Deriving MPPE Keys From MS-CHAP V2 Credentials

Document Type Expired Internet-Draft (pppext WG)
Author Glen Zorn 
Last updated 1998-11-16
Stream IETF
Intended RFC status (None)
Expired & archived
pdf htmlized (tools) htmlized bibtex
Stream WG state WG Document
Document shepherd No shepherd assigned
IESG IESG state Expired
Consensus Boilerplate Unknown
Telechat date
Responsible AD (None)
Send notices to (None)

This Internet-Draft is no longer active. A copy of the expired Internet-Draft can be found at


The Point-to-Point Protocol (PPP) [1] provides a standard method for transporting multi-protocol datagrams over point-to-point links. The PPP Compression Control Protocol [2] provides a method to negotiate and utilize compression protocols over PPP encapsulated links. Version 2 of the Microsoft Challenge-Handshake Authentication Protocol (MS-CHAP-2) [3] is a Microsoft-proprietary PPP authentication protocol, providing the functionality to which LAN-based users are accustomed while integrating the encryption and hashing algorithms used on Windows networks. Microsoft Point to Point Encryption (MPPE) [4] is a means of representing PPP packets in an encrypted form. MPPE uses the RSA RC4 [5] algorithm to provide data confidentiality. The length of the ses- sion key to be used for initializing encryption tables can be negoti- ated. MPPE currently supports 40-bit and 128-bit session keys. MPPE session keys are changed frequently; the exact frequency depends upon the options negotiated, but may be every packet. MPPE is negotiated within option 18 [6] in the Compression Control Protocol. This document describes the method used to derive the initial MPPE ses- sion keys from MS-CHAP-2 credentials. The algorithm used to change ses- sion keys during a session is described in [4].


Glen Zorn (

(Note: The e-mail addresses provided for the authors of this Internet-Draft may no longer be valid.)