Simplify instructions, reduce manual labor

1 files changed, 548 insertions, 1137 deletions

diff --git a/README.md b/README.md
index cabc443..7b39954 100644
--- a/README.md
+++ b/README.md
@@ -4,91 +4,72 @@ Keys stored on YubiKey are [non-exportable](https://web.archive.org/web/20201125
 
 **Important** If you followed this guide before Jan 2021, *PIN* and *Admin PIN* may be set to default values of `123456` and `12345678`. See [Change PIN](#change-pin) to change PINs.
 
-To suggest an improvement, please send a pull request or open an [issue](https://github.com/drduh/YubiKey-Guide/issues).
+To suggest an improvement, send a pull request or open an [issue](https://github.com/drduh/YubiKey-Guide/issues).
 
-**Tip** [drduh/Purse](https://github.com/drduh/Purse) is a password manager which uses GnuPG and YubiKey to securely store and use credentials.
+**Tip** [drduh/Purse](https://github.com/drduh/Purse) is a password manager based on GnuPG and YubiKey to securely store and use credentials.
 
-- [Purchase](#purchase)
+- [Purchase YubiKey](#purchase-yubikey)
 - [Prepare environment](#prepare-environment)
-- [Required software](#required-software)
-   * [Debian and Ubuntu](#debian-and-ubuntu)
-   * [Fedora](#fedora)
-   * [Arch](#arch)
-   * [RHEL7](#rhel7)
-   * [NixOS](#nixos)
-   * [OpenBSD](#openbsd)
-   * [macOS](#macos)
-   * [Windows](#windows)
-- [Entropy](#entropy)
-   * [OneRNG](#onerng)
-- [Generate keys](#generate-keys)
-   * [Temporary working directory](#temporary-working-directory)
-   * [Hardened configuration](#hardened-configuration)
-- [Certify key](#certify-key)
-- [Subkeys](#subkeys)
-   * [Signature key](#signature-key)
-   * [Encryption key](#encryption-key)
-   * [Authentication key](#authentication-key)
-- [Verify](#verify)
-- [Export secret keys](#export-secret-keys)
-- [Revocation certificate](#revocation-certificate)
-- [Backup](#backup)
+   * [Improving entropy](#improving-entropy)
+- [Install software](#install-software)
+- [Prepare GnuPG](#prepare-gnupg)
+   * [Configuration](#configuration)
+   * [Identity](#identity)
+   * [Expiration](#expiration)
+   * [Passphrase](#passphrase)
+- [Create Certify key](#create-certify-key)
+- [Create Subkeys](#create-subkeys)
+- [Verify keys](#verify-keys)
+- [Backup private keys](#backup-private-keys)
 - [Export public key](#export-public-key)
 - [Configure YubiKey](#configure-yubikey)
    * [Enable KDF](#enable-kdf)
    * [Change PIN](#change-pin)
    * [Set information](#set-information)
-- [Transfer keys](#transfer-keys)
-   * [Signature key](#signature-key-1)
-   * [Encryption key](#encryption-key-1)
-   * [Authentication key](#authentication-key-1)
+- [Transfer Subkeys](#transfer-subkeys)
+   * [Signature key](#signature-key)
+   * [Encryption key](#encryption-key)
+   * [Authentication key](#authentication-key)
 - [Verify transfer](#verify-transfer)
-- [Multiple YubiKeys](#multiple-yubikeys)
-   * [Switching between YubiKeys](#switching-between-yubikeys)
-- [Finish](#finish)
-- [Using keys](#using-keys)
-- [Rotating keys](#rotating-keys)
-   * [Setup environment](#setup-environment)
-   * [Renewing Subkeys](#renewing-subkeys)
-   * [Rotating keys](#rotating-keys-1)
-- [Adding notations](#adding-notations)
-- [SSH](#ssh)
-   * [Create configuration](#create-configuration)
-   * [Replace agents](#replace-agents)
-   * [Copy public key](#copy-public-key)
-   * [(Optional) Save public key for identity file configuration](#optional-save-public-key-for-identity-file-configuration)
-   * [Connect with public key authentication](#connect-with-public-key-authentication)
-   * [Import SSH keys](#import-ssh-keys)
-   * [Remote Machines (SSH Agent Forwarding)](#remote-machines-ssh-agent-forwarding)
-      + [Use ssh-agent ](#use-ssh-agent)
-      + [Use S.gpg-agent.ssh](#use-sgpg-agentssh)
-      + [Chained SSH agent forwarding](#chained-ssh-agent-forwarding)
+- [Finish setup](#finish-setup)
+- [Using YubiKey](#using-yubikey)
+   * [Encryption](#encryption)
+   * [Signature](#signature)
+   * [Configure touch](#configure-touch)
+   * [SSH](#ssh)
+      + [Replace agents](#replace-agents)
+      + [Copy public key](#copy-public-key)
+      + [Import SSH keys](#import-ssh-keys)
+      + [SSH agent forwarding](#ssh-agent-forwarding)
+         - [Use ssh-agent](#use-ssh-agent)
+         - [Use S.gpg-agent.ssh](#use-sgpg-agentssh)
+         - [Chained forwarding](#chained-forwarding)
    * [GitHub](#github)
-   * [OpenBSD](#openbsd-1)
-   * [Windows](#windows-1)
-      + [WSL](#wsl)
-   * [macOS](#macos-1)
-- [Remote Machines (GPG Agent Forwarding)](#remote-machines-gpg-agent-forwarding)
-   * [Steps for older distributions](#steps-for-older-distributions)
-   * [Chained GnuPG agent forwarding](#chained-gnupg-agent-forwarding)
-- [Using Multiple Keys](#using-multiple-keys)
-- [Adding an identity](#adding-an-identity)
-   * [Updating YubiKey](#updating-yubikey)
-- [Require touch](#require-touch)
-- [Email](#email)
-   * [Mailvelope](#mailvelope)
-   * [Mutt](#mutt)
-- [Reset](#reset)
-   * [Recovery after reset](#recovery-after-reset)
+   * [GnuPG agent forwarding](#gnupg-agent-forwarding)
+      + [Legacy distributions](#legacy-distributions)
+      + [Chained GnuPG agent forwarding](#chained-gnupg-agent-forwarding)
+   * [Using multiple YubiKeys](#using-multiple-yubikeys)
+   * [Email](#email)
+      + [Mailvelope](#mailvelope)
+      + [Mutt](#mutt)
+- [Updating keys](#updating-keys)
+   * [Renew Subkeys](#renew-subkeys)
+   * [Rotate Subkeys](#rotate-subkeys)
+- [Reset YubiKey](#reset-yubikey)
 - [Notes](#notes)
 - [Troubleshooting](#troubleshooting)
-- [Alternatives](#alternatives)
-   * [Create keys with batch](#create-keys-with-batch)
+- [Alternative solutions](#alternative-solutions)
 - [Additional resources](#additional-resources)
 
-# Purchase
+# Purchase YubiKey
+
+All YubiKeys except the blue "security key" model and the "Bio Series - FIDO Edition" are compatible with this guide. NEO models are limited to 2048-bit RSA keys.
 
-All YubiKeys except the blue "security key" model and the "Bio Series - FIDO Edition" are compatible with this guide. NEO models are limited to 2048-bit RSA keys. Compare YubiKeys [here](https://www.yubico.com/products/yubikey-hardware/compare-products-series/). A list of the YubiKeys compatible with OpenPGP is available [here](https://support.yubico.com/hc/en-us/articles/360013790259-Using-Your-YubiKey-with-OpenPGP). In May 2021, Yubico also released a press release and blog post about supporting resident ssh keys on their YubiKeys including blue "security key 5 NFC" with OpenSSH 8.2 or later, see [here](https://www.yubico.com/blog/github-now-supports-ssh-security-keys/) for more information.
+Compare YubiKeys [here](https://www.yubico.com/products/yubikey-hardware/compare-products-series/).
+
+ A list of the YubiKeys compatible with OpenPGP is available [here](https://support.yubico.com/hc/en-us/articles/360013790259-Using-Your-YubiKey-with-OpenPGP).
+
+In May 2021, Yubico also released a press release and blog post about supporting resident SSH keys on YubiKey, including blue "security key 5 NFC" with OpenSSH 8.2 or later, see [here](https://www.yubico.com/blog/github-now-supports-ssh-security-keys/) for more information.
 
 To [verify a YubiKey](https://support.yubico.com/hc/en-us/articles/360013723419-How-to-Confirm-Your-Yubico-Device-is-Genuine), visit [yubico.com/genuine](https://www.yubico.com/genuine/). Insert a Yubico device, and select *Verify Device* to begin the process. Touch the YubiKey when prompted, and if asked, allow the site to see the make and model of the device. This device attestation may help mitigate [supply chain attacks](https://media.defcon.org/DEF%20CON%2025/DEF%20CON%2025%20presentations/DEF%20CON%2025%20-%20r00killah-and-securelyfitz-Secure-Tokin-and-Doobiekeys.pdf).
 
@@ -96,18 +77,18 @@ Several portable storage devices (such as microSD cards) for storing encrypted b
 
 # Prepare environment
 
-To generate cryptographic keys, creating a dedicated secure environment is recommended.
+A dedicated, secure operating environment is recommended to generate cryptographic keys.
 
-The following is a general ranking of environments most to least likely to be compromised:
+The following is a general ranking of environments least to most hospitable to generating materials:
 
-1. Daily-use system with unrestricted network access
-1. Virtual machine on daily-use host OS (using [virt-manager](https://virt-manager.org/), VirtualBox or VMware)
-1. Dedicated and hardened [Debian](https://www.debian.org/) or [OpenBSD](https://www.openbsd.org/) system
-1. Live image, such as [Debian Live](https://www.debian.org/CD/live/) or [Tails](https://tails.boum.org/index.en.html)
+1. Daily, currently in use operating system with unrestricted network access
+1. Virtualized operating system with limited capabilities (using [virt-manager](https://virt-manager.org/), VirtualBox or VMware, for example)
+1. Dedicated and hardened [Debian](https://www.debian.org/) or [OpenBSD](https://www.openbsd.org/) installation
+1. Ephemeral [Debian Live](https://www.debian.org/CD/live/) or [Tails](https://tails.boum.org/index.en.html) booted without primary storage attached
 1. Hardened hardware and firmware ([Coreboot](https://www.coreboot.org/), [Intel ME removed](https://github.com/corna/me_cleaner))
-1. Dedicated air-gapped system without network capabilities (ARM-based Raspberry Pi or other architecturally diverse equivalent)
+1. Air-gapped system without network capabilities, preferably ARM-based Raspberry Pi or other architecturally diverse equivalent
 
-A Debian Linux live image is recommended to balance usability and security.
+Debian Live is used in this guide to balance usability and security, with some additional instructions for OpenBSD.
 
 Download the latest image and signature files:
 
@@ -185,41 +166,69 @@ $ doas dd if=debian-live-*-amd64-xfce.iso of=/dev/rsd2c bs=4m
 
 Power off, then disconnect internal hard drives and all unnecessary devices, such as the wireless card.
 
-# Required software
+## Improving entropy
 
-Boot the live image and configure networking.
+Generating cryptographic keys requires high-quality [randomness](https://www.random.org/randomness/), measured as entropy.
 
-**Note** If the screen locks, unlock with `user` / `live`
+Most operating systems use software-based pseudorandom number generators or CPU-based hardware random number generators (HRNG).
 
-Open terminal and install required software packages.
+Optionally, a device such as [OneRNG](https://onerng.info/onerng/) may be used to [increase the speed](https://lwn.net/Articles/648550/) and possibly the quality of available entropy.
 
-## Debian and Ubuntu
+Configure [rng-tools](https://wiki.archlinux.org/title/Rng-tools):
 
 ```console
-sudo apt update
-
-sudo apt -y upgrade
+sudo apt -y install at rng-tools python3-gnupg openssl
 
-sudo apt -y install \
-    wget gnupg2 gnupg-agent dirmngr \
-    cryptsetup scdaemon pcscd secure-delete \
-    yubikey-personalization
+wget https://github.com/OneRNG/onerng.github.io/raw/master/sw/onerng_3.7-1_all.deb
 ```
 
-**Note** `hopenpgp-tools` is no longer part of the latest Debian stable package repositories. To install it, go to [https://packages.debian.org/sid/hopenpgp-tools](https://packages.debian.org/sid/hopenpgp-tools) to select the correct architecture (likely `amd64`) and then an ftp server.
+Verify the package:
+
+```console
+sha256sum onerng_3.7-1_all.deb
+```
 
-Edit `/etc/apt/sources.list` and add the ftp server:
+The value must match:
 
+```console
+b7cda2fe07dce219a95dfeabeb5ee0f662f64ba1474f6b9dddacc3e8734d8f57
 ```
-deb http://ftp.debian.org/debian sid main
+
+Install the package:
+
+```console
+sudo dpkg -i onerng_3.7-1_all.deb
+
+echo "HRNGDEVICE=/dev/ttyACM0" | sudo tee /etc/default/rng-tools
 ```
 
-Then add this to `/etc/apt/preferences` (or a fragment, e.g. `/etc/apt/preferences.d/00-sid`) so that APT still prioritizes packages from the stable repository over sid.
+Insert the device and restart rng-tools:
 
+```console
+sudo atd
+
+sudo service rng-tools restart
 ```
-Package: *
-Pin: release n=sid
-Pin-Priority: 10
+
+# Install software
+
+Load the operating system and configure networking.
+
+**Note** If the screen locks on Debian Live, unlock with `user` / `live`
+
+Open terminal and install required software packages.
+
+**Debian/Ubuntu**
+
+```console
+sudo apt update
+
+sudo apt -y upgrade
+
+sudo apt -y install \
+    wget gnupg2 gnupg-agent dirmngr \
+    cryptsetup scdaemon pcscd \
+    yubikey-personalization
 ```
 
 **Note** Live Ubuntu images [may require modification](https://github.com/drduh/YubiKey-Guide/issues/116) to `/etc/apt/sources.list` and may need additional packages:
@@ -242,47 +251,38 @@ sudo service pcscd start
 ~/.local/bin/ykman openpgp info
 ```
 
-**Note** Debian 12 does not recommend installing non-Debian packaged Python applications globally. But fortunately, it is not necessary as `yubikey-manager` is available in the stable main repository:
+**Note** Debian does not recommend installing non-Debian packaged Python applications globally. But fortunately, it is not necessary as `yubikey-manager` is available in the stable main repository:
 
