Merge pull request #93 from str4d/release-0.3.1

Release 0.3.1

.github/dependabot.yml

@@ -0,0 +1,12 @@
+version: 2
+updates:
+  - package-ecosystem: github-actions
+    directory: "/"
+    schedule:
+      interval: daily
+      timezone: Etc/UTC
+    open-pull-requests-limit: 10
+    reviewers:
+      - str4d
+    assignees:
+      - str4d

.github/workflows/ci.yml

@@ -22,10 +22,10 @@ jobs:
             os: macos-latest
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - uses: actions-rs/toolchain@v1
         with:
-          toolchain: 1.51.0
+          toolchain: 1.56.0
           override: true
       - name: Install build dependencies
         run: sudo apt install ${{ matrix.build_deps }}
@@ -46,14 +46,14 @@ jobs:
           args: --verbose
 
   clippy:
-    name: Clippy (1.51.0)
+    name: Clippy (1.56.0)
     timeout-minutes: 30
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - uses: actions-rs/toolchain@v1
         with:
-          toolchain: 1.51.0
+          toolchain: 1.56.0
           components: clippy
           override: true
       - name: Install build dependencies
@@ -61,7 +61,7 @@ jobs:
       - name: Run clippy
         uses: actions-rs/clippy-check@v1
         with:
-          name: Clippy (1.51.0)
+          name: Clippy (1.56.0)
           token: ${{ secrets.GITHUB_TOKEN }}
           args: --all-features --all-targets -- -D warnings
 
@@ -71,7 +71,7 @@ jobs:
     runs-on: ubuntu-latest
     continue-on-error: true
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - uses: actions-rs/toolchain@v1
         with:
           toolchain: nightly
@@ -92,7 +92,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       # Use stable for this to ensure that cargo-tarpaulin can be built.
       - uses: actions-rs/toolchain@v1
         with:
@@ -105,7 +105,7 @@ jobs:
         with:
           args: --release --timeout 180 --out Xml
       - name: Upload coverage to Codecov
-        uses: codecov/codecov-action@v1.0.3
+        uses: codecov/codecov-action@v3.1.1
         with:
           token: ${{secrets.CODECOV_TOKEN}}
 
@@ -114,10 +114,10 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - uses: actions-rs/toolchain@v1
         with:
-          toolchain: 1.51.0
+          toolchain: 1.56.0
           override: true
       - name: Install build dependencies
         run: sudo apt install libpcsclite-dev
@@ -139,13 +139,14 @@ jobs:
     timeout-minutes: 30
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - uses: actions-rs/toolchain@v1
         with:
-          toolchain: 1.51.0
+          toolchain: 1.56.0
+          components: rustfmt
           override: true
-      - run: rustup component add rustfmt
-      - uses: actions-rs/cargo@v1
+      - name: Check formatting
+        uses: actions-rs/cargo@v1
         with:
           command: fmt
           args: -- --check

.github/workflows/release.yml

@@ -17,10 +17,14 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        name: [linux, windows, macos]
+        name:
+          - linux
+          - macos-arm64
+          - macos-x86_64
+          - windows
         include:
           - name: linux
-            os: ubuntu-16.04
+            os: ubuntu-18.04
             build_deps: >
               libpcsclite-dev
             archive_name: age-plugin-yubikey.tar.gz
@@ -31,13 +35,20 @@ jobs:
             archive_name: age-plugin-yubikey.zip
             asset_suffix: x86_64-windows.zip
 
-          - name: macos
+          - name: macos-arm64
+            os: macos-latest
+            target: aarch64-apple-darwin
+            build_flags: --target aarch64-apple-darwin
+            archive_name: age-plugin-yubikey.tar.gz
+            asset_suffix: arm64-darwin.tar.gz
+
+          - name: macos-x86_64
             os: macos-latest
             archive_name: age-plugin-yubikey.tar.gz
             asset_suffix: x86_64-darwin.tar.gz
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - uses: actions-rs/toolchain@v1
         with:
           toolchain: stable
@@ -76,12 +87,10 @@ jobs:
         if: matrix.name == 'windows'
 
       - name: Upload archive to release
-        uses: svenstaro/upload-release-action@2.2.0
+        uses: svenstaro/upload-release-action@2.3.0
         with:
-          repo_token: ${{ secrets.GITHUB_TOKEN }}
           file: ${{ matrix.archive_name }}
           asset_name: age-plugin-yubikey-$tag-${{ matrix.asset_suffix }}
-          tag: ${{ github.ref }}
           prerelease: true
         if: github.event.inputs.test != 'true'
 
@@ -98,7 +107,7 @@ jobs:
               libpcsclite-dev
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - uses: actions-rs/toolchain@v1
         with:
           toolchain: stable
@@ -137,11 +146,9 @@ jobs:
           args: --package age-plugin-yubikey --no-build --target ${{ matrix.target }}
 
       - name: Upload Debian package to release
-        uses: svenstaro/upload-release-action@2.2.0
+        uses: svenstaro/upload-release-action@2.3.0
         with:
-          repo_token: ${{ secrets.GITHUB_TOKEN }}
           file: target/${{ matrix.target }}/debian/*.deb
-          tag: ${{ github.ref }}
           file_glob: true
           prerelease: true
         if: github.event.inputs.test != 'true'

CHANGELOG.md

@@ -0,0 +1,49 @@
+# Changelog
+All notable changes to this crate 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 Rust's notion of
+[Semantic Versioning](https://semver.org/spec/v2.0.0.html). All versions prior
+to 0.3.0 are beta releases.
+
+## [Unreleased]
+
+## [0.3.1] - 2022-12-30
+### Changed
+- If a "sharing violation" error is encountered while opening a connection to a
+  YubiKey, and `scdaemon` is running (which can hold exclusive access to a
+  YubiKey indefinitely), `age-plugin-yubikey` now attempts to stop `scdaemon` by
+  interrupting it (or killing it on Windows), and then tries again to open the
+  connection.
+- Several error messages were enhanced with guidance on how to resolve their
+  respective issue.
+
+## [0.3.0] - 2022-05-02
+First non-beta release!
+
+### Changed
+- MSRV is now 1.56.0.
+- During decryption, when asked to insert a YubiKey, you can now choose to skip
+  it, allowing the client to move on to the next identity instead of returning
+  an error.
+- Certain kinds of PIN invalidity will now cause the plugin to re-request the
+  PIN instead of aborting: if the PIN is too short or too long, or if the user
+  touched the YubiKey early and "typed" an OTP.
+
+### Fixed
+- The "default" identity (provided by clients that invoke `age-plugin-yubikey`
+  using `-j yubikey`) previously caused a panic. It is now correctly treated as
+  an invalid identity (because this plugin does not support default identities).
+
+## [0.2.0] - 2021-11-22
+### Fixed
+- Attempts-before-blocked counter is now returned as part of the invalid PIN
+  error string.
+- PIN is no longer requested when fetching the recipient for a slot, or when
+  decrypting with a slot that has a PIN policy of Never.
+- Migrated to `yubikey 0.5` to fix `cargo install age-plugin-yubikey` error
+  (caused by the `yubikey-piv` crate being yanked after it was renamed).
+
+## [0.1.0] - 2021-05-02
+
+Initial beta release.

Cargo.toml

@@ -1,19 +1,19 @@
 [package]
 name = "age-plugin-yubikey"
-description = "[BETA] YubiKey plugin for age clients"
-version = "0.1.0"
+description = "YubiKey plugin for age clients"
+version = "0.3.1"
 authors = ["Jack Grigg <thestr4d@gmail.com>"]
 repository = "https://github.com/str4d/age-plugin-yubikey"
 readme = "README.md"
 keywords = ["age", "cli", "encryption", "yubikey"]
 categories = ["command-line-utilities", "cryptography"]
 license = "MIT OR Apache-2.0"
-edition = "2018"
+edition = "2021"
+rust-version = "1.56" # MSRV
 
 [package.metadata.deb]
 extended-description = """\
-An age plugin adding support for YubiKeys and other PIV hardware tokens. \
-Currently in BETA; we strongly recommend using this with a new YubiKey."""
+An age plugin adding support for YubiKeys and other PIV hardware tokens."""
 section = "utils"
 assets = [
     ["target/release/age-plugin-yubikey", "usr/bin/", "755"],
@@ -22,25 +22,33 @@ assets = [
 ]
 
 [dependencies]
-age-core = "0.6"
-age-plugin = "0.1"
+age-core = "0.8"
+age-plugin = "0.3"
 base64 = "0.13"
 bech32 = "0.8"
-console = "0.14"
-dialoguer = "0.8"
-env_logger = "0.8"
+console = { version = "0.15", default-features = false }
+dialoguer = { version = "0.9", default-features = false, features = ["password"] }
+env_logger = "0.9"
 gumdrop = "0.8"
 hex = "0.4"
 log = "0.4"
-p256 = { version = "0.7", features = ["ecdh"] }
+p256 = { version = "0.9", features = ["ecdh"] }
 pcsc = "2.4"
-rand = "0.7"
-secrecy = "0.7"
+rand = "0.8"
 sha2 = "0.9"
 which = "4.1"
 x509 = "0.2"
-x509-parser = "0.9"
-yubikey-piv = { version = "0.3", features = ["untested"] }
+x509-parser = "0.12"
+yubikey = { version = "0.5", features = ["untested"] }
+
+# Translations
+i18n-embed = { version = "0.13", features = ["desktop-requester", "fluent-system"] }
+i18n-embed-fl = "0.6"
+lazy_static = "1"
+rust-embed = "6"
+
+# GnuPG coexistence
+sysinfo = ">=0.26, <0.26.4"
 
 [dev-dependencies]
 flate2 = "1"

README.md

@@ -4,15 +4,12 @@
 like [`age`](https://age-encryption.org) and [`rage`](https://str4d.xyz/rage),
 which enables files to be encrypted to age identities stored on YubiKeys.
 
-This plugin is in **BETA**; we strongly recommend using this with a new YubiKey,
-or one that you do not care about.
-
 ## Installation
 
