Paper Info
Title
Untagging Tor: A Formal Treatment of Onion Encryption.
Abstract
Tor is a primary tool for maintaining anonymity online. It provides a low-latency, circuit-based, bidirectional secure channel between two parties through a network of onion routers, with the aim of obscuring exactly who is talking to whom, even to adversaries controlling part of the network. Tor relies heavily on cryptographic techniques, yet its onion encryption scheme is susceptible to tagging attacks (Fu and Ling 2009), which allow an active adversary controlling the first and last node of a circuit to deanonymize with near-certainty. This contrasts with less active traffic correlation attacks, where the same adversary can at best deanonymize with high probability. The Tor project has been actively looking to defend against tagging attacks and its most concrete alternative is proposal 261, which specifies a new onion encryption scheme based on a variable-input-length tweakable cipher. We provide a formal treatment of low-latency, circuit-based onion encryption, relaxed to the unidirectional setting, by expanding existing secure channel notions to the new setting and introducing circuit hiding to capture the anonymity aspect of Tor. We demonstrate that circuit hiding prevents tagging attacks and show proposal 261's relay protocol is circuit hiding and thus resistant against tagging attacks.
Year
DOI
Venue
2018
10.1007/978-3-319-78372-7_9
ADVANCES IN CRYPTOLOGY - EUROCRYPT 2018, PT III
Keywords
DocType
Volume
Anonymity,Onion routing,Secure channels,Tor Tagging attacks
Conference
10822
ISSN
Citations 
PageRank 
0302-9743
0
0.34
References 
Authors
23
2
Name
Order
Citations
PageRank
Jean Paul Degabriele11628.23
Martijn Stam2165967.36