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How to generate and air gap PGP private keys using GnuPG, Tails and YubiKey
Heads-up: guide inspired by https://github.com/drduh/YubiKey-Guide.
Requirements
- Tails USB flash drive or SD card with VeraCrypt installed
- YubiKey with OpenPGP support (firmware version
5.2.3or higher) - Computer running macOS Catalina or Big Sur
Caveats
- When copy/pasting commands that start with
$, strip out$as this character is not part of the command - When copy/pasting commands that start with
cat << "EOF", select all lines at once (fromcat << "EOF"toEOFinclusively) as they are part of the same (single) command
Setup guide (on Tails)
Step 1: boot to Tails and set admin password
Heads-up: if keyboard layout of computer isn’t “English (US)”, set “Keyboard Layout”.
Click “+” under ”Additional Settings”, then “Administration Password”, set password, click “Add” and finally “Start Tails”.
Step 2: establish network connection using ethernet cable or Wi-Fi and wait for Tor to be ready
Connected to Tor successfully
👍
Step 3: import Dennis Fokin’s and Emil Lundberg’s PGP public keys (used to verify downloads below)
Heads-up: release may be signed by another Yubico developer.
$ gpg --keyserver hkps://keys.openpgp.org --search-keys 9E885C0302F9BB9167529C2D5CBA11E6ADC7BCD1
gpg: data source: https://keys.openpgp.org:443
(1) Dennis Fokin <dennis.fokin@yubico.com>
4096 bit RSA key 0x5CBA11E6ADC7BCD1, created: 2019-09-17
Keys 1-1 of 1 for "9E885C0302F9BB9167529C2D5CBA11E6ADC7BCD1". Enter number(s), N)ext, or Q)uit > 1
gpg: key 0x5CBA11E6ADC7BCD1: public key "Dennis Fokin <dennis.fokin@yubico.com>" imported
gpg: Total number processed: 1
gpg: imported: 1
$ gpg --keyserver hkps://keys.openpgp.org --search-keys 57a9deed4c6d962a923bb691816f3ed99921835e
gpg: data source: https://keys.openpgp.org:443
(1) Emil Lundberg (Software Developer) <emil@yubico.com>
4096 bit RSA key 0x816F3ED99921835E, created: 2017-08-03
Keys 1-1 of 1 for "57a9deed4c6d962a923bb691816f3ed99921835e". Enter number(s), N)ext, or Q)uit > 1
gpg: key 0x816F3ED99921835E: public key "Emil Lundberg (Software Developer) <emil@yubico.com>" imported
gpg: Total number processed: 1
gpg: imported: 1
imported: 1
👍
Step 4: download YubiKey Manager AppImage release and associated PGP signature
$ torsocks curl -L -o ~/Downloads/yubikey-manager-qt.AppImage https://developers.yubico.com/yubikey-manager-qt/Releases/yubikey-manager-qt-latest-linux.AppImage
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 281 100 281 0 0 200 0 0:00:01 0:00:01 --:--:-- 200
100 81.9M 100 81.9M 0 0 457k 0 0:03:03 0:03:03 --:--:-- 818k
$ torsocks curl -L -o ~/Downloads/yubikey-manager-qt.AppImage.sig https://developers.yubico.com/yubikey-manager-qt/Releases/yubikey-manager-qt-latest-linux.AppImage.sig
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 285 100 285 0 0 215 0 0:00:01 0:00:01 --:--:-- 215
100 310 100 310 0 0 184 0 0:00:01 0:00:01 --:--:-- 0
Step 5: verify “YubiKey Manager” AppImage release (learn how here) and make AppImage executable
$ gpg --verify ~/Downloads/yubikey-manager-qt.AppImage.sig
gpg: assuming signed data in '/home/amnesia/Downloads/yubikey-manager-qt.AppImage'
gpg: Signature made Mon 23 Aug 10:16:06 2021 EDT
gpg: using RSA key 159CD7E4AF75DF3C5638BBCDD8588A5844E2A774
gpg: Good signature from "Emil Lundberg (Software Developer) <emil@yubico.com>" [unknown]
gpg: WARNING: This key is not certified with a trusted signature!
gpg: There is no indication that the signature belongs to the owner.
