Near field deniable communication

Abstract

There is an increasing interest of companies and government agencies to snoop on people's daily lives the increasing difficulty for people to handle such scenarios. The need for private communications is perhaps greater than ever before. Officials at the NSA have stated that “if you have enough meta-data you don’t really need content” and that “we kill people based on meta-data”. People have long needed to keep the communications among themselves private, but, increasingly, they may want to conceal not only the messages that they exchange, but also with whom they are communicating---or even the fact that they are communicating at all. This latter type of communication is said to be not only confidential and anonymous but also deniable, in the sense that despite exchanging messages, participants can plausibly deny that any such exchanges ever took place.

This dissertation develops techniques and systems that empower users in physical proximity to have mechanisms for deniable communications. Our work builds from the observation of noise in the surrounding technologies like wireless networks or powerline networks. The thesis particularly uses noise instead of protocol obfuscation to create deniable channels between individuals who do not want any third party to recognize that there is possible communication in progress.

Working with collaborators at Georgia Tech, I have built two systems to explore two approaches at the link layer of wireless channel in 802.11 protocol by means of Denali. Looking for alternate technologies I stumbled upon innocuous-looking powerline networks and led to the work Powerline Whisperer, where I explored using the physical layer in powerline cables to do deniable communication. Due to lack of available cover, the system does not presume any already established communication channel to exchange a message but rather depends on the thermal noise and the electromagnetic interference due to devices present in the medium.