }
 }

@@ -103,7 +124,7 @@ impl Display for Serial {
    }
 }

-/// YubiKey Version
+/// YubiKey version.
 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
 pub struct Version {
    /// Major version component
@@ -125,6 +146,22 @@ impl Version {
            patch: bytes[2],
        }
    }
+
+    #[cfg(feature = "untested")]
+    pub(crate) fn parse(input: &[u8]) -> Result<Self> {
+        use nom::{combinator::eof, number::complete::u8};
+
+        let (i, major) = u8(input).map_err(|_: nom::Err<()>| Error::ParseError)?;
+        let (i, minor) = u8(i).map_err(|_: nom::Err<()>| Error::ParseError)?;
+        let (i, patch) = u8(i).map_err(|_: nom::Err<()>| Error::ParseError)?;
+        let (_i, _) = eof(i).map_err(|_: nom::Err<()>| Error::ParseError)?;
+
+        Ok(Self {
+            major,
+            minor,
+            patch,
+        })
+    }
 }

 impl Display for Version {
@@ -133,8 +170,40 @@ impl Display for Version {
    }
 }

-/// YubiKey Device: this is the primary API for opening a session and
-/// performing various operations.
+impl Ord for Version {
+    fn cmp(&self, other: &Self) -> Ordering {
+        if self.major > other.major {
+            return Ordering::Greater;
+        }
+        if self.major < other.major {
+            return Ordering::Less;
+        }
+
+        if self.minor > other.minor {
+            return Ordering::Greater;
+        }
+        if self.minor < other.minor {
+            return Ordering::Less;
+        }
+
+        if self.patch > other.patch {
+            return Ordering::Greater;
+        }
+        if self.patch < other.patch {
+            return Ordering::Less;
+        }
+
+        Ordering::Equal
+    }
+}
+
+impl PartialOrd for Version {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
+/// YubiKey device: primary API for opening a session and performing various operations.
 ///
 /// Almost all functionality in this library will require an open session
 /// with a YubiKey which is represented by this type.
@@ -148,63 +217,102 @@ pub struct YubiKey {
    pub(crate) serial: Serial,
 }

+impl fmt::Debug for YubiKey {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("YubiKey")
+            .field("name", &self.name)
+            .field("version", &self.version)
+            .field("serial", &self.serial)
+            .finish_non_exhaustive()
+    }
+}
+
 impl YubiKey {
    /// Open a connection to a YubiKey.
    ///
-    /// Returns an error if there is more than one YubiKey detected.
+    /// Returns an error if more than one YubiKey is detected (or none at all).
+    ///
+    /// NOTE: If multiple YubiKeys are connected, but we are only able to
+    /// open one of them (e.g. because the other one is in use, and the
+    /// connection doesn't allow sharing), the YubiKey that we were able to
+    /// open is returned.
    ///
    /// If you need to operate in environments with more than one YubiKey
    /// attached to the same system, use [`YubiKey::open_by_serial`] or
-    ///[`yubikey_piv::Readers`] to select from the available PC/SC readers.
-    pub fn open() -> Result<Self, Error> {
-        let mut readers = Readers::open().map_err(|e| match e {
-            Error::PcscError {
-                inner: Some(pcsc::Error::NoReadersAvailable),
-            } => Error::NotFound,
-            other => other,
-        })?;
-        let mut reader_iter = readers.iter()?;
+    /// [`yubikey::reader::Context`][`Context`] to select from the available
+    /// PC/SC readers.
+    pub fn open() -> Result<Self> {
+        let mut yubikey: Option<Self> = None;
+
+        let mut readers = Context::open()?;
+        for reader in readers.iter()? {
+            if let Ok(yk_found) = reader.open() {
+                if let Some(yk_stored) = yubikey {
+                    // We found two YubiKeys, so we won't use either.
+                    // Don't reset them.
+                    let _ = yk_stored.disconnect(pcsc::Disposition::LeaveCard);
+                    let _ = yk_found.disconnect(pcsc::Disposition::LeaveCard);

-        if let Some(reader) = reader_iter.next() {
-            if reader_iter.next().is_some() {
                    error!("multiple YubiKeys detected!");
                    return Err(Error::PcscError { inner: None });
+                } else {
+                    yubikey = Some(yk_found);
+                }
+            }
        }

-            return reader.open();
-        }
-
+        if let Some(yubikey) = yubikey {
+            // We found exactly one YubiKey that we could open, so we return it.
+            Ok(yubikey)
+        } else {
            error!("no YubiKey detected!");
            Err(Error::NotFound)
        }
+    }

    /// Open a YubiKey with a specific serial number.
-    pub fn open_by_serial(serial: Serial) -> Result<Self, Error> {
-        let mut readers = Readers::open().map_err(|e| match e {
-            Error::PcscError {
-                inner: Some(pcsc::Error::NoReadersAvailable),
-            } => Error::NotFound,
-            other => other,
-        })?;
+    pub fn open_by_serial(serial: Serial) -> Result<Self> {
+        let mut readers = Context::open()?;
+
+        let mut open_error = None;

        for reader in readers.iter()? {
            let yubikey = match reader.open() {
                Ok(yk) => yk,
-                Err(_) => continue,
+                Err(e) => {
+                    // Save the first error we see that indicates we might have been able
+                    // to find a matching YubiKey.
+                    if open_error.is_none() {
+                        if let Error::PcscError {
+                            inner: Some(pcsc::Error::SharingViolation),
+                        } = e
+                        {
+                            open_error = Some(e);
+                        }
+                    }
+                    continue;
+                }
            };

            if serial == yubikey.serial() {
                return Ok(yubikey);
+            } else {
+                // We didn't want this YubiKey; don't reset it.
+                let _ = yubikey.disconnect(pcsc::Disposition::LeaveCard);
            }
        }

+        Err(if let Some(e) = open_error {
+            e
+        } else {
            error!("no YubiKey detected with serial: {}", serial);
-        Err(Error::NotFound)
+            Error::NotFound
+        })
    }

-    /// Reconnect to a YubiKey
+    /// Reconnect to a YubiKey.
    #[cfg(feature = "untested")]
-    pub fn reconnect(&mut self) -> Result<(), Error> {
+    pub fn reconnect(&mut self) -> Result<()> {
        info!("trying to reconnect to current reader");

        self.card.reconnect(
@@ -213,13 +321,10 @@ impl YubiKey {
            pcsc::Disposition::ResetCard,
        )?;

