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Title: Bypassing Tor Exit Blocking with Exit Bridge Onion Services
Tor exit blocking, in which websites disallow clients arriving from Tor, is a growing and potentially existential threat to the anonymity network. This paper introduces HebTor, a new and robust architecture for exit bridges—short-lived proxies that serve as alternative egress points for Tor. A key insight of HebTor is that exit bridges can operate as Tor onion services, allowing any device that can create outbound TCP connections to serve as an exit bridge, regardless of the presence of NATs and/or firewalls. HebTor employs a micro-payment system that compensates exit bridge operators for their services, and a privacy-preserving reputation scheme that prevents freeloading. We show that HebTor effectively thwarts server-side blocking of Tor, and we describe the security, privacy, and legal implications of our design.
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Award ID(s):
1704189 1718498
Publication Date:
Journal Name:
2020 ACM Conference on Computer and Communications Security
Page Range or eLocation-ID:
3 to 16
Sponsoring Org:
National Science Foundation
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