Cryptographically sign all of your commits with a GPG key managed by Keybase, proving to GitHub and the world that you are a real person who really wrote your code and getting that neat Verified badge next to all of your commits.
Along the way, we’ll also make sure everything is set up in a way that plays nicely with RStudio.
Did you know it’s incredibly easy to
spoof commit authors with git?
Basically, you only need to tell
git you’re a different person.
git config --global user.email "hadley@..." git config --glboal user.name "Hadley Wickham" # pretend to commit as Hadley git commit -m "Fix recode() arguments to new = old"
git doesn’t do anything to verify the commit author and,
while GitHub will try a little harder than
it’s surprisingly easy to pretend to be somewhere else in a git repo.
This can obviously lead to problems (that are admittedly mostly theoretical in my daily life) and there’s a relatively easy solution: signed commits. With signed commits, you cryptographically sign each commit with your private key that only you own, and GitHub (and others) will verify your signature with the public key pair. When GitHub knows that the real you made the commit, it adds the green badge.
In this post,
I’ll show you how to use Keybase to create your own GPG key.
Then we’ll set up
git to use this key to sign your commits,
and along the way we’ll configure
git to work with RStudio, too.
I’m using a Mac, but the process is very similar for Linux/Unix
Set up signed and verified commits #
Install Keybase and GPG #
brew install gpg brew install --cask keybase
The first line installs
GNU Privacy Guard command line tool.
It manages the cryptographic steps:
signing or encoding files with your personal GPG key.
Keybase is key directory that maps social media identities to encryption keys in a publicly auditable manner3. In other words, Keybase is place to store encryption keys and to link your identity (and those keys) to your public identities such as your accounts on Twitter or GitHub. One advantage of Keybase is that its app and command line tool make it relatively easy to generate and store GPG keys. It’s also a great way to share that key between your own computers.
Create a GPG key with Keybase #
If you don’t have a Keybase account,
open the Keybase app that we installed with
Their app will guide you through the process of creating an account.
Once you have a Keybase account,
head back to the command line4
to create a new GPG key.
Note that the
keybase cli uses the
but we’ve been talking about GPG keys.
To most people, the terms GPG and PGP are functionally interchangeable:
GPG is the
GNU Privacy Guard
which is an open-source version of
Pretty Good Privacy).
keybase pgp gen --multi
Enter your real name, which will be publicly visible in your new key: Garrick Aden-Buie Enter a public email address for your key: email@example.com Enter another email address (or <enter> when done): Push an encrypted copy of your new secret key to the Keybase.io server? [Y/n] Y When exporting to the GnuPG keychain, encrypt private keys with a passphrase? [Y/n] Y ▶ INFO PGP User ID: Garrick Aden-Buie <firstname.lastname@example.org> [primary] ▶ INFO Generating primary key (4096 bits) ▶ INFO Generating encryption subkey (4096 bits) ▶ INFO Generated new PGP key: ▶ INFO user: Garrick Aden-Buie <email@example.com> ▶ INFO 4096-bit RSA key, ID B606B038A1A5CE20, created 2021-09-12 ▶ INFO Exported new key to the local GPG keychain
To recap the process:
keybasewill first ask you for your real name and email address. Make sure these match your identity on GitHub, or at least a verified email that you use on GitHub.
Yto push a copy of the key to Keybase and
Yagain to add give your private key a passphrase.
After a few seconds, Keybase asks for your account password and then prompts you to enter a passphrase for your GPG key.
At the end of the output, note your key’s ID —
in my case,
You should also be able to find your key on your Keybase profile,
or list your local keys that
gpg knows about with
gpg --list-secret-keys --keyid-format LONG
/Users/garrick/.gnupg/pubring.kbx --------------------------------- sec rsa4096/B606B038A1A5CE20 2021-09-13 [SC] [expires: 2037-09-09] 87888BBEBC09E6093A8310F9B606B038A1A5CE20 uid [ unknown] Garrick Aden-Buie <firstname.lastname@example.org> ssb rsa4096/F4435076C9C363BD 2021-09-13 [E] [expires: 2037-09-09]
Notice that we again see our key id,
B606B038A1A5CE20, in the third line of the output.
There’s also the
[ unknown] on line 5 next to our name.
This indicates that
gpg isn’t totally confident about this key yet
and we need to tell
gpg that it can be trusted.
