# description
Structured cryptographic signature binding object type, stable identifier, canonical payload hash, issuer identity, and issuance timestamp. Required fields per AGP Implementation Profile §5.2.

# properties.issuer.description
Identity of the issuer who signed this object

# properties.issued_at.description
Timestamp at which this signature was created

# properties.payload_hash.description
Hash of the canonical JSON serialization of the signed payload (alg:base64url)