Module transcript 

Transcript: the only way to obtain bytes for a signature or MAC.

This type exists for one invariant: signing bytes without domain separation is impossible. Its constructor requires a label, and signing functions accept only Transcript, so a label cannot be forgotten: the code simply will not compile.

Otherwise, an author’s signature made in one context (revocation record, activation request, permission grant) becomes replayable in another if encodings can collide. A silent error detectable only by an attack.

Structs

Transcript

Bytes prepared for signing or MAC computation, with a mandatory domain label.