Tor exit blocking, in which websites disallow clients arriving from Tor, is a growing and potentially existential threat to the anonymity network. We introduce two architectures that provide ephemeral exit bridges for Tor which are difficult to enumerate and block. Our techniques employ a micropayment system that compensates exit bridge operators for their services, and a privacy-preserving reputation scheme that prevents freeloading. We show that our exit bridge architectures effectively thwart server-side blocking of Tor with little performance overhead.
Zhao Zhang, Wenchao Zhou, and Micah Sherr. Bypassing Tor Exit Blocking with Exit Bridge Onion Services. In ACM Conference on Computer and Communications Security (CCS), November 2020.
Zhao Zhang, Tavish Vaidya, Kartik Subramanian, Wenchao Zhou, and Micah Sherr. Ephemeral Exit Bridges for Tor. In IEEE/IFIP International Conference on Dependable Systems and Networks (DSN), June 2020.
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