 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 1.51+ installed (either via `rustup` or a system
+If your system has Rust 1.56+ installed (either via `rustup` or a system
 package), you can build directly from source:
 
 ```
@@ -21,6 +18,15 @@ 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:
+
+```
+$ sudo apt-get install pcscd
+```
+
 ### Windows Subsystem for Linux (WSL)
 
 WSL does not currently provide native support for USB devices. However, Windows
@@ -98,8 +104,15 @@ enabling YubiKeys to be used simultaneously with age and SSH.
 
 ### Manual setup and technical details
 
-`age-plugin-yubikey` only officially supports YubiKeys set up either via the
-text interface or the `--generate` flag.
+`age-plugin-yubikey` only officially supports the following YubiKey variants,
+set up either via the text interface or the `--generate` flag:
+
+- YubiKey 4 series
+- YubiKey 5 series
+
+NOTE: Nano and USB-C variants of the above are also supported. The pre-YK4
+YubiKey NEO series is **NOT** supported. The blue "Security Key by Yubico" will
+also not work (as it doesn't support PIV).
 
 In practice, any PIV token with an ECDSA P-256 key and certificate in one of the
 20 "retired" slots should work. You can list all age-compatible keys with:

i18n.toml

@@ -0,0 +1,4 @@
+fallback_language = "en-US"
+
+[fluent]
+assets_dir = "i18n"

i18n/en-US/age_plugin_yubikey.ftl

@@ -0,0 +1,220 @@
+# Copyright 2022 Jack Grigg
+#
+# Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+# http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+# <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+# option. This file may not be copied, modified, or distributed
+# except according to those terms.
+
+### Localization for strings in age-plugin-yubikey
+
+-age = age
+-yubikey = YubiKey
+-yubikeys = YubiKeys
+-age-plugin-yubikey = age-plugin-yubikey
+-pcscd = pcscd
+
+## CLI commands and flags
+
+-cmd-generate = --generate
+-cmd-identity = --identity
+-cmd-list     = --list
+-cmd-list-all = --list-all
+
+-flag-force  = --force
+-flag-serial = --serial
+-flag-slot   = --slot
+
+## YubiKey metadata
+
+pin-policy-always = Always (A PIN is required for every decryption, if set)
+pin-policy-once   = Once   (A PIN is required once per session, if set)
+pin-policy-never  = Never  (A PIN is NOT required to decrypt)
+
+touch-policy-always = Always (A physical touch is required for every decryption)
+touch-policy-cached = Cached (A physical touch is required for decryption, and is cached for 15 seconds)
+touch-policy-never  = Never  (A physical touch is NOT required to decrypt)
+
+unknown-policy = Unknown
+
+yubikey-metadata =
+    #       Serial: {$serial}, Slot: {$slot}
+    #         Name: {$name}
+    #      Created: {$created}
+    #   PIN policy: {$pin_policy}
+    # Touch policy: {$touch_policy}
+yubikey-identity =
+    {$yubikey_metadata}
+    #    Recipient: {$recipient}
+    {$identity}
+
+## CLI setup via text interface
+
+cli-setup-intro =
+    ✨ Let's get your {-yubikey} set up for {-age}! ✨
+
+    This tool can create a new {-age} identity in a free slot of your {-yubikey}.
+    It will generate an identity file that you can use with an {-age} client,
+    along with the corresponding recipient. You can also do this directly
+    with:
+    {"    "}{$generate_usage}
+
+    If you are already using a {-yubikey} with {-age}, you can select an existing
+    slot to recreate its corresponding identity file and recipient.
+
+    When asked below to select an option, use the up/down arrow keys to
+    make your choice, or press [Esc] or [q] to quit.
+
+cli-setup-insert-yk           = ⏳ Please insert the {-yubikey} you want to set up.
+cli-setup-yk-name             = {$yubikey_name} (Serial: {$yubikey_serial})
+cli-setup-select-yk           = 🔑 Select a {-yubikey}
+cli-setup-slot-usable         = Slot {$slot_index} ({$slot_name})
+cli-setup-slot-unusable       = Slot {$slot_index} (Unusable)
+cli-setup-slot-empty          = Slot {$slot_index} (Empty)
+cli-setup-select-slot         = 🕳️  Select a slot for your {-age} identity
+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-generate-new = Generate new identity in slot {$slot_index}?
+cli-setup-use-existing = Use existing identity in slot {$slot_index}?
+
+cli-setup-identity-file-name   = 📝 File name to write this identity to
+cli-setup-identity-file-exists = File exists. Overwrite it?
+
+cli-setup-finished =
+    ✅ Done! This {-yubikey} identity is ready to go.
+
+    🔑 { $is_new ->
+        [true] Here's your shiny new {-yubikey} recipient:
+       *[false] Here's the corresponding {-yubikey} recipient:
+    }
+    {"  "}{$recipient}
+
+    Here are some example things you can do with it:
+
+    - Encrypt a file to this identity:
+    {"  "}{$encrypt_usage}
+
+    - Decrypt a file with this identity:
+    {"  "}{$decrypt_usage}
+
+    - Recreate the identity file:
+    {"  "}{$identity_usage}
+
+    - Recreate the recipient:
+    {"  "}{$recipient_usage}
+
+    💭 Remember: everything breaks, have a backup plan for when this {-yubikey} does.
+
+## Programmatic usage
+
+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
+
+print-recipient = Recipient: {$recipient}
+
+printed-kind-identities = identities
+printed-kind-recipients = recipients
+printed-multiple = Generated {$kind} for {$count} slots. If you intended to select a slot, use {-flag-slot}.
+
+## YubiKey management
+
+mgr-enter-pin = Enter PIN for {-yubikey} with serial {$yubikey_serial} (default is {$default_pin})
+
+mgr-change-default-pin =
+    ✨ Your {-yubikey} is using the default PIN. Let's change it!
+    ✨ We'll also set the PUK equal to the PIN.
+
+    🔐 The PIN is up to 8 numbers, letters, or symbols. Not just numbers!
+    ❌ Your keys will be lost if the PIN and PUK are locked after 3 incorrect tries.
+
+mgr-enter-current-puk = Enter current PUK (default is {$default_puk})
+mgr-choose-new-pin    = Choose a new PIN/PUK
+mgr-repeat-new-pin    = Repeat the PIN/PUK
+mgr-pin-mismatch      = PINs don't match
+
+mgr-changing-mgmt-key =
+    ✨ Your {-yubikey} is using the default management key.
+    ✨ We'll migrate it to a PIN-protected management key.
+mgr-changing-mgmt-key-error =
+    An error occurred while setting the new management key.
+    ⚠️ SAVE THIS MANAGEMENT KEY - YOU MAY NEED IT TO MANAGE YOUR {-yubikey}! ⚠️
+    {"  "}{$management_key}
+mgr-changing-mgmt-key-success = Success!
+
+## Plugin usage
+
+plugin-err-invalid-recipient = Invalid recipient
+plugin-err-invalid-identity  = Invalid {-yubikey} stub
+plugin-err-invalid-stanza    = Invalid {-yubikey} stanza
+plugin-err-decryption-failed = Failed to decrypt {-yubikey} stanza
+
+plugin-insert-yk            = Please insert {-yubikey} with serial {$yubikey_serial}
+plugin-yk-is-plugged-in     = {-yubikey} is plugged in
+plugin-skip-this-yk         = Skip this {-yubikey}
+plugin-insert-yk-retry      = Could not open {-yubikey}. Please insert {-yubikey} with serial {$yubikey_serial}
+plugin-err-yk-not-found     = Could not find {-yubikey} with serial {$yubikey_serial}
+plugin-err-yk-opening       = Could not open {-yubikey} with serial {$yubikey_serial}
+plugin-err-yk-timed-out     = Timed out while waiting for {-yubikey} with serial {$yubikey_serial} to be inserted
+plugin-err-yk-stub-mismatch = A {-yubikey} stub did not match the {-yubikey}
+
+plugin-err-yk-invalid-pin-policy = Certificate for {-yubikey} identity contains an invalid PIN policy
+
+plugin-enter-pin            = Enter PIN for {-yubikey} with serial {$yubikey_serial}
+plugin-err-accidental-touch = Did you touch the {-yubikey} by accident?
+plugin-err-pin-too-short    = PIN was too short.
+plugin-err-pin-too-long     = PIN was too long.
+plugin-err-pin-required     = A PIN is required for {-yubikey} with serial {$yubikey_serial}
+
+## Errors
+
+err-custom-mgmt-key = Custom unprotected non-TDES management keys are not supported.
+rec-custom-mgmt-key =
+    You can use the {-yubikey} Manager CLI to change to a protected management key:
+    {"  "}{$cmd}
+
+    See here for more information about {-yubikey} Manager:
+    {"  "}{$url}
+
+err-invalid-flag-command = Flag '{$flag}' cannot be used with '{$command}'.
+err-invalid-flag-tui     = Flag '{$flag}' cannot be used with the interactive interface.
+err-invalid-pin-length   = The PIN needs to be 1-8 characters.
+err-invalid-pin-policy   = Invalid PIN policy '{$policy}' (expected [{$expected}]).
+err-invalid-slot         = Invalid slot '{$slot}' (expected number between 1 and 20).
+err-invalid-touch-policy = Invalid touch policy '{$policy}' (expected [{$expected}]).
+err-io                   = Failed to set up {-yubikey}: {$err}
+err-multiple-commands    = Only one of {-cmd-generate}, {-cmd-identity}, {-cmd-list}, {-cmd-list-all} can be specified.
+err-multiple-yubikeys    = Multiple {-yubikeys} are plugged in. Use {-flag-serial} to select a single {-yubikey}.
+err-no-empty-slots       = {-yubikey} with serial {$serial} has no empty slots.
+err-no-matching-serial   = Could not find {-yubikey} with serial {$serial}.
+err-slot-has-no-identity = Slot {$slot} does not contain an {-age} identity or compatible key.
+err-slot-is-not-empty    = Slot {$slot} is not empty. Use {-flag-force} to overwrite the slot.
+err-timed-out            = Timed out while waiting for a {-yubikey} to be inserted.
+err-use-list-for-single  = Use {-cmd-list} to print the recipient for a single slot.
+
+err-yk-no-service-macos = The Crypto Token Kit service is not running.
+rec-yk-no-service-macos =
+    You may need to restart it. See this Stack Exchange answer for more help:
+    {"  "}{$url}
+
+err-yk-no-service-pcscd = {-pcscd} is not running.
+rec-yk-no-service-pcscd =
+    If you are on Debian or Ubuntu, you can install it with:
+    {"  "}{$apt}
+
+err-yk-no-service-win = The Smart Cards for Windows service is not running.
+rec-yk-no-service-win =
+    See this troubleshooting guide for more help:
+    {"  "}{$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-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.
+err-ux-C = {"            "}

rust-toolchain

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

src/builder.rs

@@ -1,17 +1,16 @@
 use rand::{rngs::OsRng, RngCore};
 use x509::RelativeDistinguishedName;
-use yubikey_piv::{
+use yubikey::{
     certificate::{Certificate, PublicKeyInfo},
-    key::{generate as yubikey_generate, AlgorithmId, RetiredSlotId, SlotId},
-    policy::{PinPolicy, TouchPolicy},
-    Key, YubiKey,
+    piv::{generate as yubikey_generate, AlgorithmId, RetiredSlotId, SlotId},
+    Key, PinPolicy, TouchPolicy, YubiKey,
 };
 
 use crate::{
     error::Error,
+    key::{self, Stub},
     p256::Recipient,
     util::{Metadata, POLICY_EXTENSION_OID},
-    yubikey::{self, Stub},
     BINARY_NAME, USABLE_SLOTS,
 };
 
@@ -90,7 +89,7 @@ impl IdentityBuilder {
         // 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).
-        yubikey::manage(yubikey)?;
+        key::manage(yubikey)?;
 
         if let TouchPolicy::Never = touch_policy {
             // No need to touch YubiKey

src/error.rs

@@ -1,9 +1,16 @@
+use i18n_embed_fl::fl;
 use std::fmt;
 use std::io;
-use yubikey_piv::{key::RetiredSlotId, Serial};
+use yubikey::{piv::RetiredSlotId, Serial};
 
 use crate::util::slot_to_ui;
 
+macro_rules! wlnfl {
+    ($f:ident, $message_id:literal) => {
+        writeln!($f, "{}", $crate::fl!($message_id))
+    };
+}
+
 pub enum Error {
     CustomManagementKey,
     InvalidFlagCommand(String, String),
@@ -21,7 +28,7 @@ pub enum Error {
     SlotIsNotEmpty(RetiredSlotId),
     TimedOut,
     UseListForSingleSlot,
-    YubiKey(yubikey_piv::Error),
+    YubiKey(yubikey::Error),
 }
 
 impl From<io::Error> for Error {
@@ -30,8 +37,8 @@ impl From<io::Error> for Error {
     }
 }
 
-impl From<yubikey_piv::error::Error> for Error {
-    fn from(e: yubikey_piv::error::Error) -> Self {
+impl From<yubikey::Error> for Error {
+    fn from(e: yubikey::Error) -> Self {
         Error::YubiKey(e)
     }
 }
@@ -42,89 +49,178 @@ impl fmt::Debug for Error {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
             Error::CustomManagementKey => {
-                writeln!(f, "Custom unprotected management keys are not supported.")?
-            }
-            Error::InvalidFlagCommand(flag, command) => {
-                writeln!(f, "Flag '{}' cannot be used with '{}'.", flag, command)?
+                wlnfl!(f, "err-custom-mgmt-key")?;
+                let cmd = "ykman piv access change-management-key --protect";
+                let url = "https://developers.yubico.com/yubikey-manager/";
+                writeln!(
+                    f,
+                    "{}",
+                    fl!(
+                        crate::LANGUAGE_LOADER,
+                        "rec-custom-mgmt-key",
+                        cmd = cmd,
+                        url = url,
+                    ),
+                )?;
             }
+            Error::InvalidFlagCommand(flag, command) => writeln!(
+                f,
+                "{}",
+                fl!(
+                    crate::LANGUAGE_LOADER,
+                    "err-invalid-flag-command",
