Microsoft Point-to-Point Encryption (MPPE) is a protocol for encrypting data across Point-to-Point Protocol

Point-to-Point Protocol

In networking, the Point-to-Point Protocol is a data link protocol commonly used in establishing a direct connection between two networking nodes...

 (PPP) and virtual private network

Virtual private network

A virtual private network is a network that uses primarily public telecommunication infrastructure, such as the Internet, to provide remote offices or traveling users access to a central organizational network....

 (VPN) links. It uses the RSA RC4

RC4

In cryptography, RC4 is the most widely used software stream cipher and is used in popular protocols such as Secure Sockets Layer and WEP...

 encryption algorithm. MPPE supports 40-bit, 56-bit and 128-bit session keys, which are changed frequently to improve security. The exact frequency that the keys are changed is negotiated, but may be as frequent as every packet.

MPPE alone does not compress or expand data, but the protocol is often used in conjunction with Microsoft Point-to-Point Compression

Microsoft Point-to-Point Compression

Microsoft Point-to-Point Compression is a streaming data compression algorithm based on an implementation of Lempel–Ziv using a sliding window buffer...

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.

External links

• RFC 3078 (the protocol), RFC 3079 (deriving initial session keys)
• MPPE, Microsoft Point-To-Point Encryption Protocol