(a) For public key-based authentication: (1) Enforce authorized access to the corresponding private key; and (2) Map the authenticated identity to the account of the individual or group; and (b) When public key infrastructure (PKI) is used: (1) Validate certificates by constructing and verifying a certification path to an accepted trust anchor, including checking certificate status information; and (2) Implement a local cache of revocation data to support path discovery and validation.