 ```console
-sudo apt install yubikey-manager
+sudo apt install -y yubikey-manager
 ```
 
-## Fedora
+**OpenBSD**
 
 ```console
-sudo dnf install wget
-
-wget https://github.com/rpmsphere/noarch/raw/master/r/rpmsphere-release-38-1.noarch.rpm
-
-sudo rpm -Uvh rpmsphere-release*rpm
-
-sudo dnf install \
-    gnupg2 dirmngr cryptsetup gnupg2-smime \
-    pcsc-tools opensc pcsc-lite secure-delete \
-    pgp-tools yubikey-personalization-gui
+doas pkg_add gnupg pcsc-tools
 ```
 
-## Arch
+**macOS**
 
-```console
-sudo pacman -Syu gnupg pcsclite ccid hopenpgp-tools yubikey-personalization
-```
-
-## RHEL7
+Download and install [Homebrew](https://brew.sh/) and the following packages:
 
 ```console
-sudo yum install -y gnupg2 pinentry-curses pcsc-lite pcsc-lite-libs gnupg2-smime
+brew install \
+  gnupg yubikey-personalization ykman pinentry-mac wget
 ```
 
-## NixOS
+**Note** An additional Python package dependency may need to be installed to use [`ykman`](https://support.yubico.com/support/solutions/articles/15000012643-yubikey-manager-cli-ykman-user-guide) - `pip install yubikey-manager`
+
+**NixOS**
 
 Build an air-gapped NixOS LiveCD image:
 
 ```console
 ref=$(git ls-remote https://github.com/drduh/Yubikey-Guide refs/heads/master | awk '{print $1}')
 
-nix build --experimental-features "nix-command flakes" github:drduh/YubiKey-Guide/$ref#nixosConfigurations.yubikeyLive.x86_64-linux.config.system.build.isoImage
+nix build --experimental-features "nix-command flakes" \
+  github:drduh/YubiKey-Guide/$ref#nixosConfigurations.yubikeyLive.x86_64-linux.config.system.build.isoImage
 ```
 
 If you have this repository checked out:
@@ -293,7 +293,7 @@ Recommended, but optional: update `nixpkgs` and `drduh/config`:
 nix flake update --commit-lock-file
 ```
 
-Build the ISO:
+Build the image:
 
 ```console
 nix build --experimental-features "nix-command flakes" .#nixosConfigurations.yubikeyLive.x86_64-linux.config.system.build.isoImage
@@ -305,87 +305,51 @@ Copy it to a USB drive:
 sudo cp -v result/iso/yubikeyLive.iso /dev/sdb ; sync
 ```
 
-With this image, you won't need to create a [temporary working directory](#temporary-working-directory) or [harden the configuration](#hardened-configuration), as it was done when creating the image.
+Skip steps to create a temporary working directory and a hardened configuration, as they are already part of the image.
 
-## OpenBSD
+**Arch**
 
 ```console
-doas pkg_add gnupg pcsc-tools
+sudo pacman -Syu gnupg pcsclite ccid yubikey-personalization
 ```
 
-## macOS
-
-Download and install [Homebrew](https://brew.sh/) and the following packages:
+**RHEL7**
 
 ```console
-brew install gnupg yubikey-personalization hopenpgp-tools ykman pinentry-mac wget
-```
-
-**Note** An additional Python package dependency may need to be installed to use [`ykman`](https://support.yubico.com/support/solutions/articles/15000012643-yubikey-manager-cli-ykman-user-guide) - `pip install yubikey-manager`
-
-## Windows
-
-Download and install [Gpg4Win](https://www.gpg4win.org/) and [PuTTY](https://putty.org).
-
-You may also need more recent versions of [yubikey-personalization](https://developers.yubico.com/yubikey-personalization/Releases/) and [yubico-c](https://developers.yubico.com/yubico-c/Releases/).
-
-# Entropy
-
-Generating cryptographic keys requires high-quality [randomness](https://www.random.org/randomness/), measured as entropy.
-
-Most operating systems use software-based pseudorandom number generators or CPU-based hardware random number generators (HRNG).
-
-**Optional** A device such as [OneRNG](https://onerng.info/onerng/) may be used to [increase the speed](https://lwn.net/Articles/648550/) and possibly the quality of available entropy.
-
-## OneRNG
-
-Configure [rng-tools](https://wiki.archlinux.org/title/Rng-tools):
-
-```console
-sudo apt -y install at rng-tools python3-gnupg openssl
-
-wget https://github.com/OneRNG/onerng.github.io/raw/master/sw/onerng_3.7-1_all.deb
-```
-
-Verify the package:
-
-```console
-$ sha256sum onerng_3.7-1_all.deb
-b7cda2fe07dce219a95dfeabeb5ee0f662f64ba1474f6b9dddacc3e8734d8f57  onerng_3.7-1_all.deb
+sudo yum install -y gnupg2 pinentry-curses pcsc-lite pcsc-lite-libs gnupg2-smime
 ```
 
-Install the package:
+**Fedora**
 
 ```console
-sudo dpkg -i onerng_3.7-1_all.deb
-
-echo "HRNGDEVICE=/dev/ttyACM0" | sudo tee /etc/default/rng-tools
-```
+sudo dnf install wget
 
-Insert the device and restart rng-tools:
+wget https://github.com/rpmsphere/noarch/raw/master/r/rpmsphere-release-38-1.noarch.rpm
 
-```console
-sudo atd
+sudo rpm -Uvh rpmsphere-release*rpm
 
-sudo service rng-tools restart
+sudo dnf install \
+    gnupg2 dirmngr cryptsetup gnupg2-smime \
+    pcsc-tools opensc pcsc-lite secure-delete \
+    pgp-tools yubikey-personalization-gui
 ```
 
-# Generate keys
-
-## Temporary working directory
+# Prepare GnuPG
 
 Create a temporary directory which will be cleared on [reboot](https://en.wikipedia.org/wiki/Tmpfs) and set it as the GnuPG directory:
 
 ```console
-export GNUPGHOME=$(mktemp -d -t gnupg_$(date +%Y%m%d%H%M)_XXX)
+GNUPGHOME=$(mktemp -d -t gnupg-$(date +%Y-%m-%d)-XXXXXXXXXX)
 ```
 
-## Hardened configuration
+## Configuration
 
-Import or create a hardened configuration for GnuPG:
+Import or create a [hardened configuration](https://github.com/drduh/config/blob/master/gpg.conf):
 
 ```console
-wget -O $GNUPGHOME/gpg.conf https://raw.githubusercontent.com/drduh/config/master/gpg.conf
+cd $GNUPGHOME
+
+wget https://raw.githubusercontent.com/drduh/config/master/gpg.conf
 ```
 
 The options will look similar to:
@@ -414,407 +378,110 @@ use-agent
 throw-keyids
 ```
 
-**Tip** Networking can be disabled for the remainder of the setup.
-
-# Certify key
-
-The primary key to generate is the Certify key, which will be used to issue Subkeys for encryption, signature and authentication operations.
+**Note** Networking can be disabled for the remainder of the setup.
 
-The Certify key should be kept offline at all times and only accessed from a secure environment to revoke or issue Subkeys. Keys can also be generated on the YubiKey itself to avoid duplication, however for usability and durability reasons this guide recommends against doing so.
+## Identity
 
-Generate a passphrase which will be needed throughout the guide to create Subkeys. The passphrase should be memorized or written down in a secure location, ideally separate from the portable storage device used for key material.
+When creating an identity with GnuPG, the default options ask for a "Real name", "Email address" and optional "Comment".
 
-The passphrase is recommended to consist of only upper case letters and numbers for improved readability.
-
-The following command will generate strong passphrases while avoiding ambiguous characters:
+Depending on how you plan to use GnuPG, set these values respectively:
 
 ```console
-LC_ALL=C tr -dc 'A-Z1-9' < /dev/urandom | \
-    tr -d "1IOS5U" | fold -w 30 | head -n10 | \
-    sed "-es/./ /"{1..26..5} | cut -c2- | tr " " "-"
+IDENTITY="YubiKey User <yubikey@example>"
 ```
 
-Example output:
+Or use any attribute which will uniquely identity the key:
 
 ```console
-A4ZK-YRRJ-8WPM-82NY-CX9T-AGKT
-PH9Z-HFDX-QDB9-YMMC-GQZB-Z3EV
-EC3H-C42G-8E9K-VF7F-ZWT7-BTL6
-B3CA-QCCE-JMNE-VAZG-ZEYD-J3XP
-YKP4-M42X-4WWE-WEKR-C3J7-GZYF
-ZQWC-E7MN-M7CT-4Y4Z-9QFV-44VY
-KY4F-C83Q-BTYQ-V8EM-WGCR-DPZN
-GYWQ-WNAC-ERWM-XGAD-6XVD-ZCLD
-L8JL-EK8H-Z4ZF-MA93-NND8-FPKA
-WM2J-XF7L-QV6D-AWLY-Y2D8-4TQQ
+IDENTITY="My Cool YubiKey - 2024"
 ```
 
-**Tip** On Linux or OpenBSD, select the passphrase using the mouse or by double-clicking on it to copy to clipboard. Paste using the middle mouse button or `Shift`-`Insert`
-
-Generate the Certify key with GnuPG:
-
-```console
-gpg --expert --full-generate-key
-```
-
-Select `(8) RSA (set your own capabilities)`, then type `E` and `S` to deselect **Encrypt** and **Sign** actions, so the only **Current allowed actions** remaining is **Certify**:
-
-```console
-Please select what kind of key you want:
-   (1) RSA and RSA (default)
-   (2) DSA and Elgamal
-   (3) DSA (sign only)
-   (4) RSA (sign only)
-   (7) DSA (set your own capabilities)
-   (8) RSA (set your own capabilities)
-   (9) ECC and ECC
-  (10) ECC (sign only)
-  (11) ECC (set your own capabilities)
-  (13) Existing key
-  (14) Existing key from card
-Your selection? 8
+## Expiration
 
-Possible actions for a RSA key: Sign Certify Encrypt Authenticate
-Current allowed actions: Sign Certify Encrypt
+Determine the desired Subkey validity duration.
 
-   (S) Toggle the sign capability
-   (E) Toggle the encrypt capability
-   (A) Toggle the authenticate capability
-   (Q) Finished
+Setting a key expiry forces identity and credential lifecycle management. However, setting an expiry on the primary Certify key is pointless, because it can be used to simply extend itself ([revocation certificates](https://security.stackexchange.com/questions/14718/does-openpgp-key-expiration-add-to-security/79386#79386) should be used instead).
 
-Your selection? E
+This guide recommends a two year expiration for Subkeys to balance security and usability, however longer durations are possible to reduce maintenance frequency.
 
-Possible actions for a RSA key: Sign Certify Encrypt Authenticate
-Current allowed actions: Sign Certify
+When Subkeys expire, they may still be used to decrypt with GnuPG and authenticate with SSH, however they can **not** be used to encrypt nor sign new messages.
 
-   (S) Toggle the sign capability
-   (E) Toggle the encrypt capability
-   (A) Toggle the authenticate capability
-   (Q) Finished
+Subkeys must be renewed or rotated using the Certify key - see [Updating Subkeys](#updating-subkeys).
 
-Your selection? S
-
-Possible actions for a RSA key: Sign Certify Encrypt Authenticate
-Current allowed actions: Certify
-
-   (S) Toggle the sign capability
-   (E) Toggle the encrypt capability
-   (A) Toggle the authenticate capability
-   (Q) Finished
-```
-
-Type `Q` then `4096` as the requested keysize:
+Set the expiration date to two years:
 
 ```console
-Your selection? Q
-RSA keys may be between 1024 and 4096 bits long.
-What keysize do you want? (2048) 4096
-Requested keysize is 4096 bits
+EXPIRATION=2y
 ```
 
-Type `0` for key validity - there is no reason to expire the Certify key (see [Note #3](#notes)) - then type `y` to confirm.
+Or set the expiration date to a specific date to schedule maintenace:
 
 ```console
-Please specify how long the key should be valid.
-         0 = key does not expire
-      <n>  = key expires in n days
-      <n>w = key expires in n weeks
-      <n>m = key expires in n months
-      <n>y = key expires in n years
-Key is valid for? (0) 0
-Key does not expire at all
-Is this correct? (y/N) y
+EXPIRATION=2026-05-01
 ```
 
-Input any value for **Real name** and **Email address**; **Comment** is optional, then type `O` to confirm:
-
-```console
-GnuPG needs to construct a user ID to identify your key.
-
-Real name: YubiKey User
-Email address: yubikey@example
-Comment:
-You selected this USER-ID:
-    "YubiKey User <yubikey@example>"
+## Passphrase
 
-Change (N)ame, (C)omment, (E)mail or (O)kay/(Q)uit? O
-We need to generate a lot of random bytes. It is a good idea to perform
-some other action (type on the keyboard, move the mouse, utilize the
-disks) during the prime generation; this gives the random number
-generator a better chance to gain enough entropy.
-gpg: /tmp/gnupg_202401011200_TnL/trustdb.gpg: trustdb created
-gpg: directory '/tmp/gnupg_202401011200_TnL/openpgp-revocs.d' created
-gpg: revocation certificate stored as '/tmp/gnupg_202401011200_TnL/openpgp-revocs.d/4E2C1FA3372CBA96A06AC34AF0F2CFEB04341FB5.rev'
-public and secret key created and signed.
+Generate a passphrase, which will be used to issue the Certify key and Subkeys.
 
-pub   rsa4096/0xF0F2CFEB04341FB5 2024-01-01 [C]
-      Key fingerprint = 4E2C 1FA3 372C BA96 A06A  C34A F0F2 CFEB 0434 1FB5
-uid                              YubiKey User <yubikey@example>
-```
-
-Export the Certify key identifier beginning with `0x` as `KEYID` with the following command or by pasting the value manually:
-
-```console
-export KEYID=$(gpg -K | grep -Po "(0x\w+)")
-```
+The passphrase is recommended to consist of only upper case letters and numbers for improved readability. A strong diceware passphrase can also provide equivalent protection.
 
-**Optional** Existing keys may be used to sign new ones to prove ownership. Export the existing key to the working keyring and sign the new key:
+The following command will generate a strong 30-character passphrase while avoiding ambiguous characters:
 
