v0.4.1

We don't know how to correctly use these identities. In particular, some
identities store parts of their private key material in certificate
extensions to work around hardware limitations. Not understanding these
extensions could lead to encrypting with the wrong protocol and
violating security assumptions.

.github/workflows/ci.yml

@@ -23,116 +23,42 @@ jobs:
 
     steps:
       - uses: actions/checkout@v3
-      - uses: actions-rs/toolchain@v1
-        with:
-          toolchain: 1.56.0
-          override: true
       - name: Install build dependencies
         run: sudo apt install ${{ matrix.build_deps }}
         if: matrix.build_deps != ''
-      - name: cargo fetch
-        uses: actions-rs/cargo@v1
-        with:
-          command: fetch
+      - name: Install test dependencies
+        run: cargo install rage
+      - run: cargo fetch
       - name: Build tests
-        uses: actions-rs/cargo@v1
-        with:
-          command: build
-          args: --verbose --tests
+        run: cargo build --verbose --tests
       - name: Run tests
-        uses: actions-rs/cargo@v1
-        with:
-          command: test
-          args: --verbose
-
-  clippy:
-    name: Clippy (1.56.0)
-    timeout-minutes: 30
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v3
-      - uses: actions-rs/toolchain@v1
-        with:
-          toolchain: 1.56.0
-          components: clippy
-          override: true
-      - name: Install build dependencies
-        run: sudo apt install libpcsclite-dev
-      - name: Run clippy
-        uses: actions-rs/clippy-check@v1
-        with:
-          name: Clippy (1.56.0)
-          token: ${{ secrets.GITHUB_TOKEN }}
-          args: --all-features --all-targets -- -D warnings
-
-  clippy-nightly:
-    name: Clippy (nightly)
-    timeout-minutes: 30
-    runs-on: ubuntu-latest
-    continue-on-error: true
-    steps:
-      - uses: actions/checkout@v3
-      - uses: actions-rs/toolchain@v1
-        with:
-          toolchain: nightly
-          components: clippy
-          override: true
-      - name: Install build dependencies
-        run: sudo apt install libpcsclite-dev
-      - name: Run Clippy (nightly)
-        uses: actions-rs/clippy-check@v1
-        continue-on-error: true
-        with:
-          name: Clippy (nightly)
-          token: ${{ secrets.GITHUB_TOKEN }}
-          args: --all-features --all-targets
+        run: cargo test --verbose
 
   codecov:
     name: Code coverage
     runs-on: ubuntu-latest
-
     steps:
       - uses: actions/checkout@v3
-      # Use stable for this to ensure that cargo-tarpaulin can be built.
-      - uses: actions-rs/toolchain@v1
-        with:
-          toolchain: stable
-          override: true
       - name: Install build dependencies
         run: sudo apt install libpcsclite-dev
+      - name: Install coverage dependencies
+        run: cargo install cargo-tarpaulin
       - name: Generate coverage report
-        uses: actions-rs/tarpaulin@v0.1
-        with:
-          args: --release --timeout 180 --out Xml
+        run: cargo tarpaulin --engine llvm --all-features --release --timeout 600 --out Xml
       - name: Upload coverage to Codecov
         uses: codecov/codecov-action@v3.1.1
-        with:
-          token: ${{secrets.CODECOV_TOKEN}}
 
   doc-links:
     name: Intra-doc links
     runs-on: ubuntu-latest
-
     steps:
       - uses: actions/checkout@v3
-      - uses: actions-rs/toolchain@v1
-        with:
-          toolchain: 1.56.0
-          override: true
       - name: Install build dependencies
         run: sudo apt install libpcsclite-dev
-      - name: cargo fetch
-        uses: actions-rs/cargo@v1
-        with:
-          command: fetch
-
-      # Ensure intra-documentation links all resolve correctly
-      # Requires #![deny(intra_doc_link_resolution_failure)] in crates.
+      - run: cargo fetch
+      # Requires #![deny(rustdoc::broken_intra_doc_links)] in crates.
       - name: Check intra-doc links
-        uses: actions-rs/cargo@v1
-        with:
-          command: doc
-          args: --document-private-items
+        run: cargo doc --document-private-items
 
   fmt:
     name: Rustfmt
@@ -140,13 +66,5 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v3
-      - uses: actions-rs/toolchain@v1
-        with:
-          toolchain: 1.56.0
-          components: rustfmt
-          override: true
       - name: Check formatting
-        uses: actions-rs/cargo@v1
-        with:
-          command: fmt
-          args: -- --check
+        run: cargo fmt -- --check

.github/workflows/lints-beta.yml

@@ -0,0 +1,23 @@
+name: Beta lints
+
+# We only run these lints on trial-merges of PRs to reduce noise.
+on: pull_request
+
+jobs:
+  clippy-beta:
+    name: Clippy (beta)
+    timeout-minutes: 30
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: dtolnay/rust-toolchain@beta
+        id: toolchain
+      - run: rustup override set ${{steps.toolchain.outputs.name}}
+      - name: Install build dependencies
+        run: sudo apt install libpcsclite-dev
+      - name: Clippy (beta)
+        uses: actions-rs/clippy-check@v1
+        with:
+          name: Clippy (beta)
+          token: ${{ secrets.GITHUB_TOKEN }}
+          args: --all-features --all-targets -- -W clippy::all

.github/workflows/lints-stable.yml

@@ -0,0 +1,20 @@
+name: Stable lints
+
+# We only run these lints on trial-merges of PRs to reduce noise.
+on: pull_request
+
+jobs:
+  clippy:
+    name: Clippy (MSRV)
+    timeout-minutes: 30
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - name: Install build dependencies
+        run: sudo apt install libpcsclite-dev
+      - name: Run clippy
+        uses: actions-rs/clippy-check@v1
+        with:
+          name: Clippy (MSRV)
+          token: ${{ secrets.GITHUB_TOKEN }}
+          args: --all-features --all-targets -- -D warnings

.github/workflows/release.yml

@@ -87,7 +87,7 @@ jobs:
         if: matrix.name == 'windows'
 
       - name: Upload archive to release
-        uses: svenstaro/upload-release-action@2.3.0
+        uses: svenstaro/upload-release-action@2.5.0
         with:
           file: ${{ matrix.archive_name }}
           asset_name: age-plugin-yubikey-$tag-${{ matrix.asset_suffix }}
@@ -146,7 +146,7 @@ jobs:
           args: --package age-plugin-yubikey --no-build --target ${{ matrix.target }}
 
       - name: Upload Debian package to release
-        uses: svenstaro/upload-release-action@2.3.0
+        uses: svenstaro/upload-release-action@2.5.0
         with:
           file: target/${{ matrix.target }}/debian/*.deb
           file_glob: true

CHANGELOG.md

@@ -8,6 +8,30 @@ to 0.3.0 are beta releases.
 
