Authenticator assurance level
A NIST measure of how strongly an authentication process confirms that the same subject is returning.
An authenticator assurance level, or AAL, is a measure in NIST's Digital Identity Guidelines of the strength of an authentication process, meaning how confidently a service can conclude that the subject signing in controls the authenticators bound to the account. Higher levels require multiple factors and phishing-resistant, often hardware-backed, authenticators. For agents, the level at which the customer authenticated when granting a mandate is part of the mandate's evidence.
Agent Minute explains this term on 17 December 2026.
Related terms
Identity assurance levelA NIST measure of how rigorously a person's claimed identity was proofed.Strong customer authenticationAuthentication using two or more independent elements from knowledge, possession and inherence.PasskeyA phishing-resistant sign-in credential based on FIDO standards, unlocked with the device's biometrics or PIN.Digital identityThe unique representation of a subject, such as a person or organisation, engaged in an online transaction.