git/Documentation/technical/signature-format.txt

Git signature format
====================

== Overview

Git uses cryptographic signatures in various places, currently objects (tags,
commits, mergetags) and transactions (pushes). In every case, the command which
is about to create an object or transaction determines a payload from that,
calls gpg to obtain a detached signature for the payload (`gpg -bsa`) and
embeds the signature into the object or transaction.

Signatures always begin with `-----BEGIN PGP SIGNATURE-----`
and end with `-----END PGP SIGNATURE-----`, unless gpg is told to
produce RFC1991 signatures which use `MESSAGE` instead of `SIGNATURE`.

The signed payload and the way the signature is embedded depends
on the type of the object resp. transaction.