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?
A . TOTP
B . PAP
C . CHAP
D . HOTP
Answer: D
Explanation:
The question states that the HMAC counter-based codes and are valid until they are used. These are "one-time" use codes.
HOTP is an HMAC-based one-time password (OTP) algorithm.
HOTP can be used to authenticate a user in a system via an authentication server. Also, if some more steps are carried out (the server calculates subsequent OTP value and sends/displays it to the user who checks it against subsequent OTP value calculated by his token), the user can also authenticate the validation server.
Both hardware and software tokens are available from various vendors. Hardware tokens implementing OATH HOTP tend to be significantly cheaper than their competitors based on proprietary algorithms. Some products can be used for strong passwords as well as OATH HOTP.
Software tokens are available for (nearly) all major mobile/smartphone platforms.
Incorrect Answers:
A: TOTP is Time-based One-time Password. This is similar to the one-time password system used in this question. However, TOTPs expire after a period of time. In this question, the passwords (codes) expire after first use regardless of the timing of the first use.
B: PAP (Password Authentication Protocol) is a simple authentication protocol in which the user name and password is sent to a remote access server in a plaintext (unencrypted) form. PAP is not what is described in this question.
C: CHAP (Challenge-Handshake Authentication Protocol) is an authentication protocol that provides protection against replay attacks by the peer through the use of an incrementally changing identifier and of a variable challenge-value. CHAP requires that both the client and server know the plaintext of the secret, although it is never sent over the network. CHAP is not what is described in this question.
References:
https://en.wikipedia.org/wiki/HMAC-based_One-time_Password_Algorithm