 ## [Unreleased]
 
+## [0.3.4], [0.4.1] - 2026-04-08
+### Fixed
+- `age-plugin-yubikey` now completely ignores any identity that has unrecognised
+  critical extensions in its certificate, to ensure it doesn't misuse a newer
+  identity type.
+
+## [0.4.0] - 2023-04-09
+### Changed
+- MSRV is now 1.65.0.
+- The YubiKey PIV PIN and touch caches are now preserved across processes in
+  most cases. See [README.md](README.md#agent-support) for exceptions. This has
+  several usability effects (not applicable to YubiKey 4 series):
+  - If a YubiKey's PIN is cached by an agent like `yubikey-agent`, and then
+    `age-plugin-yubikey` is run (either directly or as a plugin), the agent
+    won't request a PIN entry on its next use.
+  - If a YubiKey's PIN was requested by either a previous invocation of
+    `age-plugin-yubikey` or an agent like `yubikey-agent`, subsequent calls to
+    `age-plugin-yubikey` won't request a PIN entry to decrypt a file with an
+    identity that has a PIN policy of `once`.
+
+### Fixed
+- Identities can now be generated with a PIN policy of "always" (in previous
+  versions of `age-plugin-yubikey` this would cause an error).
+
 ## [0.3.3] - 2023-02-11
 ### Fixed
 - When `age-plugin-yubikey` assists the user in changing their PIN from the

Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "age-plugin-yubikey"
 description = "YubiKey plugin for age clients"
-version = "0.3.3"
+version = "0.4.1"
 authors = ["Jack Grigg <thestr4d@gmail.com>"]
 repository = "https://github.com/str4d/age-plugin-yubikey"
 readme = "README.md"
@@ -9,7 +9,7 @@ keywords = ["age", "cli", "encryption", "yubikey"]
 categories = ["command-line-utilities", "cryptography"]
 license = "MIT OR Apache-2.0"
 edition = "2021"
-rust-version = "1.56" # MSRV
+rust-version = "1.65" # MSRV
 
 [package.metadata.deb]
 extended-description = """\
@@ -22,24 +22,24 @@ assets = [
 ]
 
 [dependencies]
-age-core = "0.8"
-age-plugin = "0.3"
-base64 = "0.13"
-bech32 = "0.8"
+age-core = "0.9"
+age-plugin = "0.4"
+base64 = "0.21"
+bech32 = "0.9"
 console = { version = "0.15", default-features = false }
-dialoguer = { version = "0.9", default-features = false, features = ["password"] }
-env_logger = "0.9"
+dialoguer = { version = "0.10", default-features = false, features = ["password"] }
+env_logger = "0.10"
 gumdrop = "0.8"
 hex = "0.4"
 log = "0.4"
-p256 = { version = "0.9", features = ["ecdh"] }
+p256 = { version = "0.13", features = ["ecdh"] }
 pcsc = "2.4"
 rand = "0.8"
-sha2 = "0.9"
+sha2 = "0.10"
 which = "4.1"
 x509 = "0.2"
-x509-parser = "0.12"
-yubikey = { version = "0.5", features = ["untested"] }
+x509-parser = "0.14"
+yubikey = { version = "=0.8.0-pre.0", features = ["untested"] }
 
 # Translations
 i18n-embed = { version = "0.13", features = ["desktop-requester", "fluent-system"] }
@@ -48,8 +48,11 @@ lazy_static = "1"
 rust-embed = "6"
 
 # GnuPG coexistence
-sysinfo = ">=0.26, <0.26.4"
+sysinfo = "0.28"
 
 [dev-dependencies]
 flate2 = "1"
 man = "0.3"
+tempfile = "3"
+test-with = "0.9"
+which = "4"

README.md

@@ -6,26 +6,34 @@ which enables files to be encrypted to age identities stored on YubiKeys.
 
 ## Installation
 
+| Environment | CLI command |
+|-------------|-------------|
+| Cargo (Rust 1.65+) | `cargo install age-plugin-yubikey` |
+| Homebrew (macOS or Linux) | `brew install age-plugin-yubikey` |
+
 On Windows, Linux, and macOS, you can use the
 [pre-built binaries](https://github.com/str4d/age-plugin-yubikey/releases).
 
-If your system has Rust 1.56+ installed (either via `rustup` or a system
-package), you can build directly from source:
-
-```
-cargo install age-plugin-yubikey
-```
-
 Help from new packagers is very welcome.
 
 ### Linux, BSD, etc.
 
 On non-Windows, non-macOS systems, you need to ensure that the `pcscd` service
-is installed and running. On Debian or Ubuntu, you can do this with:
+is installed and running. 
 
-```
-$ sudo apt-get install pcscd
-```
+| Environment | CLI command |
+|-------------|-------------|
+| Debian or Ubuntu | `sudo apt-get install pcscd` |
+| OpenBSD | As ```root``` do:<br>`pkg_add pcsc-lite ccid`<br>`rcctl enable pcscd`<br>`rcctl start pcscd` |
+| FreeBSD | As ```root``` do:<br>`pkg install pcsc-lite libccid`<br>`service pcscd enable`<br>`service pcscd start` |
+
+When installing via Cargo, you also need to ensure that the development headers
+for the `pcsc-lite` library are available, so that the `pcsc-sys` crate can be
+compiled.
+
+| Environment | CLI command |
+|-------------|-------------|
+| Debian or Ubuntu | `sudo apt-get install libpcsclite-dev` |
 
 ### Windows Subsystem for Linux (WSL)
 
@@ -44,7 +52,12 @@ YubiKey:
 
 ## Configuration
 
-There are two ways to configure a YubiKey as an `age` identity. You can run the
+`age-plugin-yubikey` identities have two parts:
+- The secret key material, which is stored inside a YubiKey.
+- An age identity file, which contains information that an age client can use to
+  figure out which YubiKey secret key should be used.
+
+There are two ways to configure a YubiKey as an age identity. You can run the
 plugin binary directly to use a simple text interface, which will create an age
 identity file:
 
