What is the primary purpose of a counter-based authentication system?

• A. To provide secure, one-time passwords for user authentication.
• B. To enforce password complexity
• C. To store user credentials securely
• D. To track login attempts

Answer: (A)

Counter-based authentication relies on a shared secret and a moving counter to generate a code that changes with each login. The token computes a one-time password from the secret and the current counter value, and the server does the same to verify it. Because the code is valid only for a specific counter value and for a single use, replayed or reused codes won’t authorize access. This mechanism provides secure, one-time passwords for user authentication, which is why it’s described as the primary purpose. It isn’t about enforcing password complexity, storing credentials securely, or tracking login attempts.