alt Hacker News-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
> How would you digitally sign a Json document and embed the signature in the document?
Embedding a signature into the same file is easy enough.
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v0.9.7 (GNU/Linux)
iEYEARECAAYFAjdYCQoACgkQJ9S6ULt1dqz6IwCfQ7wP6i/i8HhbcOSKF4ELyQB1
oCoAoOuqpRqEzr4kOkQqHRLE/b8/Rw2k =y6kj
-----END PGP SIGNATURE-----
Or use something similar to jwts, you normalize the document, sign the hash, wrap the original document with metadata and include the signature.