+                    flag = flag.as_str(),
+                    command = command.as_str(),
+                ),
+            )?,
             Error::InvalidFlagTui(flag) => writeln!(
                 f,
-                "Flag '{}' cannot be used with the interactive interface.",
-                flag
+                "{}",
+                fl!(
+                    crate::LANGUAGE_LOADER,
+                    "err-invalid-flag-tui",
+                    flag = flag.as_str(),
+                ),
             )?,
-            Error::InvalidPinLength => writeln!(f, "The PIN needs to be 1-8 characters.")?,
+            Error::InvalidPinLength => wlnfl!(f, "err-invalid-pin-length")?,
             Error::InvalidPinPolicy(s) => writeln!(
                 f,
-                "Invalid PIN policy '{}' (expected [always, once, never]).",
-                s
+                "{}",
+                fl!(
+                    crate::LANGUAGE_LOADER,
+                    "err-invalid-pin-policy",
+                    policy = s.as_str(),
+                    expected = "always, once, never",
+                ),
             )?,
             Error::InvalidSlot(slot) => writeln!(
                 f,
-                "Invalid slot '{}' (expected number between 1 and 20).",
-                slot
+                "{}",
+                fl!(crate::LANGUAGE_LOADER, "err-invalid-slot", slot = slot),
             )?,
             Error::InvalidTouchPolicy(s) => writeln!(
                 f,
-                "Invalid touch policy '{}' (expected [always, cached, never]).",
-                s
+                "{}",
+                fl!(
+                    crate::LANGUAGE_LOADER,
+                    "err-invalid-touch-policy",
+                    policy = s.as_str(),
+                    expected = "always, cached, never",
+                ),
             )?,
-            Error::Io(e) => writeln!(f, "Failed to set up YubiKey: {}", e)?,
-            Error::MultipleCommands => writeln!(
+            Error::Io(e) => writeln!(
                 f,
-                "Only one of --generate, --identity, --list, --list-all can be specified."
+                "{}",
+                fl!(crate::LANGUAGE_LOADER, "err-io", err = e.to_string()),
             )?,
-            Error::MultipleYubiKeys => writeln!(
+            Error::MultipleCommands => wlnfl!(f, "err-multiple-commands")?,
+            Error::MultipleYubiKeys => wlnfl!(f, "err-multiple-yubikeys")?,
+            Error::NoEmptySlots(serial) => writeln!(
                 f,
-                "Multiple YubiKeys are plugged in. Use --serial to select a single YubiKey."
+                "{}",
+                fl!(
+                    crate::LANGUAGE_LOADER,
+                    "err-no-empty-slots",
+                    serial = serial.to_string(),
+                ),
+            )?,
+            Error::NoMatchingSerial(serial) => writeln!(
+                f,
+                "{}",
+                fl!(
+                    crate::LANGUAGE_LOADER,
+                    "err-no-matching-serial",
+                    serial = serial.to_string(),
+                ),
             )?,
-            Error::NoEmptySlots(serial) => {
-                writeln!(f, "YubiKey with serial {} has no empty slots.", serial)?
-            }
-            Error::NoMatchingSerial(serial) => {
-                writeln!(f, "Could not find YubiKey with serial {}.", serial)?
-            }
             Error::SlotHasNoIdentity(slot) => writeln!(
                 f,
-                "Slot {} does not contain an age identity or compatible key.",
-                slot_to_ui(slot)
+                "{}",
+                fl!(
+                    crate::LANGUAGE_LOADER,
+                    "err-slot-has-no-identity",
+                    slot = slot_to_ui(slot),
+                ),
             )?,
             Error::SlotIsNotEmpty(slot) => writeln!(
                 f,
-                "Slot {} is not empty. Use --force to overwrite the slot.",
-                slot_to_ui(slot)
+                "{}",
+                fl!(
+                    crate::LANGUAGE_LOADER,
+                    "err-slot-is-not-empty",
+                    slot = slot_to_ui(slot),
+                ),
             )?,
-            Error::TimedOut => {
-                writeln!(f, "Timed out while waiting for a YubiKey to be inserted.")?
-            }
-            Error::UseListForSingleSlot => {
-                writeln!(f, "Use --list to print the recipient for a single slot.")?
-            }
+            Error::TimedOut => wlnfl!(f, "err-timed-out")?,
+            Error::UseListForSingleSlot => wlnfl!(f, "err-use-list-for-single")?,
             Error::YubiKey(e) => match e {
-                yubikey_piv::error::Error::NotFound => {
-                    writeln!(f, "Please insert the YubiKey you want to set up")?
-                }
-                yubikey_piv::error::Error::WrongPin { tries } => writeln!(
+                yubikey::Error::NotFound => wlnfl!(f, "err-yk-not-found")?,
+                yubikey::Error::PcscError {
+                    inner: Some(pcsc::Error::NoService),
+                } => {
+                    if cfg!(windows) {
+                        wlnfl!(f, "err-yk-no-service-win")?;
+                        let url = "https://learn.microsoft.com/en-us/windows/security/identity-protection/smart-cards/smart-card-debugging-information#smart-card-service";
+                        writeln!(
                             f,
-                    "Invalid PIN ({} tries remaining before it is blocked)",
-                    tries
+                            "{}",
+                            fl!(crate::LANGUAGE_LOADER, "rec-yk-no-service-win", url = url),
+                        )?;
+                    } else if cfg!(target_os = "macos") {
+                        wlnfl!(f, "err-yk-no-service-macos")?;
+                        let url = "https://apple.stackexchange.com/a/438198";
+                        writeln!(
+                            f,
+                            "{}",
+                            fl!(crate::LANGUAGE_LOADER, "rec-yk-no-service-macos", url = url),
+                        )?;
+                    } else {
+                        wlnfl!(f, "err-yk-no-service-pcscd")?;
+                        let apt = "sudo apt-get install pcscd";
+                        writeln!(
+                            f,
+                            "{}",
+                            fl!(crate::LANGUAGE_LOADER, "rec-yk-no-service-pcscd", apt = apt),
+                        )?;
+                    }
+                }
+                yubikey::Error::WrongPin { tries } => writeln!(
+                    f,
+                    "{}",
+                    fl!(crate::LANGUAGE_LOADER, "err-yk-wrong-pin", tries = tries),
                 )?,
                 e => {
-                    writeln!(f, "Error while communicating with YubiKey: {}", e)?;
+                    writeln!(
+                        f,
+                        "{}",
+                        fl!(
+                            crate::LANGUAGE_LOADER,
+                            "err-yk-general",
+                            err = e.to_string(),
+                        ),
+                    )?;
                     use std::error::Error;
                     if let Some(inner) = e.source() {
-                        writeln!(f, "Cause: {}", inner)?;
+                        writeln!(
+                            f,
+                            "{}",
+                            fl!(
+                                crate::LANGUAGE_LOADER,
+                                "err-yk-general-cause",
+                                inner_err = inner.to_string(),
+                            ),
+                        )?;
                     }
                 }
             },
         }
         writeln!(f)?;
-        writeln!(
-            f,
-            "[ Did this not do what you expected? Could an error be more useful? ]"
-        )?;
+        writeln!(f, "[ {} ]", crate::fl!("err-ux-A"))?;
         write!(
             f,
-            "[ Tell us: https://str4d.xyz/age-plugin-yubikey/report              ]"
+            "[ {}: https://str4d.xyz/age-plugin-yubikey/report {} ]",
+            crate::fl!("err-ux-B"),
+            crate::fl!("err-ux-C")
         )
     }
 }

src/format.rs

@@ -1,11 +1,10 @@
 use age_core::{
     format::{FileKey, Stanza},
     primitives::{aead_encrypt, hkdf},
+    secrecy::ExposeSecret,
 };
 use p256::{ecdh::EphemeralSecret, elliptic_curve::sec1::ToEncodedPoint};
 use rand::rngs::OsRng;
-use secrecy::ExposeSecret;
-use std::convert::TryInto;
 
 use crate::{p256::Recipient, STANZA_TAG};
 
@@ -106,7 +105,7 @@ impl RecipientLine {
         let epk = esk.public_key();
         let epk_bytes = EphemeralKeyBytes::from_public_key(&epk);
 
-        let shared_secret = esk.diffie_hellman(&pk.public_key());
+        let shared_secret = esk.diffie_hellman(pk.public_key());
 
         let mut salt = vec![];
         salt.extend_from_slice(epk_bytes.as_bytes());

src/key.rs

@@ -0,0 +1,647 @@
+//! Structs for handling YubiKeys.
+
+use age_core::{
+    format::{FileKey, FILE_KEY_BYTES},
+    primitives::{aead_decrypt, hkdf},
+    secrecy::ExposeSecret,
+};
+use age_plugin::{identity, Callbacks};
+use bech32::{ToBase32, Variant};
+use dialoguer::Password;
+use log::{debug, warn};
+use std::fmt;
+use std::io;
+use std::iter;
+use std::thread::sleep;
+use std::time::{Duration, Instant, SystemTime};
+use yubikey::{
+    certificate::{Certificate, PublicKeyInfo},
+    piv::{decrypt_data, AlgorithmId, RetiredSlotId, SlotId},
+    reader::{Context, Reader},
+    MgmKey, PinPolicy, Serial, TouchPolicy, YubiKey,
+};
+
+use crate::{
+    error::Error,
+    fl,
+    format::{RecipientLine, STANZA_KEY_LABEL},
+    p256::{Recipient, TAG_BYTES},
+    util::{otp_serial_prefix, Metadata},
+    IDENTITY_PREFIX,
+};
+
+const ONE_SECOND: Duration = Duration::from_secs(1);
+const FIFTEEN_SECONDS: Duration = Duration::from_secs(15);
+
+pub(crate) fn is_connected(reader: Reader) -> bool {
+    filter_connected(&reader)
+}
+
+pub(crate) fn filter_connected(reader: &Reader) -> bool {
+    match reader.open() {
+        Ok(_) => true,
+        Err(e) => {
+            use std::error::Error;
+            if let Some(pcsc::Error::RemovedCard) =
+                e.source().and_then(|inner| inner.downcast_ref())
+            {
+                warn!(
+                    "{}",
+                    i18n_embed_fl::fl!(
+                        crate::LANGUAGE_LOADER,
+                        "warn-yk-not-connected",
+                        yubikey_name = reader.name(),
+                    )
+                );
+                false
+            } else {
+                true
+            }
+        }
+    }
+}
+
+pub(crate) fn wait_for_readers() -> Result<Context, Error> {
+    // Start a 15-second timer waiting for a YubiKey to be inserted (if necessary).
+    let start = SystemTime::now();
+    loop {
+        let mut readers = Context::open()?;
+        if readers.iter()?.any(is_connected) {
+            break Ok(readers);
+        }
+
+        match SystemTime::now().duration_since(start) {
+            Ok(end) if end >= FIFTEEN_SECONDS => return Err(Error::TimedOut),
+            _ => sleep(ONE_SECOND),
+        }
+    }
+}
+
+/// Stops `scdaemon` if it is running.
+///
+/// Returns `true` if `scdaemon` was running and was successfully interrupted (or killed
+/// if the platform doesn't support interrupts).
+fn stop_scdaemon() -> bool {
+    debug!("Sharing violation encountered, looking for scdaemon processes to stop");
+
+    use sysinfo::{
+        Process, ProcessExt, ProcessRefreshKind, RefreshKind, Signal, System, SystemExt,
+    };
+
+    let mut interrupted = false;
+
+    let sys =
+        System::new_with_specifics(RefreshKind::new().with_processes(ProcessRefreshKind::new()));
+
+    for process in sys
+        .processes()
+        .values()
+        .filter(|val: &&Process| ["scdaemon", "scdaemon.exe"].contains(&val.name()))
+    {
+        if process
+            .kill_with(Signal::Interrupt)
+            .unwrap_or_else(|| process.kill())
+        {
+            debug!("Stopped scdaemon (PID {})", process.pid());
+            interrupted = true;
+        }
+    }
+
+    // If we did interrupt `scdaemon`, pause briefly to allow it to exit.
+    if interrupted {
+        sleep(Duration::from_millis(100));
+    }
+
+    interrupted
+}
+
+fn open_sesame(
+    op: impl Fn() -> Result<YubiKey, yubikey::Error>,
+) -> Result<YubiKey, yubikey::Error> {
+    op().or_else(|e| match e {
+        yubikey::Error::PcscError {
+            inner: Some(pcsc::Error::SharingViolation),
+        } if stop_scdaemon() => op(),
+        _ => Err(e),
+    })
+}
+
+/// Opens a connection to this reader, returning a `YubiKey` if successful.
+///
+/// This is equivalent to [`Reader::open`], but additionally handles the presence of
+/// `scdaemon` (which can indefinitely hold exclusive access to a YubiKey).