-        let pin = self
-            .pin
-            .as_ref()
-            .map(|p| Buffer::new(p.expose_secret().clone()));
+        let pin = self.pin.as_ref().map(|p| Buffer::new(p.clone()));

        let txn = Transaction::new(&mut self.card)?;
-        txn.select_application()?;
+        txn.select_piv_application()?;

        if let Some(p) = &pin {
            txn.verify_pin(p)?;
@@ -228,13 +333,48 @@ impl YubiKey {
        Ok(())
    }

-    /// Begin a transaction.
-    pub(crate) fn begin_transaction(&mut self) -> Result<Transaction<'_>, Error> {
-        // TODO(tarcieri): reconnect support
-        Ok(Transaction::new(&mut self.card)?)
+    /// Disconnect from the YubiKey.
+    ///
+    /// In case of error, ownership of the YubiKey is returned to the caller.
+    ///
+    /// # Note
+    ///
+    /// `YubiKey` implements `Drop` which automatically disconnects the card using
+    /// `Disposition::ResetCard`; you only need to call this function if you want to
+    /// handle errors or use a different disposition method.
+    pub fn disconnect(
+        self,
+        disposition: pcsc::Disposition,
+    ) -> core::result::Result<(), (Self, Error)> {
+        let Self {
+            card,
+            name,
+            pin,
+            version,
+            serial,
+        } = self;
+
+        card.disconnect(disposition).map_err(|(card, e)| {
+            (
+                Self {
+                    card,
+                    name,
+                    pin,
+                    version,
+                    serial,
+                },
+                e.into(),
+            )
+        })
    }

-    /// Get the name of the associated PC/SC card reader
+    /// Begin a transaction.
+    pub(crate) fn begin_transaction(&mut self) -> Result<Transaction<'_>> {
+        // TODO(tarcieri): reconnect support
+        Transaction::new(&mut self.card)
+    }
+
+    /// Get the name of the associated PC/SC card reader.
    pub fn name(&self) -> &str {
        &self.name
    }
@@ -254,57 +394,62 @@ impl YubiKey {
    }

    /// Get device configuration.
-    pub fn config(&mut self) -> Result<Config, Error> {
+    pub fn config(&mut self) -> Result<Config> {
        Config::get(self)
    }

-    /// Get CHUID
-    pub fn chuid(&mut self) -> Result<CHUID, Error> {
-        CHUID::get(self)
+    /// Get Cardholder Unique Identifier (CHUID).
+    pub fn chuid(&mut self) -> Result<ChuId> {
+        ChuId::get(self)
    }

-    /// Get CCCID
-    pub fn cccid(&mut self) -> Result<CCC, Error> {
-        CCC::get(self)
+    /// Get Cardholder Capability Container (CCC) Identifier.
+    pub fn cccid(&mut self) -> Result<CccId> {
+        CccId::get(self)
    }

    /// Authenticate to the card using the provided management key (MGM).
-    pub fn authenticate(&mut self, mgm_key: MgmKey) -> Result<(), Error> {
+    pub fn authenticate(&mut self, mgm_key: &MgmKey) -> Result<()> {
        let txn = self.begin_transaction()?;

        // get a challenge from the card
-        let challenge = APDU::new(Ins::Authenticate)
-            .params(ALGO_3DES, KEY_CARDMGM)
-            .data(&[TAG_DYN_AUTH, 0x02, 0x80, 0x00])
+        let card_response = Apdu::new(Ins::Authenticate)
+            .params(mgm_key.algorithm_id().into(), KEY_CARDMGM)
+            .data([TAG_DYN_AUTH, 0x02, 0x80, 0x00])
            .transmit(&txn, 261)?;

-        if !challenge.is_success() || challenge.data().len() < 12 {
+        if !card_response.is_success() || card_response.data().len() < 5 {
            return Err(Error::AuthenticationError);
        }

        // send a response to the cards challenge and a challenge of our own.
-        let response = mgm_key.decrypt(challenge.data()[4..12].try_into().unwrap());
+        let card_challenge = mgm_key.card_challenge(&card_response.data()[4..])?;
+        let challenge_len = card_challenge.len();

-        let mut data = [0u8; 22];
-        data[0] = TAG_DYN_AUTH;
-        data[1] = 20; // 2 + 8 + 2 +8
-        data[2] = 0x80;
-        data[3] = 8;
-        data[4..12].copy_from_slice(&response);
-        data[12] = 0x81;
-        data[13] = 8;
+        // If this exceeds a `u8` then the card is giving us unexpected data.
+        let auth_len = (2 + challenge_len + 2 + challenge_len)
+            .try_into()
+            .map_err(|_| Error::AuthenticationError)?;

-        if getrandom(&mut data[14..22]).is_err() {
-            error!("failed getting randomness for authentication");
-            return Err(Error::RandomnessError);
-        }
+        let mut data = Vec::with_capacity(4 + challenge_len + 2 + challenge_len);
+        data.push(TAG_DYN_AUTH);
+        data.push(auth_len);
+        data.push(0x80);
+        data.push(challenge_len as u8);
+        data.extend_from_slice(&card_challenge);
+        data.push(0x81);
+        data.push(challenge_len as u8);

-        let mut challenge = [0u8; 8];
-        challenge.copy_from_slice(&data[14..22]);
+        let mut host_challenge = vec![0u8; challenge_len];
+        SysRng
+            .try_fill_bytes(&mut host_challenge)
+            .map_err(|_| Error::GenericError)?;

-        let authentication = APDU::new(Ins::Authenticate)
-            .params(ALGO_3DES, KEY_CARDMGM)
-            .data(&data)
+        data.extend_from_slice(&host_challenge);
+
+        let authentication = Apdu::new(Ins::Authenticate)
+            .params(mgm_key.algorithm_id().into(), KEY_CARDMGM)
+            .data(data)
            .transmit(&txn, 261)?;

        if !authentication.is_success() {
@@ -312,24 +457,22 @@ impl YubiKey {
        }

        // compare the response from the card with our challenge
-        let response = mgm_key.encrypt(&challenge);
-
-        use subtle::ConstantTimeEq;
-        if response.ct_eq(&authentication.data()[4..12]).unwrap_u8() != 1 {
-            return Err(Error::AuthenticationError);
+        mgm_key.check_challenge(&host_challenge, &authentication.data()[4..])
    }

-        Ok(())
+    /// Get the PIV keys contained in this YubiKey.
+    pub fn piv_keys(&mut self) -> Result<Vec<piv::Key>> {
+        piv::Key::list(self)
    }

-    /// Deauthenticate
+    /// Deauthenticate.
    #[cfg(feature = "untested")]
-    pub fn deauthenticate(&mut self) -> Result<(), Error> {
+    pub fn deauthenticate(&mut self) -> Result<()> {
        let txn = self.begin_transaction()?;

