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About commit signature verification

Using GPG, SSH, or S/MIME, you can sign tags and commits locally. These tags or commits are marked as verified on GitHub so other people can be confident that the changes come from a trusted source.

About commit signature verification

You can sign commits and tags locally, to give other people confidence about the origin of a change you have made. If a commit or tag has a GPG, SSH, or S/MIME signature that is cryptographically verifiable, GitHub marks the commit or tag "Verified" or "Partially verified."

Verified commit

For most individual users, GPG or SSH will be the best choice for signing commits. S/MIME signatures are usually required in the context of a larger organization. SSH signatures are the simplest to generate. You can even upload your existing authentication key to GitHub to also use as a signing key. Generating a GPG signing key is more involved than generating an SSH key, but GPG has features that SSH does not. A GPG key can expire or be revoked when no longer used. GitHub shows commits that were signed with such a key as "Verified" unless the key was marked as compromised. SSH keys don't have this capability.

Commits and tags have the following verification statuses, depending on whether you have enabled vigilant mode. By default vigilant mode is not enabled. For information on how to enable vigilant mode, see "Displaying verification statuses for all of your commits."

Signing commits differs from signing off on a commit. For more information about signing off on commits, see "Managing the commit signoff policy for your repository."

Default statuses

StatusDescription
VerifiedThe commit is signed and the signature was successfully verified.
UnverifiedThe commit is signed but the signature could not be verified.
No verification statusThe commit is not signed.

Signature verification for rebase and merge

pull request で Rebase と Merge オプションを使用する場合は、ヘッド ブランチのコミットがコミット署名の検証なしでベース ブランチに追加されることに注意することが重要です。 このオプションを使用すると、元のコミットのデータとコンテンツを使用して、GitHub によって変更されたコミットが作成されます。 つまり、GitHub は、このコミットを本当に作成していないため、汎用システム ユーザーとして署名することはできません。 GitHub では、コミッターの秘密署名キーにアクセスできないため、ユーザーの代わりにコミットに署名できません。

これを回避するには、ローカルでリベースとマージを行い、変更を pull request のベース ブランチにプッシュします。

For more information, see "Rebasing and merging your commits."

Statuses with vigilant mode enabled

状態説明
Verifiedコミットは署名され、署名の検証も成功しており、コミッターは警戒モードを有効化した唯一の作者。
Partially verifiedコミットは署名され、署名の検証も成功しているが、コミットには a) コミッターではなく b) 警戒モードを有効化した 作者がいる。 この場合、コミットの署名は作者の合意を保証しないので、コミットは部分的にのみ検証されています。
Unverified次のうち当てはまるものはどれですか?
- コミットは署名されていますが、署名を確認できませんでした。
- コミットが署名されておらず、コミッターが警戒モードを有効にしています。
- コミットが署名されておらず、作成者が警戒モードを有効にしています。

Repository administrators can enforce required commit signing on a branch to block all commits that are not signed and verified. For more information, see "About protected branches."

GitHub上の署名されたコミットあるいはタグの検証ステータスをチェックして、コミットの署名が検証されない理由を見ることができます。 詳細については、「コミットおよびタグの署名の確認状態を確認する」を参照してください。

GitHub will automatically use GPG to sign commits you make using the web interface. Commits signed by GitHub will have a verified status. You can verify the signature locally using the public key available at https://github.com/web-flow.gpg. The full fingerprint of the key is 5DE3 E050 9C47 EA3C F04A 42D3 4AEE 18F8 3AFD EB23.

You can optionally choose to have GitHub GPG sign commits you make in GitHub Codespaces. For more information about enabling GPG verification for your codespaces, see "Managing GPG verification for GitHub Codespaces."

GPG commit signature verification

You can use GPG to sign commits with a GPG key that you generate yourself.

GitHub uses OpenPGP libraries to confirm that your locally signed commits and tags are cryptographically verifiable against a public key you have added to your account on GitHub.com.

To sign commits using GPG and have those commits verified on GitHub, follow these steps:

  1. Check for existing GPG keys
  2. Generate a new GPG key
  3. Add a GPG key to your GitHub account
  4. Tell Git about your signing key
  5. Sign commits
  6. Sign tags

SSH commit signature verification

You can use SSH to sign commits with an SSH key that you generate yourself. For more information, see the Git reference documentation for user.Signingkey. If you already use an SSH key to authenticate with GitHub, you can also upload that same key again for use as a signing key. There's no limit on the number of signing keys you can add to your account.

GitHub uses ssh_data, an open source Ruby library, to confirm that your locally signed commits and tags are cryptographically verifiable against a public key you have added to your account on GitHub.com.

注: SSH 署名の検証は、Git 2.34 以降で利用できます。 git の最新バージョンを入手するには、Git の Web サイトを参照してください。

To sign commits using SSH and have those commits verified on GitHub, follow these steps:

  1. Check for existing SSH keys
  2. Generate a new SSH key
  3. Add a SSH signing key to your GitHub account
  4. Tell Git about your signing key
  5. Sign commits
  6. Sign tags

S/MIME commit signature verification

You can use S/MIME to sign commits with an X.509 key issued by your organization.

GitHub uses the Debian ca-certificates package, the same trust store used by Mozilla browsers, to confirm that your locally signed commits and tags are cryptographically verifiable against a public key in a trusted root certificate.

注: S/MIME 署名の検証は、Git 2.19 以降で利用できます。 git の最新バージョンを入手するには、Git の Web サイトを参照してください。

To sign commits using S/MIME and have those commits verified on GitHub, follow these steps:

  1. Tell Git about your signing key
  2. Sign commits
  3. Sign tags

You don't need to upload your public key to GitHub.

Signature verification for bots

Organizations and GitHub Apps that require commit signing can use bots to sign commits. If a commit or tag has a bot signature that is cryptographically verifiable, GitHub marks the commit or tag as verified.

Signature verification for bots will only work if the request is verified and authenticated as the GitHub App or bot and contains no custom author information, custom committer information, and no custom signature information, such as Commits API.

Further reading