+pub(crate) fn open_connection(reader: &Reader) -> Result<YubiKey, yubikey::Error> {
+    open_sesame(|| reader.open())
+}
+
+/// Opens a YubiKey with a specific serial number.
+///
+/// This is equivalent to [`YubiKey::open_by_serial`], but additionally handles the
+/// presence of `scdaemon` (which can indefinitely hold exclusive access to a YubiKey).
+fn open_by_serial(serial: Serial) -> Result<YubiKey, yubikey::Error> {
+    open_sesame(|| YubiKey::open_by_serial(serial))
+}
+
+pub(crate) fn open(serial: Option<Serial>) -> Result<YubiKey, Error> {
+    if !Context::open()?.iter()?.any(is_connected) {
+        if let Some(serial) = serial {
+            eprintln!(
+                "{}",
+                i18n_embed_fl::fl!(
+                    crate::LANGUAGE_LOADER,
+                    "open-yk-with-serial",
+                    yubikey_serial = serial.to_string(),
+                )
+            );
+        } else {
+            eprintln!("{}", fl!("open-yk-without-serial"));
+        }
+    }
+    let mut readers = wait_for_readers()?;
+    let mut readers_iter = readers.iter()?.filter(filter_connected);
+
+    // --serial selects the YubiKey to use. If not provided, and more than one YubiKey is
+    // connected, an error is returned.
+    let yubikey = match (readers_iter.next(), readers_iter.next(), serial) {
+        (None, _, _) => unreachable!(),
+        (Some(reader), None, None) => open_connection(&reader)?,
+        (Some(reader), None, Some(serial)) => {
+            let yubikey = open_connection(&reader)?;
+            if yubikey.serial() != serial {
+                return Err(Error::NoMatchingSerial(serial));
+            }
+            yubikey
+        }
+        (Some(a), Some(b), Some(serial)) => {
+            let reader = iter::empty()
+                .chain(Some(a))
+                .chain(Some(b))
+                .chain(readers_iter)
+                .find(|reader| match open_connection(reader) {
+                    Ok(yk) => yk.serial() == serial,
+                    _ => false,
+                })
+                .ok_or(Error::NoMatchingSerial(serial))?;
+            open_connection(&reader)?
+        }
+        (Some(_), Some(_), None) => return Err(Error::MultipleYubiKeys),
+    };
+
+    Ok(yubikey)
+}
+
+pub(crate) fn manage(yubikey: &mut YubiKey) -> Result<(), Error> {
+    const DEFAULT_PIN: &str = "123456";
+    const DEFAULT_PUK: &str = "12345678";
+
+    eprintln!();
+    let pin = Password::new()
+        .with_prompt(i18n_embed_fl::fl!(
+            crate::LANGUAGE_LOADER,
+            "mgr-enter-pin",
+            yubikey_serial = yubikey.serial().to_string(),
+            default_pin = DEFAULT_PIN,
+        ))
+        .interact()?;
+    yubikey.verify_pin(pin.as_bytes())?;
+
+    // If the user is using the default PIN, help them to change it.
+    if pin == DEFAULT_PIN {
+        eprintln!();
+        eprintln!("{}", fl!("mgr-change-default-pin"));
+        eprintln!();
+        let current_puk = Password::new()
+            .with_prompt(i18n_embed_fl::fl!(
+                crate::LANGUAGE_LOADER,
+                "mgr-enter-current-puk",
+                default_puk = DEFAULT_PUK,
+            ))
+            .interact()?;
+        let new_pin = Password::new()
+            .with_prompt(fl!("mgr-choose-new-pin"))
+            .with_confirmation(fl!("mgr-repeat-new-pin"), fl!("mgr-pin-mismatch"))
+            .interact()?;
+        if new_pin.len() > 8 {
+            return Err(Error::InvalidPinLength);
+        }
+        yubikey.change_puk(current_puk.as_bytes(), new_pin.as_bytes())?;
+        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)?;
+
+        // 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!(
+                "{}",
+                i18n_embed_fl::fl!(
+                    crate::LANGUAGE_LOADER,
+                    "mgr-changing-mgmt-key-error",
+                    management_key = hex::encode(mgm_key.as_ref()),
+                )
+            );
+            e
+        })?;
+        eprintln!("{}", fl!("mgr-changing-mgmt-key-success"));
+    }
+
+    Ok(())
+}
+
+/// A reference to an age key stored in a YubiKey.
+#[derive(Debug)]
+pub struct Stub {
+    pub(crate) serial: Serial,
+    pub(crate) slot: RetiredSlotId,
+    pub(crate) tag: [u8; TAG_BYTES],
+    pub(crate) identity_index: usize,
+}
+
+impl fmt::Display for Stub {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.write_str(
+            bech32::encode(
+                IDENTITY_PREFIX,
+                self.to_bytes().to_base32(),
+                Variant::Bech32,
+            )
+            .expect("HRP is valid")
+            .to_uppercase()
+            .as_str(),
+        )
+    }
+}
+
+impl PartialEq for Stub {
+    fn eq(&self, other: &Self) -> bool {
+        self.to_bytes().eq(&other.to_bytes())
+    }
+}
+
+impl Stub {
+    /// Returns a key stub and recipient for this `(Serial, SlotId, PublicKey)` tuple.
+    ///
+    /// Does not check that the `PublicKey` matches the given `(Serial, SlotId)` tuple;
+    /// this is checked at decryption time.
+    pub(crate) fn new(serial: Serial, slot: RetiredSlotId, recipient: &Recipient) -> Self {
+        Stub {
+            serial,
+            slot,
+            tag: recipient.tag(),
+            identity_index: 0,
+        }
+    }
+
+    pub(crate) fn from_bytes(bytes: &[u8], identity_index: usize) -> Option<Self> {
+        if bytes.len() < 9 {
+            return None;
+        }
+        let serial = Serial::from(u32::from_le_bytes(bytes[0..4].try_into().unwrap()));
+        let slot: RetiredSlotId = bytes[4].try_into().ok()?;
+        Some(Stub {
+            serial,
+            slot,
+            tag: bytes[5..9].try_into().unwrap(),
+            identity_index,
+        })
+    }
+
+    fn to_bytes(&self) -> Vec<u8> {
+        let mut bytes = Vec::with_capacity(9);
+        bytes.extend_from_slice(&self.serial.0.to_le_bytes());
+        bytes.push(self.slot.into());
+        bytes.extend_from_slice(&self.tag);
+        bytes
+    }
+
+    pub(crate) fn matches(&self, line: &RecipientLine) -> bool {
+        self.tag == line.tag
+    }
+
+    /// Returns:
+    /// - `Ok(Ok(Some(connection)))` if we successfully connected to this YubiKey.
+    /// - `Ok(Ok(None))` if the user told us to skip this YubiKey.
+    /// - `Ok(Err(_))` if we encountered an error while trying to connect to the YubiKey.
+    /// - `Err(_)` on communication errors with the age client.
+    pub(crate) fn connect<E>(
+        &self,
+        callbacks: &mut dyn Callbacks<E>,
+    ) -> io::Result<Result<Option<Connection>, identity::Error>> {
+        let mut yubikey = match open_by_serial(self.serial) {
+            Ok(yk) => yk,
+            Err(yubikey::Error::NotFound) => {
+                let mut message = i18n_embed_fl::fl!(
+                    crate::LANGUAGE_LOADER,
+                    "plugin-insert-yk",
+                    yubikey_serial = self.serial.to_string(),
+                );
+
+                // If the `confirm` command is available, we loop until either the YubiKey
+                // we want is inserted, or the used explicitly skips.
+                let yubikey = loop {
+                    match callbacks.confirm(
+                        &message,
+                        &fl!("plugin-yk-is-plugged-in"),
+                        Some(&fl!("plugin-skip-this-yk")),
+                    )? {
+                        // `confirm` command is not available.
+                        Err(age_core::plugin::Error::Unsupported) => break None,
+                        // User told us to skip this key.
+                        Ok(false) => return Ok(Ok(None)),
+                        // User said they plugged it in; try it.
+                        Ok(true) => match open_by_serial(self.serial) {
+                            Ok(yubikey) => break Some(yubikey),
+                            Err(yubikey::Error::NotFound) => (),
+                            Err(_) => {
+                                return Ok(Err(identity::Error::Identity {
+                                    index: self.identity_index,
+                                    message: i18n_embed_fl::fl!(
+                                        crate::LANGUAGE_LOADER,
+                                        "plugin-err-yk-opening",
+                                        yubikey_serial = self.serial.to_string(),
+                                    ),
+                                }));
+                            }
+                        },
+                        // We can't communicate with the user.
+                        Err(age_core::plugin::Error::Fail) => {
+                            return Ok(Err(identity::Error::Identity {
+                                index: self.identity_index,
+                                message: i18n_embed_fl::fl!(
+                                    crate::LANGUAGE_LOADER,
+                                    "plugin-err-yk-opening",
+                                    yubikey_serial = self.serial.to_string(),
+                                ),
+                            }))
+                        }
+                    }
+
+                    // We're going to loop around, meaning that the first attempt failed.
+                    // Change the message to indicate this to the user.
+                    message = i18n_embed_fl::fl!(
+                        crate::LANGUAGE_LOADER,
+                        "plugin-insert-yk-retry",
+                        yubikey_serial = self.serial.to_string(),
+                    );
+                };
+
+                if let Some(yk) = yubikey {
+                    yk
+                } else {
+                    // `confirm` is not available; fall back to `message` with a timeout.
+                    if callbacks.message(&message)?.is_err() {
+                        return Ok(Err(identity::Error::Identity {
+                            index: self.identity_index,
+                            message: i18n_embed_fl::fl!(
+                                crate::LANGUAGE_LOADER,
+                                "plugin-err-yk-not-found",
+                                yubikey_serial = self.serial.to_string(),
+                            ),
+                        }));
+                    }
+
+                    // Start a 15-second timer waiting for the YubiKey to be inserted
+                    let start = SystemTime::now();
+                    loop {
+                        match open_by_serial(self.serial) {
+                            Ok(yubikey) => break yubikey,
+                            Err(yubikey::Error::NotFound) => (),
+                            Err(_) => {
+                                return Ok(Err(identity::Error::Identity {
+                                    index: self.identity_index,
+                                    message: i18n_embed_fl::fl!(
+                                        crate::LANGUAGE_LOADER,
+                                        "plugin-err-yk-opening",
+                                        yubikey_serial = self.serial.to_string(),
+                                    ),
+                                }));
+                            }
+                        }
+
+                        match SystemTime::now().duration_since(start) {
+                            Ok(end) if end >= FIFTEEN_SECONDS => {
+                                return Ok(Err(identity::Error::Identity {
+                                    index: self.identity_index,
+                                    message: i18n_embed_fl::fl!(
+                                        crate::LANGUAGE_LOADER,
+                                        "plugin-err-yk-timed-out",
+                                        yubikey_serial = self.serial.to_string(),
+                                    ),
+                                }))
+                            }
+                            _ => sleep(ONE_SECOND),
+                        }
+                    }
+                }
+            }
+            Err(_) => {
+                return Ok(Err(identity::Error::Identity {
+                    index: self.identity_index,
+                    message: i18n_embed_fl::fl!(
+                        crate::LANGUAGE_LOADER,
+                        "plugin-err-yk-opening",
+                        yubikey_serial = self.serial.to_string(),
+                    ),
+                }))
+            }
+        };
+
+        // Read the pubkey from the YubiKey slot and check it still matches.
+        let (cert, pk) = match Certificate::read(&mut yubikey, SlotId::Retired(self.slot))
+            .ok()
+            .and_then(|cert| match cert.subject_pki() {
+                PublicKeyInfo::EcP256(pubkey) => Recipient::from_encoded(pubkey)
+                    .filter(|pk| pk.tag() == self.tag)
+                    .map(|pk| (cert, pk)),
+                _ => None,
+            }) {
+            Some(pk) => pk,
+            None => {
+                return Ok(Err(identity::Error::Identity {
+                    index: self.identity_index,