-        let status_words = APDU::new(Ins::SelectApplication)
+        let status_words = Apdu::new(Ins::SelectApplication)
            .p1(0x04)
-            .data(MGMT_AID)
+            .data(mgm::APPLET_ID)
            .transmit(&txn, 255)?
            .status_words();

@@ -338,34 +481,39 @@ impl YubiKey {
                "Failed selecting mgmt application: {:04x}",
                status_words.code()
            );
-            return Err(Error::GenericError);
+            return Err(match status_words {
+                StatusWords::NotFoundError => Error::AppletNotFound {
+                    applet_name: mgm::APPLET_NAME,
+                },
+                _ => Error::GenericError,
+            });
        }

        Ok(())
    }

    /// Verify device PIN.
-    pub fn verify_pin(&mut self, pin: &[u8]) -> Result<(), Error> {
+    pub fn verify_pin(&mut self, pin: &[u8]) -> Result<()> {
        {
            let txn = self.begin_transaction()?;
            txn.verify_pin(pin)?;
        }

        if !pin.is_empty() {
-            self.pin = Some(CachedPin::new(pin.into()))
+            self.pin = Some(pin.into())
        }

        Ok(())
    }

-    /// Get the number of PIN retries
-    pub fn get_pin_retries(&mut self) -> Result<u8, Error> {
+    /// Get the number of PIN retries.
+    pub fn get_pin_retries(&mut self) -> Result<u8> {
        let txn = self.begin_transaction()?;

        // Force a re-select to unverify, because once verified the spec dictates that
        // subsequent verify calls will return a "verification not needed" instead of
        // the number of tries left...
-        txn.select_application()?;
+        txn.select_piv_application()?;

        // WRONG_PIN is expected on successful query.
        match txn.verify_pin(&[]) {
@@ -375,9 +523,9 @@ impl YubiKey {
        }
    }

-    /// Set the number of PIN retries
+    /// Set the number of PIN retries.
    #[cfg(feature = "untested")]
-    pub fn set_pin_retries(&mut self, pin_tries: u8, puk_tries: u8) -> Result<(), Error> {
+    pub fn set_pin_retries(&mut self, pin_tries: u8, puk_tries: u8) -> Result<()> {
        // Special case: if either retry count is 0, it's a successful no-op
        if pin_tries == 0 || puk_tries == 0 {
            return Ok(());
@@ -399,54 +547,41 @@ impl YubiKey {

    /// Change the Personal Identification Number (PIN).
    ///
-    /// The default PIN code is 123456
+    /// The default PIN code is `123456`.
    #[cfg(feature = "untested")]
-    pub fn change_pin(&mut self, current_pin: &[u8], new_pin: &[u8]) -> Result<(), Error> {
+    pub fn change_pin(&mut self, current_pin: &[u8], new_pin: &[u8]) -> Result<()> {
        {
            let txn = self.begin_transaction()?;
            txn.change_ref(ChangeRefAction::ChangePin, current_pin, new_pin)?;
        }

        if !new_pin.is_empty() {
-            self.pin = Some(CachedPin::new(new_pin.into()));
+            self.pin = Some(new_pin.into());
        }

        Ok(())
    }

-    /// Set PIN last changed
+    /// Set PIN last changed.
    #[cfg(feature = "untested")]
-    pub fn set_pin_last_changed(yubikey: &mut YubiKey) -> Result<(), Error> {
-        let mut data = [0u8; CB_BUF_MAX];
+    pub fn set_pin_last_changed(yubikey: &mut YubiKey) -> Result<()> {
        let txn = yubikey.begin_transaction()?;

-        let buffer = metadata::read(&txn, TAG_ADMIN)?;
-        let mut cb_data = buffer.len();
-        data[..cb_data].copy_from_slice(&buffer);
+        let mut admin_data = AdminData::read(&txn)?;

        // TODO(tarcieri): double check this is little endian
        let tnow = SystemTime::now()
-            .duration_since(UNIX_EPOCH)
-            .unwrap()
+            .duration_since(UNIX_EPOCH)?
            .as_secs()
            .to_le_bytes();

-        metadata::set_item(
-            &mut data,
-            &mut cb_data,
-            CB_OBJ_MAX,
-            TAG_ADMIN_TIMESTAMP,
-            &tnow,
-        )
-        .map_err(|e| {
-            error!("could not set pin timestamp, err = {}", e);
-            e
-        })?;
+        admin_data
+            .set_item(TAG_ADMIN_TIMESTAMP, &tnow)
+            .inspect_err(|e| error!("could not set pin timestamp, err = {}", e))?;

-        metadata::write(&txn, TAG_ADMIN, &data).map_err(|e| {
-            error!("could not write admin data, err = {}", e);
-            e
-        })?;
+        admin_data
+            .write(&txn)
+            .inspect_err(|e| error!("could not write admin data, err = {}", e))?;

        Ok(())
    }
@@ -457,21 +592,21 @@ impl YubiKey {
    ///
    /// The PUK is part of the PIV standard that the YubiKey follows.
    ///
-    /// The default PUK code is 12345678.
+    /// The default PUK code is `12345678`.
    #[cfg(feature = "untested")]
-    pub fn change_puk(&mut self, current_puk: &[u8], new_puk: &[u8]) -> Result<(), Error> {
+    pub fn change_puk(&mut self, current_puk: &[u8], new_puk: &[u8]) -> Result<()> {
        let txn = self.begin_transaction()?;
        txn.change_ref(ChangeRefAction::ChangePuk, current_puk, new_puk)
    }

-    /// Block PUK: permanently prevent the PIN from becoming unblocked
+    /// Block PUK: permanently prevent the PIN from becoming unblocked.
    #[cfg(feature = "untested")]
-    pub fn block_puk(yubikey: &mut YubiKey) -> Result<(), Error> {
+    pub fn block_puk(&mut self) -> Result<()> {
        let mut puk = [0x30, 0x42, 0x41, 0x44, 0x46, 0x30, 0x30, 0x44];
        let mut tries_remaining: i32 = -1;
        let mut flags = [0];

-        let txn = yubikey.begin_transaction()?;
+        let txn = self.begin_transaction()?;

        while tries_remaining != 0 {
            // 2 -> change puk
@@ -494,8 +629,10 @@ impl YubiKey {
            }
        }

