Cryptanalysis of Microsoft's Point-to-Point Tunneling Protocol (PPTP)

The Point-to-Point Tunneling Protocol (PPTP) is used to secure PPP connections over TCP/IP links. In this paper we analyze Microsoft's Windows NT implementation of PPTP. We show how to break both the challenge/response authentication protocol (Microsoft CHAP) and the RC4 encryption protocol (MPPE), as well as how to attack the control channel in Microsoft's implementation. These attacks do not necessarily break PPTP, but only Microsoft's implementation of the protocol.

• Type: Conference
• Year: 1998
• Where: CCS
• Authors: Bruce Schneier, Mudge
• Keywords: CCS 1998, Challenge/response Authentication Protocol, Microsoft's Implementation, Point-to-Point Tunneling Protocol, Security Privacy