Subject: I-D ACTION:draft-ietf-pppext-mppe-keys-02.txt

From: [email-masked]
Date: Thu, 28 Oct 1999 07:10:16 -0400

A New Internet-Draft is available from the on-line Internet-Drafts directories.
This draft is a work item of the Point-to-Point Protocol Extensions Working Group of the IETF.

	Title		: MPPE Key Derivation
	Author(s)	: G. Zorn
	Filename	: draft-ietf-pppext-mppe-keys-02.txt
	Pages		: 20
	Date		: 27-Oct-99
	
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.
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
session key to be used for initializing encryption tables can be
negotiated.  MPPE currently supports 40-bit, 56-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 initial MPPE session
keys from a variety of credential types.  It is expected that this memo
will be updated whenever Microsoft defines a new key derivation method
for MPPE, since its primary purpose is to provide an open, easily
accessible reference for third-parties wishing to interoperate with
Microsoft products.

The algorithm used to change session keys during a session is described
in [4].

The algorithm used to change session keys during a session is described
in [4].

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