One of the earlier forms of authentication for gaining access to a network. A user’s name and password were transmitted over a network and compared to a list of name-password pairs. Typically, the passwords stored in the table were encrypted. It is important to note that PAP was not a strong authentication method, for passwords were sent over the wire as “clear text.” Furthermore, there was no protection from replay attacks or from brute-force trial and error attacks. Because of these shortcomings, PAP is no longer in wide use.
IETF, PPP Authentication Protocols. [Online, October 1992.] Website. http://www.ietf.org/rfc/rfc1334.txt.