Describe the main characteristics of the Challenge-Handshake Authentication Protocol (CHAP).

What will be an ideal response?

The foundation of CHAP is a three-way handshake, which is accomplished during the initial authentication and may be repeated any time after the link has been established. Both the device and the authenticator share a secret key. The authenticator sends a "challenge" message to the device, which responds with a value calculated using a one-way hash function. The authenticator then compares that response against its own calculation of the expected hash value. If the values match, the authentication is acknowledged.