Two-Factor Authentication
Also known as:2FA
Two-Factor Authentication: A special case of MFA involving exactly two independent authentication factors. This concept is central to identity and access controls. In practice, clear policies, loggingLoggingThe recording of security-relevant events so activity can be monitored, investigated, and audited., regular reviews, and the strongest possible authentication are crucial.
How it works and where it fits
Two-Factor Authentication separates the subject, digital identity, authentication factor, and authorization decision. Authentication establishes who or what is presenting an identity; authorization then determines which action is permitted in the current context. Session state, device trust, request origin, and risk signals can further influence that decision.
Practical security relevance
Effective implementation requires a controlled identity lifecycle from creation through role and entitlement changes to suspension and removal. Strong authentication, least privilege, periodic recertification, and traceable logs are central. Controls must also identify abuse of legitimate accounts, because valid credentials alone do not prove that an action is legitimate.
Related concepts
- Multi-Factor AuthenticationMulti-Factor AuthenticationRequires at least two independent factors for identity verification.: Requires at least two independent factors for identity verification.
- AuthenticationAuthenticationVerification of the claimed identity of a user or system.: Verification of the claimed identity of a user or system.
- One-Time PasswordOne-Time PasswordPassword valid for only a single use or a short period.: Password valid for only a single use or a short period.
- Universal Second FactorUniversal Second FactorStandard for hardware-based strong second-factor authentication.: Standard for hardware-based strong second-factor authentication.