- Summary
- Estimated burden and prerequisites
- U2F
- GPG
- git
- SSH
- Reset
- Troubleshooting
- Optional
- References
GPG is useful for authenticating yourself over SSH and / or GPG-signing your git commits / tags. However, without hardware like the YubiKey, you would typically keep your GPG private subkeys in "plain view" on your machine, even if encrypted. That is, attackers who personally target [1, 2, 3, 4] you can compromise your machine can exfiltrate your (encrypted) private key, and your passphrase, in order to pretend to be you.
Instead, this setup lets you store your private subkeys on your YubiKey. Actually, it gives you much stronger guarantees: you cannot authenticate over SSH and / or sign GPG commits / tags without: (1) your YubiKey plugged in and operational, (2) your YubiKey PIN, and (3) touching your YubiKey. So, even if there is malware trying to get you to sign, encrypt, or authenticate something, you would almost certainly notice, because your YubiKey will flash, asking for your attention. (There is the "time of check to time of use" issue, but that is out of our scope.)
About 2-3 hours. 15 minutes could save you 15% or more on cybersecurity
insurance.
You will need macOS with Homebrew / Ubuntu / Archlinux, a password manager, and a YubiKey 5.
STRONGLY recommended: configure U2F for GitHub and Google.
Please read and follow all of the instructions carefully.
$ ./gpg.sh(Protip: set TEMPDIR=1 when preparing YubiKey for someone else to avoid
polluting your default GPG homedir.)
STRONGLY RECOMMENDED: signing your git commits and tags.
You must first set up GPG.
Then, to sign git commits and tags for a particular repository:
$ ./git.sh /path/to/git/repositoryOr, to sign git commits and tags for all repositories:
$ ./git.shNOT recommended unless you plan to use your GPG authentication subkey as your only SSH authentication key.
You must have first set up GPG. Then:
$ ./ssh.shIf you need to reset YubiKeys, you may use the following script. The script looks for every plugged YubiKey, and shows a menu to reset one specific key, or all of them. Please read and follow all of the instructions carefully. YOU WILL NOT BE ABLE TO RETRIEVE KEYS/DATA FROM THE YUBIKEY AFTER COMPLETION.
$ ./reset.shGo here for troubleshooting common issues such as unblocking a blocked card, error when pulling or pushing with git over SSH, and rebasing with git.
Go here for support on optional bits such as Keybase, VMware Fusion, Docker Content Trust, signing for different git repositories with different keys, and configuring a computer to use an already configured Yubikey.