A Framework for the Game-theoretic Analysis of Censorship Resistance

Open access


We present a game-theoretic analysis of optimal solutions for interactions between censors and censorship resistance systems (CRSs) by focusing on the data channel used by the CRS to smuggle clients’ data past the censors. This analysis leverages the inherent errors (false positives and negatives) made by the censor when trying to classify traffic as either non-circumvention traffic or as CRS traffic, as well as the underlying rate of CRS traffic. We identify Nash equilibrium solutions for several simple censorship scenarios and then extend those findings to more complex scenarios where we find that the deployment of a censorship apparatus does not qualitatively change the equilibrium solutions, but rather only affects the amount of traffic a CRS can support before being blocked. By leveraging these findings, we describe a general framework for exploring and identifying optimal strategies for the censorship circumventor, in order to maximize the amount of CRS traffic not blocked by the censor. We use this framework to analyze several scenarios with multiple data-channel protocols used as cover for the CRS. We show that it is possible to gain insights through this framework even without perfect knowledge of the censor’s (secret) values for the parameters in their utility function.

If the inline PDF is not rendering correctly, you can download the PDF file here.

  • [1] T. Alpcan and T. Ba¸sar. Network Security: A Decision and Game-Theoretic Approach. Cambridge University Press 2010.

  • [2] R. Anderson and T. Moore. The Economics of Information Security. Science 314(5799):610-613 2006.

  • [3] R. Anderson T. Moore S. Nagaraja and A. Ozment. Incentives and Information Security. Algorithmic Game Theory pages 633-649 2007.

  • [4] R. J. Aumann. Acceptable Points in General Cooperative n-Person Games. Contributions to the Theory of Games 4:287-324 1959.

  • [5] D. Blackwell. Discounted dynamic programming. The Annals of Mathematical Statistics 36(1):226-235 1965.

  • [6] F. Brandt T. Sandholm and Y. Shoham. Spiteful bidding in sealed-bid auctions. In Proceedings of the 20th International Joint Conference on Artifical Intelligence IJCAI’07 pages 1207-1214 San Francisco CA USA 2007. Morgan Kaufmann Publishers Inc.

  • [7] C. Brubaker A. Houmansadr and V. Shmatikov. CloudTransport: Using Cloud Storage for Censorship-Resistant Networking. In Proceedings of 14th Privacy Enhancing Technologies Symposium. Springer 2014.

  • [8] J. R. Crandall D. Zinn M. Byrd E. T. Barr and R. East. ConceptDoppler: A Weather Tracker for Internet Censorship. In Proceedings of the 14th ACM SIGSAC Conference on Computer and Communications Security pages 352-365 2007.

  • [9] G. Danezis. An anomaly-based censorship detection system for Tor. Technical Report 2011-09-001 The Tor Project 2011. https://research.torproject.org/techreports/detector-2011-09-09.pdf.

  • [10] G. Danezis and R. Anderson. The Economics of Censorship Resistance. Proceedings of the 3rd Annual Workship on Economics and Information Security 2004.

  • [11] R. Dingledine. Obfsproxy: The Next Step in the Censorship Arms Race. Tor Blog https://blog.torproject.org/blog/obfsproxy-next-step-censorship-arms-race February 2012. Retrieved May 2015.

  • [12] R. Dingledine N. Mathewson and P. Syverson. Tor: The Second-Generation Onion Router. In Proceedings of the 13th conference on USENIX Security Symposium-Volume 13 pages 303-320. USENIX Association 2004.

  • [13] K. P. Dyer S. E. Coull T. Ristenpart and T. Shrimpton. Protocol Misidentification Made Easy with Format-Transforming Encryption. In Proceedings of the 20th ACM conference on Computer and Communications Security November 2013.

  • [14] F. Fang P. Stone and M. Tambe. Defender strategies in domains involving frequent adversary interaction. In Proceedings of the 2015 International Conference on Autonomous Agents and Multiagent Systems pages 1663-1664. International Foundation for Autonomous Agents and Multiagent Systems 2015.

  • [15] D. Fifield C. Lan R. Hynes P. Wegmann and V. Paxson. Blocking-resistant Communication through Domain Fronting. Proceedings on Privacy Enhancing Technologies 2015(2):46-64 June 2015.

  • [16] A. Filasto and J. Applebaum. OONI: Open Observatory of Network Interference. In Proceedings of the USENIX Workshop on Free and Open Communications on the Internet. USENIX 2012.

  • [17] D. Fudenberg and E. Maskin. The folk theorem in repeated games with discounting or with incomplete information. Econometrica 54(3):533-554 1986.

  • [18] J. Geddes M. Schuchard and N. Hopper. Cover Your ACKs: Pitfalls of Covert Channel Censorship Circumvention. In Proceedings of the 20th ACM conference on Computer and Communications Security 2013.