 ```console
-gpg --export-secret-keys --armor --output /tmp/new.sec
-
-gpg --default-key $OLDKEY --sign-key $KEYID
+PASS=$(LC_ALL=C tr -dc 'A-Z1-9' < /dev/urandom | \
+  tr -d "1IOS5U" | fold -w 30 | sed "-es/./ /"{1..26..5} | \
+  cut -c2- | tr " " "-" | head -1)
 ```
 
-# Subkeys
-
-Edit the identity to add Subkeys:
+Display the password, then memorize or write it in a secure location, ideally separate from the portable storage device used for key material:
 
 ```console
-gpg --expert --edit-key $KEYID
+echo $PASS
 ```
 
-RSA with 4096-bit key length is recommended.
+This repository includes a [`passphrase.html`](passphrase.html) file which can be printed and filled out by hand to assist with passphrase transcription.
 
-Subkeys are recommended to have one or several year expirations. They must be renewed or replaced using the Certify key - see [Rotating keys](#rotating-keys).
-
-## Signature key
-
-Generate a Signature key by typing `addkey` then `4` to select the `(4) RSA (sign only)` option:
-
-```console
-gpg> addkey
-Please select what kind of key you want:
-   (3) DSA (sign only)
-   (4) RSA (sign only)
-   (5) Elgamal (encrypt only)
-   (6) RSA (encrypt only)
-   (7) DSA (set your own capabilities)
-   (8) RSA (set your own capabilities)
-  (10) ECC (sign only)
-  (11) ECC (set your own capabilities)
-  (12) ECC (encrypt only)
-  (13) Existing key
-  (14) Existing key from card
-Your selection? 4
-RSA keys may be between 1024 and 4096 bits long.
-What keysize do you want? (3072) 4096
-Requested keysize is 4096 bits
-Please specify how long the key should be valid.
-         0 = key does not expire
-      <n>  = key expires in n days
-      <n>w = key expires in n weeks
-      <n>m = key expires in n months
-      <n>y = key expires in n years
-Key is valid for? (0) 2y
-Is this correct? (y/N) y
-Really create? (y/N) y
-We need to generate a lot of random bytes. It is a good idea to perform
-some other action (type on the keyboard, move the mouse, utilize the
-disks) during the prime generation; this gives the random number
-generator a better chance to gain enough entropy.
-
-sec  rsa4096/0xF0F2CFEB04341FB5
-     created: 2024-01-01  expires: never       usage: C
-     trust: ultimate      validity: ultimate
-ssb  rsa4096/0xB3CD10E502E19637
-     created: 2024-01-01  expires: 2026-01-01  usage: S
-[ultimate] (1). YubiKey User <yubikey@example>
-```
+# Create Certify key
 
-## Encryption key
-
-Generate an Encryption key by typing `addkey` then `6` to select the `(6) RSA (encrypt only)` option:
-
-```console
-gpg> addkey
-Please select what kind of key you want:
-   (3) DSA (sign only)
-   (4) RSA (sign only)
-   (5) Elgamal (encrypt only)
-   (6) RSA (encrypt only)
-   (7) DSA (set your own capabilities)
-   (8) RSA (set your own capabilities)
-  (10) ECC (sign only)
-  (11) ECC (set your own capabilities)
-  (12) ECC (encrypt only)
-  (13) Existing key
-  (14) Existing key from card
-Your selection? 6
-RSA keys may be between 1024 and 4096 bits long.
-What keysize do you want? (3072) 4096
-Requested keysize is 4096 bits
-Please specify how long the key should be valid.
-         0 = key does not expire
-      <n>  = key expires in n days
-      <n>w = key expires in n weeks
-      <n>m = key expires in n months
-      <n>y = key expires in n years
-Key is valid for? (0) 2y
-Is this correct? (y/N) y
-Really create? (y/N) y
-We need to generate a lot of random bytes. It is a good idea to perform
-some other action (type on the keyboard, move the mouse, utilize the
-disks) during the prime generation; this gives the random number
-generator a better chance to gain enough entropy.
-
-sec  rsa4096/0xF0F2CFEB04341FB5
-     created: 2024-01-01  expires: never       usage: C
-     trust: ultimate      validity: ultimate
-ssb  rsa4096/0xB3CD10E502E19637
-     created: 2024-01-01  expires: 2026-01-01  usage: S
-ssb  rsa4096/0x30CBE8C4B085B9F7
-     created: 2024-01-01  expires: 2026-01-01  usage: E
-[ultimate] (1). YubiKey User <yubikey@example>
-```
-
-## Authentication key
+The primary key to generate is the Certify key, which will be used to issue Subkeys for encryption, signature and authentication operations.
 
-Generate an Authentication key by typing `addkey` then `8` to select the `(8) RSA (set your own capabilities)` option.
-
-**Note** Newer versions of GnuPG may set a Restricted flag on the Authenticate key (see [issue 421](https://github.com/drduh/YubiKey-Guide/issues/421)) - set the **Authenticate** action with `=A` instead.
-
-Toggle the required capabilities with `S`, `E` and `A` until **Authenticate** is the only allowed action:
-
-```console
-gpg> addkey
-Please select what kind of key you want:
-   (3) DSA (sign only)
-   (4) RSA (sign only)
-   (5) Elgamal (encrypt only)
-   (6) RSA (encrypt only)
-   (7) DSA (set your own capabilities)
-   (8) RSA (set your own capabilities)
-  (10) ECC (sign only)
-  (11) ECC (set your own capabilities)
-  (12) ECC (encrypt only)
-  (13) Existing key
-  (14) Existing key from card
-Your selection? 8
-
-Possible actions for a RSA key: Sign Encrypt Authenticate
-Current allowed actions: Sign Encrypt
-
-   (S) Toggle the sign capability
-   (E) Toggle the encrypt capability
-   (A) Toggle the authenticate capability
-   (Q) Finished
-
-Your selection? S
-
-Possible actions for a RSA key: Sign Encrypt Authenticate
-Current allowed actions: Encrypt
-
-   (S) Toggle the sign capability
-   (E) Toggle the encrypt capability
-   (A) Toggle the authenticate capability
-   (Q) Finished
-
-Your selection? E
-
-Possible actions for a RSA key: Sign Encrypt Authenticate
-Current allowed actions:
-
-   (S) Toggle the sign capability
-   (E) Toggle the encrypt capability
-   (A) Toggle the authenticate capability
-   (Q) Finished
-
-Your selection? A
-
-Possible actions for a RSA key: Sign Encrypt Authenticate
-Current allowed actions: Authenticate
-
-   (S) Toggle the sign capability
-   (E) Toggle the encrypt capability
-   (A) Toggle the authenticate capability
-   (Q) Finished
-
-Your selection? Q
-RSA keys may be between 1024 and 4096 bits long.
-What keysize do you want? (2048) 4096
-Requested keysize is 4096 bits
-Please specify how long the key should be valid.
-         0 = key does not expire
-      <n>  = key expires in n days
-      <n>w = key expires in n weeks
-      <n>m = key expires in n months
-      <n>y = key expires in n years
-Key is valid for? (0) 2y
-Is this correct? (y/N) y
-Really create? (y/N) y
-We need to generate a lot of random bytes. It is a good idea to perform
-some other action (type on the keyboard, move the mouse, utilize the
-disks) during the prime generation; this gives the random number
-generator a better chance to gain enough entropy.
+The Certify key should be kept offline at all times and only accessed from a dedicated and secure environment to issue or revoke Subkeys.
 
-sec  rsa4096/0xF0F2CFEB04341FB5
-     created: 2024-01-01  expires: never       usage: C
-     trust: ultimate      validity: ultimate
-ssb  rsa4096/0xB3CD10E502E19637
-     created: 2024-01-01  expires: 2026-01-01  usage: S
-ssb  rsa4096/0x30CBE8C4B085B9F7
-     created: 2024-01-01  expires: 2026-01-01  usage: E
-ssb  rsa4096/0xAD9E24E1B8CB9600
-     created: 2024-01-01  expires: 2026-01-01  usage: A
-[ultimate] (1). YubiKey User <yubikey@example>
-```
+This guide recommends 4096-bit RSA. Do not set an expiration date on the Certify key.
 
-Finish by saving Subkeys:
+Generate the Certify key:
 
 ```console
-gpg> save
-
-gpg> quit
+gpg --batch --passphrase "$PASS" --quick-generate-key "$IDENTITY" \
+    rsa4096 cert never
 ```
 
-**Optional** To add additional email addresses or identities, use `adduid`
-
-Edit the identity:
+Set the Certify key identifier beginning with `0x` as `KEYID` with the following command, or by entering the value manually:
 
 ```console
-gpg --expert --edit-key $KEYID
+KEYID=$(gpg -K | grep -Po "(0x\w+)")
 ```
 
-Add the new identity:
+Set the key fingerprint:
 
 ```console
-gpg> adduid
-Real name: YubiKey User
-Email address: yubikey@somewhere
-Comment:
-You selected this USER-ID:
-    "YubiKey User <yubikey@somewhere>"
-
-Change (N)ame, (C)omment, (E)mail or (O)kay/(Q)uit? o
-
-sec  rsa4096/0xF0F2CFEB04341FB5
-     created: 2024-01-01  expires: never       usage: C
-     trust: ultimate      validity: ultimate
-ssb  rsa4096/0xB3CD10E502E19637
-     created: 2024-01-01  expires: 2026-01-01  usage: S
-ssb  rsa4096/0x30CBE8C4B085B9F7
-     created: 2024-01-01  expires: 2026-01-01  usage: E
-ssb  rsa4096/0xAD9E24E1B8CB9600
-     created: 2024-01-01  expires: 2026-01-01  usage: A
-[ultimate] (1)  YubiKey User <yubikey@example>
-[ unknown] (2). YubiKey User <yubikey@somewhere>
+KEYFPR=$(gpg --fingerprint "$KEYID" | grep -Eo '([0-9A-F][0-9A-F ]{49})' | head -n 1 | tr -d ' ')
 ```
 
-Then configure ultimate trust for the new identity:
+# Create Subkeys
+
+The following command will generate Signature, Encryption and Authentication Subkeys, using the previously configured passphrase and expiration:
 
 ```console
-gpg> trust
-[...]
-Your decision? 5
-Do you really want to set this key to ultimate trust? (y/N) y
-[...]
-gpg> save
+for key_type in sign encrypt auth ; do \
+  gpg --batch --pinentry-mode=loopback \
+    --passphrase "$PASS" --quick-add-key "$KEYFPR" \
+    rsa4096 $key_type "$EXPIRATION"
+ done
 ```
 
-By default, the latest identity added will be the primary user ID. To change it, select `uid 2` or equivalent and `primary`
-
-# Verify
+# Verify keys
 
 List available secret keys:
 
@@ -822,7 +489,7 @@ List available secret keys:
 gpg -K
 ```
 
-The output will display Certify, Signature, Encryption and Authentication keys, for example:
+The output will display **[C]ertify, [S]ignature, [E]ncryption and [A]uthentication** keys:
 
 ```console
 sec   rsa4096/0xF0F2CFEB04341FB5 2024-01-01 [C]
@@ -833,56 +500,26 @@ ssb   rsa4096/0x30CBE8C4B085B9F7 2024-01-01 [E] [expires: 2026-01-01]
 ssb   rsa4096/0xAD9E24E1B8CB9600 2024-01-01 [A] [expires: 2026-01-01]
 ```
 
-**Optional** Verify with a OpenPGP [key best practice checker](https://riseup.net/en/security/message-security/openpgp/best-practices#openpgp-key-checks):
+# Backup private keys
 
-```console
-gpg --export $KEYID | hokey lint
-```
-
-hokey may warn (orange text) about cross certification for the Authentication key. GnuPG [Signing Subkey Cross-Certification](https://gnupg.org/faq/subkey-cross-certify.html) documentation has more detail on cross certification, and version 2.2.1 notes "subkey <keyid> does not sign and so does not need to be cross-certified".
-
-hokey may also indicate a problem (red text) with `Key expiration times: []` on the primary key - see [Note #3](#notes).
-
-# Export secret keys
-
-Save a copy of all keys:
-
-```console
-gpg --armor --export-secret-keys $KEYID > $GNUPGHOME/certify.key
-
-gpg --armor --export-secret-subkeys $KEYID > $GNUPGHOME/subkeys.key
-```
-
-On Windows, note that using any extension other than `.gpg` or attempting IO redirection to a file will garble the secret key, making it impossible to import it again at a later date:
+Save a copy of the Certify key and Subkeys:
 
 ```console
-gpg -o \path\to\dir\certify.gpg --armor --export-secret-keys $KEYID
+gpg --output $GNUPGHOME/$KEYID-Certify.key \
+    --batch --pinentry-mode=loopback --passphrase "$PASS" \
+    --armor --export-secret-keys $KEYID
 
-gpg -o \path\to\dir\subkeys.gpg --armor --export-secret-subkeys $KEYID
+gpg --output $GNUPGHOME/$KEYID-Subkeys.key \
+    --batch --pinentry-mode=loopback --passphrase "$PASS" \
+    --armor --export-secret-subkeys $KEYID
 ```
 
-# Revocation certificate
-
-Although the Certify key may be backed up to a secure place, the possibility of losing it cannot be ruled out. Without the Certify key, it will be impossible to renew or rotate Subkeys or generate a revocation certificate; the PGP identity will be useless. To mitigate this risk, deprecate an orphaned identity with a revocation certificate.
-
-To create one:
-
-``` console
-gpg --output $GNUPGHOME/revoke.asc --gen-revoke $KEYID
-```
-
-The `revoke.asc` file should be stored in a secondary location to the primary backup.
-
-# Backup
-
 Create an **encrypted** backup on portable storage to be kept offline in a secure and durable location.
 	
 **Tip** The [ext2](https://en.wikipedia.org/wiki/Ext2) filesystem without encryption can be mounted on Linux and OpenBSD. Use [FAT32](https://en.wikipedia.org/wiki/Fat32) or [NTFS](https://en.wikipedia.org/wiki/Ntfs) filesystem for macOS and Windows compatibility instead.
 
