Todd has been asked by the security officer to purchase a counter-based authentication system. Which of the following best describes this type of system?

This describes a behavioral biometric system (e.g., gait analysis, keystroke dynamics), which is distinct from a counter-based password system.

This describes a physical biometric system (e.g., fingerprint, iris scan), which is distinct from a counter-based password system.

Counter-based authentication systems, such as those employing HOTP (HMAC-based One-Time Password) or TOTP (Time-based One-Time Password), generate unique, single-use passwords using a shared secret key and a moving factor (like a counter or timestamp), offering strong protection against replay attacks.

While some authentication systems use passphrases, the conversion to 'virtual passwords' doesn't specifically define a counter-based system, which relies on a synchronized counter or time and a secret key for one-time password generation.