312-50V9 Question #302: Real Exam Question with Answer & Explanation

The correct answer is C: An authentication system that creates one-time passwords that are encrypted with secret keys.. A counter-based authentication system (HOTP) generates one-time passwords by applying a cryptographic HMAC function to a shared secret key combined with an incrementing counter.

Question

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?

Options

AA biometric system that bases authentication decisions on behavioral attributes.
BA biometric system that bases authentication decisions on physical attributes.
CAn authentication system that creates one-time passwords that are encrypted with secret keys.
DAn authentication system that uses passphrases that are converted into virtual passwords.

Explanation

A counter-based authentication system (HOTP) generates one-time passwords by applying a cryptographic HMAC function to a shared secret key combined with an incrementing counter.

Common mistakes.

A. This describes behavioral biometrics such as keystroke dynamics or gait recognition, which is unrelated to counter-based OTP systems.
B. This describes physical biometrics such as fingerprint or iris scanning, which is unrelated to counter-based OTP systems.
D. This describes a passphrase-to-virtual-password conversion scheme, which is a different mechanism from counter-based OTP generation using cryptographic keys and counters.

Concept tested. Counter-based one-time password (HOTP) authentication

Reference. https://www.rfc-editor.org/rfc/rfc4226

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