 As an additional backup measure, use [Paperkey](https://www.jabberwocky.com/software/paperkey/) to make a physical copy of materials. See [Linux Kernel Maintainer PGP Guide](https://www.kernel.org/doc/html/latest/process/maintainer-pgp-guide.html#back-up-your-master-key-for-disaster-recovery) for more information.
 
-It is strongly recommended to keep even encrypted OpenPGP private key material offline to deter [key overwriting attacks](https://www.kopenpgp.com/), for example.
-
 **Linux**
 
 Attach another portable storage device and check its label:
@@ -942,7 +579,9 @@ Calling ioctl() to re-read partition table.
 Syncing disks.
 ```
 
-Use [LUKS](https://askubuntu.com/questions/97196/how-secure-is-an-encrypted-luks-filesystem) to encrypt the new partition. Generate a unique passphrase which will be used to protect the filesystem:
+Use [LUKS](https://askubuntu.com/questions/97196/how-secure-is-an-encrypted-luks-filesystem) to encrypt the new partition.
+
+Generate a unique passphrase (different from the [Passphrase](#passphrase) used for the GnuPG identity) to protect the encrypted volume:
 
 ```console
 sudo cryptsetup luksFormat /dev/mmcblk0p1
@@ -1019,7 +658,7 @@ sd2> q
 No label changes
 ```
 
-Encrypt with bioctl:
+Encrypt with bioctl using a unique [Passphrase](#passphrase):
 
 ```console
 $ doas bioctl -c C -l sd2a softraid0
@@ -1058,7 +697,7 @@ doas mount /dev/sd3i /mnt/encrypted-storage
 doas cp -avi $GNUPGHOME /mnt/encrypted-storage
 ```
 
-**Note** To set up multiple YubiKeys, keep the backup mounted or remember to terminate GnuPG before [saving](https://lists.gnupg.org/pipermail/gnupg-users/2016-July/056353.html).
+**Note** To set up multiple YubiKeys, keep the backup mounted or terminate GnuPG before [saving](https://lists.gnupg.org/pipermail/gnupg-users/2016-July/056353.html).
 
 Otherwise, unmount and disconnect the encrypted volume:
 
@@ -1072,7 +711,7 @@ See [OpenBSD FAQ#14](https://www.openbsd.org/faq/faq14.html#softraidCrypto) for
 
 # Export public key
 
-**Important** Without the public key, it will **not** be possible to use GnuPG to decrypt and sign messages. However, YubiKey can still be used for SSH authentication.
+**Important** Without the public key, it will **not** be possible to use GnuPG to decrypt nor sign messages. However, YubiKey can still be used for SSH authentication.
 
 Create another partition on the portable storage device to store the public key, or reconnect networking and upload to a key server.
 
@@ -1098,14 +737,14 @@ Calling ioctl() to re-read partition table.
 Syncing disks.
 ```
 
-Create a filesystem and export the public key to it:
+Create a filesystem and export the public key:
 
 ```console
 sudo mkfs.ext2 /dev/mmcblk0p2
 
 sudo mkdir /mnt/public
 
-sudo mount /dev/mmcblk0p2 /mnt/public/
+sudo mount /dev/mmcblk0p2 /mnt/public
 
 gpg --armor --export $KEYID | sudo tee /mnt/public/$KEYID-$(date +%F).asc
 ```
@@ -1144,7 +783,7 @@ gpg -o \path\to\dir\pubkey.gpg --armor --export $KEYID
 
 **Keyserver**
 
-**Optional** Upload the public key to a public keyserver:
+**Optional** Upload the public key to a keyserver:
 
 ```console
 gpg --send-key $KEYID
@@ -1192,11 +831,9 @@ gpg/card> admin
 Admin commands are allowed
 ```
 
-**Note** If the card is locked, see [Reset](#reset).
+If the card is locked, use [Reset](#reset).
 
-**Windows**
-
-Use the [YubiKey Manager](https://developers.yubico.com/yubikey-manager) application (note, this is not the similarly named older YubiKey NEO Manager) to enable CCID functionality.
+**Windows** Use the [YubiKey Manager](https://developers.yubico.com/yubikey-manager) application (note, this is not the similarly named older YubiKey NEO Manager) to enable CCID functionality.
 
 ## Enable KDF
 
@@ -1287,13 +924,13 @@ Login data (account name): yubikey@example
 gpg/card> quit
 ```
 
-# Transfer keys
+# Transfer Subkeys
 
-**Important** Transferring keys to YubiKey is a one-way operation. Verify backups were made before proceeding. `keytocard` converts the local, on-disk key into a stub, which means the on-disk copy is no longer usable to transfer to subsequent YubiKeys.
+**Important** Verify a backup of Subkeys was made before proceeding. Transferring keys to YubiKey is a one-way operation: `keytocard` converts the local, on-disk key into a stub, which means the on-disk copy is no longer usable to transfer to subsequent YubiKeys.
 
-The currently selected key(s) are indicated with an `*`.
+The currently selected key(s) are indicated with an `*` symbol.
 
-When transferring keys, only one subkey should be selected at a time.
+When transferring keys, only one subkey must be selected at a time.
 
 ```console
 gpg --edit-key $KEYID
@@ -1399,61 +1036,22 @@ ssb>  rsa4096/0xAD9E24E1B8CB9600 2024-01-01 [A] [expires: 2026-01-01]
 
 A `>` after a tag indicates the key is stored on a smart card.
 
-# Multiple YubiKeys
+# Finish setup
 
-To provision additional YubiKeys, restore the Certify key backup and repeat [Configure YubiKey](#configure-yubikey).
+Verify you have done the following:
 
-```console
-mv -vi $GNUPGHOME $GNUPGHOME.1
+- [ ] Memorized or wrote down Certify key passphrase to a secure and durable location
+- [ ] Saved the Certify key and Subkeys to encrypted portable storage, to be kept offline
+- [ ] Memorized or wrote down passphrase to encrypted volume on portable storage
+- [ ] Exported a copy of the public key where is can be easily accessed later
+- [ ] Memorized or wrote down YubiKey user and admin PINs, which are unique and changed from default values
+- [ ] Moved Encryption, Signature and Authentication Subkeys to YubiKey (`gpg -K` shows `ssb>` for 3 Subkeys)
 
-cp -avi /mnt/encrypted-storage/tmp.XXX $GNUPGHOME
+Reboot to clear the ephemeral environment and complete setup.
 
-cd $GNUPGHOME
-```
+The YubiKey(s) are now ready for use.
 
-## Switching between YubiKeys
-
-When a GnuPG key is added to YubiKey using `keytocard`, the key is deleted from the keyring and a **stub** is added, pointing to the YubiKey. The stub identifies the GnuPG key ID and YubiKey serial number.
-
-When the operation is repeated for an additional YubiKey, the stub is overwritten and will now point to the latest YubiKey.
-
-GnuPG will request a specific YubiKey by serial number, as referenced by the stub, and will not recognize another YubiKey with a different serial number without manual intervention.
-
-Insert the first YubiKey (which has a different serial number) and run the following command:
-
-```console
-gpg-connect-agent "scd serialno" "learn --force" /bye
-```
-
-GnuPG will scan the first YubiKey for keys and recreate the stubs to point to the key ID and YubiKey serial number of the first YubiKey.
-
-To use the second YubiKey, repeat the command.
-
-
-# Finish
-
-Before completing setup, verify the following:
-
-- [ ] Saved Encryption, Signature and Authentication Subkeys to YubiKey (`gpg -K` will show `ssb>` for 3 Subkeys)
-- [ ] Saved YubiKey user and admin PINs, which are unique and were changed from default values
-- [ ] Saved Certify key passphrase to a secure and durable location
-- [ ] Saved Certify key, Subkeys and revocation certificate on encrypted portable storage, to be kept offline
-- [ ] Saved passphrase to encrypted volume on portable storage
-- [ ] Saved copy of public key where is can be easily accessed later
-
-Reboot to finish.
-
-If an ephemeral environment was not used for setup, delete secret keys from the keyring and [securely delete](https://srm.sourceforge.net/) `$GNUPGHOME`
-
-```console
-gpg --delete-secret-key $KEYID
-
-sudo srm -r $GNUPGHOME || sudo rm -rf $GNUPGHOME
-
-unset GNUPGHOME
-```
-
-# Using keys
+# Using YubiKey
 
 Initialize GnuPG:
 
@@ -1461,18 +1059,12 @@ Initialize GnuPG:
 gpg -k
 ```
 
-Change the working directory:
+Import or create a [hardened configuration](https://github.com/drduh/config/blob/master/gpg.conf):
 
 ```console
 cd ~/.gnupg
-```
 
-Download [drduh/config/gpg.conf](https://github.com/drduh/config/blob/master/gpg.conf):
-
-```console
 wget https://raw.githubusercontent.com/drduh/config/master/gpg.conf
-
-chmod 600 gpg.conf
 ```
 
 Set the following option. This avoids the problem where GnuPG will prompt, repeatedly, for the insertion of an already-inserted YubiKey:
@@ -1485,30 +1077,38 @@ echo "disable-ccid" >>scdaemon.conf
 
 > The `disable-ccid` option is only required for GnuPG versions 2.3 or later. However, setting this option does not appear to interfere with the operation of earlier versions of GnuPG so it is recommended for all installations.
 
-Install the required packages and mount the non-encrypted volume created earlier:
+Install the required packages:
 
-**Linux**
+**Debian and Ubuntu**
 
 ```console
 sudo apt update
 
 sudo apt install -y gnupg2 gnupg-agent gnupg-curl scdaemon pcscd
-
-sudo mount /dev/mmcblk0p2 /mnt
 ```
 
 **OpenBSD**
 
+Requires a reboot.
+
 ```console
 doas pkg_add gnupg pcsc-tools
 
-doas mount /dev/sd2b /mnt
+doas rcctl enable pcscd
+
+doas reboot
 ```
 
-Import the public key file:
+Mount the non-encrypted volume with the public key:
 
 ```console
-gpg --import /mnt/gpg-0x*.asc
+doas mount /dev/mmcblk0p2 /mnt
+```
+
+Import it:
+
+```console
+gpg --import /mnt/public/0x*.asc
 ```
 
 Or download the public key from a keyserver:
@@ -1528,12 +1128,12 @@ gpg/card> quit
 Edit the Certify key:
 
 ```console
-export KEYID=0xF0F2CFEB04341FB5
+KEYID=0xF0F2CFEB04341FB5
 
 gpg --edit-key $KEYID
 ```
 
-Assign ultimate trust by typing `trust` and selecting option `5`:
+Assign ultimate trust by typing `trust` and selecting option `5` then `quit`:
 
 ```console
 gpg> trust
@@ -1546,7 +1146,7 @@ gpg> quit
 
 Remove and re-insert YubiKey.
 
-Verify the status with `gpg --card-status` which should be similar to:
+Verify the status with `gpg --card-status` which will be similar to:
 
 ```console
 Reader ...........: Yubico YubiKey OTP FIDO CCID 00 00
@@ -1586,13 +1186,15 @@ ssb>  rsa4096/0xAD9E24E1B8CB9600  created: 2024-01-01  expires: 2026-01-01
 
 **Note** If `General key info..: [none]` appears in the output instead - go back and import the public key using the previous step.
 
-Encrypt a message to yourself (useful for storing credentials):
+## Encryption
+
+Encrypt a message to yourself (useful for storing credentials or protecting backups):
 
 ```console
 echo "test message string" | gpg --encrypt --armor --recipient $KEYID -o encrypted.txt
 ```
 
-To encrypt to multiple recipients or keys (the preferred key ID should be last):
+To encrypt to multiple recipients or keys (the preferred key ID goes last):
 
 ```console
 echo "test message string" | \
@@ -1611,26 +1213,9 @@ gpg: encrypted with RSA key, ID 0x0000000000000000
 test message string
 ```
 
-Sign a message:
-
-```console
-echo "test message string" | gpg --armor --clearsign > signed.txt
-```
-
-Verify the signature:
-
-```console
-$ gpg --verify signed.txt
-gpg: Signature made Mon 01 Jan 2024 12:00:00 PM UTC
-gpg:                using RSA key CF5A305B808B7A0F230DA064B3CD10E502E19637
-gpg: Good signature from "YubiKey User <yubikey@example>" [ultimate]
-Primary key fingerprint: 4E2C 1FA3 372C BA96 A06A  C34A F0F2 CFEB 0434 1FB5
-     Subkey fingerprint: CF5A 305B 808B 7A0F 230D  A064 B3CD 10E5 02E1 9637
-```
-
 Use a [shell function](https://github.com/drduh/config/blob/master/zshrc) to make encrypting files easier:
 
-```
+```console
 secret () {
         output=~/"${1}".$(date +%s).enc
         gpg --encrypt --armor --output ${output} -r 0x0000 -r 0x0001 -r 0x0002 "${1}" && echo "${1} -> ${output}"
@@ -1642,6 +1227,8 @@ reveal () {
 }
 ```
 
+Example output:
+
 ```console
 $ secret document.pdf
 document.pdf -> document.pdf.1580000000.enc
@@ -1653,227 +1240,261 @@ gpg: encrypted with RSA key, ID 0x0000000000000000
 document.pdf.1580000000.enc -> document.pdf
 ```
 
-# Rotating keys
+## Signature
 
-PGP does not provide [forward secrecy](https://en.wikipedia.org/wiki/Forward_secrecy) - a compromised key may be used to decrypt all past messages. Although keys stored on YubiKey are difficult to exploit, it is not impossible; the key and PIN could be physically compromised, or a vulnerability may be discovered in firmware or in the random number generator used to create keys, for example. Therefore, it is good practice to rotate Subkeys periodically.
+Sign a message:
 
-When a Subkey expires, it can either be renewed or replaced. Both actions require access to the Certify key.
+```console
+echo "test message string" | gpg --armor --clearsign > signed.txt
+```
 
-- Renewing Subkeys by updating expiration indicates continued possession of the Certify key and is more convenient.
+Verify the signature:
 
-- Replacing Subkeys is less convenient but potentially more secure: the new Subkeys will **not** be able to decrypt previous messages, authenticate with SSH, etc. Contacts will need to receive the updated public key and any encrypted secrets need to be decrypted and re-encrypted to new Subkeys to be usable. This process is functionally equivalent to losing the YubiKey and provisioning a new one.
+```console
+$ gpg --verify signed.txt
+gpg: Signature made Mon 01 Jan 2024 12:00:00 PM UTC
+gpg:                using RSA key CF5A305B808B7A0F230DA064B3CD10E502E19637
+gpg: Good signature from "YubiKey User <yubikey@example>" [ultimate]
+Primary key fingerprint: 4E2C 1FA3 372C BA96 A06A  C34A F0F2 CFEB 0434 1FB5
+     Subkey fingerprint: CF5A 305B 808B 7A0F 230D  A064 B3CD 10E5 02E1 9637
+```
 
-Neither rotation method is superior and it is up to personal philosophy on identity management and individual threat modeling to decide which one to use, or whether to expire Subkeys at all. Ideally, Subkeys would be ephemeral: used only once for each unique encryption, signature and authentication event, however in practice that is not really practical nor worthwhile with YubiKey. Advanced users may dedicate an air-gapped machine for frequent credential rotation.
+## Configure touch
 
-## Setup environment
+**Note** This is not possible on YubiKey NEO.
 
