An organization has introduced token-based authentication to system administrators due to risk of password compromise. The tokens have a set of numbers that automatically change every 30 seconds…

TOTP (RFC 6238) generates one-time passwords by combining a shared secret key with the current Unix timestamp, producing a code that changes at a fixed interval - typically every 30 seconds. This time-synchronization mechanism ensures codes are short-lived and cannot be reused, directly mitigating password replay attacks. Authenticator apps like Google Authenticator and Microsoft Authenticator implement TOTP.

Smart cards are physical hardware tokens that store static cryptographic credentials or certificates; they do not generate time-based rotating numeric codes.

CHAP (Challenge Handshake Authentication Protocol) is a challenge-response protocol used for point-to-point authentication, not a time-based token system.

HOTP (HMAC-based One-Time Password, RFC 4226) generates codes based on an incrementing counter (event-based), not the current time, so codes do not automatically change on a fixed time interval.