Overview

The Microsoft Point to Point Encryption scheme is a means of representing Point to Point Protocol (PPP) packets in an encrypted form.

MPPE uses the RSA RC4 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 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 in the Compression Control Protocol (CCP), and is employed within PPTP

Packet Structure

• RFC 3078 - Microsoft Point-To-Point Encryption (MPPE) Protocol
• RFC 3079 - Deriving Keys for use with Microsoft Point-to-Point Encryption (MPPE)

• PPTP
• CHAP, MS-CHAPv1,v2