+                    message: fl!("plugin-err-yk-stub-mismatch"),
+                }))
+            }
+        };
+
+        Ok(Ok(Some(Connection {
+            yubikey,
+            cert,
+            pk,
+            slot: self.slot,
+            tag: self.tag,
+            identity_index: self.identity_index,
+            cached_metadata: None,
+            last_touch: None,
+        })))
+    }
+}
+
+pub(crate) struct Connection {
+    yubikey: YubiKey,
+    cert: Certificate,
+    pk: Recipient,
+    slot: RetiredSlotId,
+    tag: [u8; 4],
+    identity_index: usize,
+    cached_metadata: Option<Metadata>,
+    last_touch: Option<Instant>,
+}
+
+impl Connection {
+    pub(crate) fn recipient(&self) -> &Recipient {
+        &self.pk
+    }
+
+    pub(crate) fn request_pin_if_necessary<E>(
+        &mut self,
+        callbacks: &mut dyn Callbacks<E>,
+    ) -> io::Result<Result<(), identity::Error>> {
+        // Check if we can skip requesting a PIN.
+        if self.cached_metadata.is_none() {
+            let (_, cert) = x509_parser::parse_x509_certificate(self.cert.as_ref()).unwrap();
+            self.cached_metadata =
+                match Metadata::extract(&mut self.yubikey, self.slot, &cert, true) {
+                    None => {
+                        return Ok(Err(identity::Error::Identity {
+                            index: self.identity_index,
+                            message: fl!("plugin-err-yk-invalid-pin-policy"),
+                        }))
+                    }
+                    metadata => metadata,
+                };
+        }
+        if let Some(PinPolicy::Never) = self.cached_metadata.as_ref().and_then(|m| m.pin_policy) {
+            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 enter_pin_msg = i18n_embed_fl::fl!(
+            crate::LANGUAGE_LOADER,
+            "plugin-enter-pin",
+            yubikey_serial = self.yubikey.serial().to_string(),
+        );
+        let mut message = enter_pin_msg.clone();
+        let pin = loop {
+            message = match callbacks.request_secret(&message)? {
+                Ok(pin) => match pin.expose_secret().len() {
+                    // A PIN must be between 6 and 8 characters.
+                    6..=8 => break pin,
+                    // If the string is 44 bytes and starts with the YubiKey's serial
+                    // encoded as 12-byte modhex, the user probably touched the YubiKey
+                    // early and "typed" an OTP.
+                    44 if pin
+                        .expose_secret()
+                        .starts_with(&otp_serial_prefix(self.yubikey.serial())) =>
+                    {
+                        format!("{} {}", fl!("plugin-err-accidental-touch"), enter_pin_msg)
+                    }
+                    // Otherwise, the PIN is either too short or too long.
+                    0..=5 => format!("{} {}", fl!("plugin-err-pin-too-short"), enter_pin_msg),
+                    _ => format!("{} {}", fl!("plugin-err-pin-too-long"), enter_pin_msg),
+                },
+                Err(_) => {
+                    return Ok(Err(identity::Error::Identity {
+                        index: self.identity_index,
+                        message: i18n_embed_fl::fl!(
+                            crate::LANGUAGE_LOADER,
+                            "plugin-err-pin-required",
+                            yubikey_serial = self.yubikey.serial().to_string(),
+                        ),
+                    }))
+                }
+            };
+        };
+        if let Err(e) = self.yubikey.verify_pin(pin.expose_secret().as_bytes()) {
+            return Ok(Err(identity::Error::Identity {
+                index: self.identity_index,
+                message: format!("{:?}", Error::YubiKey(e)),
+            }));
+        }
+        Ok(Ok(()))
+    }
+
+    pub(crate) fn unwrap_file_key(&mut self, line: &RecipientLine) -> Result<FileKey, ()> {
+        assert_eq!(self.tag, line.tag);
+
+        // Check if the touch policy requires a touch.
+        let needs_touch = match (
+            self.cached_metadata.as_ref().and_then(|m| m.touch_policy),
+            self.last_touch,
+        ) {
+            (Some(TouchPolicy::Always), _) | (Some(TouchPolicy::Cached), None) => true,
+            (Some(TouchPolicy::Cached), Some(last)) if last.elapsed() >= FIFTEEN_SECONDS => true,
+            _ => false,
+        };
+
+        // The YubiKey API for performing scalar multiplication takes the point in its
+        // uncompressed SEC-1 encoding.
+        let shared_secret = match decrypt_data(
+            &mut self.yubikey,
+            line.epk_bytes.decompress().as_bytes(),
+            AlgorithmId::EccP256,
+            SlotId::Retired(self.slot),
+        ) {
+            Ok(res) => res,
+            Err(_) => return Err(()),
+        };
+
+        // If we requested a touch and reached here, the user touched the YubiKey.
+        if needs_touch {
+            if let Some(TouchPolicy::Cached) =
+                self.cached_metadata.as_ref().and_then(|m| m.touch_policy)
+            {
+                self.last_touch = Some(Instant::now());
+            }
+        }
+
+        let mut salt = vec![];
+        salt.extend_from_slice(line.epk_bytes.as_bytes());
+        salt.extend_from_slice(self.pk.to_encoded().as_bytes());
+
+        let enc_key = hkdf(&salt, STANZA_KEY_LABEL, shared_secret.as_ref());
+
+        // A failure to decrypt is fatal, because we assume that we won't
+        // encounter 32-bit collisions on the key tag embedded in the header.
+        match aead_decrypt(&enc_key, FILE_KEY_BYTES, &line.encrypted_file_key) {
+            Ok(pt) => Ok(TryInto::<[u8; FILE_KEY_BYTES]>::try_into(&pt[..])
+                .unwrap()
+                .into()),
+            Err(_) => Err(()),
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use yubikey::{piv::RetiredSlotId, Serial};
+
+    use super::Stub;
+
+    #[test]
+    fn stub_round_trip() {
+        let stub = Stub {
+            serial: Serial::from(42),
+            slot: RetiredSlotId::R1,
+            tag: [7; 4],
+            identity_index: 0,
+        };
+
+        let encoded = stub.to_bytes();
+        assert_eq!(Stub::from_bytes(&[], 0), None);
+        assert_eq!(Stub::from_bytes(&encoded, 0), Some(stub));
+        assert_eq!(Stub::from_bytes(&encoded[..encoded.len() - 1], 0), None);
+    }
+}

src/main.rs

@@ -1,24 +1,31 @@
-use std::convert::{TryFrom, TryInto};
+#![forbid(unsafe_code)]
+
 use std::fs::{File, OpenOptions};
 use std::io::{self, Write};
 
 use age_plugin::run_state_machine;
 use dialoguer::{Confirm, Input, Select};
 use gumdrop::Options;
-use yubikey_piv::{
+use i18n_embed::{
+    fluent::{fluent_language_loader, FluentLanguageLoader},
+    DesktopLanguageRequester,
+};
+use lazy_static::lazy_static;
+use rust_embed::RustEmbed;
+use yubikey::{
     certificate::PublicKeyInfo,
-    key::{RetiredSlotId, SlotId},
-    policy::{PinPolicy, TouchPolicy},
-    Key, Readers, Serial,
+    piv::{RetiredSlotId, SlotId},
+    reader::Context,
+    Key, PinPolicy, Serial, TouchPolicy,
 };
 
 mod builder;
 mod error;
 mod format;
+mod key;
 mod p256;
 mod plugin;
 mod util;
-mod yubikey;
 
 use error::Error;
 
@@ -51,6 +58,23 @@ const USABLE_SLOTS: [RetiredSlotId; 20] = [
     RetiredSlotId::R20,
 ];
 
+#[derive(RustEmbed)]
+#[folder = "i18n"]
+struct Translations;
+
+const TRANSLATIONS: Translations = Translations {};
+
+lazy_static! {
+    static ref LANGUAGE_LOADER: FluentLanguageLoader = fluent_language_loader!();
+}
+
+#[macro_export]
+macro_rules! fl {
+    ($message_id:literal) => {{
+        i18n_embed_fl::fl!($crate::LANGUAGE_LOADER, $message_id)
+    }};
+}
+
 #[derive(Debug, Options)]
 struct PluginOptions {
     #[options(help = "Print this help message and exit.")]
@@ -148,7 +172,7 @@ impl TryFrom<PluginOptions> for PluginFlags {
 }
 
 fn generate(flags: PluginFlags) -> Result<(), Error> {
-    let mut yubikey = yubikey::open(flags.serial)?;
+    let mut yubikey = key::open(flags.serial)?;
 
     let (stub, recipient, metadata) = builder::IdentityBuilder::new(flags.slot)
         .with_name(flags.name)
@@ -165,9 +189,9 @@ fn generate(flags: PluginFlags) -> Result<(), Error> {
 fn print_single(
     serial: Option<Serial>,
     slot: RetiredSlotId,
-    printer: impl Fn(yubikey::Stub, p256::Recipient, util::Metadata),
+    printer: impl Fn(key::Stub, p256::Recipient, util::Metadata),
 ) -> Result<(), Error> {
-    let mut yubikey = yubikey::open(serial)?;
+    let mut yubikey = key::open(serial)?;
 
     let mut keys = Key::list(&mut yubikey)?.into_iter().filter_map(|key| {
         // - We only use the retired slots.
@@ -184,7 +208,7 @@ fn print_single(
         .find(|(_, s, _)| s == &slot)
         .ok_or(Error::SlotHasNoIdentity(slot))?;
 
-    let stub = yubikey::Stub::new(yubikey.serial(), slot, &recipient);
+    let stub = key::Stub::new(yubikey.serial(), slot, &recipient);
     let metadata = x509_parser::parse_x509_certificate(key.certificate().as_ref())
         .ok()
         .and_then(|(_, cert)| util::Metadata::extract(&mut yubikey, slot, &cert, true))
@@ -199,13 +223,13 @@ fn print_multiple(
     kind: &str,
     serial: Option<Serial>,
     all: bool,
-    printer: impl Fn(yubikey::Stub, p256::Recipient, util::Metadata),
+    printer: impl Fn(key::Stub, p256::Recipient, util::Metadata),
 ) -> Result<(), Error> {
-    let mut readers = Readers::open()?;
+    let mut readers = Context::open()?;
 
     let mut printed = 0;
-    for reader in readers.iter()?.filter(yubikey::filter_connected) {
-        let mut yubikey = reader.open()?;
+    for reader in readers.iter()?.filter(key::filter_connected) {
+        let mut yubikey = key::open_connection(&reader)?;
         if let Some(serial) = serial {
             if yubikey.serial() != serial {
                 continue;
@@ -228,7 +252,7 @@ fn print_multiple(
                 _ => continue,
             };
 
-            let stub = yubikey::Stub::new(yubikey.serial(), slot, &recipient);
+            let stub = key::Stub::new(yubikey.serial(), slot, &recipient);
             let metadata = match x509_parser::parse_x509_certificate(key.certificate().as_ref())
                 .ok()
                 .and_then(|(_, cert)| util::Metadata::extract(&mut yubikey, slot, &cert, all))
@@ -245,8 +269,13 @@ fn print_multiple(
     }
     if printed > 1 {
         eprintln!(
-            "Generated {} for {} slots. If you intended to select a slot, use --slot.",
-            kind, printed,
+            "{}",
+            i18n_embed_fl::fl!(
+                LANGUAGE_LOADER,
+                "printed-multiple",
+                kind = kind,
+                count = printed,
+            )
         );
     }
 
@@ -257,7 +286,7 @@ fn print_details(
     kind: &str,
     flags: PluginFlags,
     all: bool,
-    printer: impl Fn(yubikey::Stub, p256::Recipient, util::Metadata),
+    printer: impl Fn(key::Stub, p256::Recipient, util::Metadata),
 ) -> Result<(), Error> {
     if let Some(slot) = flags.slot {
         print_single(flags.serial, slot, printer)
@@ -273,7 +302,12 @@ fn identity(flags: PluginFlags) -> Result<(), Error> {
             "--identity".into(),
         ));
     }
-    print_details("identities", flags, false, util::print_identity)
+    print_details(
+        &fl!("printed-kind-identities"),
+        flags,
+        false,
+        util::print_identity,
+    )
 }
 
 fn list(flags: PluginFlags, all: bool) -> Result<(), Error> {
@@ -287,10 +321,15 @@ fn list(flags: PluginFlags, all: bool) -> Result<(), Error> {
         ));
     }
 
-    print_details("recipients", flags, all, |_, recipient, metadata| {
+    print_details(
+        &fl!("printed-kind-recipients"),
+        flags,
+        all,
+        |_, recipient, metadata| {
             println!("{}", metadata);
             println!("{}", recipient.to_string());
-    })
+        },
+    )
 }
 
 fn main() -> Result<(), Error> {
@@ -300,6 +339,12 @@ fn main() -> Result<(), Error> {
         .parse_default_env()
         .init();
 
+    let requested_languages = DesktopLanguageRequester::requested_languages();
+    i18n_embed::select(&*LANGUAGE_LOADER, &TRANSLATIONS, &requested_languages).unwrap();
+    // Unfortunately the common Windows terminals don't support Unicode Directionality
+    // Isolation Marks, so we disable them for now.
+    LANGUAGE_LOADER.set_use_isolating(false);
+
     let opts = PluginOptions::parse_args_default_or_exit();
 
     if [opts.generate, opts.identity, opts.list, opts.list_all]
@@ -335,39 +380,39 @@ fn main() -> Result<(), Error> {
         }
         let flags: PluginFlags = opts.try_into()?;
 
-        eprintln!("✨ Let's get your YubiKey set up for age! ✨");
-        eprintln!();
-        eprintln!("This tool can create a new age identity in a free slot of your YubiKey.");
-        eprintln!("It will generate an identity file that you can use with an age client,");
-        eprintln!("along with the corresponding recipient. You can also do this directly");
-        eprintln!("with:");
-        eprintln!("    age-plugin-yubikey --generate");
-        eprintln!();