Primary key fingerprint: 57A9 DEED 4C6D 962A 923B B691 816F 3ED9 9921 835E
Subkey fingerprint: 159C D7E4 AF75 DF3C 5638 BBCD D858 8A58 44E2 A774
$ chmod +x ~/Downloads/yubikey-manager-qt.AppImage
Good signature
👍
Step 6: create and source ykman Bash alias
echo 'alias ykman="$HOME/Downloads/yubikey-manager-qt.AppImage ykman"' >> ~/.bashrc
source ~/.bashrc
Step 7 (optional): copy “YubiKey Manager” AppImage to “Persistent” folder (requires Tails “Personal Data” persistence feature to be enabled)
Heads-up: once copied, one can persistently run
~/Downloads/yubikey-manager-qt.AppImage ykmanto manage YubiKeys.
cp ~/Downloads/yubikey-manager-qt.AppImage ~/Persistent/
Step 8: generate master key (used to sign signing, encryption and authentication subkeys)
When asked for passphrase, create and memorize strong passphrase or use output from gpg --gen-random --armor 0 24 (and store password in air-gapped password manager).
$ gpg --expert --full-generate-key
gpg (GnuPG) 2.2.12; Copyright (C) 2018 Free Software Foundation, Inc.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
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
Your selection? 11
Possible actions for a ECDSA/EdDSA key: Sign Certify Authenticate
Current allowed actions: Sign Certify
(S) Toggle the sign capability
(A) Toggle the authenticate capability
(Q) Finished
Your selection? S
Possible actions for a ECDSA/EdDSA key: Sign Certify Authenticate
Current allowed actions: Certify
(S) Toggle the sign capability
(A) Toggle the authenticate capability
(Q) Finished
Your selection? Q
Please select which elliptic curve you want:
(1) Curve 25519
(3) NIST P-256
(4) NIST P-384
(5) NIST P-521
(6) Brainpool P-256
(7) Brainpool P-384
(8) Brainpool P-512
(9) secp256k1
Your selection? 1
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
GnuPG needs to construct a user ID to identify your key.
Real name: John Doe
Email address: john@example.net
Comment:
You selected this USER-ID:
"John Doe <john@example.net>"
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: key 0xC2709D13BAB4763C marked as ultimately trusted
gpg: directory '/home/amnesia/.gnupg/openpgp-revocs.d' created
gpg: revocation certificate stored as '/home/amnesia/.gnupg/openpgp-revocs.d/C82270B62BA89271A00A6037C2709D13BAB4763C.rev'
public and secret key created and signed.
pub ed25519/0xC2709D13BAB4763C 2021-07-21 [C]
Key fingerprint = C822 70B6 2BA8 9271 A00A 6037 C270 9D13 BAB4 763C
uid John Doe <john@example.net>
Step 9: set master key ID environment variable
Replace 0xC2709D13BAB4763C with master key ID.
KEY_ID=0xC2709D13BAB4763C
Step 10 (optional): sign master key using another master key
Import signing master key (if necessary)
Replace /path/to/signing/master.asc with signing master key path.
$ gpg --import /path/to/signing/master.asc
gpg: key 0xDFCECB410CE8A745: public key "John Doe <john@example.net>" imported
gpg: key 0xDFCECB410CE8A745: secret key imported
gpg: Total number processed: 1
gpg: imported: 1
gpg: secret keys read: 1
gpg: secret keys imported: 1
Sign master key
Replace 0xDFCECB410CE8A745 with signing master key ID.
$ gpg --ask-cert-level --default-key 0xDFCECB410CE8A745 --sign-key $KEY_ID
sec ed25519/0xC2709D13BAB4763C
created: 2021-07-21 expires: never usage: C
trust: ultimate validity: ultimate
[ultimate] (1). John Doe <john@example.net>
gpg: using "0xDFCECB410CE8A745" as default secret key for signing
sec ed25519/0xC2709D13BAB4763C
created: 2021-07-21 expires: never usage: C
trust: ultimate validity: ultimate
Primary key fingerprint: C822 70B6 2BA8 9271 A00A 6037 C270 9D13 BAB4 763C
John Doe <john@example.net>
How carefully have you verified the key you are about to sign actually belongs
to the person named above? If you don't know what to answer, enter "0".
(0) I will not answer. (default)
(1) I have not checked at all.
(2) I have done casual checking.
(3) I have done very careful checking.
Your selection? (enter '?' for more information): 3
Are you sure that you want to sign this key with your
key "John Doe <john@example.net>" (0xDFCECB410CE8A745)
I have checked this key very carefully.