-To renew or rotate Subkeys, follow the same process as generating keys: boot to a secure environment, install required software and disconnect networking.
+By default, YubiKey will perform cryptographic operations without requiring any action from the user after the key is unlocked once with the PIN.
 
-Connect the portable storage device with the Certify key and identify the disk label:
+To require a touch for each key operation, install [YubiKey Manager](https://developers.yubico.com/yubikey-manager/) and use the Admin PIN to set policy:
+
+Encryption:
 
 ```console
-$ sudo dmesg | tail
-mmc0: new high speed SDHC card at address a001
-mmcblk0: mmc0:a001 SS16G 14.8 GiB (ro)
-mmcblk0: p1 p2
+ykman openpgp keys set-touch dec on
 ```
 
-Decrypt and mount the encrypted volume:
+Signature:
 
 ```console
-sudo cryptsetup luksOpen /dev/mmcblk0p1 secret
-
-sudo mount /dev/mapper/secret /mnt/encrypted-storage
+ykman openpgp keys set-touch sig on
 ```
 
-Import the Certify key and configuration to a temporary working directory.
+Authentication:
 
 ```console
-export GNUPGHOME=$(mktemp -d -t gnupg_$(date +%Y%m%d%H%M)_XXX)
-
-gpg --import /mnt/encrypted-storage/tmp.XXX/certify.key
-
-cp -v /mnt/encrypted-storage/tmp.XXX/gpg.conf $GNUPGHOME
+ykman openpgp keys set-touch aut on
 ```
 
-Edit the Certify key:
+**Note** Versions of YubiKey Manager before 5.1.0 use `enc` instead of `dec` for encryption. Older versions of YubiKey Manager use `touch` instead of `set-touch`
 
-```console
-export KEYID=0xF0F2CFEB04341FB5
+To view and adjust policy options:
 
-gpg --expert --edit-key $KEYID
 ```
+ykman openpgp keys set-touch -h
+```
+
+`Cached` or `Cached-Fixed` may be desirable for YubiKey use with email clients.
 
-## Renewing Subkeys
+YubiKey will blink when it is waiting for a touch. On Linux, [maximbaz/yubikey-touch-detector](https://github.com/maximbaz/yubikey-touch-detector) can be used to indicate YubiKey is waiting for a touch.
 
-To renew Subkeys, the expiry time associated with the corresponding public key will need to be updated, which will require access to the Certify key.
+## SSH
 
-Start by editing the identity:
+Import or create a [hardened configuration](https://github.com/drduh/config/blob/master/gpg-agent.conf):
 
 ```console
-gpg --edit-key $KEYID
-```
+cd ~/.gnupg
 
-Select all expired keys:
+wget https://raw.githubusercontent.com/drduh/config/master/gpg-agent.conf
+```
 
-```console
-gpg> key 1
+**Important** The `cache-ttl` options do **not** apply when using YubiKey as a smart card, because the PIN is [cached by the smart card itself](https://dev.gnupg.org/T3362). To clear the PIN from cache (equivalent to `default-cache-ttl` and `max-cache-ttl`), unplug YubiKey, or set `forcesig` when editing the card to be prompted for the PIN each time.
 
-gpg> key 2
+**Tip** Set `pinentry-program` to `/usr/bin/pinentry-gnome3` for a GUI-based prompt.
 
-gpg> key 3
+**macOS**
 
-sec  rsa4096/0xF0F2CFEB04341FB5
-     created: 2024-01-01  expires: never       usage: C
-     trust: ultimate      validity: ultimate
-ssb* rsa4096/0xB3CD10E502E19637
-     created: 2024-01-01  expires: 2026-01-01  usage: S
-ssb* rsa4096/0x30CBE8C4B085B9F7
-     created: 2024-01-01  expires: 2026-01-01  usage: E
-ssb* rsa4096/0xAD9E24E1B8CB9600
-     created: 2024-01-01  expires: 2026-01-01  usage: A
-[ultimate] (1). YubiKey User <yubikey@example>
-```
+Install pinentry with `brew install pinentry-mac` then edit `gpg-agent.conf` to set the `pinentry-program` path to:
 
-Use `expire` to configure the expiration date. This will **not** expire valid keys.
+* Apple Silicon Macs: `/opt/homebrew/bin/pinentry-mac`
+* Intel Macs: `/usr/local/bin/pinentry-mac`
+* MacGPG Suite: `/usr/local/MacGPG2/libexec/pinentry-mac.app/Contents/MacOS/pinentry-mac`
 
-```console
-gpg> expire
-Changing expiration time for a subkey.
-Please specify how long the key should be valid.
-         0 = key does not expire
-      <n>  = key expires in n days
-      <n>w = key expires in n weeks
-      <n>m = key expires in n months
-      <n>y = key expires in n years
-Key is valid for? (0)
-```
+Then run `gpgconf --kill gpg-agent` for the change to take effect.
 
-Set the expiration date, then `save`
+To use graphical applications on macOS, [additional setup is required](https://jms1.net/yubikey/make-ssh-use-gpg-agent.md).
 
-Next, [Export public keys](#export-public-keys):
+Create `$HOME/Library/LaunchAgents/gnupg.gpg-agent.plist` with the following contents:
 
-```console
-gpg --armor --export $KEYID > $KEYID-$(date +%F).asc
+```
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN"
+  "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+    <dict>
+        <key>Label</key>
+        <string>gnupg.gpg-agent</string>
+        <key>RunAtLoad</key>
+        <true/>
+        <key>KeepAlive</key>
+        <false/>
+        <key>ProgramArguments</key>
+        <array>
+            <string>/usr/local/MacGPG2/bin/gpg-connect-agent</string>
+            <string>/bye</string>
+        </array>
+    </dict>
+</plist>
 ```
 
-Transfer the public key to the destination host, and then import it:
+Load it:
 
 ```console
-gpg --import 0x*.asc
+launchctl load $HOME/Library/LaunchAgents/gnupg.gpg-agent.plist
 ```
 
-Alternatively, publish to a public key server to update the expiration:
+Create `$HOME/Library/LaunchAgents/gnupg.gpg-agent-symlink.plist` with the following contens:
 
-```console
-gpg --send-key $KEYID
+```
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/ProperyList-1.0/dtd">
+<plist version="1.0">
+    <dict>
+        <key>Label</key>
+        <string>gnupg.gpg-agent-symlink</string>
+        <key>ProgramArguments</key>
+        <array>
+            <string>/bin/sh</string>
+            <string>-c</string>
+            <string>/bin/ln -sf $HOME/.gnupg/S.gpg-agent.ssh $SSH_AUTH_SOCK</string>
+        </array>
+        <key>RunAtLoad</key>
+        <true/>
+    </dict>
+</plist>
 ```
 
-Download the public key with updated expiration:
+Load it:
 
 ```console
-gpg --recv $KEYID
+launchctl load $HOME/Library/LaunchAgents/gnupg.gpg-agent-symlink.plist
 ```
 
-The validity of the GnuPG identity will be extended, allowing it to be used again for encryption, signature and authentication operations. The SSH public key does **not** need to be updated on remote hosts.
+Reboot or to activate changes.
 
-## Rotating keys
+**Windows**
 
-Follow the original procedure to generate and add [Subkeys](#subkeys).
+Windows can already have some virtual smart card readers installed, like the one provided for Windows Hello. To verify YubiKey is the correct one used by scdaemon, add it to its configuration.
 
-Previous Subkeys may be kept or deleted from the identity.
+Find the YubiKey label using PowerShell:
 
-Finish by exporting new keys:
+```powershell
+PS C:\WINDOWS\system32> Get-PnpDevice -Class SoftwareDevice | Where-Object {$_.FriendlyName -like "*YubiKey*"} | Select-Object -ExpandProperty FriendlyName
+Yubico YubiKey OTP+FIDO+CCID 0
+```
 
-```console
-gpg --armor --export-secret-keys $KEYID > $GNUPGHOME/certify.key
+See [How to setup Signed Git Commits with a YubiKey NEO and GPG and Keybase on Windows (2018)](https://www.hanselman.com/blog/HowToSetupSignedGitCommitsWithAYubiKeyNEOAndGPGAndKeybaseOnWindows.aspx) for more information.
 
-gpg --armor --export-secret-subkeys $KEYID > $GNUPGHOME/subkeys.key
+Edit `%APPDATA%/gnupg/scdaemon.conf` to add:
+
+```console
+reader-port <device name, e.g. Yubico YubiKey OTP+FIDO+CCID 0>
 ```
 
-Copy the **new** temporary working directory to encrypted storage, which should still be mounted:
+Edit `%APPDATA%/gnupg/gpg-agent.conf` to add:
 
 ```console
-sudo cp -avi $GNUPGHOME /mnt/encrypted-storage
+enable-ssh-support
+enable-putty-support
 ```
 
-There should now be at least two versions of the Certify and Subkeys:
+Restart the agent:
 
 ```console
-ls /mnt/encrypted-storage
+gpg-connect-agent killagent /bye
+gpg-connect-agent /bye
 ```
 
-Unmount and close the encrypted volume:
+Verify YubiKey details:
 
 ```console
-sudo umount /mnt/encrypted-storage
-
-sudo cryptsetup luksClose /dev/mapper/secret
+gpg --card-status
 ```
 
-Export the updated public key:
+Import the public key and set ultimate trust:
 
 ```console
-sudo mkdir /mnt/public
+gpg --import <path to public key file>
+```
 
-sudo mount /dev/mmcblk0p2 /mnt/public
+Retrieve the public key id:
 
-gpg --armor --export $KEYID | sudo tee /mnt/public/$KEYID-$(date +%F).asc
+```console
+gpg --list-public-keys
+```
 
-sudo umount /mnt/public
+Export the SSH public key:
+
+```console
+gpg --export-ssh-key <public key id>
 ```
 
-Disconnect the storage device and follow the original steps to transfer new Subkeys (4, 5 and 6) to YubiKey, replacing existing ones. Reboot or securely erase the GnuPG temporary working directory.
+Copy the public SSH key to a file - it corresponds to the secret key on YubiKey and can be copied to SSH destination hosts.
 
-# Adding notations
+Create a shortcut that points to `gpg-connect-agent /bye` and place it in the startup folder `shell:startup` to make sure the agent starts after reboot. Modify the shortcut properties so it starts in a "Minimized" window.
 
-Notations can be added to user ID(s) and can be used in conjunction with [Keyoxide](https://keyoxide.org) to create [OpenPGP identity proofs](https://docs.keyoxide.org/wiki/identity-proof-formats/).
+PuTTY can now be used for public-key SSH authentication. When the server asks for public-key verification, PuTTY will forward the request to GnuPG, which will prompt for a PIN to authorize the operation.
 
-Adding notations requires access to the Certify key.
+**WSL**
 
-After configuring the environment, follow any of the guides listed under "Adding proofs" in the Keyoxide ["Guides"](https://keyoxide.org/guides/) page up until the notation is saved using the `save` command.
+The goal is to configure SSH client inside WSL work together with the Windows agent, such as gpg-agent.exe.
 
-Export the public key:
+See the [WSL agent architecture](media/schema_gpg.png) illustration for an overview.
 
-```console
-gpg --export $KEYID > pubkey.asc
-```
+**Note** GnuPG forwarding for cryptographic operations is not supported. See [vuori/weasel-pageant](https://github.com/vuori/weasel-pageant) for more information.
 
-Transfer the public key and import it:
+One way to forward is just `ssh -A` (still need to eval weasel to setup local ssh-agent), and only relies on OpenSSH. In this track, `ForwardAgent` and `AllowAgentForwarding` in ssh/sshd config may be involved. However, when using ssh socket forwarding, do not enable `ForwardAgent` in ssh config. See [SSH Agent Forwarding](#remote-machines-ssh-agent-forwarding) for more information. This requires Ubuntu 16.04 or newer for WSL and Kleopatra.
 
-```console
-gpg --import pubkey.asc
-```
+Download [vuori/weasel-pageant](https://github.com/vuori/weasel-pageant).
 
-Use `showpref` to verify notions were correctly added.
+Add `eval $(/mnt/c/<path of extraction>/weasel-pageant -r -a /tmp/S.weasel-pageant)` to the shell rc file. Use a named socket here so it can be used in the `RemoteForward` directive of `~/.ssh/config`. Source it with `source ~/.bashrc`.
 
-# SSH
+Display the SSH key with `$ ssh-add -l`
 
-**Tip** YubiKey can be used directly for SSH only, without GnuPG features, starting in [OpenSSH v8.2](https://www.openssh.com/txt/release-8.2). For more information, see [vorburger/ed25519-sk.md](https://github.com/vorburger/vorburger.ch-Notes/blob/develop/security/ed25519-sk.md) and [Yubico - GitHub now supports SSH security keys](https://www.yubico.com/blog/github-now-supports-ssh-security-keys/).
+Edit `~/.ssh/config` to add the following for each agent forwarding host:
 
-[gpg-agent](https://wiki.archlinux.org/title/GnuPG#SSH_agent) supports the OpenSSH ssh-agent protocol (`enable-ssh-support`) as well as PuTTy's Pageant on Windows (`enable-putty-support`). This means it can be used instead of the traditional ssh-agent / pageant. There are some differences from ssh-agent, notably that gpg-agent does not _cache_ keys rather it converts, encrypts and stores them persistently as keys, then makes them available to ssh clients. Any existing ssh private keys should be deleted after importing to GnuPG agent.
+```console
+RemoteForward <remote SSH socket path> /tmp/S.weasel-pageant
+```
 
-When importing the key to `gpg-agent`, a passphrase will be required to encrypt within the key store. GnuPG can cache both passphrases with `cache-ttl` options. Note than when removing the old private key after importing to `gpg-agent`, keep the `.pub` key file around for use in specifying ssh identities (e.g. `ssh -i /path/to/identity.pub`).
+**Note** The remote SSH socket path can be found with `gpgconf --list-dirs agent-ssh-socket`
 
-Missing from `gpg-agent` ssh agent support is the ability to remove keys. `ssh-add -d/-D` have no effect. Instead, use the `gpg-connect-agent` utility to lookup a keygrip, match it with the desired ssh key fingerprint (as an MD5) and then delete that keygrip. The [gnupg-users mailing list](https://lists.gnupg.org/pipermail/gnupg-users/2016-August/056499.html) has more information.
+Add the following to the shell rc file:
 
-## Create configuration
+```console
+export SSH_AUTH_SOCK=$(gpgconf --list-dirs agent-ssh-socket)
+```
 
-Create a hardened configuration for gpg-agent by downloading [drduh/config/gpg-agent.conf](https://github.com/drduh/config/blob/master/gpg-agent.conf):
+Add the following to `/etc/ssh/sshd_config`:
 
