Defending Anonymous Communications Against Passive Logging Attacks
SP '03 Proceedings of the 2003 IEEE Symposium on Security and Privacy
The predecessor attack: An analysis of a threat to anonymous communications systems
ACM Transactions on Information and System Security (TISSEC)
SP '06 Proceedings of the 2006 IEEE Symposium on Security and Privacy
Tor: the second-generation onion router
SSYM'04 Proceedings of the 13th conference on USENIX Security Symposium - Volume 13
Low-resource routing attacks against tor
Proceedings of the 2007 ACM workshop on Privacy in electronic society
Denial of service or denial of security?
Proceedings of the 14th ACM conference on Computer and communications security
Metrics for Security and Performance in Low-Latency Anonymity Systems
PETS '08 Proceedings of the 8th international symposium on Privacy Enhancing Technologies
Bridging and Fingerprinting: Epistemic Attacks on Route Selection
PETS '08 Proceedings of the 8th international symposium on Privacy Enhancing Technologies
As-awareness in Tor path selection
Proceedings of the 16th ACM conference on Computer and communications security
Sampled traffic analysis by internet-exchange-level adversaries
PET'07 Proceedings of the 7th international conference on Privacy enhancing technologies
PET'07 Proceedings of the 7th international conference on Privacy enhancing technologies
The traffic analysis of continuous-time mixes
PET'04 Proceedings of the 4th international conference on Privacy Enhancing Technologies
Users get routed: traffic correlation on tor by realistic adversaries
Proceedings of the 2013 ACM SIGSAC conference on Computer & communications security
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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. We design and implement Changing of the Guards (COGS), a simulation-based research framework to study Tor's entry guard design. Using COGS, we empirically demonstrate that natural, short-term entry guard churn and explicit time-based entry guard rotation contribute to clients using more entry guards than they should, and thus increase the likelihood of profiling attacks. This churn significantly degrades Tor clients' anonymity. To understand the security and performance implications of current and alternative entry guard selection algorithms, we simulate tens of thousands of Tor clients using COGS based on Tor's entry guard selection and rotation algorithms, with real entry guard data collected over the course of eight months from the live Tor network.