Really sign? (y/N) y
Step 11: create signing, encryption and authentication subkeys
$ gpg --expert --edit-key $KEY_ID
gpg (GnuPG) 2.2.12; Copyright (C) 2018 Free Software Foundation, Inc.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Secret key is available.
sec ed25519/0xC2709D13BAB4763C
created: 2021-07-21 expires: never usage: C
trust: ultimate validity: ultimate
[ultimate] (1). John Doe <john@example.net>
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
Your selection? 10
Please select which elliptic curve you want:
(1) Curve 25519
(3) NIST P-256
(4) NIST P-384
(5) NIST P-521
(6) Brainpool P-256
(7) Brainpool P-384
(8) Brainpool P-512
(9) secp256k1
Your selection? 1
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) 1y
Key expires at Thu 21 Jul 2022 03:21:04 PM UTC
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 ed25519/0xC2709D13BAB4763C
created: 2021-07-21 expires: never usage: C
trust: ultimate validity: ultimate
ssb ed25519/0x02EDC61B6543509B
created: 2021-07-21 expires: 2022-07-21 usage: S
[ultimate] (1). John Doe <john@example.net>
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
Your selection? 12
Please select which elliptic curve you want:
(1) Curve 25519
(3) NIST P-256
(4) NIST P-384
(5) NIST P-521
(6) Brainpool P-256
(7) Brainpool P-384
(8) Brainpool P-512
(9) secp256k1
Your selection? 1
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) 1y
Key expires at Thu 21 Jul 2022 03:21:25 PM UTC
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 ed25519/0xC2709D13BAB4763C
created: 2021-07-21 expires: never usage: C
trust: ultimate validity: ultimate
ssb ed25519/0x02EDC61B6543509B
created: 2021-07-21 expires: 2022-07-21 usage: S
ssb cv25519/0xD4634E0D6E2DD8BF
created: 2021-07-21 expires: 2022-07-21 usage: E
[ultimate] (1). John Doe <john@example.net>
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
Your selection? 11
Possible actions for a ECDSA/EdDSA key: Sign Authenticate
Current allowed actions: Sign
(S) Toggle the sign capability
(A) Toggle the authenticate capability
(Q) Finished
Your selection? S
Possible actions for a ECDSA/EdDSA key: Sign Authenticate
Current allowed actions:
(S) Toggle the sign capability
(A) Toggle the authenticate capability
(Q) Finished
Your selection? A
Possible actions for a ECDSA/EdDSA key: Sign Authenticate
Current allowed actions: Authenticate
(S) Toggle the sign capability
(A) Toggle the authenticate capability
(Q) Finished
Your selection? Q
Please select which elliptic curve you want:
(1) Curve 25519
(3) NIST P-256
(4) NIST P-384
(5) NIST P-521
(6) Brainpool P-256
(7) Brainpool P-384
(8) Brainpool P-512
(9) secp256k1
Your selection? 1
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) 1y
Key expires at Thu 21 Jul 2022 03:21:53 PM UTC
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 ed25519/0xC2709D13BAB4763C
created: 2021-07-21 expires: never usage: C
trust: ultimate validity: ultimate
ssb ed25519/0x02EDC61B6543509B
created: 2021-07-21 expires: 2022-07-21 usage: S
ssb cv25519/0xD4634E0D6E2DD8BF
created: 2021-07-21 expires: 2022-07-21 usage: E
ssb ed25519/0x1E7B69B238FFA21B
created: 2021-07-21 expires: 2022-07-21 usage: A
[ultimate] (1). John Doe <john@example.net>
gpg> save
Step 12: mount backup volume (formatted using exFAT)
Click “Places”, then “Home”, then backup volume (“Samsung BAR” in example below), enter admin password and finally click “Authenticate”.
Step 13: set backup volume name environment variable
VOLUME_NAME="Samsung BAR"
Step 14: create VeraCrypt encrypted volume (used to store master key and subkeys)
$ /home/amnesia/Persistent/veracrypt --text --create "/media/amnesia/$VOLUME_NAME/tails"
Volume type:
1) Normal
2) Hidden
Select [1]: 1
Enter volume size (sizeK/size[M]/sizeG): 10M
Encryption Algorithm:
1) AES
2) Serpent
3) Twofish
4) Camellia
5) Kuznyechik
6) AES(Twofish)
7) AES(Twofish(Serpent))
8) Camellia(Kuznyechik)
9) Camellia(Serpent)
10) Kuznyechik(AES)
11) Kuznyechik(Serpent(Camellia))
12) Kuznyechik(Twofish)
13) Serpent(AES)
14) Serpent(Twofish(AES))
15) Twofish(Serpent)
Select [1]: 7
Hash algorithm:
1) SHA-512
2) Whirlpool
3) SHA-256
4) Streebog
Select [1]: 1
Filesystem:
1) None
2) FAT
3) Linux Ext2
4) Linux Ext3
5) Linux Ext4
6) NTFS
7) exFAT
8) Btrfs
Select [2]: 2
Enter password:
Re-enter password:
Enter PIM:
Enter keyfile path [none]:
Please type at least 320 randomly chosen characters and then press Enter:
Done: 100.000% Speed: 2.7 MiB/s Left: 0 s
The VeraCrypt volume has been successfully created.