-        if let Ok(data) = metadata::read(&txn, TAG_ADMIN) {
-            if let Ok(item) = metadata::get_item(&data, TAG_ADMIN_FLAGS_1) {
+        // Attempt to set the "PUK blocked" flag in admin data.
+        let mut admin_data = AdminData::read(&txn)
+            .inspect(|data| {
+                if let Ok(item) = data.get_item(TAG_ADMIN_FLAGS_1) {
                    if item.len() == flags.len() {
                        flags.copy_from_slice(item)
                    } else {
@@ -506,22 +643,13 @@ impl YubiKey {
                        );
                    }
                }
-        }
+            })
+            .unwrap_or_default();

        flags[0] |= ADMIN_FLAGS_1_PUK_BLOCKED;
-        let mut data = [0u8; CB_BUF_MAX];
-        let mut cb_data: usize = data.len();

-        if metadata::set_item(
-            &mut data,
-            &mut cb_data,
-            CB_OBJ_MAX,
-            TAG_ADMIN_FLAGS_1,
-            &flags,
-        )
-        .is_ok()
-        {
-            if metadata::write(&txn, TAG_ADMIN, &data[..cb_data]).is_err() {
+        if admin_data.set_item(TAG_ADMIN_FLAGS_1, &flags).is_ok() {
+            if admin_data.write(&txn).is_err() {
                error!("could not write admin metadata");
            }
        } else {
@@ -534,45 +662,49 @@ impl YubiKey {
    /// Unblock a Personal Identification Number (PIN) using a previously
    /// configured PIN Unblocking Key (PUK).
    #[cfg(feature = "untested")]
-    pub fn unblock_pin(&mut self, puk: &[u8], new_pin: &[u8]) -> Result<(), Error> {
+    pub fn unblock_pin(&mut self, puk: &[u8], new_pin: &[u8]) -> Result<()> {
        let txn = self.begin_transaction()?;
        txn.change_ref(ChangeRefAction::UnblockPin, puk, new_pin)
    }

-    /// Fetch an object from the YubiKey
+    /// Fetch an object from the YubiKey.
    #[cfg(feature = "untested")]
-    pub fn fetch_object(&mut self, object_id: ObjectId) -> Result<Buffer, Error> {
+    pub fn fetch_object(&mut self, object_id: ObjectId) -> Result<Buffer> {
        let txn = self.begin_transaction()?;
        txn.fetch_object(object_id)
    }

-    /// Save an object
+    /// Save an object.
    #[cfg(feature = "untested")]
-    pub fn save_object(&mut self, object_id: ObjectId, indata: &mut [u8]) -> Result<(), Error> {
+    pub fn save_object(&mut self, object_id: ObjectId, indata: &mut [u8]) -> Result<()> {
        let txn = self.begin_transaction()?;
        txn.save_object(object_id, indata)
    }

-    /// Get an auth challenge
+    /// Get an auth challenge.
    #[cfg(feature = "untested")]
-    pub fn get_auth_challenge(&mut self) -> Result<[u8; 8], Error> {
+    pub fn get_auth_challenge(&mut self) -> Result<[u8; 8]> {
        let txn = self.begin_transaction()?;

-        let response = APDU::new(Ins::Authenticate)
+        let response = Apdu::new(Ins::Authenticate)
            .params(ALGO_3DES, KEY_CARDMGM)
-            .data(&[0x7c, 0x02, 0x81, 0x00])
+            .data([0x7c, 0x02, 0x81, 0x00])
            .transmit(&txn, 261)?;

        if !response.is_success() {
            return Err(Error::AuthenticationError);
        }

-        Ok(response.data()[4..12].try_into().unwrap())
+        Ok(response
+            .data()
+            .get(4..12)
+            .ok_or(Error::SizeError)?
+            .try_into()?)
    }

-    /// Verify an auth response
+    /// Verify an auth response.
    #[cfg(feature = "untested")]
-    pub fn verify_auth_response(&mut self, response: [u8; 8]) -> Result<(), Error> {
+    pub fn verify_auth_response(&mut self, response: [u8; 8]) -> Result<()> {
        let mut data = [0u8; 12];
        data[0] = 0x7c;
        data[1] = 0x0a;
@@ -583,9 +715,9 @@ impl YubiKey {
        let txn = self.begin_transaction()?;

        // send the response to the card and a challenge of our own.
-        let status_words = APDU::new(Ins::Authenticate)
+        let status_words = Apdu::new(Ins::Authenticate)
            .params(ALGO_3DES, KEY_CARDMGM)
-            .data(&data)
+            .data(data)
            .transmit(&txn, 261)?
            .status_words();

@@ -602,7 +734,7 @@ impl YubiKey {
    ///
    /// The reset function is only available when both pins are blocked.
    #[cfg(feature = "untested")]
-    pub fn reset_device(&mut self) -> Result<(), Error> {
+    pub fn reset_device(&mut self) -> Result<()> {
        let templ = [0, Ins::Reset.code(), 0, 0];
        let txn = self.begin_transaction()?;
        let status_words = txn.transfer_data(&templ, &[], 255)?.status_words();
@@ -618,23 +750,37 @@ impl YubiKey {
 impl<'a> TryFrom<&'a Reader<'_>> for YubiKey {
    type Error = Error;

-    fn try_from(reader: &'a Reader<'_>) -> Result<Self, Error> {
-        let mut card = reader.connect().map_err(|e| {
-            error!("error connecting to reader '{}': {}", reader.name(), e);
-            e
-        })?;
+    fn try_from(reader: &'a Reader<'_>) -> Result<Self> {
+        let mut card = reader
+            .connect()
+            .inspect_err(|e| error!("error connecting to reader '{}': {}", reader.name(), e))?;

        info!("connected to reader: {}", reader.name());

-        let (version, serial) = {
+        let mut app_version_serial = || -> Result<(Version, Serial)> {
            let txn = Transaction::new(&mut card)?;
-            txn.select_application()?;
+            txn.select_piv_application()?;

            let v = txn.get_version()?;
            let s = txn.get_serial(v)?;
-            (v, s)
+            Ok((v, s))
        };

