Editing Authentication protocol (section)

====CHAP - [[Challenge-handshake authentication protocol]]====

The authentication process in this protocol is always initiated by the server/host and can be performed anytime during the session, even repeatedly. The server sends a random string (usually 128B long). The client uses the password and the string received as input to a hash function and then sends the result together with username in plain text. The server uses the username to apply the same function and compares the calculated and received hash. An authentication is successful when the calculated and received hashes match.