MD5

An industry-standard one-way, 128-bit hashing scheme, developed by RSA Data Security, Inc., and used by various Point-to-Point Protocol (PPP) vendors for encrypted authentication. A hashing scheme is a method for transforming data (for example, a password) in such a way that the result is unique and cannot be changed back to its original form. The CHAP authentication protocol uses challenge-response with one-way MD5 hashing on the response. In this way, you can prove to the server that you know your password without actually sending the password over the network.