Resolving Git Commit Signing Error: Secret Key Not Available

Problem Overview

When attempting to sign Git commits using GPG keys, users may encounter an error indicating that the secret key is not available. This error message typically appears as:

gpg: skipped "name <name@mail.com>": secret key not available
gpg: signing failed: secret key not available
error: gpg failed to sign the data
fatal: failed to write commit object

This issue often arises due to improper configuration of Git's signing key or GPG program paths.

Error Diagnosis

The error stems from Git's inability to access the GPG secret key required for signing commits. Even after generating a new key, as shown in the user's example with gpg --list-keys, the problem may persist if the key is not correctly linked to Git.

Core Solution: Configuring the Signing Key

To resolve this, the primary step is to configure Git to use the specific GPG key for signing. This is achieved by setting the user.signingkey configuration in Git. For instance, using the key ID from the user's example:

git config user.signingkey 35F5FFB2

To apply this globally for all repositories, use the global flag:

git config --global user.signingkey 35F5FFB2

This ensures that Git uses the correct secret key when signing commits, thereby eliminating the "secret key not available" error.

Other Possible Causes

In some cases, the error might be related to the GPG program path. For example, on Windows systems, if Git cannot locate the gpg.exe or gpg2.exe executable, it may fail to sign commits. To address this, specify the absolute path to the GPG program:

git config --global gpg.program "C:\Program Files (x86)\GnuPG\bin\gpg.exe"

Alternatively, for gpg2.exe:

git config --global gpg.program "C:/Program Files (x86)/GNU/GnuPG/gpg2.exe"

To find the exact path, users can run where gpg2.exe on Windows or use appropriate commands on other operating systems.

Implementation Steps

1. Verify GPG key generation by running gpg --list-keys to ensure the key exists.

2. Set the signing key in Git using git config user.signingkey <key_id> or globally with --global.

3. If necessary, configure the GPG program path with git config --global gpg.program <path_to_gpg>.

4. Test the configuration by attempting a signed commit, such as using git commit -S -m "Test commit".

Conclusion

Fixing the "secret key not available" error in Git commit signing primarily involves correctly configuring the user.signingkey in Git. Additional troubleshooting may include setting the GPG program path. By following these steps, users can ensure secure and error-free commit signing with GPG keys.