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Challenge Handshake Authentication Protocol (CHAP) is a process of authenticating a user to a network entity, which may be any server, e.g., the web or internet service provider (ISP).
CHAP is primarily used for security purposes. For example, users provide authenticated plain text passwords when accessing remote servers, which also are authenticated prior to user access.
CHAP ensures that the server sends a challenge to the client after the client establishes a network connection to access a web/ISP server. This challenge is received via the same network line. The client uses a hash function to calculate a specific value that is then sent to the server, which matches the incoming value against the server’s calculated value. If the values match, the client is granted server access. Otherwise, the connection is automatically terminated.
Peers randomly adopt this procedure and continuously send calculated values to an authenticating server, which, in turn, continuously authenticates peers based on calculated values.