CAS-002 · Question #843
ABC Corporation has introduced token-based authentication to system administrators due to the risk of password compromise. The tokens have a set of HMAC counter-based codes and are valid until they…
The correct answer is D. HOTP. HOTP (HMAC-based One-Time Password) uses a counter-based mechanism where each code is valid until used, directly matching the described token behavior.
Question
ABC Corporation has introduced token-based authentication to system administrators due to the risk of password compromise. The tokens have a set of HMAC counter-based codes and are valid until they are used. Which of the following types of authentication mechanisms does this statement describe?
Options
- ATOTP
- BPAP
- CCHAP
- DHOTP
How the community answered
(28 responses)- C4% (1)
- D96% (27)
Why each option
HOTP (HMAC-based One-Time Password) uses a counter-based mechanism where each code is valid until used, directly matching the described token behavior.
TOTP generates time-based codes that expire after a short fixed window (typically 30 seconds), not counter-based codes that persist until used.
PAP (Password Authentication Protocol) transmits static passwords in plaintext over PPP links and has no token-based or HMAC counter mechanism.
CHAP uses a three-way challenge-response handshake for identity verification without sending plaintext passwords, but is not a token-based or counter-based OTP system.
HOTP, defined in RFC 4226, generates one-time passwords using HMAC combined with a counter that increments with each authentication event. The generated code remains valid indefinitely until it is consumed in a successful authentication, which precisely matches the description of counter-based codes that are valid until used.
Concept tested: HOTP counter-based one-time password authentication
Source: https://datatracker.ietf.org/doc/html/rfc4226
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