Module scheme 

Signature scheme identifiers for Witness::scheme (D39).

These are choir-local numbers rather than multicodec entries, unlike ContentHash’s codec byte, and the difference is deliberate: multicodec names a key type, while a verifier needs the construction — which bytes were actually signed. A WebAuthn signature covers authenticator_data ‖ SHA-256(client_data_json) rather than the message, and no curve identifier says that.

Constants

ED25519

Ed25519 over the signed bytes directly. The only scheme that existed before D39, which is why an absent super::Witness::scheme means this one.

WEBAUTHN_ES256

WebAuthn ES256 (D39): ECDSA P-256 with SHA-256, over authenticator_data ‖ SHA-256(client_data_json), where the challenge inside client_data_json is the entry’s super::OpEntry::signing_hash.