Secure In-Band Wireless Pairing

This paper presents the first wireless pairing protocol that works in-band, with no pre-shared keys, and protects against MITM attacks. The main innovation is a new key exchange message constructed in a manner that ensures an adversary can neither hide the fact that a message was transmitted, nor alter its payload without being detected. Thus, any attempt by an adversary to interfere with the key exchange translates into the pairing devices detecting either invalid pairing messages or an unacceptable increase in the number of such messages. We analytically prove that our design is secure against MITM attacks, and show that our protocol is practical by implementing a prototype using off-the-shelf 802.11 cards. An evaluation of our protocol on two busy wireless networks (MIT’s campus network and a reproduction of the SIGCOMM 2010 network using traces) shows that it can effectively implement key exchange in a real-world environment.