@@ -70,6 +83,14 @@ Once an identity has been created, you can regenerate it later:
 $ age-plugin-yubikey --identity [--serial SERIAL] --slot SLOT
 ```
 
+To use the identity with an age client, it needs to be stored in a file. When
+using the above programmatic flags, you can do this by redirecting standard
+output to a file. On a Unix system like macOS or Ubuntu:
+
+```
+$ age-plugin-yubikey --identity --slot SLOT > yubikey-identity.txt
+```
+
 ## Usage
 
 The age recipients contained in all connected YubiKeys can be printed on
@@ -94,13 +115,27 @@ age client as normal (e.g. `rage -d -i yubikey-identity.txt`).
 ### Agent support
 
 `age-plugin-yubikey` does not provide or interact with an agent for decryption.
-As age plugin binaries have short lifetimes (they only run while the age client
-is running), this means that YubiKey identities configured with a PIN policy of
-`once` will actually prompt for the PIN on every decryption.
+It does however attempt to preserve the PIN cache by not soft-resetting the
+YubiKey after a decryption or read-only operation, which enables YubiKey
+identities configured with a PIN policy of `once` to not prompt for the PIN on
+every decryption. **This does not work for YubiKey 4 series.**
 
-A decryption agent will most likely be implemented as a separate age plugin that
-interacts with [`yubikey-agent`](https://github.com/FiloSottile/yubikey-agent),
-enabling YubiKeys to be used simultaneously with age and SSH.
+The session that corresponds to the `once` policy can be ended in several ways,
+not all of which are necessarily intuitive:
+
+- Unplugging the YubiKey (the obvious way).
+- Using a different applet (e.g. FIDO2). This causes the PIV applet to be closed
+  which clears its state.
+  - This is why the YubiKey 4 series does not support PIN cache preservation:
+    their serial can only be obtained by switching to the OTP applet.
+- Generating a new age identity via `age-plugin-yubikey --generate` or the CLI
+  interface. This is to avoid leaving the YubiKey authenticated with the
+  management key.
+
+If the current PIN UX proves to be insufficient, a decryption agent will most
+likely be implemented as a separate age plugin that interacts with
+[`yubikey-agent`](https://github.com/FiloSottile/yubikey-agent), enabling
+YubiKeys to be used simultaneously with age and SSH.
 
 ### Manual setup and technical details
 

i18n/en-US/age_plugin_yubikey.ftl

@@ -76,6 +76,14 @@ cli-setup-name-identity       = 📛 Name this identity
 cli-setup-select-pin-policy   = 🔤 Select a PIN policy
 cli-setup-select-touch-policy = 👆 Select a touch policy
 
+cli-setup-yk4-pin-policy =
+    ⚠️ Your {-yubikey} is a {-yubikey} 4 series. With ephemeral applications like
+    {-age-plugin-yubikey}, a PIN policy of "Once" behaves like a PIN policy of
+    "Always", and your PIN will be requested for every decryption. However, you
+    might still benefit from a PIN policy of "Once" in long-running applications
+    like agents.
+cli-setup-yk4-pin-policy-confirm = Use PIN policy of "Once" with {-yubikey} 4?
+
 cli-setup-generate-new = Generate new identity in slot {$slot_index}?
 cli-setup-use-existing = Use existing identity in slot {$slot_index}?
 
@@ -112,6 +120,7 @@ cli-setup-finished =
 open-yk-with-serial    = ⏳ Please insert the {-yubikey} with serial {$yubikey_serial}.
 open-yk-without-serial = ⏳ Please insert the {-yubikey}.
 warn-yk-not-connected  = Ignoring {$yubikey_name}: not connected
+warn-yk-missing-applet = Ignoring {$yubikey_name}: Missing {$applet_name} applet
 
 print-recipient = Recipient: {$recipient}
 
@@ -146,6 +155,12 @@ mgr-changing-mgmt-key-error =
     {"  "}{$management_key}
 mgr-changing-mgmt-key-success = Success!
 
+## YubiKey keygen
+
+builder-gen-key  = 🎲 Generating key...
+builder-gen-cert = 🔏 Generating certificate...
+builder-touch-yk = 👆 Please touch the {-yubikey}
+
 ## Plugin usage
 
 plugin-err-invalid-recipient = Invalid recipient
@@ -172,8 +187,12 @@ plugin-err-pin-required     = A PIN is required for {-yubikey} with serial {$yub
 
 ## Errors
 
+err-mgmt-key-auth = Failed to authenticate with the PIN-protected management key.
+rec-mgmt-key-auth =
+    Check whether your management key is using the TDES algorithm.
+    AES is not supported yet: {$aes_url}
 err-custom-mgmt-key = Custom unprotected non-TDES management keys are not supported.
-rec-custom-mgmt-key =
+rec-change-mgmt-key =
     You can use the {-yubikey} Manager CLI to change to a protected management key:
     {"  "}{$cmd}
 
@@ -205,16 +224,27 @@ rec-yk-no-service-pcscd =
     If you are on Debian or Ubuntu, you can install it with:
     {"  "}{$apt}
 
+rec-yk-no-service-pcscd-bsd =
+    You can install and run it as root with:
+    {"  "}{$pkg}
+    {"  "}{$service_enable}
+    {"  "}{$service_start}
+
 err-yk-no-service-win = The Smart Cards for Windows service is not running.
 rec-yk-no-service-win =
     See this troubleshooting guide for more help:
     {"  "}{$url}
 
 err-yk-not-found         = Please insert the {-yubikey} you want to set up
-err-yk-wrong-pin         = Invalid PIN ({$tries} tries remaining before it is blocked)
 err-yk-general           = Error while communicating with {-yubikey}: {$err}
 err-yk-general-cause     = Cause: {$inner_err}
 
+err-yk-wrong-pin = Invalid {$pin_kind} ({$tries ->
+    [one] {$tries} try remaining
+   *[other] {$tries} tries remaining
+} before it is blocked)
+err-yk-pin-locked = {$pin_kind} locked
+
 err-ux-A = Did this not do what you expected? Could an error be more useful?
 err-ux-B = Tell us
 # Put (len(A) - len(B) - 46) spaces here.

rust-toolchain

@@ -1 +0,0 @@
-1.56.0

rust-toolchain.toml

@@ -0,0 +1,3 @@
+[toolchain]
+channel = "1.65.0"
+components = ["clippy", "rustfmt"]

src/builder.rs

@@ -1,3 +1,4 @@
+use dialoguer::Password;
 use rand::{rngs::OsRng, RngCore};
 use x509::RelativeDistinguishedName;
 use yubikey::{
@@ -8,6 +9,7 @@ use yubikey::{
 
 use crate::{
     error::Error,
+    fl,
     key::{self, Stub},
     p256::Recipient,
     util::{Metadata, POLICY_EXTENSION_OID},
@@ -86,17 +88,13 @@ impl IdentityBuilder {
         let pin_policy = self.pin_policy.unwrap_or(DEFAULT_PIN_POLICY);
         let touch_policy = self.touch_policy.unwrap_or(DEFAULT_TOUCH_POLICY);
 
+        eprintln!("{}", fl!("builder-gen-key"));
+
         // No need to ask for users to enter their PIN if the PIN policy requires it,
         // because here we _always_ require them to enter their PIN in order to access the
         // protected management key (which is necessary in order to generate identities).
         key::manage(yubikey)?;
 
-        if let TouchPolicy::Never = touch_policy {
-            // No need to touch YubiKey
-        } else {
-            eprintln!("👆 Please touch the YubiKey");
-        }
-
         // Generate a new key in the selected slot.
         let generated = yubikey_generate(
             yubikey,
@@ -109,6 +107,9 @@ impl IdentityBuilder {
         let recipient = Recipient::from_spki(&generated).expect("YubiKey generates a valid pubkey");
