Module authenticator_data 

Authenticator data parsing.

The authenticator data (authData) is a binary structure defined in WebAuthn §6.1. It is produced by the authenticator hardware and carries the RP ID binding, user-presence/verification flags, a sign counter, and (during registration) the new credential’s public key encoded as a COSE_Key.

Binary layout

Offset   Len   Field
──────   ───   ─────────────────────────────────────────────────
     0    32   rpIdHash   — SHA-256 of the RP ID
    32     1   flags      — bitmask (UP / UV / AT / ED)
    33     4   signCount  — big-endian u32
    37     *   attestedCredentialData (present iff AT flag is set)
             16   aaguid
              2   credentialIdLength  (big-endian u16)
              *   credentialId
              *   credentialPublicKey (CBOR-encoded COSE_Key)
     *     *   extensions (CBOR map, present iff ED flag is set)

Structs

AttestedCredentialData

Credential data embedded in the authenticator data during registration.

AuthenticatorData

Fully parsed authenticator data.

AuthenticatorFlags

Decoded flags byte from authenticator data.

Enums

CoseKey

A decoded COSE_Key from the credential’s authenticator data.

Functions

parse_authenticator_data

Parse the raw authenticator data bytes into an AuthenticatorData.

parse_cose_key

Decode a CBOR-encoded COSE_Key and return it as a CoseKey.