How to Use the Command 'git verify-commit' (with Examples)

The git verify-commit command is a valuable tool in the Git ecosystem for ensuring the authenticity and integrity of commits. It is primarily used to check if a commit has been signed with a valid GPG key. This verification step is crucial in environments where ensuring the identity of the commit author is vital, such as in open-source projects or corporate repositories. By verifying commits, project maintainers and collaborators can ensure that the code history has not been tampered with and that commits are genuinely authored by trusted contributors.

Use Case 1: Check Commits for a GPG Signature

Code:

git verify-commit commit_hash1 optional_commit_hash2 ...

Motivation:

In collaborative software development projects, especially those with a significant number of contributors, it is crucial to verify the authenticity of commits. This process helps confirm that the commit was made by a trusted individual and not an unauthorized entity. By employing the git verify-commit command, you can ensure that each commit has been signed with a valid GPG signature, thereby securing the integrity of the codebase.

Explanation:

• git: The command-line tool used for version control.
• verify-commit: Sub-command used to verify GPG signatures attached to commits.
• commit_hash1 optional_commit_hash2 ...: This argument represents one or more commit hashes that you wish to verify. The command checks each specified commit for a GPG signature.

Example Output:

gpg: Signature made Tue 21 Feb 2023 11:22:33 AM CET
gpg:                using RSA key ABCDEFGH12345678
gpg: Good signature from "Your Name <your.email@example.com>"

In this output, the signature information related to the specified commit is displayed. The message shows the signature’s creation time, the key used for signing, and a confirmation that the signature is valid.

Use Case 2: Check Commits for a GPG Signature and Show Details of Each Commit

Code:

git verify-commit commit_hash1 optional_commit_hash2 ... --verbose

Motivation:

Sometimes, merely verifying the existence of a GPG signature is not enough. As a project maintainer or developer, you might want to view additional details about each verified commit, such as who signed the commit and any extra signature-related data. Using the --verbose option allows you to gain deeper insights into the metadata associated with the signature, thus providing a comprehensive view of commit credentials and potential debugging data.

Explanation:

• --verbose: This flag requests the verbose output from the command. It shows additional details related to the GPG signature, providing more context to the verification process.

Example Output:

commit commit_hash1
gpg: Signature made Tue 21 Feb 2023 11:22:33 AM CET
gpg:                using RSA key ABCDEFGH12345678
gpg: Good signature from "Your Name <your.email@example.com>"
Primary key fingerprint: 1234 5678 90AB CDEF 1234  5678 90AB CDEF 1234 5678

Here, the output provides not only the basic signature verification information but also the commit hash, the primary key fingerprint, and other pertinent details that can help understand the signing context.

Use Case 3: Check Commits for a GPG Signature and Print the Raw Details

Code:

git verify-commit commit_hash1 optional_commit_hash2 ... --raw

Motivation:

In cases where automated scripts or deeper integrations are required, raw data output might be ideal. Developers often need raw, unformatted data to feed into other systems or log files, allowing for further analysis or traceability. By using the --raw flag, you can obtain unprocessed output, which can be leveraged in automated workflows or detailed post-processing tasks.

Explanation:

• --raw: This option provides raw, unformatted output of the verification process. This is particularly useful for further processing in scripts or feeding into other tools for additional analysis.

Example Output:

8446:040000008283b7 SIG abcdefghiABCDEFGHIJKLM gpgsig -----BEGIN PGP SIGNATURE-----
 Version: GnuPG vX.X.X (GNU/Linux)
 ...
 -----END PGP SIGNATURE-----

The raw output contains low-level details and unstructured data blocks pertaining to the GPG signature. The text may include the PGP signature block, key details, version information, or other raw metadata gathered during the verification process.

Conclusion:

The git verify-commit command is an essential aspect of secure software development, particularly when authenticity and trustworthiness are paramount. Whether checking basic signatures, exploring detailed commit credentials, or acquiring raw data for automation, understanding and utilizing this command effectively can significantly enhance the robustness of your version control practices. As part of a broader security strategy, it contributes to safeguarding the integrity of your codebase against unauthorized changes.