-        eprintln!("If you are already using a YubiKey with age, you can select an existing");
-        eprintln!("slot to recreate its corresponding identity file and recipient.");
-        eprintln!();
-        eprintln!("When asked below to select an option, use the up/down arrow keys to");
-        eprintln!("make your choice, or press [Esc] or [q] to quit.");
+        eprintln!(
+            "{}",
+            i18n_embed_fl::fl!(
+                LANGUAGE_LOADER,
+                "cli-setup-intro",
+                generate_usage = "age-plugin-yubikey --generate",
+            )
+        );
         eprintln!();
 
-        if !Readers::open()?.iter()?.any(yubikey::is_connected) {
-            eprintln!("⏳ Please insert the YubiKey you want to set up.");
+        if !Context::open()?.iter()?.any(key::is_connected) {
+            eprintln!("{}", fl!("cli-setup-insert-yk"));
         };
-        let mut readers = yubikey::wait_for_readers()?;
+        let mut readers = key::wait_for_readers()?;
 
         // Filter out readers we can't connect to.
-        let readers_list: Vec<_> = readers.iter()?.filter(yubikey::filter_connected).collect();
+        let readers_list: Vec<_> = readers.iter()?.filter(key::filter_connected).collect();
 
         let reader_names = readers_list
             .iter()
             .map(|reader| {
-                reader
-                    .open()
-                    .map(|yk| format!("{} (Serial: {})", reader.name(), yk.serial()))
+                key::open_connection(reader).map(|yk| {
+                    i18n_embed_fl::fl!(
+                        LANGUAGE_LOADER,
+                        "cli-setup-yk-name",
+                        yubikey_name = reader.name(),
+                        yubikey_serial = yk.serial().to_string(),
+                    )
+                })
             })
             .collect::<Result<Vec<_>, _>>()?;
         let mut yubikey = match Select::new()
-            .with_prompt("🔑 Select a YubiKey")
+            .with_prompt(fl!("cli-setup-select-yk"))
             .items(&reader_names)
             .default(0)
             .interact_opt()?
@@ -410,9 +455,20 @@ fn main() -> Result<(), Error> {
                 let i = i + 1;
 
                 match occupied {
-                    Some(Some(name)) => format!("Slot {} ({})", i, name),
-                    Some(None) => format!("Slot {} (Unusable)", i),
-                    None => format!("Slot {} (Empty)", i),
+                    Some(Some(name)) => i18n_embed_fl::fl!(
+                        LANGUAGE_LOADER,
+                        "cli-setup-slot-usable",
+                        slot_index = i,
+                        slot_name = name.as_str(),
+                    ),
+                    Some(None) => i18n_embed_fl::fl!(
+                        LANGUAGE_LOADER,
+                        "cli-setup-slot-unusable",
+                        slot_index = i,
+                    ),
+                    None => {
+                        i18n_embed_fl::fl!(LANGUAGE_LOADER, "cli-setup-slot-empty", slot_index = i)
+                    }
                 }
             })
             .collect();
@@ -420,7 +476,7 @@ fn main() -> Result<(), Error> {
         let ((stub, recipient, metadata), is_new) = {
             let (slot_index, slot) = loop {
                 match Select::new()
-                    .with_prompt("🕳️  Select a slot for your age identity")
+                    .with_prompt(fl!("cli-setup-select-slot"))
                     .items(&slots)
                     .default(0)
                     .interact_opt()?
@@ -444,10 +500,14 @@ fn main() -> Result<(), Error> {
                 };
 
                 if Confirm::new()
-                    .with_prompt(&format!("Use existing identity in slot {}?", slot_index))
+                    .with_prompt(i18n_embed_fl::fl!(
+                        LANGUAGE_LOADER,
+                        "cli-setup-use-existing",
+                        slot_index = slot_index,
+                    ))
                     .interact()?
                 {
-                    let stub = yubikey::Stub::new(yubikey.serial(), slot, &recipient);
+                    let stub = key::Stub::new(yubikey.serial(), slot, &recipient);
                     let (_, cert) =
                         x509_parser::parse_x509_certificate(key.certificate().as_ref()).unwrap();
                     let metadata =
@@ -460,18 +520,19 @@ fn main() -> Result<(), Error> {
             } else {
                 let name = Input::<String>::new()
                     .with_prompt(format!(
-                        "📛 Name this identity [{}]",
+                        "{} [{}]",
+                        fl!("cli-setup-name-identity"),
                         flags.name.as_deref().unwrap_or("age identity TAG_HEX")
                     ))
                     .allow_empty(true)
                     .interact_text()?;
 
                 let pin_policy = match Select::new()
-                    .with_prompt("🔤 Select a PIN policy")
+                    .with_prompt(fl!("cli-setup-select-pin-policy"))
                     .items(&[
-                        "Always (A PIN is required for every decryption, if set)",
-                        "Once   (A PIN is required once per session, if set)",
-                        "Never  (A PIN is NOT required to decrypt)",
+                        fl!("pin-policy-always"),
+                        fl!("pin-policy-once"),
+                        fl!("pin-policy-never"),
                     ])
                     .default(
                         [PinPolicy::Always, PinPolicy::Once, PinPolicy::Never]
@@ -491,17 +552,18 @@ fn main() -> Result<(), Error> {
                 };
 
                 let touch_policy = match Select::new()
-                        .with_prompt("👆 Select a touch policy")
+                    .with_prompt(fl!("cli-setup-select-touch-policy"))
                     .items(&[
-                            "Always (A physical touch is required for every decryption)",
-                            "Cached (A physical touch is required for decryption, and is cached for 15 seconds)",
-                            "Never  (A physical touch is NOT required to decrypt)",
+                        fl!("touch-policy-always"),
+                        fl!("touch-policy-cached"),
+                        fl!("touch-policy-never"),
                     ])
                     .default(
                         [TouchPolicy::Always, TouchPolicy::Cached, TouchPolicy::Never]
                             .iter()
-                                .position(|p| p == &flags
-                                    .touch_policy.unwrap_or(builder::DEFAULT_TOUCH_POLICY))
+                            .position(|p| {
+                                p == &flags.touch_policy.unwrap_or(builder::DEFAULT_TOUCH_POLICY)
+                            })
                             .unwrap(),
                     )
                     .interact_opt()?
@@ -514,7 +576,11 @@ fn main() -> Result<(), Error> {
                 };
 
                 if Confirm::new()
-                    .with_prompt(&format!("Generate new identity in slot {}?", slot_index))
+                    .with_prompt(i18n_embed_fl::fl!(
+                        LANGUAGE_LOADER,
+                        "cli-setup-generate-new",
+                        slot_index = slot_index,
+                    ))
                     .interact()?
                 {
                     eprintln!();
@@ -537,7 +603,7 @@ fn main() -> Result<(), Error> {
 
         eprintln!();
         let file_name = Input::<String>::new()
-            .with_prompt("📝 File name to write this identity to")
+            .with_prompt(fl!("cli-setup-identity-file-name"))
             .default(format!(
                 "age-yubikey-identity-{}.txt",
                 hex::encode(stub.tag)
@@ -552,7 +618,7 @@ fn main() -> Result<(), Error> {
             Ok(file) => file,
             Err(e) if e.kind() == io::ErrorKind::AlreadyExists => {
                 if Confirm::new()
-                    .with_prompt("File exists. Overwrite it?")
+                    .with_prompt(fl!("cli-setup-identity-file-exists"))
                     .interact()?
                 {
                     File::create(&file_name)?
@@ -563,54 +629,56 @@ fn main() -> Result<(), Error> {
             Err(e) => return Err(e.into()),
         };
 
-        writeln!(file, "{}", metadata)?;
-        writeln!(file, "#    Recipient: {}", recipient)?;
-        writeln!(file, "{}", stub.to_string())?;
+        writeln!(
+            file,
+            "{}",
+            i18n_embed_fl::fl!(
+                LANGUAGE_LOADER,
+                "yubikey-identity",
+                yubikey_metadata = metadata.to_string(),
+                recipient = recipient.to_string(),
+                identity = stub.to_string(),
+            )
+        )?;
         file.sync_data()?;
 
         // If `rage` binary is installed, use it in examples. Otherwise default to `age`.
         let age_binary = which::which("rage").map(|_| "rage").unwrap_or("age");
 
-        eprintln!();
-        eprintln!("✅ Done! This YubiKey identity is ready to go.");
-        eprintln!();
-        if is_new {
-            eprintln!("🔑 Here's your shiny new YubiKey recipient:");
-        } else {
-            eprintln!("🔑 Here's the corresponding YubiKey recipient:");
-        }
-        eprintln!("  {}", recipient);
-        eprintln!();
-        eprintln!("Here are some example things you can do with it:");
-        eprintln!();
-        eprintln!("- Encrypt a file to this identity:");
-        eprintln!(
+        let encrypt_usage = format!(
             "$ cat foo.txt | {} -r {} -o foo.txt.age",
             age_binary, recipient
         );
-        eprintln!();
-        eprintln!("- Decrypt a file with this identity:");
-        eprintln!(
+        let decrypt_usage = format!(
             "$ cat foo.txt.age | {} -d -i {} > foo.txt",
             age_binary, file_name
         );
-        eprintln!();
-        eprintln!("- Recreate the identity file:");
-        eprintln!(
+        let identity_usage = format!(
             "$ age-plugin-yubikey -i --serial {} --slot {} > {}",
             stub.serial,
             util::slot_to_ui(&stub.slot),
             file_name,
         );
-        eprintln!();
-        eprintln!("- Recreate the recipient:");
-        eprintln!(
+        let recipient_usage = format!(
             "$ age-plugin-yubikey -l --serial {} --slot {}",
             stub.serial,
             util::slot_to_ui(&stub.slot),
         );
+
         eprintln!();
-        eprintln!("💭 Remember: everything breaks, have a backup plan for when this YubiKey does.");
+        eprintln!(
+            "{}",
+            i18n_embed_fl::fl!(
+                LANGUAGE_LOADER,
+                "cli-setup-finished",
+                is_new = if is_new { "true" } else { "false" },
+                recipient = recipient.to_string(),
+                encrypt_usage = encrypt_usage,
+                decrypt_usage = decrypt_usage,
+                identity_usage = identity_usage,
+                recipient_usage = recipient_usage,
+            )
+        );
 
         Ok(())
     }

src/p256.rs

@@ -1,7 +1,6 @@
 use bech32::{ToBase32, Variant};
 use p256::elliptic_curve::sec1::{FromEncodedPoint, ToEncodedPoint};
 use sha2::{Digest, Sha256};
-use std::convert::TryInto;
 use std::fmt;
 
 use crate::RECIPIENT_PREFIX;
@@ -48,7 +47,7 @@ impl Recipient {
     /// This accepts both compressed (as used by the plugin) and uncompressed (as used in
     /// the YubiKey certificate) encodings.
     pub(crate) fn from_encoded(encoded: &p256::EncodedPoint) -> Option<Self> {
-        p256::PublicKey::from_encoded_point(&encoded).map(Recipient)
+        p256::PublicKey::from_encoded_point(encoded).map(Recipient)
     }
 
     /// Returns the compressed SEC-1 encoding of this recipient.

src/plugin.rs

@@ -7,12 +7,12 @@ use age_plugin::{
 use std::collections::HashMap;
 use std::io;
 
-use crate::{format, p256::Recipient, yubikey, PLUGIN_NAME};
+use crate::{fl, format, key, p256::Recipient, PLUGIN_NAME};
 
 #[derive(Debug, Default)]
 pub(crate) struct RecipientPlugin {
     recipients: Vec<Recipient>,
-    yubikeys: Vec<yubikey::Stub>,
+    yubikeys: Vec<key::Stub>,
 }
 
 impl RecipientPluginV1 for RecipientPlugin {
@@ -23,7 +23,7 @@ impl RecipientPluginV1 for RecipientPlugin {
         bytes: &[u8],
     ) -> Result<(), recipient::Error> {
         if let Some(pk) = if plugin_name == PLUGIN_NAME {
-            Recipient::from_bytes(&bytes)
+            Recipient::from_bytes(bytes)
         } else {
             None
         } {
@@ -32,7 +32,7 @@ impl RecipientPluginV1 for RecipientPlugin {
         } else {
             Err(recipient::Error::Recipient {
                 index,
-                message: "Invalid recipient".to_owned(),
+                message: fl!("plugin-err-invalid-recipient"),
             })
         }
     }
@@ -44,7 +44,7 @@ impl RecipientPluginV1 for RecipientPlugin {
         bytes: &[u8],
