This project addresses the Tor exit blocking problem, in which websites disallow clients arriving from Tor. This problem 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.
This repo contains two independent packages, eebt and hebtor. To be specific, eebt corresponds to our first publication, Ephemeral Exit Bridges for Tor (DSN2020), and hebtor corresponds to our second publication, Bypassing Tor Exit Blocking with Exit Bridge Onion Services (CCS2020). Both packages are fully open-sourced under GPLv2 license.