The VeraCrypt volume has been successfully created.
👍
Step 15: mount VeraCrypt encrypted volume
Click “Applications”, then “Utilities”, then “Unlock VeraCrypt Volumes”, then “Add”, select “tails” file on backup volume, click “Open”, enter password and finally click “Unlock”.
Step 16: rename VeraCrypt encrypted volume
Replace tcrypt-1793 with directory found using ls /dev/mapper and ignore dirty bit is set error.
$ ls /dev/mapper
control TailsData_unlocked tcrypt-1793 tcrypt-1793_1 tcrypt-1793_2
$ sudo fatlabel /dev/mapper/tcrypt-1793 Tails
We trust you have received the usual lecture from the local System
Administrator. It usually boils down to these three things:
#1) Respect the privacy of others.
#2) Think before you type.
#3) With great power comes great responsibility.
[sudo] password for amnesia:
fatlabel: warning - lowercase labels might not work properly with DOS or Windows
0x25: Dirty bit is set. Fs was not properly unmounted and some data may be corrupt.
Automatically removing dirty bit.
Step 17: set VeraCrypt encrypted volume name environment variable
Replace 3FDC-B4EB with directory found using ls /media/amnesia.
$ ls /media/amnesia
3FDC-B4EB LaCie 'Samsung BAR'
$ ENCRYPTED_VOLUME_NAME="3FDC-B4EB"
Step 18: export master key, subkeys and public key to VeraCrypt encrypted volume
$ gpg --armor --export-secret-keys $KEY_ID > /media/amnesia/$ENCRYPTED_VOLUME_NAME/master.asc
$ gpg --armor --export-secret-subkeys $KEY_ID > /media/amnesia/$ENCRYPTED_VOLUME_NAME/sub.asc
$ gpg --armor --export $KEY_ID > /media/amnesia/$ENCRYPTED_VOLUME_NAME/pub.asc
Step 19: copy public key to backup volume
Replace johndoe with name associated to master key.
cp /media/amnesia/$ENCRYPTED_VOLUME_NAME/pub.asc "/media/amnesia/$VOLUME_NAME/johndoe.asc"
Step 20: dismount VeraCrypt encrypted volume
Click “Applications”, then “Utilities”, then “Unlock VeraCrypt Volumes” and finally click “x”.
Step 21: back up tails file
Heads-up: files stored in
tailsinclude private keys which, if lost, results in loosing one’s cryptographic identity (safeguard backup mindfully).
Heads-up: never unlock
tailson macOS (or any other computer that isn’t air-gapped and hardened).
Step 22: insert and provision YubiKey
Heads-up: default user PIN is
123456and default admin PIN is12345678.
$ gpg --card-edit
Reader ...........: 1050:0404:X:0
Application ID ...: D*******************************
Version ..........: 3.4
Manufacturer .....: Yubico
Serial number ....: 1*******
Name of cardholder: [not set]
Language prefs ...: [not set]
Sex ..............: unspecified
URL of public key : [not set]
Login data .......: [not set]
Signature PIN ....: not forced
Key attributes ...: rsa2048 rsa2048 rsa2048
Max. PIN lengths .: 127 127 127
PIN retry counter : 3 0 3
Signature counter : 0
KDF setting ......: on
Signature key ....: [none]
Encryption key....: [none]
Authentication key: [none]
General key info..: [none]
gpg/card> admin
Admin commands are allowed
gpg/card> passwd
gpg: OpenPGP card no. D******************************* detected
1 - change PIN
2 - unblock PIN
3 - change Admin PIN
4 - set the Reset Code
Q - quit
Your selection? 1
PIN changed.
1 - change PIN
2 - unblock PIN
3 - change Admin PIN
4 - set the Reset Code
Q - quit
Your selection? 3
PIN changed.
1 - change PIN
2 - unblock PIN
3 - change Admin PIN
4 - set the Reset Code
Q - quit
Your selection? Q
gpg/card> name
Cardholder's surname: Doe
Cardholder's given name: John
gpg/card> lang
Language preferences: en
gpg/card> login
Login data (account name): john@example.net
gpg/card> list
Reader ...........: 1050:0404:X:0
Application ID ...: D*******************************
Version ..........: 3.4
Manufacturer .....: Yubico
Serial number ....: 1*******
Name of cardholder: John Doe
Language prefs ...: en
Sex ..............: unspecified
URL of public key : [not set]
Login data .......: john@example.net
Signature PIN ....: not forced
Key attributes ...: rsa2048 rsa2048 rsa2048
Max. PIN lengths .: 127 127 127
PIN retry counter : 3 0 3
Signature counter : 0
KDF setting ......: on
Signature key ....: [none]
Encryption key....: [none]
Authentication key: [none]
General key info..: [none]
gpg/card> quit
Step 23: move signing, encryption and authentication subkeys to YubiKey
$ gpg --edit-key $KEY_ID
gpg (GnuPG) 2.2.12; Copyright (C) 2018 Free Software Foundation, Inc.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Secret key is available.
