Module wire 

The ACT envelope: encoding, signing and verification.

An ACT is a CBOR map with four keys:

{
  "v":      uint,   ; format version, currently 1
  "alg":    tstr,   ; signature algorithm, currently "Ed25519"
  "claims": bstr,   ; CBOR-encoded ActClaims - the signed bytes
  "sig":    bstr,   ; 64-byte raw Ed25519 signature over "claims"
  "kid":    tstr,   ; optional key identifier, for rotation
}

The signature covers the claims byte string exactly as it appears, not a re-serialization of the decoded claims. A verifier therefore never needs to reproduce the issuer’s encoding decisions byte for byte, which is the usual source of signature failures in formats that sign a canonicalized structure.

v and alg exist because neither superseded format carried either. Without a version there is no way to roll a format change out, and without an algorithm identifier there is no way to migrate off Ed25519.

Structs

ActEnvelope

The outer envelope, as it appears on the wire.

Verifier

What a verifier requires of a token.

Constants

ALGORITHM_ED25519

The only signature algorithm this version defines.

FORMAT_VERSION

Current ACT format version.

MAX_ACT_BYTES

Maximum accepted size of an encoded ACT, in bytes.

Functions

claims_to_signing_payload

Encodes claims into the exact byte string the signature must cover.

envelope_from_parts

Assembles an envelope from claims bytes and a detached signature.

verify

Verifies an encoded ACT and returns its claims.

Type Aliases

PublicKeyBytes

A raw Ed25519 public key.