+        match app_version_serial() {
+            Err(e) => {
+                error!("Could not use reader: {}", e);
+
+                // We were unable to use the card, so we've effectively only connected as
+                // a side-effect of determining this. Avoid disrupting its internal state
+                // any further (e.g. preserve the PIN cache of whatever applet is selected
+                // currently).
+                if let Err((_, e)) = card.disconnect(pcsc::Disposition::LeaveCard) {
+                    error!("Failed to disconnect gracefully from card: {}", e);
+                }
+
+                Err(e)
+            }
+            Ok((version, serial)) => {
                let yubikey = YubiKey {
                    card,
                    name: String::from(reader.name()),
@@ -646,3 +792,5 @@ impl<'a> TryFrom<&'a Reader<'_>> for YubiKey {
                Ok(yubikey)
            }
        }
+    }
+}
@@ -0,0 +1,85 @@
+Certificate:
+    Data:
+        Version: 3 (0x2)
+        Serial Number:
+            d4:29:8f:df:8a:af:7b:c0:d7:bf:19:9d:90:d5:ef:ca
+    Signature Algorithm: sha256WithRSAEncryption
+        Issuer: CN=Ferdinand Linnenberg CA
+        Validity
+            Not Before: Feb 10 12:25:37 2022 GMT
+            Not After : May 15 12:25:37 2024 GMT
+        Subject: CN=Bob
+        Subject Public Key Info:
+            Public Key Algorithm: rsaEncryption
+                Public-Key: (2048 bit)
+                Modulus:
+                    00:d5:27:9b:99:1b:3a:36:64:36:c8:e5:78:64:b6:
+                    9d:70:9d:29:6c:0e:85:91:4b:78:3b:dc:16:c3:09:
+                    8c:d3:74:20:8c:6f:ed:c3:90:c9:1b:4d:80:d5:46:
+                    da:52:7f:d2:2f:bc:b2:f7:40:8d:ad:dd:24:b9:5c:
+                    dc:a2:21:2f:48:ec:06:93:8b:89:f0:cd:63:ff:a1:
+                    fd:ce:36:d5:07:7a:1e:0e:cf:68:a8:c1:b3:7f:62:
+                    84:b7:e1:cf:25:7b:3f:a8:3c:ac:07:1a:fd:c2:e1:
+                    e0:9e:26:24:c1:0d:6d:9d:c6:57:6a:b4:39:28:3d:
+                    88:3e:c9:6a:89:90:72:4a:7b:75:c5:5e:1b:5e:5c:
+                    32:54:a3:ff:eb:01:68:7f:89:b4:4c:01:3f:08:8e:
+                    6c:61:49:60:26:0b:26:58:81:d7:1a:57:ee:52:5c:
+                    05:47:de:da:eb:b5:92:9d:5b:ce:26:18:44:59:3e:
+                    27:d0:61:86:e2:f4:c6:d9:c7:2b:1f:cb:ea:78:f0:
+                    a1:a9:57:d7:98:4c:c1:2f:ae:6a:38:b4:34:53:2e:
+                    5a:9e:f8:58:c7:51:e7:fd:b8:27:cd:87:72:26:c1:
+                    7d:14:c7:cd:fb:f2:04:8a:c4:8f:61:cf:a8:78:bd:
+                    21:be:28:cb:e8:a8:65:29:28:82:46:2f:18:e6:ff:
+                    6f:53
+                Exponent: 65537 (0x10001)
+        X509v3 extensions:
+            X509v3 Basic Constraints: 
+                CA:FALSE
+            X509v3 Subject Key Identifier: 
+                B5:A5:F0:37:25:97:AD:BE:F1:43:52:45:4D:8B:A0:5E:E9:78:21:B8
+            X509v3 Authority Key Identifier: 
+                keyid:26:4E:EB:B0:A5:1B:08:A8:90:2A:85:04:73:84:B5:A5:2C:61:D6:91
+                DirName:/CN=Ferdinand Linnenberg CA
+                serial:8C:E0:40:D9:D8:60:E5:77
+
+            X509v3 Extended Key Usage: 
+                TLS Web Client Authentication
+            X509v3 Key Usage: 
+                Digital Signature
+    Signature Algorithm: sha256WithRSAEncryption
+         19:f3:eb:c1:95:e6:d5:a9:33:d7:2e:02:d8:3a:91:84:81:14:
+         93:fc:03:4d:b1:4b:9d:0b:9b:94:93:9f:1a:0d:87:31:a1:fa:
+         a6:c7:3a:6b:18:24:12:ab:28:fb:c8:e3:09:a2:5d:50:49:00:
+         d9:18:e6:4a:09:18:e0:1c:da:d3:19:96:3d:74:72:fe:e0:8f:
+         ee:59:54:66:2e:57:72:b8:91:55:06:13:e5:9e:89:a2:3a:13:
+         3b:45:30:d3:cd:15:0e:81:eb:4f:b0:6a:a4:6d:00:7d:5b:c0:
+         4a:7f:97:d0:27:27:31:ae:3e:72:f1:74:fe:86:8e:29:a9:42:
+         23:26:22:db:08:8b:df:e9:d3:83:8d:81:10:36:d7:33:68:5e:
+         cb:93:cb:1e:12:c8:cb:be:5e:5c:8e:58:b0:1d:06:5e:c9:98:
+         b7:f1:49:fe:c4:03:de:b4:2b:da:9d:2c:7d:98:37:1c:6c:a8:
+         95:21:6f:23:e3:2e:09:bc:6c:e5:ed:e2:50:d8:f7:da:45:39:
+         d8:34:8a:57:0c:4f:d0:0d:80:06:d6:34:63:72:27:d1:50:d1:
+         d2:21:2c:97:57:17:98:02:95:3a:96:ed:75:9f:cc:f3:b8:f1:
+         3a:85:f9:58:08:9b:a0:75:fd:9b:fd:31:dd:08:dc:14:3d:f4:
+         68:aa:d4:30
+-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----
@@ -0,0 +1,30 @@
+-----BEGIN ENCRYPTED PRIVATE KEY-----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+-----END ENCRYPTED PRIVATE KEY-----
@@ -3,39 +3,38 @@
 #![forbid(unsafe_code)]
 #![warn(missing_docs, rust_2018_idioms, trivial_casts, unused_qualifications)]

-use getrandom::getrandom;
-use lazy_static::lazy_static;
+use cipher::common::{getrandom::SysRng, Generate};
 use log::trace;
-use rsa::{hash::Hash::SHA2_256, PaddingScheme, PublicKey};
+use once_cell::sync::Lazy;
+use rsa::{pkcs1v15, RsaPublicKey};
 use sha2::{Digest, Sha256};
-use std::convert::TryInto;
-use std::{env, sync::Mutex};
-use x509::RelativeDistinguishedName;
-use yubikey_piv::{
-    certificate::{Certificate, PublicKeyInfo},
-    key::{self, AlgorithmId, Key, RetiredSlotId, SlotId},
-    policy::{PinPolicy, TouchPolicy},
-    Error, MgmKey, YubiKey,
+use signature::hazmat::PrehashVerifier;
+use std::{env, str::FromStr, sync::Mutex, time::Duration};
+use x509_cert::{der::Encode, name::Name, serial_number::SerialNumber, time::Validity};
+use yubikey::{
+    certificate::{yubikey_signer, Certificate},
+    piv::{self, AlgorithmId, Key, ManagementSlotId, RetiredSlotId, SlotId},
+    Error, MgmKey, PinPolicy, Serial, TouchPolicy, YubiKey,
 };