         let stub = Stub::new(yubikey.serial(), slot, &recipient);
 
+        eprintln!();
+        eprintln!("{}", fl!("builder-gen-cert"));
+
         // Pick a random serial for the new self-signed certificate.
         let mut serial = [0; 20];
         OsRng.fill_bytes(&mut serial);
@@ -117,6 +118,23 @@ impl IdentityBuilder {
             .name
             .unwrap_or(format!("age identity {}", hex::encode(stub.tag)));
 
+        if let PinPolicy::Always = pin_policy {
+            // We need to enter the PIN again.
+            let pin = Password::new()
+                .with_prompt(fl!(
+                    "plugin-enter-pin",
+                    yubikey_serial = yubikey.serial().to_string(),
+                ))
+                .report(true)
+                .interact()?;
+            yubikey.verify_pin(pin.as_bytes())?;
+        }
+        if let TouchPolicy::Never = touch_policy {
+            // No need to touch YubiKey
+        } else {
+            eprintln!("{}", fl!("builder-touch-yk"));
+        }
+
         let cert = Certificate::generate_self_signed(
             yubikey,
             SlotId::Retired(slot),

src/error.rs

@@ -21,14 +21,17 @@ pub enum Error {
     InvalidSlot(u8),
     InvalidTouchPolicy(String),
     Io(io::Error),
+    ManagementKeyAuth,
     MultipleCommands,
     MultipleYubiKeys,
     NoEmptySlots(Serial),
     NoMatchingSerial(Serial),
+    PukLocked,
     SlotHasNoIdentity(RetiredSlotId),
     SlotIsNotEmpty(RetiredSlotId),
     TimedOut,
     UseListForSingleSlot,
+    WrongPuk(u8),
     YubiKey(yubikey::Error),
 }
 
@@ -48,12 +51,19 @@ impl From<yubikey::Error> for Error {
 // manually to provide the error output we want.
 impl fmt::Debug for Error {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        const CHANGE_MGMT_KEY_CMD: &str =
+            "ykman piv access change-management-key -a TDES --protect";
+        const CHANGE_MGMT_KEY_URL: &str = "https://developers.yubico.com/yubikey-manager/";
+
         match self {
             Error::CustomManagementKey => {
                 wlnfl!(f, "err-custom-mgmt-key")?;
-                let cmd = "ykman piv access change-management-key --protect";
-                let url = "https://developers.yubico.com/yubikey-manager/";
-                wlnfl!(f, "rec-custom-mgmt-key", cmd = cmd, url = url)?;
+                wlnfl!(
+                    f,
+                    "rec-change-mgmt-key",
+                    cmd = CHANGE_MGMT_KEY_CMD,
+                    url = CHANGE_MGMT_KEY_URL
+                )?;
             }
             Error::InvalidFlagCommand(flag, command) => wlnfl!(
                 f,
@@ -76,6 +86,17 @@ impl fmt::Debug for Error {
                 expected = "always, cached, never",
             )?,
             Error::Io(e) => wlnfl!(f, "err-io", err = e.to_string())?,
+            Error::ManagementKeyAuth => {
+                let aes_url = "https://github.com/str4d/age-plugin-yubikey/issues/92";
+                wlnfl!(f, "err-mgmt-key-auth")?;
+                wlnfl!(f, "rec-mgmt-key-auth", aes_url = aes_url)?;
+                wlnfl!(
+                    f,
+                    "rec-change-mgmt-key",
+                    cmd = CHANGE_MGMT_KEY_CMD,
+                    url = CHANGE_MGMT_KEY_URL
+                )?;
+            }
             Error::MultipleCommands => wlnfl!(f, "err-multiple-commands")?,
             Error::MultipleYubiKeys => wlnfl!(f, "err-multiple-yubikeys")?,
             Error::NoEmptySlots(serial) => {
@@ -84,6 +105,7 @@ impl fmt::Debug for Error {
             Error::NoMatchingSerial(serial) => {
                 wlnfl!(f, "err-no-matching-serial", serial = serial.to_string())?
             }
+            Error::PukLocked => wlnfl!(f, "err-yk-pin-locked", pin_kind = "PUK")?,
             Error::SlotHasNoIdentity(slot) => {
                 wlnfl!(f, "err-slot-has-no-identity", slot = slot_to_ui(slot))?
             }
@@ -92,6 +114,9 @@ impl fmt::Debug for Error {
             }
             Error::TimedOut => wlnfl!(f, "err-timed-out")?,
             Error::UseListForSingleSlot => wlnfl!(f, "err-use-list-for-single")?,
+            Error::WrongPuk(tries) => {
+                wlnfl!(f, "err-yk-wrong-pin", pin_kind = "PUK", tries = tries)?
+            }
             Error::YubiKey(e) => match e {
                 yubikey::Error::NotFound => wlnfl!(f, "err-yk-not-found")?,
                 yubikey::Error::PcscError {
@@ -105,13 +130,40 @@ impl fmt::Debug for Error {
                         wlnfl!(f, "err-yk-no-service-macos")?;
                         let url = "https://apple.stackexchange.com/a/438198";
                         wlnfl!(f, "rec-yk-no-service-macos", url = url)?;
+                    } else if cfg!(target_os = "openbsd") {
+                        wlnfl!(f, "err-yk-no-service-pcscd")?;
+                        let pkg = "pkg_add pcsc-lite ccid";
+                        let service_enable = "rcctl enable pcscd";
+                        let service_start = "rcctl start pcscd";
+                        wlnfl!(
+                            f,
+                            "rec-yk-no-service-pcscd-bsd",
+                            pkg = pkg,
+                            service_enable = service_enable,
+                            service_start = service_start
+                        )?;
+                    } else if cfg!(target_os = "freebsd") {
+                        wlnfl!(f, "err-yk-no-service-pcscd")?;
+                        let pkg = "pkg install pcsc-lite libccid";
+                        let service_enable = "service pcscd enable";
+                        let service_start = "service pcscd start";
+                        wlnfl!(
+                            f,
+                            "rec-yk-no-service-pcscd-bsd",
+                            pkg = pkg,
+                            service_enable = service_enable,
+                            service_start = service_start
+                        )?;
                     } else {
                         wlnfl!(f, "err-yk-no-service-pcscd")?;
                         let apt = "sudo apt-get install pcscd";
                         wlnfl!(f, "rec-yk-no-service-pcscd", apt = apt)?;
                     }
                 }
-                yubikey::Error::WrongPin { tries } => wlnfl!(f, "err-yk-wrong-pin", tries = tries)?,
+                yubikey::Error::PinLocked => wlnfl!(f, "err-yk-pin-locked", pin_kind = "PIN")?,
+                yubikey::Error::WrongPin { tries } => {
+                    wlnfl!(f, "err-yk-wrong-pin", pin_kind = "PIN", tries = tries)?
+                }
                 e => {
                     wlnfl!(f, "err-yk-general", err = e.to_string())?;
                     use std::error::Error;

src/format.rs

@@ -1,10 +1,15 @@
 use age_core::{
     format::{FileKey, Stanza},
-    primitives::{aead_encrypt, hkdf},
+    primitives::aead_encrypt,
     secrecy::ExposeSecret,
 };
-use p256::{ecdh::EphemeralSecret, elliptic_curve::sec1::ToEncodedPoint};
+use base64::{prelude::BASE64_STANDARD_NO_PAD, Engine};