sec ed25519/0xC2709D13BAB4763C
created: 2021-07-21 expires: never usage: C
trust: ultimate validity: ultimate
ssb ed25519/0x02EDC61B6543509B
created: 2021-07-21 expires: 2022-07-21 usage: S
ssb cv25519/0xD4634E0D6E2DD8BF
created: 2021-07-21 expires: 2022-07-21 usage: E
ssb ed25519/0x1E7B69B238FFA21B
created: 2021-07-21 expires: 2022-07-21 usage: A
[ultimate] (1). John Doe <john@example.net>
gpg> key 1
sec ed25519/0xC2709D13BAB4763C
created: 2021-07-21 expires: never usage: C
trust: ultimate validity: ultimate
ssb* ed25519/0x02EDC61B6543509B
created: 2021-07-21 expires: 2022-07-21 usage: S
ssb cv25519/0xD4634E0D6E2DD8BF
created: 2021-07-21 expires: 2022-07-21 usage: E
ssb ed25519/0x1E7B69B238FFA21B
created: 2021-07-21 expires: 2022-07-21 usage: A
[ultimate] (1). John Doe <john@example.net>
gpg> keytocard
Please select where to store the key:
(1) Signature key
(3) Authentication key
Your selection? 1
sec ed25519/0xC2709D13BAB4763C
created: 2021-07-21 expires: never usage: C
trust: ultimate validity: ultimate
ssb* ed25519/0x02EDC61B6543509B
created: 2021-07-21 expires: 2022-07-21 usage: S
ssb cv25519/0xD4634E0D6E2DD8BF
created: 2021-07-21 expires: 2022-07-21 usage: E
ssb ed25519/0x1E7B69B238FFA21B
created: 2021-07-21 expires: 2022-07-21 usage: A
[ultimate] (1). John Doe <john@example.net>
gpg> key 1
sec ed25519/0xC2709D13BAB4763C
created: 2021-07-21 expires: never usage: C
trust: ultimate validity: ultimate
ssb ed25519/0x02EDC61B6543509B
created: 2021-07-21 expires: 2022-07-21 usage: S
ssb cv25519/0xD4634E0D6E2DD8BF
created: 2021-07-21 expires: 2022-07-21 usage: E
ssb ed25519/0x1E7B69B238FFA21B
created: 2021-07-21 expires: 2022-07-21 usage: A
[ultimate] (1). John Doe <john@example.net>
gpg> key 2
sec ed25519/0xC2709D13BAB4763C
created: 2021-07-21 expires: never usage: C
trust: ultimate validity: ultimate
ssb ed25519/0x02EDC61B6543509B
created: 2021-07-21 expires: 2022-07-21 usage: S
ssb* cv25519/0xD4634E0D6E2DD8BF
created: 2021-07-21 expires: 2022-07-21 usage: E
ssb ed25519/0x1E7B69B238FFA21B
created: 2021-07-21 expires: 2022-07-21 usage: A
[ultimate] (1). John Doe <john@example.net>
gpg> keytocard
Please select where to store the key:
(2) Encryption key
Your selection? 2
sec ed25519/0xC2709D13BAB4763C
created: 2021-07-21 expires: never usage: C
trust: ultimate validity: ultimate
ssb ed25519/0x02EDC61B6543509B
created: 2021-07-21 expires: 2022-07-21 usage: S
ssb* cv25519/0xD4634E0D6E2DD8BF
created: 2021-07-21 expires: 2022-07-21 usage: E
ssb ed25519/0x1E7B69B238FFA21B
created: 2021-07-21 expires: 2022-07-21 usage: A
[ultimate] (1). John Doe <john@example.net>
gpg> key 2
sec ed25519/0xC2709D13BAB4763C
created: 2021-07-21 expires: never usage: C
trust: ultimate validity: ultimate
ssb ed25519/0x02EDC61B6543509B
created: 2021-07-21 expires: 2022-07-21 usage: S
ssb cv25519/0xD4634E0D6E2DD8BF
created: 2021-07-21 expires: 2022-07-21 usage: E
ssb ed25519/0x1E7B69B238FFA21B
created: 2021-07-21 expires: 2022-07-21 usage: A
[ultimate] (1). John Doe <john@example.net>
gpg> key 3
sec ed25519/0xC2709D13BAB4763C
created: 2021-07-21 expires: never usage: C
trust: ultimate validity: ultimate
ssb ed25519/0x02EDC61B6543509B
created: 2021-07-21 expires: 2022-07-21 usage: S
