TY - GEN
T1 - Using Blockchains for Censorship-Resistant Bootstrapping in Anonymity Networks
AU - Han, Yang
AU - Xu, Dawei
AU - Gao, Jiaqi
AU - Zhu, Liehuang
N1 - Publisher Copyright:
© 2022, Springer Nature Switzerland AG.
PY - 2022
Y1 - 2022
N2 - With Tor being a popular anonymity network, many censors and ISPs have blocked access to it. Tor relies on privately and selectively distributing IPs of circumvention proxies (i.e., bridges) to censored clients for censorship evasion. However, existing distributors are still vulnerable to blocking or compromising anonymity. This paper introduces Antiblok, a new and practical channel for bridge distribution leveraging blockchain, a globally decentralized environment. A key insight of Antiblok is that all blockchain transactions are under pseudonymous identities, allowing requesting clients to fetch bridge information while maintaining anonymity, regardless of the trustworthiness of blockchain nodes. To prevent the use of off-chain communication channels, we present an account sharing protocol based on DH key exchange. The unblockability of Antiblok depends on the economic consequences of blocking the Ethereum system. We show that Antiblok effectively thwarts client-side blocking of the distribution channel for Tor bridges, and we describe the security of our design.
AB - With Tor being a popular anonymity network, many censors and ISPs have blocked access to it. Tor relies on privately and selectively distributing IPs of circumvention proxies (i.e., bridges) to censored clients for censorship evasion. However, existing distributors are still vulnerable to blocking or compromising anonymity. This paper introduces Antiblok, a new and practical channel for bridge distribution leveraging blockchain, a globally decentralized environment. A key insight of Antiblok is that all blockchain transactions are under pseudonymous identities, allowing requesting clients to fetch bridge information while maintaining anonymity, regardless of the trustworthiness of blockchain nodes. To prevent the use of off-chain communication channels, we present an account sharing protocol based on DH key exchange. The unblockability of Antiblok depends on the economic consequences of blocking the Ethereum system. We show that Antiblok effectively thwarts client-side blocking of the distribution channel for Tor bridges, and we describe the security of our design.
KW - Anti-censorship
KW - Blockchain
KW - Covert communication
KW - Tor
UR - http://www.scopus.com/inward/record.url?scp=85137041269&partnerID=8YFLogxK
U2 - 10.1007/978-3-031-15777-6_14
DO - 10.1007/978-3-031-15777-6_14
M3 - Conference contribution
AN - SCOPUS:85137041269
SN - 9783031157769
T3 - Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
SP - 240
EP - 260
BT - Information and Communications Security - 24th International Conference, ICICS 2022, Proceedings
A2 - Alcaraz, Cristina
A2 - Chen, Liqun
A2 - Li, Shujun
A2 - Samarati, Pierangela
PB - Springer Science and Business Media Deutschland GmbH
T2 - 24th International Conference on Information and Communications Security, ICICS 2022
Y2 - 5 September 2022 through 8 September 2022
ER -