 ```console
-cd ~/.gnupg
+StreamLocalBindUnlink yes
+```
 
-wget https://raw.githubusercontent.com/drduh/config/master/gpg-agent.conf
+Reload SSH daemon:
+
+```console
+sudo service sshd reload
 ```
 
-**Important** The `cache-ttl` options do **not** apply when using YubiKey as a smart card, because the PIN is [cached by the smart card itself](https://dev.gnupg.org/T3362). To clear the PIN from cache (equivalent to `default-cache-ttl` and `max-cache-ttl`), unplug YubiKey, or set `forcesig` when editing the card to be prompted for the PIN each time.
+Unplug YubiKey, disconnect or reboot. Log back into Windows, open a WSL console and enter `ssh-add -l` - no output should appear.
 
-**Tip** Set `pinentry-program /usr/bin/pinentry-gnome3` for a GUI-based prompt. If the _pinentry_ graphical dialog doesn't show and this error appears: `sign_and_send_pubkey: signing failed: agent refused operation`, install the `dbus-user-session` package and restart the computer for the `dbus` user session to be fully inherited; this is because behind the scenes, `pinentry` complains about `No $DBUS_SESSION_BUS_ADDRESS found`, falls back to `curses` but doesn't find the expected `tty`.
+Plug in YubiKey, enter the same command to display the ssh key.
 
-On macOS, use `brew install pinentry-mac` and set the program path to `pinentry-program /usr/local/bin/pinentry-mac` for Intel Macs, `/opt/homebrew/bin/pinentry-mac` for ARM/Apple Silicon Macs or `pinentry-program /usr/local/MacGPG2/libexec/pinentry-mac.app/Contents/MacOS/pinentry-mac` if using MacGPG Suite. For the configuration to take effect, run `gpgconf --kill gpg-agent`
+Connect to the remote host and use `ssh-add -l` to confirm forwarding works.
+
+Agent forwarding may be chained through multiple hosts. Follow the same [protocol](#remote-host-configuration) to configure each host.
 
-## Replace agents
+### Replace agents
 
 To launch `gpg-agent` for use by SSH, use the `gpg-connect-agent /bye` or `gpgconf --launch gpg-agent` commands.
 
@@ -1905,9 +1526,9 @@ When using `ForwardAgent` for ssh-agent forwarding, `SSH_AUTH_SOCK` only needs t
 
 For `S.gpg-agent.ssh` (see [SSH Agent Forwarding](#remote-machines-ssh-agent-forwarding) for more info), `SSH_AUTH_SOCK` should also be set on the *remote*. However, `GPG_TTY` should not be set on the *remote*, explanation specified in that section.
 
-## Copy public key
+### Copy public key
 
-**Note** It is **not** necessary to import the GnuPG public key in order to use SSH.
+**Note** It is **not** necessary to import the GnuPG public key in order to use SSH only.
 
 Copy and paste the output from `ssh-add` to the server's `authorized_keys` file:
 
@@ -1916,9 +1537,7 @@ $ ssh-add -L
 ssh-rsa AAAAB4NzaC1yc2EAAAADAQABAAACAz[...]zreOKM+HwpkHzcy9DQcVG2Nw== cardno:000605553211
 ```
 
-## (Optional) Save public key for identity file configuration
-
-By default, SSH attempts to use all the identities available via the agent. It's often a good idea to manage exactly which keys SSH will use to connect to a server, for example to separate different roles or [to avoid being fingerprinted by untrusted ssh servers](https://words.filippo.io/ssh-whoami-filippo-io/). To do this you'll need to use the command line argument `-i [identity_file]` or the `IdentityFile` and `IdentitiesOnly` options in `.ssh/config`.
+**Optional** Save the public key for identity file configuration. By default, SSH attempts to use all the identities available via the agent. It's often a good idea to manage exactly which keys SSH will use to connect to a server, for example to separate different roles or [to avoid being fingerprinted by untrusted ssh servers](https://words.filippo.io/ssh-whoami-filippo-io/). To do this you'll need to use the command line argument `-i [identity_file]` or the `IdentityFile` and `IdentitiesOnly` options in `.ssh/config`.
 
 The argument provided to `IdentityFile` is traditionally the path to the _private_ key file (for example `IdentityFile ~/.ssh/id_rsa`). For YubiKey, `IdentityFile` must point to the _public_ key file, and `ssh` will select the appropriate private key from those available via ssh-agent. To prevent `ssh` from trying all keys in the agent, use `IdentitiesOnly yes` along with one or more `-i` or `IdentityFile` options for the target host.
 
@@ -1940,7 +1559,7 @@ Host github.com
 EOF
 ```
 
-## Connect with public key authentication
+Connect with public key authentication:
 
 ```console
 $ ssh git@github.com -vvv
@@ -1965,7 +1584,7 @@ debug1: Authentication succeeded (publickey).
 
 **Tip** To make multiple connections or securely transfer many files, use the [ControlMaster](https://en.wikibooks.org/wiki/OpenSSH/Cookbook/Multiplexing) ssh option.
 
-## Import SSH keys
+### Import SSH keys
 
 If there are existing SSH keys to make available via `gpg-agent`, they will need to be imported. Then, remove the original private keys. When importing the key, `gpg-agent` uses the key filename as the label - this makes it easier to follow where the key originated from. In this example, we're starting with just the YubiKey in place and importing `~/.ssh/id_rsa`:
 
@@ -1996,9 +1615,9 @@ $ ssh-add -E md5 -l
 
 When using the key `pinentry` will be invoked to request the key passphrase. The passphrase will be cached for up to 10 idle minutes between uses, up to a maximum of 2 hours.
 
-## Remote Machines (SSH Agent Forwarding)
+### SSH agent forwarding
 
-**Note** SSH Agent Forwarding can [add additional risk](https://matrix.org/blog/2019/05/08/post-mortem-and-remediations-for-apr-11-security-incident/#ssh-agent-forwarding-should-be-disabled) - proceed with caution!
+**Warning** SSH Agent Forwarding can [add additional risk](https://matrix.org/blog/2019/05/08/post-mortem-and-remediations-for-apr-11-security-incident/#ssh-agent-forwarding-should-be-disabled) - proceed with caution!
 
 There are two methods for ssh-agent forwarding, one is provided by OpenSSH and the other is provided by GnuPG.
 
@@ -2006,13 +1625,13 @@ The latter one may be more insecure as raw socket is just forwarded (not like `S
 
 For example, tmux does not have environment variables such as `$SSH_AUTH_SOCK` when connecting to remote hosts and attaching an existing session. For each shell, find the socket and `export SSH_AUTH_SOCK=/tmp/ssh-agent-xxx/xxxx.socket`. However, with `S.gpg-agent.ssh` in a fixed place, it can be used as the ssh-agent in shell rc files.
 
-### Use ssh-agent 
+#### Use ssh-agent
 
 You should now be able to use `ssh -A remote` on the _local_ host to log into _remote_ host, and should then be able to use YubiKey as if it were connected to the remote host. For example, using e.g. `ssh-add -l` on that remote host will show the public key from the YubiKey (`cardno:`). Always use `ForwardAgent yes` only for a single host, never for all servers.
 
-### Use S.gpg-agent.ssh
+#### Use S.gpg-agent.ssh
 
-First you need to go through [Remote Machines (GPG Agent Forwarding)](#remote-machines-gpg-agent-forwarding), know the conditions for gpg-agent forwarding and know the location of `S.gpg-agent.ssh` on both the local and the remote.
+First you need to go through [GnuPG agent forwarding)](#gnupg-agent-forwarding), know the conditions for gpg-agent forwarding and know the location of `S.gpg-agent.ssh` on both the local and the remote.
 
 You may use the command:
 
@@ -2043,7 +1662,7 @@ After sourcing the shell rc file, `ssh-add -l` will return the correct public ke
 
 **Note** In this process no gpg-agent in the remote is involved, hence `gpg-agent.conf` in the remote is of no use. Also pinentry is invoked locally.
 
-### Chained SSH agent forwarding
+#### Chained forwarding
 
 If you use `ssh-agent` provided by OpenSSH and want to forward it into a *third* box, you can just `ssh -A third` on the *remote*.
 
@@ -2054,17 +1673,15 @@ Host third
   Hostname third-host.tld
   StreamLocalBindUnlink yes
   RemoteForward /run/user/1000/gnupg/S.gpg-agent.ssh /run/user/1000/gnupg/S.gpg-agent.ssh
-  # RemoteForward [remote socket] [local socket]
-  # Note that ForwardAgent is not wanted here!
+  #RemoteForward [remote socket] [local socket]
+  #Note that ForwardAgent is not wanted here!
 ```
 
 The path must be set according to `gpgconf --list-dirs agent-ssh-socket` on *remote* and *third* hosts.
 
 ## GitHub
 
-YubiKey can be used to sign commits and tags, and authenticate SSH to GitHub.
-
-Manage SSH and PGP keys in [Settings](https://github.com/settings/keys).
+YubiKey can be used to sign commits and tags, and authenticate SSH to GitHub when configured in [Settings](https://github.com/settings/keys).
 
 Configure a signing key:
 
@@ -2072,13 +1689,13 @@ Configure a signing key:
 git config --global user.signingkey $KEYID
 ```
 
-The `user.email` option must match the email address associated with the PGP identity.
+**Important** The `user.email` option must match the email address associated with the PGP identity.
 
 To sign commits or tags, use the `-S` option.
 
 **Windows**
 
-To configure authentication:
+Configure authentication:
 
 ```console
 git config --global core.sshcommand "plink -agent"
@@ -2086,194 +1703,11 @@ git config --global core.sshcommand "plink -agent"
 git config --global gpg.program 'C:\Program Files (x86)\GnuPG\bin\gpg.exe'
 ```
 
-Update the repository URL to `git@github.com:USERNAME/repository` and any authenticated commands will be authorized by YubiKey.
+Then update the repository URL to `git@github.com:USERNAME/repository`
 
 **Note** For the error `gpg: signing failed: No secret key` - run `gpg --card-status` with YubiKey plugged in and try the git command again.
 