ssb cv25519/0xD4634E0D6E2DD8BF
created: 2021-07-21 expires: 2022-07-21 usage: E
ssb* ed25519/0x1E7B69B238FFA21B
created: 2021-07-21 expires: 2022-07-21 usage: A
[ultimate] (1). John Doe <john@example.net>
gpg> keytocard
Please select where to store the key:
(3) Authentication key
Your selection? 3
sec ed25519/0xC2709D13BAB4763C
created: 2021-07-21 expires: never usage: C
trust: ultimate validity: ultimate
ssb ed25519/0x02EDC61B6543509B
created: 2021-07-21 expires: 2022-07-21 usage: S
ssb cv25519/0xD4634E0D6E2DD8BF
created: 2021-07-21 expires: 2022-07-21 usage: E
ssb* ed25519/0x1E7B69B238FFA21B
created: 2021-07-21 expires: 2022-07-21 usage: A
[ultimate] (1). John Doe <john@example.net>
gpg> save
Step 24: require YubiKey user interaction for signing, encryption and authentication operations
$ ykman openpgp keys set-touch sig on --force
Enter Admin PIN:
$ ykman openpgp keys set-touch enc on --force
Enter Admin PIN:
$ ykman openpgp keys set-touch aut on --force
Enter Admin PIN:
$ ykman openpgp keys set-touch att on --force
Enter Admin PIN:
$ ykman openpgp info
OpenPGP version: 3.4
Application version: 5.4.3
PIN tries remaining: 3
Reset code tries remaining: 0
Admin PIN tries remaining: 3
Touch policies
Signature key On
Encryption key On
Authentication key On
Attestation key On
On
👍
Step 25 (optional): disable all YubiKey interfaces except for OpenPGP over USB
Heads-up: increase
sleepdelay if “Error: No YubiKey detected!” error is thrown.
$ ykman config usb --disable FIDO2 --disable HSMAUTH --disable OATH --disable OTP --disable PIV --disable U2F --enable OPENPGP --force
$ ykman config nfc --disable-all --force
Step 26 (optional): enable YubiKey configuration lock
Heads-up: configuration lock prevents configuring YubiKey without entering lock code (store lock code in air-gapped password manager).
$ ykman config set-lock-code --generate
Using a randomly generated lock code: cce9181f4a97bac00459419986510d40
Lock configuration with this lock code? [y/N]: y
Step 27 (optional): extend expiry date of signing, encryption and authentication subkeys (required once a year)
Mount backup volume (formatted using exFAT)
Click “Places”, then “Home”, then backup volume (“Samsung BAR” in example below), enter admin password and finally click “Authenticate”.
Mount VeraCrypt encrypted volume
Click “Applications”, then “Utilities”, then “Unlock VeraCrypt Volumes”, then “Add”, select “tails” file on backup volume, click “Open”, enter password and finally click “Unlock”.
Import master key
$ gpg --import /media/amnesia/Tails/master.asc
gpg: key 0xC2709D13BAB4763C: 1 signature not checked due to a missing key
gpg: key 0xC2709D13BAB4763C: public key "John Doe <john@example.net>" imported
gpg: key 0xC2709D13BAB4763C: secret key imported
gpg: Total number processed: 1
gpg: imported: 1
gpg: secret keys read: 1
gpg: secret keys imported: 1
gpg: no ultimately trusted keys found
Set master key ID environment variable
KEY_ID=0xC2709D13BAB4763C
Extend expiry date of signing, encryption and authentication subkeys
$ gpg --edit-key $KEY_ID
gpg (GnuPG) 2.2.12; Copyright (C) 2018 Free Software Foundation, Inc.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Secret key is available.