  • [19] B. Hahn R. Nithyanand P. Gill and R. Johnson. Games Without Frontiers: Investigating Video Games as a Covert Channel. http://arxiv.org/pdf/1503.05904v2.pdf 2015. Retrieved May 2015.

  • [20] A. Houmansadr T. Riedl N. Borisov and A. Singer. IP over Voice-over-IP for Censorship Circumvention. arXiv preprint arXiv:1207.2683 2012.

  • [21] S. Khattak T. Elahi L. Simon C. M. Swanson S. J. Murdoch and I. Goldberg. SoK: Making Sense of Censorship Resistance Systems. Proceedings on Privacy Enhancing Technologies 2016(4) 2016.

  • [22] A. Lewman. Iran Partially Blocks Encrypted Network Traffic. Tor Blog https://blog.torproject.org/blog/iran-partially-blocksencrypted-network-traffic February 2012. Retrieved May 2015.

  • [23] K. Leyton-Brown and Y. Shoham. Essentials of Game Theory: A Concise Multidisciplinary Introduction. Synthesis Lectures on Artificial Intelligence and Machine Learning 2(1):1-88 2008.

  • [24] S. Li M. Schliep and N. Hopper. Facet: Streaming over Videoconferencing for Censorship Circumvention. In Proceedings of the Workshop on Privacy in the Electronic Society November 2014.

  • [25] M. H. Manshaei Q. Zhu T. Alpcan T. Bac¸sar and J.-P. Hubaux. Game Theory meets Network Security and Privacy. ACM Computing Surveys 45(3):25 2013.

  • [26] H. Mohajeri Moghaddam B. Li M. Derakhshani and I. Goldberg. SkypeMorph: Protocol Obfuscation for Tor Bridges. In Proceedings of the 19th ACM conference on Computer and Communications Security October 2012.

  • [27] J. Morgan K. Steiglitz and G. Reis. The spite motive and equilibrium behavior in auctions. Contributions in Economic Analysis & Policy 2(1) 2003.

  • [28] M. J. Osborne. An introduction to game theory. Oxford University Press New York 2003.

  • [29] J. Pita M. Jain J. Marecki F. Ordóñez C. Portway M. Tambe C. Western P. Paruchuri and S. Kraus. Deployed ARMOR Protection: The Application of a Game Theoretic Model for Security at the Los Angeles International Airport. In Proceedings of the 7th International Joint Conference on Autonomous Agents and Multiagent Systems: Industrial Track pages 125-132. International Foundation for Autonomous Agents and Multiagent Systems 2008.

  • [30] Psiphon Inc. Psiphon. https://psiphon.ca. Retrieved May 2015.

  • [31] S. Roy C. Ellis S. Shiva D. Dasgupta V. Shandilya and Q. Wu. A Survey of Game Theory as Applied to Network Security. In 2010 43rd Hawaii International Conference on System Sciences pages 1-10. IEEE 2010.

  • [32] Sandvine. Global Internet Phenomena Report - Spotlight encrypted Internet traffic. https://www.sandvine.com/downloads/general/globalinternet-phenomena/2016/global-internet-phenomenaspotlight-encrypted-internet-traffic.pdf.

  • [33] Y. Shoham and K. Leyton-Brown. Multiagent Systems: Algorithmic Game-Theoretic and Logical Foundations. Cambridge University Press 2008.

  • [34] T. Tor Project. Tor Mertics Portal: Bridge users by country. https://metrics.torproject.org/userstats-bridge-country.html 2016. Retrieved May 2016.

  • [35] M. C. Tschantz S. Afroz V. Paxson and J. Tygar. On Modeling the Costs of Censorship. arXiv preprint arXiv:1409.3211 2014.

  • [36] P. Vines and T. Kohno. Rook: Using Video Games as a Low- Bandwidth Censorship Resistant Communication Platform. http://homes.cs.washington.edu/~yoshi/papers/tech-reportrook.pdf 2015. Retrieved May 2015.

  • [37] VPN Gate. VPN Gate Latest Activity Logs. http://www.vpngate.net/en/lastlog.aspx 2016. Retrieved May 2016.

  • [38] Q. Wang X. Gong G. T. K. Nguyen A. Houmansadr and N. Borisov. CensorSpoofer: Asymmetric Communication using IP Spoofing for Censorship-Resistant Web Browsing. In Proceedings of the 19th ACM conference on Computer and Communications Security October 2012.

  • [39] Z. Weinberg J. Wang V. Yegneswaran L. Briesemeister S. Cheung F. Wang and D. Boneh. StegoTorus: A Camouflage Proxy for the Tor Anonymity System. In Proceedings of the 19th ACM conference on Computer and Communications Security October 2012.

  • [40] J. Wright A. Darer and O. Farnan. Detecting Internet Filtering from Geographic Time Series. http://arxiv.org/pdf/1507.05819v1.pdf July 2015. Retrieved August 2015.

Journal information
All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 456 261 12
PDF Downloads 174 101 4