Trust your own key, ultimately #
gpg interactive prompt to edit your key, then run
I trust ultimately and finally run
gpg --edit-key B606B038A1A5CE20
gpg> trust # Please decide how far you trust this user to correctly verify other users' keys # (by looking at passports, checking fingerprints from different sources, etc.) # # 1 = I don't know or won't say # 2 = I do NOT trust # 3 = I trust marginally # 4 = I trust fully # 5 = I trust ultimately # m = back to the main menu # # Your decision? 5 # Do you really want to set this key to ultimate trust? (y/N) y gpg> save # Key not changed so no update needed.
Now if you run
gpg --list-secret-keys again,
[ultimate] next to your name.
gpg --list-secret-keys --keyid-format LONG
/Users/garrick/.gnupg/pubring.kbx --------------------------------- sec rsa4096/B606B038A1A5CE20 2021-09-13 [SC] [expires: 2037-09-09] 87888BBEBC09E6093A8310F9B606B038A1A5CE20 uid [ultimate] Garrick Aden-Buie <email@example.com> ssb rsa4096/F4435076C9C363BD 2021-09-13 [E] [expires: 2037-09-09]
Configure git to always sign your commits #
git to always sign your commits is straightforward.
Update the git global config to sign commits using your default key
with the following two commands,
replacing my key id in the first command with your key id.
git config --global user.signingkey B606B038A1A5CE20 git config --global commit.gpgsign true
Add your key to GitHub #
Now you need to tell GitHub about your new GPG key.
Using your key id, ask Keybase to export the public key that matches your private GPG key.
Here we’ll pipe it to
pbcopy to copy it into the system clipboard.
keybase pgp export -q B606B038A1A5CE20 | pbcopy
Then head over to github.com/settings/keys, click on New GPG key, and paste and add your key into GitHub.
Check your signed commit powers #
At this point,
git will try to sign your commits,
but if you’re also using MacOS like me
there’s a good chance you’ll run into a problem when you try to commit a file.
# in a git repo touch test.txt git add test.txt git commit -m "test signed commits" # error: gpg failed to sign the data # fatal: failed to write commit object
This error message isn’t entirely helpful,
but you can try to sign some random text with
to expose the underlying error.
echo "test" | gpg --clear-sign
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 test gpg: signing failed: Inappropriate ioctl for device gpg: [stdin]: clear-sign failed: Inappropriate ioctl for device
The problem in my case is that I have an “Inappropriate ioctl for device.”
Take that error to your
favorite web search engine
and you’ll find a resolution.
If you also run into this
you need to add the following line to
~/.zshrc (if you’re using
Z shell, the latest default on MacOS) or
Save the file and then close and re-open your terminal window.
When you test
gpg signing again,
you should be prompted with a full-terminal prompt to enter your password.
echo "test" | gpg --clear-sign
┌───────────────────────────────────────────────────────────────┐ │ Please enter the passphrase to unlock the OpenPGP secret key: │ │ "Garrick Aden-Buie <firstname.lastname@example.org>" │ │ 4096-bit RSA key, ID B606B038A1A5CE20, │ │ created 2021-09-13. │ │ │ │ │ │ Passphrase: _________________________________________________ │ │ │ │ <OK> <Cancel> │ └───────────────────────────────────────────────────────────────┘
Enter your key’s passphrase and, if everything works, you should see a message like this:
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 test -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEh4iLvrwJ5gk6gxD5tgawOKGlziAFAmE/UYkACgkQtgawOKGl ziAzgg/7Bl6cCapi+k2OrxPafl811G4x7fC4PQWCJKWXinUjkZK/8+o6jM+ZQp+4 gc1wv0gBfNyKNkTmMg/qiQhuLYiujSH9pyjaoMgO9QoYvUuPituSjV7RQOfAhlHD N+wgkACPd3PH2kQVFj8Jw3Nkesrpgby9t/S6sSiLZf284rMfx31ua1/l4tsHWowP 5a+FRujDtarWJ1/zL9pgMkr9kkWEejqpzGVLrVKrB3xsPLyGnPf8BW+an7CwkkDS umJulX3Ck1u14DRgIyj4VdwfCkkCle0uyZcLorZsqDP5GC/3ZKcpDe6XgSSKz0O0 HVvm4bTqBBmesVNWHVuFmYGmmXFU/sYvYoHOy3wvLiCu/hbRhBvboUcogW79/PWR Gw/DYln5W1ClIKH9LsU0GpydSTMMhXZySEp+r1OCl4sQqKCe6Ka3ex+3lOHyym7F U5rgfH6tmu6U2Jtn8QEFg106vxQDQ76TIRVS9xvicH98PJQnhoyg3jtu5tMbITz1 oev0Z11vq76mw3MFmVx455AVqxplGM/4qB9HsmNWTsi0fGoFa/vlbBN3vJQn0xaX 2PSXKWlkZiyd+WplWsOH2OnZ8V8s2cHNxlKsSPrWQNflYsDtO8vANwAFjiJK2Bkq YLPCcwzEVSwFrLRRXt5Crcpc/32ZqrfvcLe0G+ACWQYAhktwJnQ= =S1iU -----END PGP SIGNATURE-----
And if you try to
git commit again, it should work!
