For more information, visit How to Create an X509 Certificate.
From your Git repository, execute the following set of commands.
git config --local commit.gpgsign 'true'
git config --local gpg.program 'gpgsm'
git config --local user.name 'John Doe'
git config --local user.email '[email protected]'
git config --local user.signingkey 'Thumbprint'
git commit -S -m 'Your Commit Message'
git cat-file commit HEAD
tree 4eedc1902c2f7e309435241915f8f16c47e49726
author Darin Egan <[email protected]> 1542811784 +0000
committer Darin Egan <[email protected]> 1542967722 +0000
gpgsig -----BEGIN SIGNED MESSAGE-----
MIAGCSqGSIb3DQEHAqCAMIACAQExDzANBglghkgBZQMEAgEFADCABgkqhkiG9w0B
...
tLPqrL2mmYp0NRnnV/q/Zus3fEfasqG8o4rAt1rhHfU5wL/KC4XuoJR+AAAAAAAA
-----END SIGNED MESSAGE-----
Genesis
Fin.