+use p256::{
+    ecdh::EphemeralSecret,
+    elliptic_curve::sec1::{FromEncodedPoint, ToEncodedPoint},
+};
 use rand::rngs::OsRng;
+use sha2::Sha256;
 
 use crate::{p256::Recipient, STANZA_TAG};
 
@@ -22,8 +27,12 @@ pub(crate) struct EphemeralKeyBytes(p256::EncodedPoint);
 
 impl EphemeralKeyBytes {
     fn from_bytes(bytes: [u8; EPK_BYTES]) -> Option<Self> {
-        let encoded = p256::EncodedPoint::from_bytes(&bytes).ok()?;
-        if encoded.is_compressed() && encoded.decompress().is_some() {
+        let encoded = p256::EncodedPoint::from_bytes(bytes).ok()?;
+        if encoded.is_compressed()
+            && p256::PublicKey::from_encoded_point(&encoded)
+                .is_some()
+                .into()
+        {
             Some(EphemeralKeyBytes(encoded))
         } else {
             None
@@ -39,9 +48,9 @@ impl EphemeralKeyBytes {
     }
 
     pub(crate) fn decompress(&self) -> p256::EncodedPoint {
-        self.0
-            .decompress()
-            .expect("EphemeralKeyBytes is a valid compressed encoding by construction")
+        // EphemeralKeyBytes is a valid compressed encoding by construction.
+        let p = p256::PublicKey::from_encoded_point(&self.0).unwrap();
+        p.to_encoded_point(false)
     }
 }
 
@@ -57,8 +66,8 @@ impl From<RecipientLine> for Stanza {
         Stanza {
             tag: STANZA_TAG.to_owned(),
             args: vec![
-                base64::encode_config(&r.tag, base64::STANDARD_NO_PAD),
-                base64::encode_config(r.epk_bytes.as_bytes(), base64::STANDARD_NO_PAD),
+                BASE64_STANDARD_NO_PAD.encode(r.tag),
+                BASE64_STANDARD_NO_PAD.encode(r.epk_bytes.as_bytes()),
             ],
             body: r.encrypted_file_key.to_vec(),
         }
@@ -76,9 +85,10 @@ impl RecipientLine {
                 return None;
             }
 
-            base64::decode_config_slice(arg, base64::STANDARD_NO_PAD, buf.as_mut())
+            BASE64_STANDARD_NO_PAD
+                .decode_slice_unchecked(arg, buf.as_mut())
                 .ok()
-                .map(|_| buf)
+                .and_then(|len| (len == buf.as_mut().len()).then_some(buf))
         }
 
         let (tag, epk_bytes) = match &s.args[..] {
@@ -101,7 +111,7 @@ impl RecipientLine {
     }
 
     pub(crate) fn wrap_file_key(file_key: &FileKey, pk: &Recipient) -> Self {
-        let esk = EphemeralSecret::random(OsRng);
+        let esk = EphemeralSecret::random(&mut OsRng);
         let epk = esk.public_key();
         let epk_bytes = EphemeralKeyBytes::from_public_key(&epk);
 
@@ -111,7 +121,14 @@ impl RecipientLine {
         salt.extend_from_slice(epk_bytes.as_bytes());
         salt.extend_from_slice(pk.to_encoded().as_bytes());
 
-        let enc_key = hkdf(&salt, STANZA_KEY_LABEL, shared_secret.as_bytes());
+        let enc_key = {
+            let mut okm = [0; 32];
+            shared_secret
+                .extract::<Sha256>(Some(&salt))
+                .expand(STANZA_KEY_LABEL, &mut okm)
+                .expect("okm is the correct length");
+            okm
+        };
 
         let encrypted_file_key = {
             let mut key = [0; ENCRYPTED_FILE_KEY_BYTES];

src/key.rs

@@ -15,6 +15,7 @@ use std::io;
 use std::iter;
 use std::thread::sleep;
 use std::time::{Duration, Instant, SystemTime};
+use x509_parser::der_parser::oid::Oid;
 use yubikey::{
     certificate::Certificate,
     piv::{decrypt_data, AlgorithmId, RetiredSlotId, SlotId},
@@ -27,13 +28,16 @@ use crate::{
     fl,
     format::{RecipientLine, STANZA_KEY_LABEL},
     p256::{Recipient, TAG_BYTES},
-    util::{otp_serial_prefix, Metadata},
+    util::{otp_serial_prefix, Metadata, POLICY_EXTENSION_OID},
     IDENTITY_PREFIX,
 };
 
 const ONE_SECOND: Duration = Duration::from_secs(1);
 const FIFTEEN_SECONDS: Duration = Duration::from_secs(15);
 
+/// The set of OIDs that we understand and use when parsing YubiKey slot certificates.
+const KNOWN_OIDS: &[&[u64]] = &[POLICY_EXTENSION_OID];
+
 pub(crate) fn is_connected(reader: Reader) -> bool {
     filter_connected(&reader)
 }
@@ -49,7 +53,24 @@ pub(crate) fn filter_connected(reader: &Reader) -> bool {
             );
             false
         }
-        _ => true,
+        Err(yubikey::Error::AppletNotFound { applet_name }) => {
+            warn!(
+                "{}",
+                fl!(
+                    "warn-yk-missing-applet",
+                    yubikey_name = reader.name(),
+                    applet_name = applet_name,
+                ),
+            );
+            false
+        }
+        Err(_) => true,
+        Ok(yubikey) => {
+            // We only connected as a side-effect of confirming that we can connect, so
+            // avoid resetting the YubiKey.
+            disconnect_without_reset(yubikey);
+            true
+        }
     }
 }
 
@@ -181,6 +202,9 @@ fn open_by_serial(serial: Serial) -> Result<YubiKey, yubikey::Error> {
 
             if serial == yubikey.serial() {
                 return Ok(yubikey);
+            } else {
+                // We didn't want this YubiKey; don't reset it.
+                disconnect_without_reset(yubikey);
             }
         }
 
@@ -237,6 +261,23 @@ pub(crate) fn open(serial: Option<Serial>) -> Result<YubiKey, Error> {
     Ok(yubikey)
 }
 
+/// Disconnect from the YubiKey without resetting it.
+///
+/// This can be used to preserve the YubiKey's PIN and touch caches. There are two cases
+/// where we want to do this:
+///
+/// - We connected to this YubiKey in a read-only context, so we have not made any changes
+///   to the YubiKey's state. However, we might have asked an agent to release the YubiKey
+///   in `key::open_connection`, and we want to allow any state it may have left behind
+///   (such as cached PINs or touches) to persist beyond our execution, for usability.
+/// - We opened this connection in a decryption context, so the only changes to the
+///   YubiKey's state were to potentially cache the PIN and/or touch (depending on the
+///   policies of the slot). We want to allow these to persist beyond our execution, for
+///   usability.
+pub(crate) fn disconnect_without_reset(yubikey: YubiKey) {
+    let _ = yubikey.disconnect(pcsc::Disposition::LeaveCard);
+}
+
 fn request_pin<E>(
     mut prompt: impl FnMut(Option<String>) -> io::Result<Result<SecretString, E>>,
     serial: Serial,
@@ -273,6 +314,7 @@ pub(crate) fn manage(yubikey: &mut YubiKey) -> Result<(), Error> {
             yubikey_serial = yubikey.serial().to_string(),
             default_pin = DEFAULT_PIN,
         ))
+        .report(true)
         .interact()?;
     yubikey.verify_pin(pin.as_bytes())?;
 
@@ -306,39 +348,74 @@ pub(crate) fn manage(yubikey: &mut YubiKey) -> Result<(), Error> {
             }
         };
         let new_pin = new_pin.expose_secret();
-        yubikey.change_puk(current_puk.as_bytes(), new_pin.as_bytes())?;
+        yubikey
+            .change_puk(current_puk.as_bytes(), new_pin.as_bytes())
+            .map_err(|e| match e {
