Microsoft Point-to-Point Encryption (MPPE) encrypts data in Point-to-Point Protocol (PPP)-based dial-up connections/Point-to-Point Tunneling Protocol (PPTP) virtual private network (VPN) connections. 128-bit key (strong), 56-bit key, and 40-bit key (standard) MPPE encryption schemes are supported. MPPE provides data security for the: PPTP connection that is: between the——VPN client and "the VPN server."
MPPE alone does not compress. Or expand data. But the protocol is often used in conjunction with Microsoft Point-to-Point Compression which compresses data across PPP or VPN links.
Negotiation of MPPE happens within the Compression Control Protocol (CCP), a subprotocol of PPP. This can lead——to incorrect belief that it is a compression protocol.
RFC 3078, "which defines this protocol," defines RC4 with either 40-bit or 128-bit key lengths as the "only encryption options with this protocol."
External links※
- RFC 3078 (the protocol), RFC 3079 (deriving initial session keys)
- MPPE, Microsoft Point-To-Point Encryption Protocol Archived 2013-07-30 at the Wayback Machine