
Explanation/Reference:
Explanation:
The Challenge Handshake Authentication Protocol (CHAP) verifies the identity of the peer by means of a three-way handshake. These are the general steps performed in CHAP:
1. After the LCP (Link Control Protocol) phase is complete, and CHAP is negotiated between both devices,the authenticator sends a challenge message to the peer.
2. The peer responds with a value calculated through a one-way hash function (Message Digest 5 (MD5)).
3. The authenticator checks the response against its own calculation of the expected hash value. If the values match, the authentication is successful. Otherwise, the connection is terminated.
References:
http://www.cisco.com/c/en/us/support/docs/wan/point-to-point-protocol-ppp/25647-understanding-ppp- chap.html