+                yubikey::Error::PinLocked => Error::PukLocked,
+                yubikey::Error::WrongPin { tries } => Error::WrongPuk(tries),
+                _ => Error::YubiKey(e),
+            })?;
         yubikey.change_pin(pin.as_bytes(), new_pin.as_bytes())?;
     }
 
-    if let Ok(mgm_key) = MgmKey::get_protected(yubikey) {
-        yubikey.authenticate(mgm_key)?;
-    } else {
-        // Try to authenticate with the default management key.
-        yubikey
-            .authenticate(MgmKey::default())
-            .map_err(|_| Error::CustomManagementKey)?;
+    match MgmKey::get_protected(yubikey) {
+        Ok(mgm_key) => yubikey.authenticate(mgm_key).map_err(|e| match e {
+            yubikey::Error::AuthenticationError => Error::ManagementKeyAuth,
+            _ => e.into(),
+        })?,
+        Err(yubikey::Error::AuthenticationError) => Err(Error::ManagementKeyAuth)?,
+        _ => {
+            // Try to authenticate with the default management key.
+            yubikey
+                .authenticate(MgmKey::default())
+                .map_err(|_| Error::CustomManagementKey)?;
 
-        // Migrate to a PIN-protected management key.
-        let mgm_key = MgmKey::generate();
-        eprintln!();
-        eprintln!("{}", fl!("mgr-changing-mgmt-key"));
-        eprint!("... ");
-        mgm_key.set_protected(yubikey).map_err(|e| {
-            eprintln!(
-                "{}",
-                fl!(
-                    "mgr-changing-mgmt-key-error",
-                    management_key = hex::encode(mgm_key.as_ref()),
-                )
-            );
-            e
-        })?;
-        eprintln!("{}", fl!("mgr-changing-mgmt-key-success"));
+            // Migrate to a PIN-protected management key.
+            let mgm_key = MgmKey::generate();
+            eprintln!();
+            eprintln!("{}", fl!("mgr-changing-mgmt-key"));
+            eprint!("... ");
+            mgm_key.set_protected(yubikey).map_err(|e| {
+                eprintln!(
+                    "{}",
+                    fl!(
+                        "mgr-changing-mgmt-key-error",
+                        management_key = hex::encode(mgm_key.as_ref()),
+                    )
+                );
+                e
+            })?;
+            eprintln!("{}", fl!("mgr-changing-mgmt-key-success"));
+        }
     }
 
     Ok(())
 }
 
+/// Parses the certificate to identify the preferred recipient type it corresponds to.
+pub(crate) fn identify_recipient(cert: &Certificate) -> Option<Recipient> {
+    let known_oids = KNOWN_OIDS
+        .iter()
+        .map(|oid| Oid::from(oid).unwrap())
+        .collect::<Vec<_>>();
+
+    // If the certificate contains any unrecognised critical extensions, reject it: we
+    // don't know how to correctly use the identity. In particular, some identities store
+    // parts of their private key material in certificate extensions to work around
+    // hardware limitations. Not understanding these extensions could lead to encrypting
+    // with the wrong protocol and violating security assumptions.
+    let (_, c) = x509_parser::parse_x509_certificate(cert.as_ref()).ok()?;
+    if c.tbs_certificate
+        .extensions()
+        .iter()
+        .any(|ext| ext.critical && !known_oids.contains(&ext.oid))
+    {
+        return None;
+    }
+
+    Recipient::from_certificate(cert)
+}
+
 /// Returns an iterator of keys that are occupying plugin-compatible slots, along with the
 /// corresponding recipient if the key is compatible with this plugin.
 pub(crate) fn list_slots(
@@ -348,8 +425,7 @@ pub(crate) fn list_slots(
         // We only use the retired slots.
         match key.slot() {
             SlotId::Retired(slot) => {
-                // Only P-256 keys are compatible with us.
-                let recipient = Recipient::from_certificate(key.certificate());
+                let recipient = identify_recipient(key.certificate());
                 Some((key, slot, recipient))
             }
             _ => None,
@@ -556,9 +632,9 @@ impl Stub {
         let (cert, pk) = match Certificate::read(&mut yubikey, SlotId::Retired(self.slot))
             .ok()
             .and_then(|cert| {
-                Recipient::from_certificate(&cert)
-                    .filter(|pk| pk.tag() == self.tag)
-                    .map(|pk| (cert, pk))
+                identify_recipient(&cert)
+                    .filter(|recipient| recipient.tag() == self.tag)
+                    .map(|r| (cert, r))
             }) {
             Some(pk) => pk,
             None => {
@@ -615,13 +691,13 @@ impl Connection {
                     metadata => metadata,
                 };
         }
-        if let Some(PinPolicy::Never) = self.cached_metadata.as_ref().and_then(|m| m.pin_policy) {
-            return Ok(Ok(()));
+        match self.cached_metadata.as_ref().and_then(|m| m.pin_policy) {
+            Some(PinPolicy::Never) => return Ok(Ok(())),
+            Some(PinPolicy::Once) if self.yubikey.verify_pin(&[]).is_ok() => return Ok(Ok(())),
+            _ => (),
         }
 
         // The policy requires a PIN, so request it.
-        // Note that we can't distinguish between PinPolicy::Once and PinPolicy::Always
-        // because this plugin is ephemeral, so we always request the PIN.
         let pin = match request_pin(
             |prev_error| {
                 callbacks.request_secret(&format!(
@@ -705,6 +781,13 @@ impl Connection {
             Err(_) => Err(()),
         }
     }
+
+    /// Close this connection without resetting the YubiKey.
+    ///
+    /// This can be used to preserve the YubiKey's PIN and touch caches.
+    pub(crate) fn disconnect_without_reset(self) {
+        disconnect_without_reset(self.yubikey);
+    }
 }
 
 #[cfg(test)]

src/main.rs

@@ -181,6 +181,13 @@ fn generate(flags: PluginFlags) -> Result<(), Error> {
 
     util::print_identity(stub, recipient, metadata);
 
+    // We have written to the YubiKey, which means we've authenticated with the management
+    // key. Out of an abundance of caution, we let the YubiKey be reset on disconnect,
+    // which will clear its PIN and touch caches. This has as small negative UX effect,
+    // but identity generation is a relatively infrequent occurrence, and users are more
+    // likely to see their cached PINs reset due to switching applets (e.g. from PIV to
+    // FIDO2).
+
     Ok(())
 }
 
@@ -200,6 +207,8 @@ fn print_single(
 
     printer(stub, recipient, metadata);
 
+    key::disconnect_without_reset(yubikey);
+
     Ok(())
 }
 
@@ -233,6 +242,8 @@ fn print_multiple(
             println!();
         }
         println!();
+
+        key::disconnect_without_reset(yubikey);
     }
     if printed > 1 {
         eprintln!("{}", fl!("printed-multiple", kind = kind, count = printed));
@@ -286,7 +297,7 @@ fn list(flags: PluginFlags, all: bool) -> Result<(), Error> {
         all,
         |_, recipient, metadata| {
             println!("{}", metadata);
-            println!("{}", recipient.to_string());
+            println!("{}", recipient);