-## OpenBSD
-
-Install and enable tools for use with PC/SC drivers, cards, readers, then reboot to recognize YubiKey:
-
-```console
-doas pkg_add pcsc-tools
-
-doas rcctl enable pcscd
-
-doas reboot
-```
-
-## Windows
-
-Windows can already have some virtual smart card readers installed, like the one provided for Windows Hello. To verify YubiKey is the correct one used by scdaemon, add it to its configuration.
-
-Find the YubiKey label using PowerShell:
-
-```powershell
-PS C:\WINDOWS\system32> Get-PnpDevice -Class SoftwareDevice | Where-Object {$_.FriendlyName -like "*YubiKey*"} | Select-Object -ExpandProperty FriendlyName
-Yubico YubiKey OTP+FIDO+CCID 0
-```
-
-See [How to setup Signed Git Commits with a YubiKey NEO and GPG and Keybase on Windows (2018)](https://www.hanselman.com/blog/HowToSetupSignedGitCommitsWithAYubiKeyNEOAndGPGAndKeybaseOnWindows.aspx) for more information.
-
-Edit `%APPDATA%/gnupg/scdaemon.conf` to add:
-
-```console
-reader-port <device name, e.g. Yubico YubiKey OTP+FIDO+CCID 0>
-```
-
-Edit `%APPDATA%/gnupg/gpg-agent.conf` to add:
-
-```console
-enable-ssh-support
-enable-putty-support
-```
-
-Restart the agent:
-
-```console
-gpg-connect-agent killagent /bye
-gpg-connect-agent /bye
-```
-
-Verify YubiKey details:
-
-```console
-gpg --card-status
-```
-
-Import the public key and set ultimate trust:
-
-```console
-gpg --import <path to public key file>
-```
-
-Retrieve the public key id:
-
-```console
-gpg --list-public-keys
-```
-
-Export the SSH public key:
-
-```console
-gpg --export-ssh-key <public key id>
-```
-
-Copy the public SSH key to a file - it corresponds to the secret key on YubiKey and can be copied to SSH destination hosts.
-
-Create a shortcut that points to `gpg-connect-agent /bye` and place it in the startup folder `shell:startup` to make sure the agent starts after reboot. Modify the shortcut properties so it starts in a "Minimized" window.
-
-PuTTY can now be used for public-key SSH authentication. When the server asks for public-key verification, PuTTY will forward the request to GnuPG, which will prompt for a PIN to authorize the operation.
-
-### WSL
-
-The goal is to configure SSH client inside WSL work together with the Windows agent, such as gpg-agent.exe.
-
-![WSL agent architecture](media/schema_gpg.png)
-
-**Note** GnuPG forwarding for cryptographic operations is not supported. See [vuori/weasel-pageant](https://github.com/vuori/weasel-pageant) for more information.
-
-One way to forward is just `ssh -A` (still need to eval weasel to setup local ssh-agent), and only relies on OpenSSH. In this track, `ForwardAgent` and `AllowAgentForwarding` in ssh/sshd config may be involved. However, when using ssh socket forwarding, do not enable `ForwardAgent` in ssh config. See [SSH Agent Forwarding](#remote-machines-ssh-agent-forwarding) for more information. This requires Ubuntu 16.04 or newer for WSL and Kleopatra.
-
-Download [vuori/weasel-pageant](https://github.com/vuori/weasel-pageant).
-
-Add `eval $(/mnt/c/<path of extraction>/weasel-pageant -r -a /tmp/S.weasel-pageant)` to the shell rc file. Use a named socket here so it can be used in the `RemoteForward` directive of `~/.ssh/config`. Source it with `source ~/.bashrc`.
-
-Display the SSH key with `$ ssh-add -l`
-
-Edit `~/.ssh/config` to add the following for each agent forwarding host:
-
-```console
-RemoteForward <remote SSH socket path> /tmp/S.weasel-pageant
-```
-
-**Note** The remote SSH socket path can be found with `gpgconf --list-dirs agent-ssh-socket`
-
-Add the following to the shell rc file:
-
-```console
-export SSH_AUTH_SOCK=$(gpgconf --list-dirs agent-ssh-socket)
-```
-
-Add the following to `/etc/ssh/sshd_config`:
-
-```console
-StreamLocalBindUnlink yes
-```
-
-Reload SSH daemon:
-
-```console
-sudo service sshd reload
-```
-
-Unplug YubiKey, disconnect or reboot. Log back into Windows, open a WSL console and enter `ssh-add -l` - no output should appear.
-
-Plug in YubiKey, enter the same command to display the ssh key.
-
-Connect to the remote host and use `ssh-add -l` to confirm forwarding works.
-
-Agent forwarding may be chained through multiple hosts. Follow the same [protocol](#remote-host-configuration) to configure each host.
-
-## macOS
-
-To use gui applications on macOS, [a little bit more setup is needed](https://jms1.net/yubikey/make-ssh-use-gpg-agent.md).
-
-Create `$HOME/Library/LaunchAgents/gnupg.gpg-agent.plist` with the following contents:
-
-```
-<?xml version="1.0" encoding="UTF-8"?>
-<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN"
-  "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
-<plist version="1.0">
-    <dict>
-        <key>Label</key>
-        <string>gnupg.gpg-agent</string>
-        <key>RunAtLoad</key>
-        <true/>
-        <key>KeepAlive</key>
-        <false/>
-        <key>ProgramArguments</key>
-        <array>
-            <string>/usr/local/MacGPG2/bin/gpg-connect-agent</string>
-            <string>/bye</string>
-        </array>
-    </dict>
-</plist>
-```
-
-```console
-launchctl load $HOME/Library/LaunchAgents/gnupg.gpg-agent.plist
-```
-
-Create `$HOME/Library/LaunchAgents/gnupg.gpg-agent-symlink.plist` with the following contens:
-
-```
-<?xml version="1.0" encoding="UTF-8"?>
-<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/ProperyList-1.0/dtd">
-<plist version="1.0">
-    <dict>
-        <key>Label</key>
-        <string>gnupg.gpg-agent-symlink</string>
-        <key>ProgramArguments</key>
-        <array>
-            <string>/bin/sh</string>
-            <string>-c</string>
-            <string>/bin/ln -sf $HOME/.gnupg/S.gpg-agent.ssh $SSH_AUTH_SOCK</string>
-        </array>
-        <key>RunAtLoad</key>
-        <true/>
-    </dict>
-</plist>
-```
-
-```console
-launchctl load $HOME/Library/LaunchAgents/gnupg.gpg-agent-symlink.plist
-```
-
-Reboot or log out and log back in to activate these changes.
-
-# Remote Machines (GPG Agent Forwarding)
+## GnuPG agent forwarding
 
 YubiKey can be used sign git commits and decrypt files on remote hosts with GPG Agent Forwarding. To ssh through another network, especially to push to/pull from GitHub using ssh, see [Remote Machines (SSH Agent forwarding)](#remote-machines-ssh-agent-forwarding).
 
@@ -2289,9 +1723,9 @@ Import the public key on the remote host. On the local host, copy the public key
 scp ~/.gnupg/pubring.kbx remote:~/.gnupg/
 ```
 
-On modern distributions such as Fedora 30, there is no need to set `RemoteForward` in `~/.ssh/config`
+On modern distributions, such as Fedora 30, there is no need to set `RemoteForward` in `~/.ssh/config`
 
-## Steps for older distributions
+### Legacy distributions
 
 On the local host, run:
 
@@ -2316,7 +1750,7 @@ Host
   Hostname remote-host.tld
   StreamLocalBindUnlink yes
   RemoteForward /run/user/1000/gnupg/S.gpg-agent /run/user/1000/gnupg/S.gpg-agent.extra
-  # RemoteForward [remote socket] [local socket]
+  #RemoteForward [remote socket] [local socket]
 ```
 
 It may be necessary to edit `gpg-agent.conf` on the *local* host to add the following information:
@@ -2332,7 +1766,7 @@ extra-socket /run/user/1000/gnupg/S.gpg-agent.extra
 
 See [Issue #85](https://github.com/drduh/YubiKey-Guide/issues/85) for more information and troubleshooting.
 
-## Chained GnuPG agent forwarding
+### Chained GnuPG agent forwarding
 
 Assume you have gone through the steps above and have `S.gpg-agent` on the *remote*, and you would like to forward this agent into a *third* box, first you may need to configure `sshd_config` of *third* in the same way as *remote*, then in the ssh config of *remote*, add the following lines:
 
@@ -2341,16 +1775,20 @@ Host third
   Hostname third-host.tld
   StreamLocalBindUnlink yes
   RemoteForward /run/user/1000/gnupg/S.gpg-agent /run/user/1000/gnupg/S.gpg-agent
-  # RemoteForward [remote socket] [local socket]
+  #RemoteForward [remote socket] [local socket]
 ```
 
 You should change the path according to `gpgconf --list-dirs agent-socket` on *remote* and *third*.
 
 **Note** On *local* you have `S.gpg-agent.extra` whereas on *remote* and *third*, you only have `S.gpg-agent`
 
-# Using Multiple Keys
+## Using multiple YubiKeys
+
+When a GnuPG key is added to YubiKey using `keytocard`, the key is deleted from the keyring and a **stub** is added, pointing to the YubiKey. The stub identifies the GnuPG key ID and YubiKey serial number.
+
+When a Subkey is added to an additional YubiKey, the stub is overwritten and will now point to the latest YubiKey. GnuPG will request a specific YubiKey by serial number, as referenced by the stub, and will not recognize another YubiKey with a different serial number.
 
-To use a single identity with multiple YubiKeys - or to replace a lost card with another - issue this command to switch keys:
+To scan an additional YubiKey and recreate the correct stub:
 
 ```console
 gpg-connect-agent "scd serialno" "learn --force" /bye
@@ -2378,195 +1816,199 @@ chmod +x ~/scripts/remove-keygrips.sh
 
 See discussion in Issues [#19](https://github.com/drduh/YubiKey-Guide/issues/19) and [#112](https://github.com/drduh/YubiKey-Guide/issues/112) for more information and troubleshooting steps.
 
-# Adding an identity
+## Email
 
-To add an identity after creating and backing up a YubiKey, first add the identity to the Certify key, and then reset YubiKey and use `keytocard` to move the Subkeys to the card again.
+YubiKey can be used to decrypt and sign emails and attachments using [Thunderbird](https://www.thunderbird.net/), [Enigmail](https://www.enigmail.net) and [Mutt](http://www.mutt.org/). Thunderbird supports OAuth 2 authentication and can be used with Gmail. See [this EFF guide](https://ssd.eff.org/en/module/how-use-pgp-linux) for more information. Mutt has OAuth 2 support since version 2.0.
 
-Follow the same process as generating keys: boot to a secure environment, install required software and disconnect networking.
+### Mailvelope
 
-Connect the portable storage device with the Certify key and identify the disk label:
+[Mailvelope](https://www.mailvelope.com/en) allows YubiKey to be used with Gmail and others.
 
-```console
-$ sudo dmesg | tail
-mmc0: new high speed SDHC card at address a001
-mmcblk0: mmc0:a001 SS16G 14.8 GiB (ro)
-mmcblk0: p1 p2
-```
+**Important** Mailvelope [does not work](https://github.com/drduh/YubiKey-Guide/issues/178) with the `throw-keyids` option set in `gpg.conf`
 
-Decrypt and mount the encrypted volume:
+On macOS, install gpgme using Homebrew:
 
 ```console
-sudo cryptsetup luksOpen /dev/mmcblk0p1 secret
-
-sudo mount /dev/mapper/secret /mnt/encrypted-storage
+brew install gpgme
 ```
 
-Restore the backup to a temporary directory:
-
-```console
-export GNUPGHOME=$(mktemp -d -t gnupg_$(date +%Y%m%d%H%M)_XXX)
+To allow Chrome to run gpgme, edit `~/Library/Application\ Support/Google/Chrome/NativeMessagingHosts/gpgmejson.json` to add:
 
-cp -avi /mnt/encrypted-storage/tmp.XXX/* $GNUPGHOME
+```json
+{
+    "name": "gpgmejson",
+    "description": "Integration with GnuPG",
+    "path": "/usr/local/bin/gpgme-json",
+    "type": "stdio",
+    "allowed_origins": [
+        "chrome-extension://kajibbejlbohfaggdiogboambcijhkke/"
+    ]
+}
 ```
 
-Edit the Certify key:
+Edit the default path to allow Chrome to find GnuPG:
 
 ```console
-gpg --expert --edit-key $KEYID
+sudo launchctl config user path /usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin
 ```
 
-Add the identity and set ultimate trust:
+Finally, install the [Mailvelope extension](https://chromewebstore.google.com/detail/mailvelope/kajibbejlbohfaggdiogboambcijhkke) from the Chrome web store.
 
-```console
-gpg> adduid
+### Mutt
 
-gpg> trust
-Your decision? 5
+Mutt has both CLI and TUI interfaces - the latter provides powerful functions for processing email. In addition, PGP can be integrated such that cryptographic operations can be done without leaving TUI.
 
-gpg> save
-```
+To enable GnuPG support, copy `/usr/share/doc/mutt/samples/gpg.rc`
 
-Export Certify and Subkeys again:
+Edit the file to enable options `pgp_default_key`, `pgp_sign_as` and `pgp_autosign`
 
-```console
-gpg --armor --export-secret-keys $KEYID > $GNUPGHOME/certify.key
+`source` the file in `muttrc`
 
-gpg --armor --export-secret-subkeys $KEYID > $GNUPGHOME/subkeys.key
-```
+**Important** `pinentry-tty` set as the pinentry program in `gpg-agent.conf` is reported to cause problems with Mutt TUI, because it uses curses. It is recommended to use `pinentry-curses` or other graphic pinentry program instead.
 
-Export the public key:
+# Updating keys
 
-```console
-gpg --armor --export $KEYID | sudo tee /mnt/public/gpg-$KEYID-$(date +%F).asc
-```
+PGP does not provide [forward secrecy](https://en.wikipedia.org/wiki/Forward_secrecy), meaning a compromised key may be used to decrypt all past messages. Although keys stored on YubiKey are more difficult to exploit, it is not impossible: the key and PIN could be physically compromised, or a vulnerability may be discovered in firmware or in the random number generator used to create keys, for example. Therefore, it is recommended practice to rotate Subkeys periodically.
 
-**Note** On Windows, using an extension other than `.gpg` or attempting IO redirection to a file will result in a nonfunctional private key.
+When a Subkey expires, it can either be renewed or replaced. Both actions require access to the Certify key.
 
-```console
-gpg -o \path\to\dir\certify.gpg --armor --export-secret-keys $KEYID
+- Renewing Subkeys by updating expiration indicates continued possession of the Certify key and is more convenient.
 
-gpg -o \path\to\dir\subkeys.gpg --armor --export-secret-subkeys $KEYID
+- Replacing Subkeys is less convenient but potentially more secure: the new Subkeys will **not** be able to decrypt previous messages, authenticate with SSH, etc. Contacts will need to receive the updated public key and any encrypted secrets need to be decrypted and re-encrypted to new Subkeys to be usable. This process is functionally equivalent to losing the YubiKey and provisioning a new one.
 
-gpg -o \path\to\dir\pubkey.gpg --armor --export $KEYID
-```
+Neither rotation method is superior and it is up to personal philosophy on identity management and individual threat modeling to decide which one to use, or whether to expire Subkeys at all. Ideally, Subkeys would be ephemeral: used only once for each unique encryption, signature and authentication event, however in practice that is not really practical nor worthwhile with YubiKey. Advanced users may dedicate an air-gapped machine for frequent credential rotation.
+
+To renew or rotate Subkeys, follow the same process as generating keys: boot to a secure environment, install required software and disconnect networking.
 
-Copy the **new** working directory to encrypted storage, which should still be mounted:
+Connect the portable storage device with the Certify key and identify the disk label:
 
 ```console
-sudo cp -avi $GNUPGHOME /mnt/encrypted-storage
+$ sudo dmesg | tail
+mmc0: new high speed SDHC card at address a001
+mmcblk0: mmc0:a001 SS16G 14.8 GiB (ro)
+mmcblk0: p1 p2
 ```
 
-Unmount and close the encrypted volume:
+Decrypt and mount the encrypted volume:
 
 ```console
-sudo umount /mnt/encrypted-storage
+sudo cryptsetup luksOpen /dev/mmcblk0p1 secret
 
