Authentication Protocols
PPPsupports different authentication protocols, PAP, CHAP, MS-CHAP v1 and MS- CHAP v2 is supported. Which authentication protocol to use is negotiated during LCP negotiation.
PAP
PAP (Password Authentication Protocol) is a simple, plaintext authentication scheme, which means that user name and password are sent in plaintext. PAP is therefore not a secure authentication protocol.
CHAP
CHAP (Challenge Handshake Authentication Protocol) is a challenge-response authentication protocol specified in RFC 1994. CHAP uses a MD5 one-way encryption scheme to hash the response to a challenge issued by the DFL-700. CHAP is better then PAP in that the password is never sent over the link. Instead the password is used to create the one-way MD5 hash. That means that CHAP requires passwords to be stored in a reversibly encrypted form.
MS-CHAP v1
MS-CHAP v1 (Microsoft Challenge Handshake Authentication Protocol version 1) is similar to CHAP, the main difference is that with MS-CHAP v1 the password only needs to be stored as a MD4 hash instead of a reversibly encrypted form. Another difference is that MS- CHAP v1 uses MD4 instead of MD5.
MS-CHAP v2
MS-CHAP v2 (Microsoft Challenge Handshake Authentication Protocol version 1) is more secure then MS-CHAP v1 as it provides two –way authentication.
MPPE, Microsoft Point-To-Point Encryption
MPPE is used is used to encrypt Point-to-Point Protocol (PPP) packets. MPPE uses the RSA RC4 algorithm to provide data confidentiality. The length of the session key to be used for the encryption can be negotiated. MPPE currently supports 40-bit, 56-bit and 128-bit RC4 session keys.
