CS 151-04 Anonymous Communications Theory

We know how to communicate a message so that only the recipient can read the message. (We can just encrypt the message.) But how can we communicate over the Internet without anyone learning *who* we are communicating with? Anonymous channels can help the Iranian protester who wishes to inform the world what is happening in the streets of Tehran by tweeting videos and the netizen in Moscow who wants to read the BBC news (currently banned in Russia). We could use Tor (i.e., “The onion router,” inspired by Chaum's onion routing idea) or VPN, but both are easily blocked, and neither guarantees privacy from the adversary with full view of the network traffic (e.g., a standard model for a resourceful ISP- or AS-level adversary). In this course, we present cryptography-style definitions of anonymity and study state-of-the-art techniques for achieving provable anonymity.