-lazy_static! {
-    /// Provide thread-safe access to a YubiKey
-    static ref YUBIKEY: Mutex<YubiKey> = init_yubikey();
-}
-
-/// One-time test initialization and setup
-fn init_yubikey() -> Mutex<YubiKey> {
+static YUBIKEY: Lazy<Mutex<YubiKey>> = Lazy::new(|| {
    // Only show logs if `RUST_LOG` is set
    if env::var("RUST_LOG").is_ok() {
        env_logger::builder().format_timestamp(None).init();
    }

-    let yubikey = YubiKey::open().unwrap();
+    let yubikey = if let Ok(serial) = env::var("YUBIKEY_SERIAL") {
+        let serial = Serial::from_str(&serial).unwrap();
+        YubiKey::open_by_serial(serial).unwrap()
+    } else {
+        YubiKey::open().unwrap()
+    };
+
    trace!("serial: {}", yubikey.serial());
    trace!("version: {}", yubikey.version());

    Mutex::new(yubikey)
-}
+});

 //
 // CCCID support
@@ -44,12 +43,15 @@ fn init_yubikey() -> Mutex<YubiKey> {
 #[test]
 #[ignore]
 fn test_get_cccid() {
-    let mut yubikey = YUBIKEY.lock().unwrap();
+    let mut yubikey = match YUBIKEY.lock() {
+        Ok(yubikey) => yubikey,
+        Err(poison) => poison.into_inner(),
+    };

    match yubikey.cccid() {
        Ok(cccid) => trace!("CCCID: {:?}", cccid),
        Err(Error::NotFound) => trace!("CCCID not found"),
-        Err(err) => panic!("error getting CCCID: {:?}", err),
+        Err(err) => panic!("error getting CCCID: {err:?}"),
    }
 }

@@ -60,12 +62,15 @@ fn test_get_cccid() {
 #[test]
 #[ignore]
 fn test_get_chuid() {
-    let mut yubikey = YUBIKEY.lock().unwrap();
+    let mut yubikey = match YUBIKEY.lock() {
+        Ok(yubikey) => yubikey,
+        Err(poison) => poison.into_inner(),
+    };

    match yubikey.chuid() {
        Ok(chuid) => trace!("CHUID: {:?}", chuid),
        Err(Error::NotFound) => trace!("CHUID not found"),
-        Err(err) => panic!("error getting CHUID: {:?}", err),
+        Err(err) => panic!("error getting CHUID: {err:?}"),
    }
 }

@@ -76,7 +81,10 @@ fn test_get_chuid() {
 #[test]
 #[ignore]
 fn test_get_config() {
-    let mut yubikey = YUBIKEY.lock().unwrap();
+    let mut yubikey = match YUBIKEY.lock() {
+        Ok(yubikey) => yubikey,
+        Err(poison) => poison.into_inner(),
+    };
    let config_result = yubikey.config();
    assert!(config_result.is_ok());
    trace!("config: {:?}", config_result.unwrap());
@@ -89,7 +97,10 @@ fn test_get_config() {
 #[test]
 #[ignore]
 fn test_list_keys() {
-    let mut yubikey = YUBIKEY.lock().unwrap();
+    let mut yubikey = match YUBIKEY.lock() {
+        Ok(yubikey) => yubikey,
+        Err(poison) => poison.into_inner(),
+    };
    let keys_result = Key::list(&mut yubikey);
    assert!(keys_result.is_ok());
    trace!("keys: {:?}", keys_result.unwrap());
@@ -102,46 +113,96 @@ fn test_list_keys() {
 #[test]
 #[ignore]
 fn test_verify_pin() {
-    let mut yubikey = YUBIKEY.lock().unwrap();
+    let mut yubikey = match YUBIKEY.lock() {
+        Ok(yubikey) => yubikey,
+        Err(poison) => poison.into_inner(),
+    };
    assert!(yubikey.verify_pin(b"000000").is_err());
    assert!(yubikey.verify_pin(b"123456").is_ok());
 }

+//
+// Management key support
+//
+
+#[cfg(feature = "untested")]
+#[test]
+#[ignore]
+fn test_set_mgmkey() {
+    let mut rng = SysRng;
+    let mut yubikey = match YUBIKEY.lock() {
+        Ok(yubikey) => yubikey,
+        Err(poison) => poison.into_inner(),
+    };
+    let default_key = MgmKey::get_default(&yubikey).unwrap();
+
+    assert!(yubikey.verify_pin(b"123456").is_ok());
+    assert!(MgmKey::get_protected(&mut yubikey).is_err());
+    assert!(yubikey.authenticate(&default_key).is_ok());
+
+    // Set a protected management key.
+    assert!(MgmKey::generate_for(&yubikey, &mut rng)
+        .unwrap()
+        .set_protected(&mut yubikey)
+        .is_ok());
+    let protected = MgmKey::get_protected(&mut yubikey).unwrap();
+    assert!(yubikey.authenticate(&default_key).is_err());
+    assert!(yubikey.authenticate(&protected).is_ok());
+
+    // Set a manual management key.
+    let manual = MgmKey::generate_for(&yubikey, &mut rng).unwrap();
+    assert!(manual.set_manual(&mut yubikey, false).is_ok());
+    assert!(MgmKey::get_protected(&mut yubikey).is_err());
+    assert!(yubikey.authenticate(&default_key).is_err());
+    assert!(yubikey.authenticate(&protected).is_err());
+    assert!(yubikey.authenticate(&manual).is_ok());
+
+    // Set back to the default management key.
+    assert!(MgmKey::set_default(&mut yubikey).is_ok());
+    assert!(MgmKey::get_protected(&mut yubikey).is_err());
+    assert!(yubikey.authenticate(&protected).is_err());
+    assert!(yubikey.authenticate(&manual).is_err());
+    assert!(yubikey.authenticate(&default_key).is_ok());
+}
+
 //
 // Certificate support
 //

