Challenge handshake authentication protocol

What is the Challenge handshake authentication protocol?

The Challenge Handshake Authentication Protocol (CHAP) is a security protocol used for authenticating the identity of devices or users in a computer network. CHAP functions by creating a challenge-response mechanism between a client and a server. During the authentication process, the server sends a challenge message to the client, and the client responds with the correct answer – most commonly, a shared password between the two nodes.

The server then compares the received response with its own calculation to verify the authenticity of the client. CHAP goes a long way in preventing replay attacks and provides a higher level of security compared to simpler password-based authentication methods, given the presence of a dynamic challenge that changes with each authentication attempt.