1Git signature format 2==================== 3 4== Overview 5 6Git uses cryptographic signatures in various places, currently objects (tags, 7commits, mergetags) and transactions (pushes). In every case, the command which 8is about to create an object or transaction determines a payload from that, 9calls gpg to obtain a detached signature for the payload (`gpg -bsa`) and 10embeds the signature into the object or transaction. 11 12Signatures always begin with `-----BEGIN PGP SIGNATURE-----` 13and end with `-----END PGP SIGNATURE-----`, unless gpg is told to 14produce RFC1991 signatures which use `MESSAGE` instead of `SIGNATURE`. 15 16The signed payload and the way the signature is embedded depends 17on the type of the object resp. transaction. 18 19== Tag signatures 20 21- created by: `git tag -s` 22- payload: annotated tag object 23- embedding: append the signature to the unsigned tag object 24- example: tag `signedtag` with subject `signed tag` 25 26---- 27object 04b871796dc0420f8e7561a895b52484b701d51a 28type commit 29tag signedtag 30tagger C O Mitter <committer@example.com> 1465981006 +0000 31 32signed tag 33 34signed tag message body 35-----BEGIN PGP SIGNATURE----- 36Version: GnuPG v1 37 38iQEcBAABAgAGBQJXYRhOAAoJEGEJLoW3InGJklkIAIcnhL7RwEb/+QeX9enkXhxn 39rxfdqrvWd1K80sl2TOt8Bg/NYwrUBw/RWJ+sg/hhHp4WtvE1HDGHlkEz3y11Lkuh 408tSxS3qKTxXUGozyPGuE90sJfExhZlW4knIQ1wt/yWqM+33E9pN4hzPqLwyrdods 41q8FWEqPPUbSJXoMbRPw04S5jrLtZSsUWbRYjmJCHzlhSfFWW4eFd37uquIaLUBS0 42rkC3Jrx7420jkIpgFcTI2s60uhSQLzgcCwdA2ukSYIRnjg/zDkj8+3h/GaROJ72x 43lZyI6HWixKJkWw8lE9aAOD9TmTW9sFJwcVAzmAuFX2kUreDUKMZduGcoRYGpD7E= 44=jpXa 45-----END PGP SIGNATURE----- 46---- 47 48- verify with: `git verify-tag [-v]` or `git tag -v` 49 50---- 51gpg: Signature made Wed Jun 15 10:56:46 2016 CEST using RSA key ID B7227189 52gpg: Good signature from "Eris Discordia <discord@example.net>" 53gpg: WARNING: This key is not certified with a trusted signature! 54gpg: There is no indication that the signature belongs to the owner. 55Primary key fingerprint: D4BE 2231 1AD3 131E 5EDA 29A4 6109 2E85 B722 7189 56object 04b871796dc0420f8e7561a895b52484b701d51a 57type commit 58tag signedtag 59tagger C O Mitter <committer@example.com> 1465981006 +0000 60 61signed tag 62 63signed tag message body 64----