     ) -> Result<(), recipient::Error> {
         if let Some(stub) = if plugin_name == PLUGIN_NAME {
-            yubikey::Stub::from_bytes(&bytes, index)
+            key::Stub::from_bytes(bytes, index)
         } else {
             None
         } {
@@ -53,7 +53,7 @@ impl RecipientPluginV1 for RecipientPlugin {
         } else {
             Err(recipient::Error::Identity {
                 index,
-                message: "Invalid Yubikey stub".to_owned(),
+                message: fl!("plugin-err-invalid-identity"),
             })
         }
     }
@@ -68,7 +68,15 @@ impl RecipientPluginV1 for RecipientPlugin {
         let mut yk_errors = vec![];
         for stub in &self.yubikeys {
             match stub.connect(&mut callbacks)? {
-                Ok(conn) => yk_recipients.push(conn.recipient().clone()),
+                Ok(Some(conn)) => yk_recipients.push(conn.recipient().clone()),
+                Ok(None) => yk_errors.push(recipient::Error::Identity {
+                    index: stub.identity_index,
+                    message: i18n_embed_fl::fl!(
+                        crate::LANGUAGE_LOADER,
+                        "plugin-err-yk-opening",
+                        yubikey_serial = stub.serial.to_string(),
+                    ),
+                }),
                 Err(e) => yk_errors.push(match e {
                     identity::Error::Identity { index, message } => {
                         recipient::Error::Identity { index, message }
@@ -88,7 +96,7 @@ impl RecipientPluginV1 for RecipientPlugin {
                     self.recipients
                         .iter()
                         .chain(yk_recipients.iter())
-                        .map(|pk| format::RecipientLine::wrap_file_key(&file_key, &pk).into())
+                        .map(|pk| format::RecipientLine::wrap_file_key(&file_key, pk).into())
                         .collect()
                 })
                 .collect())
@@ -100,7 +108,7 @@ impl RecipientPluginV1 for RecipientPlugin {
 
 #[derive(Debug, Default)]
 pub(crate) struct IdentityPlugin {
-    yubikeys: Vec<yubikey::Stub>,
+    yubikeys: Vec<key::Stub>,
 }
 
 impl IdentityPluginV1 for IdentityPlugin {
@@ -111,7 +119,7 @@ impl IdentityPluginV1 for IdentityPlugin {
         bytes: &[u8],
     ) -> Result<(), identity::Error> {
         if let Some(stub) = if plugin_name == PLUGIN_NAME {
-            yubikey::Stub::from_bytes(&bytes, index)
+            key::Stub::from_bytes(bytes, index)
         } else {
             None
         } {
@@ -120,7 +128,7 @@ impl IdentityPluginV1 for IdentityPlugin {
         } else {
             Err(identity::Error::Identity {
                 index,
-                message: "Invalid Yubikey stub".to_owned(),
+                message: fl!("plugin-err-invalid-identity"),
             })
         }
     }
@@ -133,11 +141,8 @@ impl IdentityPluginV1 for IdentityPlugin {
         let mut file_keys = HashMap::with_capacity(files.len());
 
         // Filter to files / stanzas for which we have matching YubiKeys
-        let mut candidate_stanzas: Vec<(
-            &yubikey::Stub,
-            HashMap<usize, Vec<format::RecipientLine>>,
-        )> = self
-            .yubikeys
+        let mut candidate_stanzas: Vec<(&key::Stub, HashMap<usize, Vec<format::RecipientLine>>)> =
+            self.yubikeys
                 .iter()
                 .map(|stub| (stub, HashMap::new()))
                 .collect();
@@ -145,11 +150,11 @@ impl IdentityPluginV1 for IdentityPlugin {
         for (file, stanzas) in files.iter().enumerate() {
             for (stanza_index, stanza) in stanzas.iter().enumerate() {
                 match (
-                    format::RecipientLine::from_stanza(&stanza).map(|res| {
+                    format::RecipientLine::from_stanza(stanza).map(|res| {
                         res.map_err(|_| identity::Error::Stanza {
                             file_index: file,
                             stanza_index,
-                            message: "Invalid yubikey stanza".to_owned(),
+                            message: fl!("plugin-err-invalid-stanza"),
                         })
                     }),
                     file_keys.contains_key(&file),
@@ -206,13 +211,22 @@ impl IdentityPluginV1 for IdentityPlugin {
 
         for (stub, files) in candidate_stanzas.iter() {
             let mut conn = match stub.connect(&mut callbacks)? {
-                Ok(conn) => conn,
+                // The user skipped this YubiKey.
+                Ok(None) => continue,
+                // We connected to this YubiKey.
+                Ok(Some(conn)) => conn,
+                // We failed to connect to this YubiKey.
                 Err(e) => {
                     callbacks.error(e)?.unwrap();
                     continue;
                 }
             };
 
+            if let Err(e) = conn.request_pin_if_necessary(&mut callbacks)? {
+                callbacks.error(e)?.unwrap();
+                continue;
+            }
+
             for (&file_index, stanzas) in files {
                 if file_keys.contains_key(&file_index) {
                     // We decrypted this file with an earlier YubiKey.
@@ -220,7 +234,7 @@ impl IdentityPluginV1 for IdentityPlugin {
                 }
 
                 for (stanza_index, line) in stanzas.iter().enumerate() {
-                    match conn.unwrap_file_key(&line) {
+                    match conn.unwrap_file_key(line) {
                         Ok(file_key) => {
                             // We've managed to decrypt this file!
                             file_keys.entry(file_index).or_insert(Ok(file_key));
@@ -230,7 +244,7 @@ impl IdentityPluginV1 for IdentityPlugin {
                             .error(identity::Error::Stanza {
                                 file_index,
                                 stanza_index,
-                                message: "Failed to decrypt YubiKey stanza".to_owned(),
+                                message: fl!("plugin-err-decryption-failed"),
                             })?
                             .unwrap(),
                     }

src/util.rs

@@ -1,13 +1,14 @@
 use std::fmt;
+use std::iter;
 
 use x509_parser::{certificate::X509Certificate, der_parser::oid::Oid};
-use yubikey_piv::{
-    key::{RetiredSlotId, SlotId},
-    policy::{PinPolicy, TouchPolicy},
-    Serial, YubiKey,
+use yubikey::{
+    piv::{RetiredSlotId, SlotId},
+    PinPolicy, Serial, TouchPolicy, YubiKey,
 };
 
-use crate::{error::Error, p256::Recipient, yubikey::Stub, BINARY_NAME, USABLE_SLOTS};
+use crate::fl;
+use crate::{error::Error, key::Stub, p256::Recipient, BINARY_NAME, USABLE_SLOTS};
 
 pub(crate) const POLICY_EXTENSION_OID: &[u64] = &[1, 3, 6, 1, 4, 1, 41482, 3, 8];
 
@@ -42,24 +43,31 @@ pub(crate) fn touch_policy_from_string(s: String) -> Result<TouchPolicy, Error>
     }
 }
 
-pub(crate) fn pin_policy_to_str(policy: Option<PinPolicy>) -> &'static str {
+pub(crate) fn pin_policy_to_str(policy: Option<PinPolicy>) -> String {
     match policy {
-        Some(PinPolicy::Always) => "Always (A PIN is required for every decryption, if set)",
-        Some(PinPolicy::Once) => "Once   (A PIN is required once per session, if set)",
-        Some(PinPolicy::Never) => "Never  (A PIN is NOT required to decrypt)",
-        _ => "Unknown",
+        Some(PinPolicy::Always) => fl!("pin-policy-always"),
+        Some(PinPolicy::Once) => fl!("pin-policy-once"),
+        Some(PinPolicy::Never) => fl!("pin-policy-never"),
+        _ => fl!("unknown-policy"),
     }
 }
 
-pub(crate) fn touch_policy_to_str(policy: Option<TouchPolicy>) -> &'static str {
+pub(crate) fn touch_policy_to_str(policy: Option<TouchPolicy>) -> String {
     match policy {
-        Some(TouchPolicy::Always) => "Always (A physical touch is required for every decryption)",
-        Some(TouchPolicy::Cached) => {
-            "Cached (A physical touch is required for decryption, and is cached for 15 seconds)"
+        Some(TouchPolicy::Always) => fl!("touch-policy-always"),
+        Some(TouchPolicy::Cached) => fl!("touch-policy-cached"),
+        Some(TouchPolicy::Never) => fl!("touch-policy-never"),
+        _ => fl!("unknown-policy"),
     }
-        Some(TouchPolicy::Never) => "Never  (A physical touch is NOT required to decrypt)",
-        _ => "Unknown",
 }
+
+const MODHEX: &str = "cbdefghijklnrtuv";
+pub(crate) fn otp_serial_prefix(serial: Serial) -> String {
+    iter::repeat(0)
+        .take(4)
+        .chain((0..8).rev().map(|i| (serial.0 >> (4 * i)) & 0x0f))
+        .map(|i| MODHEX.char_indices().nth(i as usize).unwrap().1)
+        .collect()
 }
 
 pub(crate) fn extract_name(cert: &X509Certificate, all: bool) -> Option<(String, bool)> {
@@ -96,8 +104,8 @@ pub(crate) struct Metadata {
     slot: RetiredSlotId,
     name: String,
     created: String,
-    pin_policy: Option<PinPolicy>,
-    touch_policy: Option<TouchPolicy>,
+    pub(crate) pin_policy: Option<PinPolicy>,
+    pub(crate) touch_policy: Option<TouchPolicy>,
 }
 
 impl Metadata {
@@ -111,8 +119,8 @@ impl Metadata {
         // using the same certificate extension as PIV attestations.
         // https://developers.yubico.com/PIV/Introduction/PIV_attestation.html
         let policies = |c: &X509Certificate| {
-            c.extensions()
-                .get(&Oid::from(POLICY_EXTENSION_OID).unwrap())
+            c.tbs_certificate
+                .find_extension(&Oid::from(POLICY_EXTENSION_OID).unwrap())
                 // If the encoded extension doesn't have 2 bytes, we assume it is invalid.
                 .filter(|policy| policy.value.len() >= 2)
                 .map(|policy| {
@@ -138,13 +146,13 @@ impl Metadata {
         extract_name(cert, all)
             .map(|(name, ours)| {
                 if ours {
-                    let (pin_policy, touch_policy) = policies(&cert);
+                    let (pin_policy, touch_policy) = policies(cert);
                     (name, pin_policy, touch_policy)
                 } else {
                     // We can extract the PIN and touch policies via an attestation. This
                     // is slow, but the user has asked for all compatible keys, so...
                     let (pin_policy, touch_policy) =
-                        yubikey_piv::key::attest(yubikey, SlotId::Retired(slot))
+                        yubikey::piv::attest(yubikey, SlotId::Retired(slot))
                             .ok()
                             .and_then(|buf| {
                                 x509_parser::parse_x509_certificate(&buf)
@@ -169,19 +177,19 @@ impl Metadata {
 
 impl fmt::Display for Metadata {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        writeln!(
-            f,
-            "#       Serial: {}, Slot: {}",
-            self.serial,
-            slot_to_ui(&self.slot)
-        )?;
-        writeln!(f, "#         Name: {}", self.name)?;
-        writeln!(f, "#      Created: {}", self.created)?;
-        writeln!(f, "#   PIN policy: {}", pin_policy_to_str(self.pin_policy))?;
         write!(
             f,
-            "# Touch policy: {}",
-            touch_policy_to_str(self.touch_policy)
+            "{}",
+            i18n_embed_fl::fl!(
+                crate::LANGUAGE_LOADER,
+                "yubikey-metadata",
+                serial = self.serial.to_string(),
+                slot = slot_to_ui(&self.slot),
+                name = self.name.as_str(),
+                created = self.created.as_str(),
+                pin_policy = pin_policy_to_str(self.pin_policy),
+                touch_policy = touch_policy_to_str(self.touch_policy),
+            )
         )
     }
 }
@@ -189,10 +197,24 @@ impl fmt::Display for Metadata {
 pub(crate) fn print_identity(stub: Stub, recipient: Recipient, metadata: Metadata) {
     let recipient = recipient.to_string();
     if !console::user_attended() {
-        eprintln!("Recipient: {}", recipient);
+        eprintln!(
+            "{}",
+            i18n_embed_fl::fl!(
+                crate::LANGUAGE_LOADER,
+                "print-recipient",
+                recipient = recipient.as_str(),
+            )
+        );
     }
 
-    println!("{}", metadata);
-    println!("#    Recipient: {}", recipient);
-    println!("{}", stub.to_string());
+    println!(
+        "{}",
+        i18n_embed_fl::fl!(
+            crate::LANGUAGE_LOADER,
+            "yubikey-identity",
+            yubikey_metadata = metadata.to_string(),
+            recipient = recipient,
+            identity = stub.to_string(),
+        )
+    );
 }

src/yubikey.rs

@@ -1,409 +0,0 @@
-//! Structs for handling YubiKeys.
-
-use age_core::{
-    format::{FileKey, FILE_KEY_BYTES},
-    primitives::{aead_decrypt, hkdf},
-};
-use age_plugin::{identity, Callbacks};
-use bech32::{ToBase32, Variant};
-use dialoguer::Password;
-use log::warn;
-use secrecy::ExposeSecret;
-use std::convert::TryInto;
-use std::fmt;
-use std::io;
-use std::iter;
-use std::thread::sleep;
-use std::time::{Duration, SystemTime};
-use yubikey_piv::{
-    certificate::{Certificate, PublicKeyInfo},
-    key::{decrypt_data, AlgorithmId, RetiredSlotId, SlotId},
