---
term: "Authenticator assurance level"
category: "Agent identity (KYA)"
url: https://agenticopenfinance.com/glossary/authenticator-assurance-level
source: AgenticOpenFinance glossary
---

# 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.

Related terms: [Identity assurance level](https://agenticopenfinance.com/glossary/identity-assurance-level.md), [Strong customer authentication](https://agenticopenfinance.com/glossary/strong-customer-authentication.md), [Passkey](https://agenticopenfinance.com/glossary/passkey.md), [Digital identity](https://agenticopenfinance.com/glossary/digital-identity.md)