sec ed25519/0xC2709D13BAB4763C
created: 2021-07-21 expires: never usage: C
trust: unknown validity: unknown
ssb ed25519/0x02EDC61B6543509B
created: 2021-07-21 expires: 2022-07-21 usage: S
ssb cv25519/0xD4634E0D6E2DD8BF
created: 2021-07-21 expires: 2022-07-21 usage: E
ssb ed25519/0x1E7B69B238FFA21B
created: 2021-07-21 expires: 2022-07-21 usage: A
[ unknown] (1). John Doe <john@example.net>
gpg> key 1
sec ed25519/0xC2709D13BAB4763C
created: 2021-07-21 expires: never usage: C
trust: unknown validity: unknown
ssb* ed25519/0x02EDC61B6543509B
created: 2021-07-21 expires: 2022-07-21 usage: S
ssb cv25519/0xD4634E0D6E2DD8BF
created: 2021-07-21 expires: 2022-07-21 usage: E
ssb ed25519/0x1E7B69B238FFA21B
created: 2021-07-21 expires: 2022-07-21 usage: A
[ unknown] (1). John Doe <john@example.net>
gpg> key 2
sec ed25519/0xC2709D13BAB4763C
created: 2021-07-21 expires: never usage: C
trust: unknown validity: unknown
ssb* ed25519/0x02EDC61B6543509B
created: 2021-07-21 expires: 2022-07-21 usage: S
ssb* cv25519/0xD4634E0D6E2DD8BF
created: 2021-07-21 expires: 2022-07-21 usage: E
ssb ed25519/0x1E7B69B238FFA21B
created: 2021-07-21 expires: 2022-07-21 usage: A
[ unknown] (1). John Doe <john@example.net>
gpg> key 3
sec ed25519/0xC2709D13BAB4763C
created: 2021-07-21 expires: never usage: C
trust: unknown validity: unknown
ssb* ed25519/0x02EDC61B6543509B
created: 2021-07-21 expires: 2022-07-21 usage: S
ssb* cv25519/0xD4634E0D6E2DD8BF
created: 2021-07-21 expires: 2022-07-21 usage: E
ssb* ed25519/0x1E7B69B238FFA21B
created: 2021-07-21 expires: 2022-07-21 usage: A
[ unknown] (1). John Doe <john@example.net>
gpg> expire
Are you sure you want to change the expiration time for multiple subkeys? (y/N) y
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) 1y
Key expires at Thu 21 Jul 2022 03:32:11 PM UTC
Is this correct? (y/N) y
sec ed25519/0xC2709D13BAB4763C
created: 2021-07-21 expires: never usage: C
trust: unknown validity: unknown
ssb* ed25519/0x02EDC61B6543509B
created: 2021-07-21 expires: 2022-07-21 usage: S
ssb* cv25519/0xD4634E0D6E2DD8BF
created: 2021-07-21 expires: 2022-07-21 usage: E
ssb* ed25519/0x1E7B69B238FFA21B
created: 2021-07-21 expires: 2022-07-21 usage: A
[ unknown] (1). John Doe <john@example.net>
gpg> save
Export public key to VeraCrypt encrypted volume
$ gpg --armor --export $KEY_ID > /media/amnesia/Tails/pub.asc
Copy public key to backup volume
Replace Samsung BAR with backup volume name and johndoe with name associated to master key.
cp /media/amnesia/Tails/pub.asc "/media/amnesia/Samsung BAR/johndoe.asc"
Dismount VeraCrypt encrypted volume
Click “Applications”, then “Utilities”, then “Unlock VeraCrypt Volumes” and finally click “x”.
Step 28: shutdown computer
👍
Usage guide (on macOS)
Step 1: install Homebrew
$ /bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install.sh)"
$ uname -m | grep arm64 && echo 'export PATH=$PATH:/opt/homebrew/bin' >> ~/.zshrc && source ~/.zshrc
Step 2: disable Homebrew analytics
brew analytics off
Step 3: install GnuPG and pinentry-mac
brew install gnupg pinentry-mac
Step 4: import public key
Replace Samsung BAR with backup volume name and johndoe with name associated to master key.
$ gpg --keyid-format 0xlong --import "/Volumes/Samsung BAR/johndoe.asc"
gpg: directory '/Users/sunknudsen/.gnupg' created
gpg: keybox '/Users/sunknudsen/.gnupg/pubring.kbx' created
gpg: key 0xC2709D13BAB4763C: 1 signature not checked due to a missing key
gpg: /Users/sunknudsen/.gnupg/trustdb.gpg: trustdb created
gpg: key 0xC2709D13BAB4763C: public key "John Doe <john@example.net>" imported
gpg: Total number processed: 1
gpg: imported: 1
gpg: no ultimately trusted keys found
Step 5: insert YubiKey and import private key stubs
$ gpg --card-status
Reader ...........: Yubico YubiKey CCID
Application ID ...: D*******************************
Application type .: OpenPGP
Version ..........: 0.0
Manufacturer .....: Yubico
Serial number ....: 1*******
Name of cardholder: John Doe
Language prefs ...: en
Salutation .......:
URL of public key : [not set]
Login data .......: john@example.net
Signature PIN ....: not forced
Key attributes ...: ed25519 cv25519 ed25519
Max. PIN lengths .: 127 127 127
PIN retry counter : 3 0 3
Signature counter : 0
KDF setting ......: off
UIF setting ......: Sign=on Decrypt=on Auth=on
Signature key ....: ACE1 3F15 90C1 A8C9 D942 51E3 02ED C61B 6543 509B
created ....: 2021-07-21 18:44:34
Encryption key....: 0524 00F4 8E1D 085A F3E1 61EC D463 4E0D 6E2D D8BF
created ....: 2021-07-21 18:44:52
Authentication key: A27B 582F 1F62 03BA 549B 3D44 1E7B 69B2 38FF A21B
created ....: 2021-07-21 18:45:13
General key info..: sub ed25519/0x02EDC61B6543509B 2021-07-21 John Doe <john@example.net>
sec# ed25519/0xC2709D13BAB4763C created: 2021-07-21 expires: never
ssb> ed25519/0x02EDC61B6543509B created: 2021-07-21 expires: 2022-07-21
card-no: 0006 1*******
ssb> cv25519/0xD4634E0D6E2DD8BF created: 2021-07-21 expires: 2022-07-21
card-no: 0006 1*******
ssb> ed25519/0x1E7B69B238FFA21B created: 2021-07-21 expires: 2022-07-21
card-no: 0006 1*******
👍
Step 6: set master key ID environment variable
Replace 0xC2709D13BAB4763C with master key ID.
