Changing of the Guards: A Framework for Understanding and Improving Entry Guard Selection in Tor
Tor is the most popular low-latency anonymity overlay network for the Internet, protecting the privacy of hundreds of thousands of people every day. To ensure a high level of security against certain attacks, Tor currently utilizes special nodes called entry guards as each client's long-term entry point into the anonymity network. While the use of entry guards provides clear and well-studied security benefits, it is unclear how well the current entry guard design achieves its security goals in practice. The authors design and implement Changing Of the Guards (COGS), a simulation-based research framework to study Tor's entry guard design.