I worked with Professor Sebastian Angel of the Computer and Information Science Department on developing an anonymous communications system to hide user metadata. Metadata is information that enables an adversary to determine who users are talking to and when they are talking. Our project also addresses two issues faced by prior anonymous communications protocols: the lack of ability to store messages over time and the fact that most anonymous communications systems have too few users. To solve these problems, I found a way to co-opt non-users into generating fake traffic that hides the activities of real users.
Over the course of the summer, I built a network of servers that took in real user messages, added in hundreds of thousands of fake messages, and randomly shuffled the messages to confuse adversaries about user relationships. Consenting non-users could send fake messages to the system simply by installing a Chrome extension, making their activity indistinguishable from the activities of legitimate users. The system followed a standard known as differential privacy, where the amount of privacy leakage is bounded by the variables ε and δ. I did extensive research on various composition theorems to ensure that our system could meet acceptable ε and δ standards over time.