KEY_ID=0xC2709D13BAB4763C
Step 7: configure GnuPG
Create or override dirmngr.conf
Heads-up: back up current config using cp ~/.gnupg/dirmngr.conf ~/.gnupg/dirmngr.conf.backup (if necessary).
cat << "EOF" > ~/.gnupg/dirmngr.conf
disable-ipv6
keyserver hkps://keys.openpgp.org
EOF
Create or override gpg.conf
Heads-up: back up current config using cp ~/.gnupg/gpg.conf ~/.gnupg/gpg.conf.backup (if necessary).
cat << EOF > ~/.gnupg/gpg.conf
cert-digest-algo SHA512
charset utf-8
default-key $KEY_ID
default-preference-list SHA512 SHA384 SHA256 AES256 AES192 AES ZLIB BZIP2 ZIP Uncompressed
fixed-list-mode
keyid-format 0xlong
keyserver hkps://keys.openpgp.org
list-options show-uid-validity
no-comments
no-emit-version
no-symkey-cache
personal-cipher-preferences AES256 AES192 AES
personal-compress-preferences ZLIB BZIP2 ZIP Uncompressed
personal-digest-preferences SHA512 SHA384 SHA256
require-cross-certification
s2k-cipher-algo AES256
s2k-digest-algo SHA512
throw-keyids
use-agent
verify-options show-uid-validity
with-fingerprint
EOF
Back up and overwrite gpg-agent.conf
Heads-up: back up current config using cp ~/.gnupg/gpg-agent.conf ~/.gnupg/gpg-agent.conf.backup (if necessary).
cat << EOF > ~/.gnupg/gpg-agent.conf
default-cache-ttl 60
default-cache-ttl-ssh 60
enable-ssh-support
max-cache-ttl 120
max-cache-ttl-ssh 120
pinentry-program $(brew --prefix)/bin/pinentry-mac
EOF
Step 8: configure shell
cat << "EOF" >> ~/.zshrc
export GPG_TTY="$(tty)"
export SSH_AUTH_SOCK=$(gpgconf --list-dirs agent-ssh-socket)
gpgconf --launch gpg-agent
gpg-connect-agent UPDATESTARTUPTTY /bye > /dev/null
EOF
source ~/.zshrc
Step 9: generate SSH public key
Replace john@example.net with email and johndoe with name associated to master key.
$ mkdir -p ~/.ssh
$ ssh-add -L | awk '{print $1 " " $2 " john@example.net"}' | tee ~/.ssh/johndoe.pub
ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIJ62kuKCXcufbvQeXS8h5D6PW233AMBXHzKpXO0EhmJ6 john@example.net
ssh-ed25519 AAAAC3Nz… john@example.net
👍
Step 10: reload gpg-agent (required to enable pinentry-mac)
$ gpgconf --kill gpg-agent
$ gpgconf --launch gpg-agent
$ gpg-connect-agent UPDATESTARTUPTTY /bye
OK
OK
👍
Step 11 (optional): enable Git signing
git config --global commit.gpgsign true
git config --global gpg.program $(which gpg)
git config --global user.signingkey $KEY_ID
Step 12 (optional): publish public key to hkps://keys.openpgp.org
$ gpg --send-keys $KEY_ID
gpg: sending key 0xC2709D13BAB4763C to hkps://keys.openpgp.org
gpg: sending key 0xC2709D13BAB4763C to hkps://keys.openpgp.org
👍