Which authentication method used with PPP uses a nonce (random number) to hash the password and prevent replay attacks?

The Challenge Handshake Authentication Protocol (CHAP) works by sending a random number called the challenge. This challenge is received by the authenticating router and used to hash the password. The password is transferred to the challenging router and authenticates the authenticating router. The Password Authentication Protocol transmits the username and password in clear text. There is no protocol called PSAP; therefore, it is an invalid answer. The Lightweight Directory Access Protocol is a protocol used to look up data, and it is used primarily with Active Directory. It does not provide encryption by itself but can be used with SSL/TLS to provide encryption.