Prep Yubikey

Attention

Yubikey Password/PINs may be up to 127 ASCII characters long.

Default Yubikey Passwords

Default User Pin

123456

Default Admin Pin

12345678

Verify Geniue Yubikey

Ensure Yubikey is geniue and has not been tampered with during any step of the supply chain.

  1. https://www.yubico.com/genuine/

  2. Verify Device

  3. Touch Yubikey when prompted.

Note

Yubico must be able to see the make and model of the device during the verification process.

Verification Complete is displayed for genuine keys. Failure means potential compromise and should be thrown out after it is confirmed to fail again.

Reset Yubikey

This will destroy any openpgp material on the key and reset to the default key state. Do this even if the Yubikey is new.

Reset Yubikey openpgp.
ykman openpgp reset

Alternatively using the Yubikey Personalization Tool will provide options to do this via a GUI.

Note

If the Yubikey is not brand new, ensure you are not deleting any other 2FA configurations.

Show current Yubikey card shows with default values.
gpg --card-status

  • If not found, re-insert the key. There is a known race condition that may occur with older GPG libraries.

  • Ensure latest firmware version using Yubikey Manager.

  • Ensure device has CCID mode enabled using Yubikey Manager. Most firmware past 3.1.8 will have this permenantly enabled and not listed.

Configure Yubikey

Configure behavior of Yubikey so short touches will provide GPG material, while long touches will provide Yubico OTP. This prevents accidental touches spewing keystrokes into whatever is open. NFC is also disabled to force physical touch to use key.

  1. Yubikey Manager › Applications › OTP

  2. Delete Slot 1.

  3. Configure Slot 2 to use Yubico OTP.

Note

Newer keys can just use the swap button.

../../../../_images/yubikey-otp.png

Swapped button press lengths.

  1. Yubikey Manager › Interfaces › NFC › Disable All

  2. Save Interfaces

../../../../_images/yubikey-nfc.png

All NFC options are disabled to requirement phyiscal presence.

Setup openpgp on Yubikey

Prepare Yubikey to load GPG key material.

Edit openpgp application on Yubikey.
$ gpg --card-edit

Reader ...........: Yubico YubiKey OTP FIDO CCID 0
Application ID ...: XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
Version ..........: 3.4
Manufacturer .....: Yubico
Serial number ....: XXXXXXXXXX
Name of cardholder: [not set]
Language prefs ...: [not set]
Sex ..............: unspecified
URL of public key : [not set]
Login data .......: [not set]
Signature PIN ....: forced
Key attributes ...: rsa4096 rsa4096 rsa4096
Max. PIN lengths .: 127 127 127
PIN retry counter : 3 3 3
Signature counter : 0
Set the admin password (Remember to use the Default PIN if needed).
gpg/card> admin
Admin commands are allowed

gpg/card> passwd
gpg: OpenPGP card no. XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX detected

1 - change PIN
2 - unblock PIN
3 - change Admin PIN
4 - set the Reset Code
Q - quit

Your selection? 3
PIN changed.

Your selection? Q
Set the user password (Remember to use the Default PIN if needed).
gpg/card> admin
Admin commands are allowed

gpg/card> passwd
gpg: OpenPGP card no. XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX detected

1 - change PIN
2 - unblock PIN
3 - change Admin PIN
4 - set the Reset Code
Q - quit

Your selection? 1
PIN changed.

Your selection? Q
Set the name used in the GPG credentials to load.
gpg/card> name
Cardholders surname: {USER LAST NAME}
Cardholders given name: {USER FIRST NAME}
Set the language for the GPG user.
gpg/card> lang
Language preferences: en
Set the URL to locaiton of user’s GPG public key.
gpg/card> url
URL to retrieve public key: https://keybase.io/{USER}/pgp_keys.asc

Note

As shown using https://keybase.io as the location, but any publically accessible location with the public key material will work.

Set login to GPG email account used.
gpg/card> login
Login data (account name): {GPG USER EMAIL ADDRESS}
Set forcesig to always require PIN to access GPG key material.
gpg/card> forcesig
Verify configuration and quit to save.
gpg/card> {PRESS ENTER}

Reader ...........: Yubico YubiKey OTP FIDO CCID 0
Application ID ...: XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
Version ..........: 3.4
Manufacturer .....: Yubico
Serial number ....: XXXXXXXXXX
Name of cardholder: {USER FIRST NAME} {USER LAST NAME}
Language prefs ...: en
Sex ..............: unspecified
URL of public key : https://keybase.io/{USER}/pgp_keys.asc
Login data .......: {GPG USER EMAIL ADDRESS}
Signature PIN ....: forced
Key attributes ...: rsa4096 rsa4096 rsa4096
Max. PIN lengths .: 127 127 127
PIN retry counter : 3 3 3
Signature counter : 0

gpg/card> quit
Require touch each time authentication, encryption or signing request occurs.
ykman openpgp set-touch aut fixed
ykman openpgp set-touch sig fixed
ykman openpgp set-touch enc fixed

Note

Fixed is the same as on but requires a new certificate to be loaded if this option is ever disabled.