TY - JOUR
T1 - Treat Randomness With Care
T2 - Breaking and Provably Fixing Anonymity of Tor Proposal 295
AU - Chao, Daichong
AU - Zhu, Liehuang
AU - Xu, Dawei
N1 - Publisher Copyright:
© 2014 IEEE.
PY - 2025
Y1 - 2025
N2 - Tor proposal 295, currently the only open proposal for onion encryption (OE), emerged from a work presented at CRYPTO 2017 and has garnered significant attention from the Tor team for its strong security and efficiency base. However, upon closer examination, it is evident that the design of proposal 295 exhibits a critical flaw—namely, the randomness within the intermediate onion layers is incomplete. This incompleteness renders proposal 295 noncompliant with the Tor-specific anonymity notion known as CircuitHiding, introduced at EUROCRYPT 2018. In this article, we highlight this anonymity flaw that trivially breaks the CircuitHiding notion. We propose a lightweight fix and rigorously prove the security of the corrected design. To our knowledge, this article provides the first formal treatment of proposal 295, contributing to Tor’s cryptographic infrastructure. Given that OE has gained prominence as a critical tool for privacy-preserving Internet of Things (IoT) applications, a thorough analysis of its anonymity property is crucial for securing these applications.
AB - Tor proposal 295, currently the only open proposal for onion encryption (OE), emerged from a work presented at CRYPTO 2017 and has garnered significant attention from the Tor team for its strong security and efficiency base. However, upon closer examination, it is evident that the design of proposal 295 exhibits a critical flaw—namely, the randomness within the intermediate onion layers is incomplete. This incompleteness renders proposal 295 noncompliant with the Tor-specific anonymity notion known as CircuitHiding, introduced at EUROCRYPT 2018. In this article, we highlight this anonymity flaw that trivially breaks the CircuitHiding notion. We propose a lightweight fix and rigorously prove the security of the corrected design. To our knowledge, this article provides the first formal treatment of proposal 295, contributing to Tor’s cryptographic infrastructure. Given that OE has gained prominence as a critical tool for privacy-preserving Internet of Things (IoT) applications, a thorough analysis of its anonymity property is crucial for securing these applications.
KW - Anonymity
KW - Tor
KW - anonymous communication
KW - provable security
UR - https://www.scopus.com/pages/publications/105003696814
U2 - 10.1109/JIOT.2025.3563336
DO - 10.1109/JIOT.2025.3563336
M3 - Article
AN - SCOPUS:105003696814
SN - 2327-4662
VL - 12
SP - 32965
EP - 32979
JO - IEEE Internet of Things Journal
JF - IEEE Internet of Things Journal
IS - 16
ER -