Identity proofing establishes that a subject is who they claim to be. Digital authentication establishes that a subject attempting to access a digital service is in control of one or more valid authenticators associated with that subject’s digital identity. For services in which return visits are applicable, successfully authenticating provides reasonable risk-based assurances that the subject accessing the service today is the same as that which accessed the service previously. Digital identity presents a technical challenge because this process often involves proofing individuals over an open network, and always involves the authentication of individual subjects over an open network to access digital government services. The processes and technologies to establish and use digital identities offer multiple opportunities for impersonation and other attacks.
These technical guidelines supersede NIST Special Publication SP 800-63-2. Agencies use these guidelines as part of the risk assessment and implementation of their digital service(s). These guidelines provide mitigations of an authentication error’s negative impacts by separating the individual elements of identity assurance into discrete, component parts. For non-federated systems, agencies will select two components, referred to as Identity Assurance Level (IAL) and Authenticator Assurance Level (AAL). For federated systems, agencies will select a third component, Federation Assurance Level (FAL).
AAL (Authenticator Assurance Level ) refers to the authentication process.