Modules
RFC 9530 Digest Fields: build, parse, and verify Content-Digest,
Repr-Digest, Want-Content-Digest, and Want-Repr-Digest.
Error struct returned by all HTTPDigest functions.
Verifies Content-Digest on incoming Plug requests.
A Req request step that computes and attaches Content-Digest on
outgoing requests.
Incremental digest computation for large bodies.