-sudo cryptsetup luksClose /dev/mapper/secret
+sudo mount /dev/mapper/secret /mnt/encrypted-storage
 ```
 
-## Updating YubiKey
+Mount the non-encrypted public partition:
 
-Now that keys have been updated with the new identity, they will need to be loaded to YubiKey.
+```console
+sudo mkdir /mnt/public
 
-First, [Reset](#reset) the OpenPGP applet, then follow the steps to [Configure YubiKey](#configure-yubikey) again.
+sudo mount /dev/mmcblk0p2 /mnt/public
+```
 
-Next, [Transfer Keys](#transfer-keys) and reboot or securely erase the temporary working directory.
+Copy the original private key materials to a temporary working directory:
 
-Finally, re-import the public key, as described in [Using Keys](#using-keys).
+```console
+GNUPGHOME=$(mktemp -d -t gnupg-$(date +%Y-%m-%d)-XXXXXXXXXX)
 
-Use `gpg -K` to verify the identity is listed.
+cp -rv /mnt/encrypted-storage/* $GNUPGHOME
+```
 
-# Require touch
+Confirm the identity is available, set it and the key fingerprint:
 
-**Note** This is not possible on YubiKey NEO.
+```console
+gpg -K
 
-By default, YubiKey will perform cryptographic operations without requiring any action from the user after the key is unlocked once with the PIN.
+KEYID=0xF0F2CFEB04341FB5
 
-To require a touch for each key operation, install [YubiKey Manager](https://developers.yubico.com/yubikey-manager/) and recall the Admin PIN:
+KEYFPR=$(gpg --fingerprint "$KEYID" | grep -Eo '([0-9A-F][0-9A-F ]{49})' | head -n 1 | tr -d ' ')
+```
 
-Encryption:
+Recall the identity passphrase and set it, for example:
 
 ```console
-ykman openpgp keys set-touch dec on
+PASS=ABCD-0123-IJKL-4567-QRST-UVWX
 ```
 
-Signature:
+## Renew Subkeys
+
+Determine the updated expiration, for example:
 
 ```console
-ykman openpgp keys set-touch sig on
+EXPIRATION=2026-09-01
+
+EXPIRATION=2y
 ```
 
-Authentication:
+Renew the Subkeys:
 
 ```console
-ykman openpgp keys set-touch aut on
+gpg --batch --pinentry-mode=loopback \
+  --passphrase "$PASS" --quick-set-expire "$KEYFPR" "$EXPIRATION" "*"
 ```
 
-**Note** Versions of YubiKey Manager before 5.1.0 use `enc` instead of `dec` for encryption.
+Export the updated public key:
 
-**Note** Older versions of YubiKey Manager use `touch` instead of `set-touch`
+```console
+gpg --armor --export $KEYID | sudo tee /mnt/public/$KEYID-$(date +%F).asc
+```
 
-To view and adjust policy options:
+Transfer the public key to the destination host and import it:
 
-```
-ykman openpgp keys set-touch -h
+```console
+gpg --import 0x*.asc
 ```
 
-If the YubiKey is going to be used within an email client which opens and verifies mail, `Cached` or `Cached-Fixed` may be desirable.
+Alternatively, publish to a public key server and download it:
 
-YubiKey will blink when it is waiting for a touch. On Linux, [maximbaz/yubikey-touch-detector](https://github.com/maximbaz/yubikey-touch-detector) can be used to indicate YubiKey is waiting for a touch.
+```console
+gpg --send-key $KEYID
 
-# Email
+gpg --recv $KEYID
+```
 
-YubiKey can be used to decrypt and sign emails and attachments using [Thunderbird](https://www.thunderbird.net/), [Enigmail](https://www.enigmail.net) and [Mutt](http://www.mutt.org/). Thunderbird supports OAuth 2 authentication and can be used with Gmail. See [this EFF guide](https://ssd.eff.org/en/module/how-use-pgp-linux) for more information. Mutt has OAuth 2 support since version 2.0.
+The validity of the GnuPG identity will be extended, allowing it to be used again for encryption and signature operations.
 
-## Mailvelope
+The SSH public key does **not** need to be updated on remote hosts.
 
-[Mailvelope](https://www.mailvelope.com/en) allows YubiKey to be used with Gmail and others.
+## Rotate Subkeys
 
-**Important** Mailvelope [does not work](https://github.com/drduh/YubiKey-Guide/issues/178) with the `throw-keyids` option set in `gpg.conf`
+Follow the original procedure to [Create Subkeys](#create-subkeys).
 
-On macOS, install gpgme using Homebrew:
+Previous Subkeys can be deleted from the identity.
 
-```console
-brew install gpgme
-```
+Finish by transfering new Subkeys to YubiKey.
 
-To allow Chrome to run gpgme, edit `~/Library/Application\ Support/Google/Chrome/NativeMessagingHosts/gpgmejson.json` to add:
+Copy the **new** temporary working directory to encrypted storage, which is still mounted:
 
-```json
-{
-    "name": "gpgmejson",
-    "description": "Integration with GnuPG",
-    "path": "/usr/local/bin/gpgme-json",
-    "type": "stdio",
-    "allowed_origins": [
-        "chrome-extension://kajibbejlbohfaggdiogboambcijhkke/"
-    ]
-}
+```console
+sudo cp -avi $GNUPGHOME /mnt/encrypted-storage
 ```
 
-Edit the default path to allow Chrome to find GnuPG:
+Unmount and close the encrypted volume:
 
 ```console
-sudo launchctl config user path /usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin
+sudo umount /mnt/encrypted-storage
+
+sudo cryptsetup luksClose /dev/mapper/secret
 ```
 
-Finally, install the [Mailvelope extension](https://chromewebstore.google.com/detail/mailvelope/kajibbejlbohfaggdiogboambcijhkke) from the Chrome web store.
+Export the updated public key:
 
-## Mutt
+```console
+sudo mkdir /mnt/public
 
-Mutt has both CLI and TUI interfaces - the latter provides powerful functions for processing email. In addition, PGP can be integrated such that cryptographic operations can be done without leaving TUI.
+sudo mount /dev/mmcblk0p2 /mnt/public
 
-To enable GnuPG support, copy `/usr/share/doc/mutt/samples/gpg.rc`
+gpg --armor --export $KEYID | sudo tee /mnt/public/$KEYID-$(date +%F).asc
 
-Edit the file to enable options `pgp_default_key`, `pgp_sign_as` and `pgp_autosign`
+sudo umount /mnt/public
+```
 
-`source` the file in `muttrc`
+Disconnect the storage device and follow the original steps to transfer new Subkeys (`4`, `5` and `6`) to YubiKey, replacing existing ones.
 
-**Important** `pinentry-tty` set as the pinentry program in `gpg-agent.conf` is reported to cause problems with Mutt TUI, because it uses curses. It is recommended to use `pinentry-curses` or other graphic pinentry program instead.
+Reboot or securely erase the GnuPG temporary working directory.
 
-# Reset
+# Reset YubiKey
 
 If PIN attempts are exceeded, the YubiKey is locked and must be [Reset](https://developers.yubico.com/ykneo-openpgp/ResetApplet.html) and set up again using the encrypted backup.
 
@@ -2600,21 +2042,17 @@ Reset code:  NOT SET
 Admin PIN:   12345678
 ```
 
-## Recovery after reset
-
-To reset YubiKey from the Certify key backup (such as the one on encrypted portable storage described in [Backup](#backup)), follow [Rotating keys](#rotating-keys) to setup the environment, then [Configure YubiKey](#configure-yubikey).
-
 # Notes
 
 1. YubiKey has two configurations, invoked with either a short or long press. By default, the short-press mode is configured for HID OTP; a brief touch will emit an OTP string starting with `cccccccc`. OTP mode can be swapped to the second configuration via the YubiKey Personalization tool or disabled entirely using [YubiKey Manager](https://developers.yubico.com/yubikey-manager): `ykman config usb -d OTP`
 
 1. Using YubiKey for GnuPG keys does not prevent use of other features, such as [WebAuthn](https://en.wikipedia.org/wiki/WebAuthn), [OTP](https://www.yubico.com/resources/glossary/otp/) and [static password](https://support.yubico.com/hc/en-us/articles/360016614980-Understanding-Core-Static-Password-Features).
 
-1. Setting a key expiry forces identity and credential lifecycle management. However, setting an expiry on the primary Certify key is useless, because it can be used to simply extend itself. [Revocation certificates](https://security.stackexchange.com/questions/14718/does-openpgp-key-expiration-add-to-security/79386#79386) should be used instead.
+1. Add additional identities to a Certify key with the `adduid` command during setup, then trust it ultimately with `trust` and `5` to configure for use.
 
-1. To switch between multiple identities on different YubiKeys, unplug the first YubiKey and restart gpg-agent, ssh-agent and pinentry with `pkill gpg-agent ; pkill ssh-agent ; pkill pinentry ; eval $(gpg-agent --daemon --enable-ssh-support)` then insert the other YubiKey and run `gpg-connect-agent updatestartuptty /bye`
+1. To switch between YubiKeys, unplug the first YubiKey and restart gpg-agent, ssh-agent and pinentry with `pkill "gpg-agent|ssh-agent|pinentry" ; eval $(gpg-agent --daemon --enable-ssh-support)` then insert the other YubiKey and run `gpg-connect-agent updatestartuptty /bye`
 
-1. To use YubiKey on multiple computers, import the corresponding public keys. Confirm see YubiKey is visible with `gpg --card-status`, then trust the imported public keys ultimately. `gpg --list-secret-keys` will show the correct and trusted key.
+1. To use YubiKey on multiple computers, import the corresponding public keys. Confirm see YubiKey is visible with `gpg --card-status`, then trust the imported public keys ultimately with `trust` and `5`. `gpg --list-secret-keys` will show the correct and trusted key.
 
 # Troubleshooting
 
@@ -2628,7 +2066,7 @@ To reset YubiKey from the Certify key backup (such as the one on encrypted porta
 
 - If you receive the error, `Yubikey core error: no yubikey present` - make sure the YubiKey is inserted correctly. It should blink once when plugged in.
 
-- If you still receive the error, `Yubikey core error: no yubikey present` - you likely need to install newer versions of yubikey-personalize as outlined in [Required software](#required-software).
+- If you still receive the error, `Yubikey core error: no yubikey present` - you likely need to install newer versions of yubikey-personalize as outlined in [Install software](#install-software).
 
 - If you receive the error, `Yubikey core error: write error` - YubiKey is likely locked. Install and run yubikey-personalization-gui to unlock it.
 
@@ -2667,12 +2105,11 @@ gpg: [stdin]: encryption failed: Unusable public key
 
 - If you receive the error, `gpg: 0x0000000000000000: skipped: Unusable public key`, `signing failed: Unusable secret key`, or `encryption failed: Unusable public key` the Subkey may be expired and can no longer be used to encrypt nor sign messages. It can still be used to decrypt and authenticate, however.
 
-- If the GnuPG public key is lost, follow [this guide](https://www.nicksherlock.com/2021/08/recovering-lost-gpg-public-keys-from-your-yubikey/) to recover it from YubiKey.
-
-- Refer to Yubico article [Troubleshooting Issues with GPG](https://support.yubico.com/hc/en-us/articles/360013714479-Troubleshooting-Issues-with-GPG) for additional guidance.
+- If the _pinentry_ graphical dialog does not show and this error appears: `sign_and_send_pubkey: signing failed: agent refused operation`, install the `dbus-user-session` package and restart for the `dbus` user session to be fully inherited. This is because `pinentry` complains about `No $DBUS_SESSION_BUS_ADDRESS found`, falls back to `curses` but doesn't find the expected `tty`
 
 - If, when you try the above `--card-status` command, you get receive the error, `gpg: selecting card failed: No such device` or `gpg: OpenPGP card not available: No such device`, it's possible that the latest release of pcscd is now requires polkit rules to operate properly. Create the following file to allow users in the `wheel` group to use the card. Be sure to restart pcscd when you're done to allow the new rules to take effect.
-```
+
+```console
 cat << EOF >  /etc/polkit-1/rules.d/99-pcscd.rules
 polkit.addRule(function(action, subject) {
         if (action.id == "org.debian.pcsc-lite.access_card" &&
@@ -2689,41 +2126,15 @@ polkit.addRule(function(action, subject) {
 EOF
 ```
 
-# Alternatives
-
-* [`smlx/piv-agent`](https://github.com/smlx/piv-agent) - SSH and GnuPG agent which can be used with PIV devices
-* [`keytotpm`](https://www.gnupg.org/documentation/manuals/gnupg/OpenPGP-Key-Management.html) - use GnuPG with TPM systems
-
-## Create keys with batch
-
-Keys can also be generated using template files and the `batch` parameter - see [GnuPG documentation](https://www.gnupg.org/documentation/manuals/gnupg/Unattended-GPG-key-generation.html).
-
-Use the example [gen-params-rsa4096](contrib/gen-params-rsa4096) or [gen-params-ed25519](contrib/gen-params-ed25519) template (the latter requires GnuPG v2.1.7).
-
-Generate the Certify key:
-
-```console
-gpg --batch --generate-key gen-params-rsa4096
-```
-
-Verify the Certify key:
+- If the public key is lost, follow [this guide](https://www.nicksherlock.com/2021/08/recovering-lost-gpg-public-keys-from-your-yubikey/) to recover it from YubiKey.
 
-```console
-gpg --list-key
-```
-
-Export the Certify key ID, extract its fingerprint and create the Subkeys:
-
-```console
-export KEYID=0xF0F2CFEB04341FB5
-KEYFPR=$(gpg --fingerprint "$KEYID" | grep -Eo '([0-9A-F][0-9A-F ]{49})' | head -n 1 | tr -d ' ')
-
-gpg --quick-add-key "$KEYFPR" rsa4096 sign 2y
+- Refer to Yubico article [Troubleshooting Issues with GPG](https://support.yubico.com/hc/en-us/articles/360013714479-Troubleshooting-Issues-with-GPG) for additional guidance.
 
-gpg --quick-add-key "$KEYFPR" rsa4096 encrypt 2y
+# Alternative solutions
 
-gpg --quick-add-key "$KEYFPR" rsa4096 auth 2y
-```
+* [`vorburger/ed25519-sk.md`](https://github.com/vorburger/vorburger.ch-Notes/blob/develop/security/ed25519-sk.md) - use YubiKey for SSH without GnuPG
+* [`smlx/piv-agent`](https://github.com/smlx/piv-agent) - SSH and GnuPG agent which can be used with PIV devices
+* [`keytotpm`](https://www.gnupg.org/documentation/manuals/gnupg/OpenPGP-Key-Management.html) - use GnuPG with TPM systems
 
 # Additional resources