You can sign tags locally using GPG or S/MIME.

Note: GitHub Desktop does not support commit signing.

  1. To sign a tag, add -s to your git tag command.

    git tag -s mytag
    # Creates a signed tag
    
  2. Verify your signed tag it by running git tag -v [tag-name].

    git tag -v mytag
    # Verifies the signed tag
    

Further reading