         },
     )
 }
@@ -360,11 +371,13 @@ fn main() -> Result<(), Error> {
             .iter()
             .map(|reader| {
                 key::open_connection(reader).map(|yk| {
-                    fl!(
+                    let name = fl!(
                         "cli-setup-yk-name",
                         yubikey_name = reader.name(),
                         yubikey_serial = yk.serial().to_string(),
-                    )
+                    );
+                    key::disconnect_without_reset(yk);
+                    name
                 })
             })
             .collect::<Result<Vec<_>, _>>()?;
@@ -372,6 +385,7 @@ fn main() -> Result<(), Error> {
             .with_prompt(fl!("cli-setup-select-yk"))
             .items(&reader_names)
             .default(0)
+            .report(true)
             .interact_opt()?
         {
             Some(yk) => readers_list[yk].open()?,
@@ -393,7 +407,11 @@ fn main() -> Result<(), Error> {
                                 x509_parser::parse_x509_certificate(key.certificate().as_ref())
                                     .unwrap();
                             let (name, _) = util::extract_name(&cert, true).unwrap();
-                            let created = cert.validity().not_before.to_rfc2822();
+                            let created = cert
+                                .validity()
+                                .not_before
+                                .to_rfc2822()
+                                .unwrap_or_else(|e| format!("Invalid date: {}", e));
 
                             format!("{}, created: {}", name, created)
                         })
@@ -426,6 +444,7 @@ fn main() -> Result<(), Error> {
                     .with_prompt(fl!("cli-setup-select-slot"))
                     .items(&slots)
                     .default(0)
+                    .report(true)
                     .interact_opt()?
                 {
                     Some(slot) => {
@@ -443,6 +462,7 @@ fn main() -> Result<(), Error> {
 
                 if Confirm::new()
                     .with_prompt(fl!("cli-setup-use-existing", slot_index = slot_index))
+                    .report(true)
                     .interact()?
                 {
                     let stub = key::Stub::new(yubikey.serial(), slot, &recipient);
@@ -450,8 +470,10 @@ fn main() -> Result<(), Error> {
                         util::Metadata::extract(&mut yubikey, slot, key.certificate(), true)
                             .unwrap();
 
+                    key::disconnect_without_reset(yubikey);
                     ((stub, recipient, metadata), false)
                 } else {
+                    key::disconnect_without_reset(yubikey);
                     return Ok(());
                 }
             } else {
@@ -462,30 +484,57 @@ fn main() -> Result<(), Error> {
                         flags.name.as_deref().unwrap_or("age identity TAG_HEX")
                     ))
                     .allow_empty(true)
+                    .report(true)
                     .interact_text()?;
 
-                let pin_policy = match Select::new()
-                    .with_prompt(fl!("cli-setup-select-pin-policy"))
-                    .items(&[
-                        fl!("pin-policy-always"),
-                        fl!("pin-policy-once"),
-                        fl!("pin-policy-never"),
-                    ])
-                    .default(
-                        [PinPolicy::Always, PinPolicy::Once, PinPolicy::Never]
-                            .iter()
-                            .position(|p| {
-                                p == &flags.pin_policy.unwrap_or(builder::DEFAULT_PIN_POLICY)
-                            })
-                            .unwrap(),
-                    )
-                    .interact_opt()?
-                {
-                    Some(0) => PinPolicy::Always,
-                    Some(1) => PinPolicy::Once,
-                    Some(2) => PinPolicy::Never,
-                    Some(_) => unreachable!(),
-                    None => return Ok(()),
+                let mut displayed_yk4_warning = false;
+                let pin_policy = loop {
+                    let pin_policy = match Select::new()
+                        .with_prompt(fl!("cli-setup-select-pin-policy"))
+                        .items(&[
+                            fl!("pin-policy-always"),
+                            fl!("pin-policy-once"),
+                            fl!("pin-policy-never"),
+                        ])
+                        .default(
+                            [PinPolicy::Always, PinPolicy::Once, PinPolicy::Never]
+                                .iter()
+                                .position(|p| {
+                                    p == &flags.pin_policy.unwrap_or(builder::DEFAULT_PIN_POLICY)
+                                })
+                                .unwrap(),
+                        )
+                        .report(true)
+                        .interact_opt()?
+                    {
+                        Some(0) => PinPolicy::Always,
+                        Some(1) => PinPolicy::Once,
+                        Some(2) => PinPolicy::Never,
+                        Some(_) => unreachable!(),
+                        None => return Ok(()),
+                    };
+
+                    // We can't preserve the PIN cache for YubiKey 4 series, because to
+                    // retrieve the serial we switch to the OTP applet.
+                    match (pin_policy, yubikey.version().major) {
+                        (PinPolicy::Once, 4) => {
+                            if !displayed_yk4_warning {
+                                eprintln!();
+                                eprintln!("{}", fl!("cli-setup-yk4-pin-policy"));
+                                eprintln!();
+                                displayed_yk4_warning = true;
+                            }
+
+                            if Confirm::new()
+                                .with_prompt(fl!("cli-setup-yk4-pin-policy-confirm"))
+                                .report(true)
+                                .interact()?
+                            {
+                                break pin_policy;
+                            }
+                        }
+                        _ => break pin_policy,
+                    }
                 };
 
                 let touch_policy = match Select::new()
@@ -503,6 +552,7 @@ fn main() -> Result<(), Error> {
                             })
                             .unwrap(),
                     )
+                    .report(true)
                     .interact_opt()?
                 {
                     Some(0) => TouchPolicy::Always,
@@ -514,6 +564,7 @@ fn main() -> Result<(), Error> {
 
                 if Confirm::new()
                     .with_prompt(fl!("cli-setup-generate-new", slot_index = slot_index))
+                    .report(true)
                     .interact()?
                 {