git commit -m "test signed commits"
[main (root-commit) 4c4573f] test signed commits 1 file changed, 0 insertions(+), 0 deletions(-) create mode 100644 test.txt
Note that you can be extra sure by looking at the
git log with signatures.
git log --show-signature
commit 4c4573f2fbed44eab6c0f4a08a38a9f8292580cf (HEAD -> main) gpg: Signature made Mon Sep 13 09:34:59 2021 EDT gpg: using RSA key 87888BBEBC09E6093A8310F9B606B038A1A5CE20 gpg: Good signature from "Garrick Aden-Buie <email@example.com>" [ultimate] Author: Garrick Aden-Buie <firstname.lastname@example.org> Date: Mon Sep 13 09:34:59 2021 -0400 test signed commits
Install a pinentry app #
Remember that console dialog that appeared when we committed our test commit above?
Yes, it’s fun and retro,
but it isn’t going to work inside RStudio
when the IDE runs
git commands for you to commit your files.
In this step, we’ll install
a modern method for providing a passphrase for your key,
that also integrates with MacOS’s Keychain
so you don’t have to enter the passphrase with every commit.
If you’re using Windows, you might want to check out the
you may want to use
you could also
gpg-agent to cache your passphrase
if none of the above options work for you.
pinentry-mac is easy with
brew install pinentry-mac
Then we need to configure
gpg to use
pinentry-mac for its passphrase needs.
Add the line below to
# vim ~/.gnupg/gpg-agent.conf pinentry-program /usr/local/bin/pinentry-mac
Or you can create the file and add the line in one command:
echo "pinentry-program /usr/local/bin/pinentry-mac" >> ~/.gnupg/gpg-agent.conf
Finally, restart the
gpg-agent so that
pinentry-mac is used for passphrase entry.
gpgconf --kill gpg-agent
When you create your next commit in RStudio,
you’ll be prompted with a dialog box to enter your passphrase.
If you select the Save in Keychain option,
you won’t be prompted again;
git will use the passphrase in your Keychain
to sign your commit with the GPG key you created with Keybase!
Import your GPG key on another computer #
If you’d like to use the same GPG key on another computer,
first make sure that you have
Keybase and gpg installed.
Then you can export the existing key
(both its public and secret versions)
from Keybase into
keybase pgp export -q B606B038A1A5CE20 | gpg --import keybase pgp export -q B606B038A1A5CE20 --secret | gpg --allow-secret-key-import --import
Again, you’ll want to tell
trust this key ultimately.
gpg --edit-key B606B038A1A5CE20 gpg> trust # pick "5 = I trust ultimately" gpg> save
Links and Resources #
Here’s a short list of links that were helpful to me while figuring out this process. Hopefully, everything above just works for you, but if not then maybe the posts below will help you out:
gpg-agent to cache your passphrase without a pinentry GUI
If you don’t want to or can’t
install a pinentry app,
you can get
gpg-agent to cache your passphrase for a fixed period of time,
say 8 hours.
When you start your day — or when the cache expires — you’ll need to sign something or commit once from the command line to re-enter your passphrase.
The first step is to configure
to remember your key’s password for the day (8 hours or 28,800 seconds).
# ~/.gnupg/gpg-agent.conf default-cache-ttl 28800 max-cache-ttl 28800
You’ll need to restart
gpg-agent so that it picks up the new configuration.
gpgconf --kill gpg-agent
At this point,
git commit will automatically be signed using your default key.
The first commit of the day
will require you to enter your password,
which does mean that
the RStudio Git UI won’t be able to sign the first commit
until you’ve asked
gpg to sign something for you.
To get around this, you can unlock your gpg key by signing anything at the start of your work day or whenever the 8 hour time limit runs out.
echo "open sesame" | gpg -s > /dev/null # prompt for password
Windows users, I’m sorry! I don’t own anything that runs Windows. 😒 ↩︎
gitversion 2.0 or later. Check with
git --versionor upgrade git to the latest version with
brew install git. ↩︎
You could also create a GPG/PGP key in the Keybase app in the identities section of your profile, but I’m using the command line so it’s easier to copy-paste. ↩︎