-    readers::Reader,
-    yubikey::Serial,
-    MgmKey, Readers, YubiKey,
-};
-
-use crate::{
-    error::Error,
-    format::{RecipientLine, STANZA_KEY_LABEL},
-    p256::{Recipient, TAG_BYTES},
-    IDENTITY_PREFIX,
-};
-
-const ONE_SECOND: Duration = Duration::from_secs(1);
-const FIFTEEN_SECONDS: Duration = Duration::from_secs(15);
-
-pub(crate) fn is_connected(reader: Reader) -> bool {
-    filter_connected(&reader)
-}
-
-pub(crate) fn filter_connected(reader: &Reader) -> bool {
-    match reader.open() {
-        Ok(_) => true,
-        Err(e) => {
-            use std::error::Error;
-            if let Some(pcsc::Error::RemovedCard) =
-                e.source().and_then(|inner| inner.downcast_ref())
-            {
-                warn!("Ignoring {}: not connected", reader.name());
-                false
-            } else {
-                true
-            }
-        }
-    }
-}
-
-pub(crate) fn wait_for_readers() -> Result<Readers, Error> {
-    // Start a 15-second timer waiting for a YubiKey to be inserted (if necessary).
-    let start = SystemTime::now();
-    loop {
-        let mut readers = Readers::open()?;
-        if readers.iter()?.any(is_connected) {
-            break Ok(readers);
-        }
-
-        match SystemTime::now().duration_since(start) {
-            Ok(end) if end >= FIFTEEN_SECONDS => return Err(Error::TimedOut),
-            _ => sleep(ONE_SECOND),
-        }
-    }
-}
-
-pub(crate) fn open(serial: Option<Serial>) -> Result<YubiKey, Error> {
-    if !Readers::open()?.iter()?.any(is_connected) {
-        if let Some(serial) = serial {
-            eprintln!("⏳ Please insert the YubiKey with serial {}.", serial);
-        } else {
-            eprintln!("⏳ Please insert the YubiKey.");
-        }
-    }
-    let mut readers = wait_for_readers()?;
-    let mut readers_iter = readers.iter()?.filter(filter_connected);
-
-    // --serial selects the YubiKey to use. If not provided, and more than one YubiKey is
-    // connected, an error is returned.
-    let yubikey = match (readers_iter.next(), readers_iter.next(), serial) {
-        (None, _, _) => unreachable!(),
-        (Some(reader), None, None) => reader.open()?,
-        (Some(reader), None, Some(serial)) => {
-            let yubikey = reader.open()?;
-            if yubikey.serial() != serial {
-                return Err(Error::NoMatchingSerial(serial));
-            }
-            yubikey
-        }
-        (Some(a), Some(b), Some(serial)) => {
-            let reader = iter::empty()
-                .chain(Some(a))
-                .chain(Some(b))
-                .chain(readers_iter)
-                .find(|reader| match reader.open() {
-                    Ok(yk) => yk.serial() == serial,
-                    _ => false,
-                })
-                .ok_or(Error::NoMatchingSerial(serial))?;
-            reader.open()?
-        }
-        (Some(_), Some(_), None) => return Err(Error::MultipleYubiKeys),
-    };
-
-    Ok(yubikey)
-}
-
-pub(crate) fn manage(yubikey: &mut YubiKey) -> Result<(), Error> {
-    eprintln!();
-    let pin = Password::new()
-        .with_prompt(&format!(
-            "Enter PIN for YubiKey with serial {} (default is 123456)",
-            yubikey.serial(),
-        ))
-        .interact()?;
-    yubikey.verify_pin(pin.as_bytes())?;
-
-    // If the user is using the default PIN, help them to change it.
-    if pin == "123456" {
-        eprintln!();
-        eprintln!("✨ Your YubiKey is using the default PIN. Let's change it!");
-        eprintln!("✨ We'll also set the PUK equal to the PIN.");
-        eprintln!();
-        eprintln!("🔐 The PIN is up to 8 numbers, letters, or symbols. Not just numbers!");
-        eprintln!(
-            "❌ Your keys will be lost if the PIN and PUK are locked after 3 incorrect tries."
-        );
-        eprintln!();
-        let current_puk = Password::new()
-            .with_prompt("Enter current PUK (default is 12345678)")
-            .interact()?;
-        let new_pin = Password::new()
-            .with_prompt("Choose a new PIN/PUK")
-            .with_confirmation("Repeat the PIN/PUK", "PINs don't match")
-            .interact()?;
-        if new_pin.len() > 8 {
-            return Err(Error::InvalidPinLength);
-        }
-        yubikey.change_puk(current_puk.as_bytes(), new_pin.as_bytes())?;
-        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)?;
-
-        // Migrate to a PIN-protected management key.
-        let mgm_key = MgmKey::generate()?;
-        eprintln!();
-        eprintln!("✨ Your YubiKey is using the default management key.");
-        eprintln!("✨ We'll migrate it to a PIN-protected management key.");
-        eprint!("... ");
-        mgm_key.set_protected(yubikey).map_err(|e| {
-            eprintln!("An error occurred while setting the new management key.");
-            eprintln!("⚠️ SAVE THIS MANAGEMENT KEY - YOU MAY NEED IT TO MANAGE YOUR YubiKey! ⚠️");
-            eprintln!("  {}", hex::encode(mgm_key.as_ref()));
-            e
-        })?;
-        eprintln!("Success!");
-    }
-
-    Ok(())
-}
-
-/// A reference to an age key stored in a YubiKey.
-#[derive(Debug)]
-pub struct Stub {
-    pub(crate) serial: Serial,
-    pub(crate) slot: RetiredSlotId,
-    pub(crate) tag: [u8; TAG_BYTES],
-    identity_index: usize,
-}
-
-impl fmt::Display for Stub {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.write_str(
-            bech32::encode(
-                IDENTITY_PREFIX,
-                self.to_bytes().to_base32(),
-                Variant::Bech32,
-            )
-            .expect("HRP is valid")
-            .to_uppercase()
-            .as_str(),
-        )
-    }
-}
-
-impl PartialEq for Stub {
-    fn eq(&self, other: &Self) -> bool {
-        self.to_bytes().eq(&other.to_bytes())
-    }
-}
-
-impl Stub {
-    /// Returns a key stub and recipient for this `(Serial, SlotId, PublicKey)` tuple.
-    ///
-    /// Does not check that the `PublicKey` matches the given `(Serial, SlotId)` tuple;
-    /// this is checked at decryption time.
-    pub(crate) fn new(serial: Serial, slot: RetiredSlotId, recipient: &Recipient) -> Self {
-        Stub {
-            serial,
-            slot,
-            tag: recipient.tag(),
-            identity_index: 0,
-        }
-    }
-
-    pub(crate) fn from_bytes(bytes: &[u8], identity_index: usize) -> Option<Self> {
-        let serial = Serial::from(u32::from_le_bytes(bytes[0..4].try_into().unwrap()));
-        let slot: RetiredSlotId = bytes[4].try_into().ok()?;
-        Some(Stub {
-            serial,
-            slot,
-            tag: bytes[5..9].try_into().unwrap(),
-            identity_index,
-        })
-    }
-
-    fn to_bytes(&self) -> Vec<u8> {
-        let mut bytes = Vec::with_capacity(9);
-        bytes.extend_from_slice(&self.serial.0.to_le_bytes());
-        bytes.push(self.slot.into());
-        bytes.extend_from_slice(&self.tag);
-        bytes
-    }
-
-    pub(crate) fn matches(&self, line: &RecipientLine) -> bool {
-        self.tag == line.tag
-    }
-
-    pub(crate) fn connect<E>(
-        &self,
-        callbacks: &mut dyn Callbacks<E>,
-    ) -> io::Result<Result<Connection, identity::Error>> {
-        let mut yubikey = match YubiKey::open_by_serial(self.serial) {
-            Ok(yk) => yk,
-            Err(yubikey_piv::Error::NotFound) => {
-                if callbacks
-                    .message(&format!(
-                        "Please insert YubiKey with serial {}",
-                        self.serial
-                    ))?
-                    .is_err()
-                {
-                    return Ok(Err(identity::Error::Identity {
-                        index: self.identity_index,
-                        message: format!("Could not find YubiKey with serial {}", self.serial),
-                    }));
-                }
-
-                // Start a 15-second timer waiting for the YubiKey to be inserted
-                let start = SystemTime::now();
-                loop {
-                    match YubiKey::open_by_serial(self.serial) {
-                        Ok(yubikey) => break yubikey,
-                        Err(yubikey_piv::Error::NotFound) => (),
-                        Err(_) => {
-                            return Ok(Err(identity::Error::Identity {
-                                index: self.identity_index,
-                                message: format!(
-                                    "Could not open YubiKey with serial {}",
-                                    self.serial
-                                ),
-                            }));
-                        }
-                    }
-
-                    match SystemTime::now().duration_since(start) {
-                        Ok(end) if end >= FIFTEEN_SECONDS => {
-                            return Ok(Err(identity::Error::Identity {
-                                index: self.identity_index,
-                                message: format!(
-                                "Timed out while waiting for YubiKey with serial {} to be inserted",
-                                self.serial
-                            ),
-                            }))
-                        }
-                        _ => sleep(ONE_SECOND),
-                    }
-                }
-            }
-            Err(_) => {
-                return Ok(Err(identity::Error::Identity {
-                    index: self.identity_index,
-                    message: format!("Could not open YubiKey with serial {}", self.serial),
-                }))
-            }
-        };
-
-        // Read the pubkey from the YubiKey slot and check it still matches.
-        let pk = match Certificate::read(&mut yubikey, SlotId::Retired(self.slot))
-            .ok()
-            .and_then(|cert| match cert.subject_pki() {
-                PublicKeyInfo::EcP256(pubkey) => {
-                    Recipient::from_encoded(pubkey).filter(|pk| pk.tag() == self.tag)
-                }
-                _ => None,
-            }) {
-            Some(pk) => pk,
-            None => {
-                return Ok(Err(identity::Error::Identity {
-                    index: self.identity_index,
-                    message: "A YubiKey stub did not match the YubiKey".to_owned(),
-                }))
-            }
-        };
-
-        let pin = match callbacks.request_secret(&format!(
-            "Enter PIN for YubiKey with serial {}",
-            self.serial
-        ))? {
-            Ok(pin) => pin,
-            Err(_) => {
-                return Ok(Err(identity::Error::Identity {
-                    index: self.identity_index,
-                    message: format!("A PIN is required for YubiKey with serial {}", self.serial),
-                }))
-            }
-        };
-        if yubikey.verify_pin(pin.expose_secret().as_bytes()).is_err() {
-            return Ok(Err(identity::Error::Identity {
-                index: self.identity_index,
-                message: "Invalid YubiKey PIN".to_owned(),
-            }));
-        }
-
-        Ok(Ok(Connection {
-            yubikey,
-            pk,
-            slot: self.slot,
-            tag: self.tag,
-        }))
-    }
-}
-
-pub(crate) struct Connection {
-    yubikey: YubiKey,
-    pk: Recipient,
-    slot: RetiredSlotId,
-    tag: [u8; 4],
-}
-
-impl Connection {
-    pub(crate) fn recipient(&self) -> &Recipient {
-        &self.pk
-    }
-
-    pub(crate) fn unwrap_file_key(&mut self, line: &RecipientLine) -> Result<FileKey, ()> {
-        assert_eq!(self.tag, line.tag);
-
-        // The YubiKey API for performing scalar multiplication takes the point in its
-        // uncompressed SEC-1 encoding.
-        let shared_secret = match decrypt_data(
-            &mut self.yubikey,
-            line.epk_bytes.decompress().as_bytes(),
-            AlgorithmId::EccP256,
-            SlotId::Retired(self.slot),
-        ) {
-            Ok(res) => res,
-            Err(_) => return Err(()),
-        };
-
-        let mut salt = vec![];
-        salt.extend_from_slice(line.epk_bytes.as_bytes());
-        salt.extend_from_slice(self.pk.to_encoded().as_bytes());
-
-        let enc_key = hkdf(&salt, STANZA_KEY_LABEL, shared_secret.as_ref());
-
-        // A failure to decrypt is fatal, because we assume that we won't
-        // encounter 32-bit collisions on the key tag embedded in the header.
-        match aead_decrypt(&enc_key, FILE_KEY_BYTES, &line.encrypted_file_key) {
-            Ok(pt) => Ok(TryInto::<[u8; FILE_KEY_BYTES]>::try_into(&pt[..])
-                .unwrap()
-                .into()),
-            Err(_) => Err(()),
-        }
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use yubikey_piv::{key::RetiredSlotId, Serial};
-
-    use super::Stub;
-
-    #[test]
-    fn stub_round_trip() {
-        let stub = Stub {
-            serial: Serial::from(42),
-            slot: RetiredSlotId::R1,
-            tag: [7; 4],
-            identity_index: 0,
-        };
-
-        let encoded = stub.to_bytes();
-        assert_eq!(Stub::from_bytes(&encoded, 0), Some(stub));
-    }
-}