-fn generate_self_signed_cert(algorithm: AlgorithmId) -> Certificate {
+fn generate_self_signed_cert<KT: yubikey_signer::KeyType>() -> Certificate {
    let mut yubikey = YUBIKEY.lock().unwrap();
+    let default_key = MgmKey::get_default(&yubikey).unwrap();

    assert!(yubikey.verify_pin(b"123456").is_ok());
-    assert!(yubikey.authenticate(MgmKey::default()).is_ok());
+    assert!(yubikey.authenticate(&default_key).is_ok());

    let slot = SlotId::Retired(RetiredSlotId::R1);

    // Generate a new key in the selected slot.
-    let generated = key::generate(
+    let generated = piv::generate(
        &mut yubikey,
        slot,
-        algorithm,
+        KT::ALGORITHM,
        PinPolicy::Default,
        TouchPolicy::Default,
    )
    .unwrap();

-    let mut serial = [0u8; 20];
-    getrandom(&mut serial).unwrap();
+    // 0x80 0x00 ... (20bytes) is invalid because of high MSB (serial will keep the sign)
+    // we'll limit ourselves to 19 bytes serial.
+    let serial = <[u8; 19]>::generate();
+    let serial = SerialNumber::new(&serial[..]).expect("serial can't be more than 20 bytes long");
+    let validity = Validity::from_now(Duration::new(500000, 0)).unwrap();

    // Generate a self-signed certificate for the new key.
-    let extensions: &[x509::Extension<'_, &[u64]>] = &[];
-    let cert_result = Certificate::generate_self_signed(
+    let cert_result = Certificate::generate_self_signed::<_, KT>(
        &mut yubikey,
        slot,
        serial,
-        None,
-        &[RelativeDistinguishedName::common_name("testSubject")],
+        validity,
+        Name::from_str("CN=testSubject").expect("parse name"),
        generated,
-        extensions,
+        |_builder| Ok(()),
    );

    assert!(cert_result.is_ok());
@@ -153,57 +214,247 @@ fn generate_self_signed_cert(algorithm: AlgorithmId) -> Certificate {
 #[test]
 #[ignore]
 fn generate_self_signed_rsa_cert() {
-    let cert = generate_self_signed_cert(AlgorithmId::Rsa1024);
+    let cert = generate_self_signed_cert::<yubikey_signer::YubiRsa<yubikey_signer::Rsa1024>>();

    //
    // Verify that the certificate is signed correctly
    //

-    let pubkey = match cert.subject_pki() {
-        PublicKeyInfo::Rsa { pubkey, .. } => pubkey,
-        _ => unreachable!(),
-    };
+    let pubkey = RsaPublicKey::try_from(cert.subject_pki()).expect("valid rsa key");
+    let pubkey = pkcs1v15::VerifyingKey::<Sha256>::new(pubkey);

-    let data = cert.as_ref();
+    let data = cert.cert.to_der().expect("serialize certificate");
    let tbs_cert_len = u16::from_be_bytes(data[6..8].try_into().unwrap()) as usize;
    let msg = &data[4..8 + tbs_cert_len];
-    let sig = &data[data.len() - 128..];
-
+    let sig = pkcs1v15::Signature::try_from(&data[data.len() - 128..]).unwrap();
    let hash = Sha256::digest(msg);

-    assert!(pubkey
-        .verify(
-            PaddingScheme::PKCS1v15Sign {
-                hash: Some(SHA2_256)
-            },
-            &hash,
-            sig
-        )
-        .is_ok());
+    assert!(pubkey.verify_prehash(&hash, &sig).is_ok());
+}
+
+#[test]
+#[ignore]
+fn generate_rsa3072() {
+    let mut yubikey = YUBIKEY.lock().unwrap();
+    let version = yubikey.version();
+    let default_key = MgmKey::get_default(&yubikey).unwrap();
+
+    assert!(yubikey.authenticate(&default_key).is_ok());
+
+    let slot = SlotId::Retired(RetiredSlotId::R1);
+
+    // Generate a new key in the selected slot.
+    let generated = piv::generate(
+        &mut yubikey,
+        slot,
+        AlgorithmId::Rsa3072,
+        PinPolicy::Default,
+        TouchPolicy::Default,
+    );
+
+    match generated {
+        Ok(key) => {
+            let pubkey = key.subject_public_key;
+            assert!(pubkey.bit_len() > 3072)
+        }
+        Err(e) => assert!((version.major, version.minor) < (5, 7) && e == Error::AlgorithmError),
+    }
 }

 #[test]
 #[ignore]
 fn generate_self_signed_ec_cert() {
-    let cert = generate_self_signed_cert(AlgorithmId::EccP256);
+    let cert = generate_self_signed_cert::<p256::NistP256>();

    //
    // Verify that the certificate is signed correctly
    //

-    let pubkey = match cert.subject_pki() {
-        PublicKeyInfo::EcP256(pubkey) => pubkey,
-        _ => unreachable!(),
-    };
+    let vk = p256::ecdsa::VerifyingKey::try_from(cert.subject_pki()).expect("ecdsa key expected");

-    let data = cert.as_ref();
+    let data = cert.cert.to_der().expect("serialize certificate");
    let tbs_cert_len = data[6] as usize;
    let sig_algo_len = data[7 + tbs_cert_len + 1] as usize;
    let sig_start = 7 + tbs_cert_len + 2 + sig_algo_len + 3;
    let msg = &data[4..7 + tbs_cert_len];
-    let sig = &data[sig_start..];
+    let sig = p256::ecdsa::Signature::from_der(&data[sig_start..]).unwrap();

