Which series of steps correctly describes how a challenge-and-response authentication protocol
functions?

A.
1. The authenticator sends a random challenge string to the subject being authenticated.
2. The subject being authenticated hashes the challenge using a shared secret password to form a response back to the authenticator.
3. The authenticator performs the same hash method with the same shared secret password to calculate a local response and compare it with the received response.
4. If these match, the subject is authenticated.

B.
1. The subject being authenticated sends a random challenge string to the authenticator.
2. The authenticator encrypts the challenge string with a private key and sends the encrypted random challenge string back to the subject being authenticated.
3. The subject being authenticated decrypts the random challenge string with the public key and compare it to the original random challenge.
4. If these match, the subject is authenticated.

C.
1. The subject being authenticated sends a random challenge string to the authenticator.
2. The authenticator encrypts the challenge string with a shared secret password and sends the encrypted random challenge string back to the subject being authenticated.
3. The subject being authenticated decrypts the random challenge string using the same shared secret key and compare it to the original random challenge.
4. If these match, the subject is authenticated..