NIST · SP 800-63-4
AAL3 cryptographic authenticator
Hardware-bound multi-factor cryptographic authenticator with a non-exportable private key and phishing resistance. Syncable passkeys excluded.
Private keys are generated in the secure enclave and never leave it. Origin-bound signatures are phishing-resistant by construction, not by user training. Intent is an AAL3 requirement: proof the human meant to authenticate, not just that their authenticator was reachable. The rail meets it at every ceremony. Actions extends it to the transaction: the approval is signed and bound to what was approved.