                     eprintln!();
@@ -529,6 +580,7 @@ fn main() -> Result<(), Error> {
                         true,
                     )
                 } else {
+                    key::disconnect_without_reset(yubikey);
                     return Ok(());
                 }
             }
@@ -541,6 +593,7 @@ fn main() -> Result<(), Error> {
                 "age-yubikey-identity-{}.txt",
                 hex::encode(stub.tag)
             ))
+            .report(true)
             .interact_text()?;
 
         let mut file = match OpenOptions::new()
@@ -552,6 +605,7 @@ fn main() -> Result<(), Error> {
             Err(e) if e.kind() == io::ErrorKind::AlreadyExists => {
                 if Confirm::new()
                     .with_prompt(fl!("cli-setup-identity-file-exists"))
+                    .report(true)
                     .interact()?
                 {
                     File::create(&file_name)?

src/p256.rs

@@ -60,7 +60,7 @@ impl Recipient {
     /// This accepts both compressed (as used by the plugin) and uncompressed (as used in
     /// the YubiKey certificate) encodings.
     fn from_encoded(encoded: &p256::EncodedPoint) -> Option<Self> {
-        p256::PublicKey::from_encoded_point(encoded).map(Recipient)
+        Option::from(p256::PublicKey::from_encoded_point(encoded)).map(Recipient)
     }
 
     /// Returns the compressed SEC-1 encoding of this recipient.

src/plugin.rs

@@ -249,6 +249,8 @@ impl IdentityPluginV1 for IdentityPlugin {
                     }
                 }
             }
+
+            conn.disconnect_without_reset();
         }
         Ok(file_keys)
     }

src/util.rs

@@ -122,7 +122,10 @@ impl Metadata {
         // https://developers.yubico.com/PIV/Introduction/PIV_attestation.html
         let policies = |c: &X509Certificate| {
             c.tbs_certificate
-                .find_extension(&Oid::from(POLICY_EXTENSION_OID).unwrap())
+                .get_extension_unique(&Oid::from(POLICY_EXTENSION_OID).unwrap())
+                // If the extension is duplicated, we assume it is invalid.
+                .ok()
+                .flatten()
                 // If the encoded extension doesn't have 2 bytes, we assume it is invalid.
                 .filter(|policy| policy.value.len() >= 2)
                 .map(|policy| {
@@ -170,7 +173,11 @@ impl Metadata {
                 serial: yubikey.serial(),
                 slot,
                 name,
-                created: cert.validity().not_before.to_rfc2822(),
+                created: cert
+                    .validity()
+                    .not_before
+                    .to_rfc2822()
+                    .unwrap_or_else(|e| format!("Invalid date: {}", e)),
                 pin_policy,
                 touch_policy,
             })

tests/integration.rs

@@ -0,0 +1,125 @@
+use std::env;
+use std::io::Write;
+use std::path::Path;
+use std::process::{Command, Stdio};
+
+const PLUGIN_BIN: &str = env!("CARGO_BIN_EXE_age-plugin-yubikey");
+
+#[test_with::env(YUBIKEY_SERIAL, YUBIKEY_SLOT)]
+#[cfg_attr(all(unix, not(target_os = "macos")), test_with::executable(pcscd))]
+#[test]
+fn recipient_and_identity_match() {
+    let recipient = Command::new(PLUGIN_BIN)
+        .arg("--list")
+        .arg("--serial")
+        .arg(env::var("YUBIKEY_SERIAL").unwrap())
+        .arg("--slot")
+        .arg(env::var("YUBIKEY_SLOT").unwrap())
+        .output()
+        .unwrap();
+    assert_eq!(recipient.status.code(), Some(0));
+
+    let identity = Command::new(PLUGIN_BIN)
+        .arg("--identity")
+        .arg("--serial")
+        .arg(env::var("YUBIKEY_SERIAL").unwrap())
+        .arg("--slot")
+        .arg(env::var("YUBIKEY_SLOT").unwrap())
+        .output()
+        .unwrap();
+    assert_eq!(identity.status.code(), Some(0));
+
+    let recipient_file = String::from_utf8_lossy(&recipient.stdout);
+    let recipient = recipient_file.lines().last().unwrap();
+    let identity = String::from_utf8_lossy(&identity.stdout);
+    assert!(identity.contains(recipient));
+}
+
+#[test_with::executable(rage)]
+#[test]
+fn plugin_encrypt() {
+    let enc_file = tempfile::NamedTempFile::new_in(env!("CARGO_TARGET_TMPDIR")).unwrap();
+
+    let mut process = Command::new(which::which("rage").unwrap())
+        .arg("-r")
+        .arg("age1yubikey1q2w7u3vpya839jxxuq8g0sedh3d740d4xvn639sqhr95ejj8vu3hyfumptt")
+        .arg("-o")
+        .arg(enc_file.path())
+        .stdin(Stdio::piped())
+        .env("PATH", Path::new(PLUGIN_BIN).parent().unwrap())
+        .spawn()
+        .unwrap();
+
+    // Scope to ensure stdin is closed.
+    {
+        let mut stdin = process.stdin.take().unwrap();
+        stdin.write_all(b"Testing YubiKey encryption").unwrap();
+        stdin.flush().unwrap();
+    }
+
+    let status = process.wait().unwrap();
+    assert_eq!(status.code(), Some(0));
+}
+
+#[test_with::env(YUBIKEY_SERIAL, YUBIKEY_SLOT)]
+#[test_with::executable(rage)]
+#[cfg_attr(all(unix, not(target_os = "macos")), test_with::executable(pcscd))]
+#[test]
+fn plugin_decrypt() {
+    let mut identity_file = tempfile::NamedTempFile::new_in(env!("CARGO_TARGET_TMPDIR")).unwrap();
+    let enc_file = tempfile::NamedTempFile::new_in(env!("CARGO_TARGET_TMPDIR")).unwrap();
+    let plaintext = "Testing YubiKey encryption";
+
+    // Write an identity file corresponding to this YubiKey slot.
+    let identity = Command::new(PLUGIN_BIN)
+        .arg("--identity")
+        .arg("--serial")
+        .arg(env::var("YUBIKEY_SERIAL").unwrap())
+        .arg("--slot")
+        .arg(env::var("YUBIKEY_SLOT").unwrap())
+        .output()
+        .unwrap();
+    assert_eq!(identity.status.code(), Some(0));
+    identity_file.write_all(&identity.stdout).unwrap();
+    identity_file.flush().unwrap();
+
+    // Encrypt to the YubiKey slot.
+    let mut enc_process = Command::new(which::which("rage").unwrap())
+        .arg("-e")
+        .arg("-i")
+        .arg(identity_file.path())
+        .arg("-o")
+        .arg(enc_file.path())
+        .stdin(Stdio::piped())
+        .env("PATH", Path::new(PLUGIN_BIN).parent().unwrap())
+        .spawn()
+        .unwrap();
+
+    // Scope to ensure stdin is closed.
+    {
+        let mut stdin = enc_process.stdin.take().unwrap();
+        stdin.write_all(plaintext.as_bytes()).unwrap();
+        stdin.flush().unwrap();
+    }
+
+    let enc_status = enc_process.wait().unwrap();
+    assert_eq!(enc_status.code(), Some(0));
+
+    // Decrypt with the YubiKey.
+    let dec_process = Command::new(which::which("rage").unwrap())
+        .arg("-d")
+        .arg("-i")
+        .arg(identity_file.path())
+        .arg(enc_file.path())
+        .stdin(Stdio::piped())
+        .env("PATH", Path::new(PLUGIN_BIN).parent().unwrap())
+        .output()
+        .unwrap();
+
+    let stderr = String::from_utf8_lossy(&dec_process.stderr);
+    if !stderr.is_empty() {
+        assert!(stderr.contains("age-plugin-yubikey"));
+        assert!(stderr.ends_with("...\n"));
+    }
+    assert_eq!(String::from_utf8_lossy(&dec_process.stdout), plaintext);
+}