3,621 research outputs found
Seeking Anonymity in an Internet Panopticon
Obtaining and maintaining anonymity on the Internet is challenging. The state
of the art in deployed tools, such as Tor, uses onion routing (OR) to relay
encrypted connections on a detour passing through randomly chosen relays
scattered around the Internet. Unfortunately, OR is known to be vulnerable at
least in principle to several classes of attacks for which no solution is known
or believed to be forthcoming soon. Current approaches to anonymity also appear
unable to offer accurate, principled measurement of the level or quality of
anonymity a user might obtain.
Toward this end, we offer a high-level view of the Dissent project, the first
systematic effort to build a practical anonymity system based purely on
foundations that offer measurable and formally provable anonymity properties.
Dissent builds on two key pre-existing primitives - verifiable shuffles and
dining cryptographers - but for the first time shows how to scale such
techniques to offer measurable anonymity guarantees to thousands of
participants. Further, Dissent represents the first anonymity system designed
from the ground up to incorporate some systematic countermeasure for each of
the major classes of known vulnerabilities in existing approaches, including
global traffic analysis, active attacks, and intersection attacks. Finally,
because no anonymity protocol alone can address risks such as software exploits
or accidental self-identification, we introduce WiNon, an experimental
operating system architecture to harden the uses of anonymity tools such as Tor
and Dissent against such attacks.Comment: 8 pages, 10 figure
Herbivore: A Scalable and Efficient Protocol for Anonymous Communication
Anonymity is increasingly important for networked applications
amidst concerns over censorship and privacy. In this paper, we describe Herbivore, a peer-to-peer, scalable, tamper-resilient communication system that provides provable anonymity and privacy. Building on dining cryptographer networks, Herbivore scales by partitioning the network into anonymizing cliques. Adversaries able to monitor all network traffic cannot deduce the identity of a sender or receiver beyond an anonymizing clique. In addition to strong anonymity, Herbivore simultaneously provides high efficiency and scalability, distinguishing it from other anonymous communication protocols. Performance measurements from a prototype implementation show that the system can achieve high bandwidths and low latencies when deployed over the Internet
Development and Analysis of Deterministic Privacy-Preserving Policies Using Non-Stochastic Information Theory
A deterministic privacy metric using non-stochastic information theory is
developed. Particularly, minimax information is used to construct a measure of
information leakage, which is inversely proportional to the measure of privacy.
Anyone can submit a query to a trusted agent with access to a non-stochastic
uncertain private dataset. Optimal deterministic privacy-preserving policies
for responding to the submitted query are computed by maximizing the measure of
privacy subject to a constraint on the worst-case quality of the response
(i.e., the worst-case difference between the response by the agent and the
output of the query computed on the private dataset). The optimal
privacy-preserving policy is proved to be a piecewise constant function in the
form of a quantization operator applied on the output of the submitted query.
The measure of privacy is also used to analyze the performance of -anonymity
methodology (a popular deterministic mechanism for privacy-preserving release
of datasets using suppression and generalization techniques), proving that it
is in fact not privacy-preserving.Comment: improved introduction and numerical exampl
Hang With Your Buddies to Resist Intersection Attacks
Some anonymity schemes might in principle protect users from pervasive
network surveillance - but only if all messages are independent and unlinkable.
Users in practice often need pseudonymity - sending messages intentionally
linkable to each other but not to the sender - but pseudonymity in dynamic
networks exposes users to intersection attacks. We present Buddies, the first
systematic design for intersection attack resistance in practical anonymity
systems. Buddies groups users dynamically into buddy sets, controlling message
transmission to make buddies within a set behaviorally indistinguishable under
traffic analysis. To manage the inevitable tradeoffs between anonymity
guarantees and communication responsiveness, Buddies enables users to select
independent attack mitigation policies for each pseudonym. Using trace-based
simulations and a working prototype, we find that Buddies can guarantee
non-trivial anonymity set sizes in realistic chat/microblogging scenarios, for
both short-lived and long-lived pseudonyms.Comment: 15 pages, 8 figure
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