-    use ring::signature::{UnparsedPublicKey, ECDSA_P256_SHA256_ASN1};
-    let ring_pk = UnparsedPublicKey::new(&ECDSA_P256_SHA256_ASN1, pubkey.as_bytes());
-    assert!(ring_pk.verify(msg, sig).is_ok());
+    use p256::ecdsa::signature::Verifier;
+    assert!(vk.verify(msg, &sig).is_ok());
+}
+
+#[test]
+#[ignore]
+fn generate_self_signed_cv_cert() {
+    let cert = generate_self_signed_cert::<ed25519_dalek::SigningKey>();
+
+    //
+    // Verify that the certificate is signed correctly
+    //
+
+    let pubkey =
+        ed25519_dalek::VerifyingKey::try_from(cert.subject_pki()).expect("ed25519 key expected");
+
+    let data = cert.cert.to_der().expect("serialize certificate");
+    let cert_len = data[2] as usize;
+    let tbs_cert_len = data[5] as usize;
+    let sig_algo_len: usize = 64;
+    let sig_start = cert_len - sig_algo_len + 3;
+    let msg = &data[3..6 + tbs_cert_len];
+    let sig =
+        ed25519_dalek::Signature::from_slice(&data[sig_start..sig_start + sig_algo_len]).unwrap();
+
+    use ed25519_dalek::Verifier;
+    assert!(pubkey.verify(msg, &sig).is_ok());
+}
+
+#[test]
+#[ignore]
+fn test_slot_id_display() {
+    assert_eq!(format!("{}", SlotId::Authentication), "Authentication");
+    assert_eq!(format!("{}", SlotId::Signature), "Signature");
+    assert_eq!(format!("{}", SlotId::KeyManagement), "KeyManagement");
+    assert_eq!(
+        format!("{}", SlotId::CardAuthentication),
+        "CardAuthentication"
+    );
+    assert_eq!(format!("{}", SlotId::Attestation), "Attestation");
+    assert_eq!(format!("{}", SlotId::Retired(RetiredSlotId::R1)), "R1");
+    assert_eq!(format!("{}", SlotId::Retired(RetiredSlotId::R2)), "R2");
+    assert_eq!(format!("{}", SlotId::Retired(RetiredSlotId::R3)), "R3");
+    assert_eq!(format!("{}", SlotId::Retired(RetiredSlotId::R4)), "R4");
+    assert_eq!(format!("{}", SlotId::Retired(RetiredSlotId::R5)), "R5");
+    assert_eq!(format!("{}", SlotId::Retired(RetiredSlotId::R6)), "R6");
+    assert_eq!(format!("{}", SlotId::Retired(RetiredSlotId::R7)), "R7");
+    assert_eq!(format!("{}", SlotId::Retired(RetiredSlotId::R8)), "R8");
+    assert_eq!(format!("{}", SlotId::Retired(RetiredSlotId::R9)), "R9");
+    assert_eq!(format!("{}", SlotId::Retired(RetiredSlotId::R10)), "R10");
+    assert_eq!(format!("{}", SlotId::Retired(RetiredSlotId::R11)), "R11");
+    assert_eq!(format!("{}", SlotId::Retired(RetiredSlotId::R12)), "R12");
+    assert_eq!(format!("{}", SlotId::Retired(RetiredSlotId::R13)), "R13");
+    assert_eq!(format!("{}", SlotId::Retired(RetiredSlotId::R14)), "R14");
+    assert_eq!(format!("{}", SlotId::Retired(RetiredSlotId::R15)), "R15");
+    assert_eq!(format!("{}", SlotId::Retired(RetiredSlotId::R16)), "R16");
+    assert_eq!(format!("{}", SlotId::Retired(RetiredSlotId::R17)), "R17");
+    assert_eq!(format!("{}", SlotId::Retired(RetiredSlotId::R18)), "R18");
+    assert_eq!(format!("{}", SlotId::Retired(RetiredSlotId::R19)), "R19");
+    assert_eq!(format!("{}", SlotId::Retired(RetiredSlotId::R20)), "R20");
+
+    assert_eq!(
+        format!("{}", SlotId::Management(ManagementSlotId::Pin)),
+        "Pin"
+    );
+    assert_eq!(
+        format!("{}", SlotId::Management(ManagementSlotId::Puk)),
+        "Puk"
+    );
+    assert_eq!(
+        format!("{}", SlotId::Management(ManagementSlotId::Management)),
+        "Management"
+    );
+}
+
+//
+// Metadata
+//
+
+#[test]
+#[ignore]
+fn test_read_metadata() {
+    let mut yubikey = match YUBIKEY.lock() {
+        Ok(yubikey) => yubikey,
+        Err(poison) => poison.into_inner(),
+    };
+    let default_key = MgmKey::get_default(&yubikey).unwrap();
+
+    assert!(yubikey.verify_pin(b"123456").is_ok());
+    assert!(yubikey.authenticate(&default_key).is_ok());
+
+    let slot = SlotId::Retired(RetiredSlotId::R1);
+
+    // Generate a new key in the selected slot.
+    let generated = piv::generate(
+        &mut yubikey,
+        slot,
+        AlgorithmId::EccP256,
+        PinPolicy::Default,
+        TouchPolicy::Default,
+    )
+    .unwrap();
+
+    match piv::metadata(&mut yubikey, slot) {
+        Ok(metadata) => assert_eq!(metadata.public, Some(generated)),
+        Err(Error::NotSupported) => {
+            // Some YubiKeys don't support metadata
+            eprintln!("metadata not supported by this YubiKey");
+        }
+        Err(err) => panic!("{}", err),
+    }
+}
+
+#[test]
+#[ignore]
+fn test_read_metadata_missing_key() {
+    let mut yubikey = YUBIKEY.lock().unwrap();
+    let default_key = MgmKey::get_default(&yubikey).unwrap();
+
+    assert!(yubikey.verify_pin(b"123456").is_ok());
+    assert!(yubikey.authenticate(&default_key).is_ok());
+
+    // we assume that at least one of these slots is empty
+    let slots_to_check = [
+        RetiredSlotId::R10,
+        RetiredSlotId::R11,
+        RetiredSlotId::R12,
+        RetiredSlotId::R13,
+        RetiredSlotId::R14,
+        RetiredSlotId::R15,
+        RetiredSlotId::R16,
+        RetiredSlotId::R17,
+        RetiredSlotId::R18,
+        RetiredSlotId::R19,
+        RetiredSlotId::R20,
+    ];
+
+    for slot in slots_to_check {
+        let slot = SlotId::Retired(slot);
+
+        match piv::metadata(&mut yubikey, slot) {
+            Ok(_) => {
+                eprintln!("Key {} exists", slot);
+            }
+            Err(Error::NotSupported) => {
+                // Some YubiKeys don't support metadata
+                eprintln!("metadata not supported by this YubiKey");
+                return;
+            }
+            Err(Error::NotFound) => {
+                eprintln!("Key {} doesn't exist, ok.", slot);
+                return;
+            }
+            Err(err) => panic!("{}", err),
+        }
+    }
+
+    panic!("No empty slots to check");
+}
+
+#[test]
+#[ignore]
+fn test_parse_cert_from_der() {
+    let bob_der = std::fs::read("tests/assets/Bob.der").expect(".der file not found");
+    let cert = Certificate::from_bytes(bob_der).expect("Failed to parse valid certificate");
+    assert_eq!(
+        cert.subject(),
+        "CN=Bob",
+        "Subject is {} should be CN=Bob",
+        cert.subject()
+    );
+    assert_eq!(
+        cert.issuer(),
+        "CN=Ferdinand Linnenberg CA",
+        "Issuer is {} should be {}",
+        cert.issuer(),
+        "CN=Ferdinand Linnenberg CA"
+    );
 }