BT-Crowds: Crowds-Style Anonymity with Bluetooth and Java

Vaha-Sipila, A.; Virtanen, Teemupekka

doi:10.1109/hicss.2005.128

Cited by 7 publications

(4 citation statements)

References 3 publications

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“…This recursive evaluation is guaranteed to be exact (i.e., no rounding errors), provided the transition probabilities are rational. We provide the details of our approach and show its result when applied to Itai and Rodeh's leader election protocol, as well as the Crowds protocol [30], a protocol for anonymous web browsing that has been adapted, among others, to Bluetooth [32] and wireless Internet [4]. These examples show (as expected) that model reduction prior to counterexample generation may obtain even shorter regular expressions.…”

Section: Introductionmentioning

confidence: 78%

Regular Expressions for PCTL Counterexamples

Damman

Han

Katoen

2008

2008 Fifth International Conference on Quantitative Evaluation of Systems

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Counterexamples for probabilistic reachability in Markov chains are sets of paths that all reach a goal state and whose cumulative likelihood exceeds a threshold. This paper is concerned with the issue of how to conveniently represent these sets. Experiments, partially substantiated with combinatorial arguments, show that the cardinality of such sets may be excessive. To obtain compact representations of counterexamples we suggest to use regular expressions. We present a simple algorithm to generate minimal regular expressions and adopt a recursive scheme to determine their likelihood. Markov chain reduction prior to counterexample generation may yield even shorter regular expressions. The feasibility of the approach is illustrated by means two protocols: leader election and the Crowds protocol.

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Section: Introductionmentioning

confidence: 78%

Regular Expressions for PCTL Counterexamples

Damman

Han

Katoen

2008

2008 Fifth International Conference on Quantitative Evaluation of Systems

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“…With regard to recent implementations of Crowds for providing sender anonymity, an example over bluetooth with Java technology is described in . The system developed is one‐way only, on account of the fact that the mobility of nodes cannot guarantee a valid two‐way path.…”

Section: Introductionmentioning

confidence: 99%

On collaborative anonymous communications in lossy networks

Rebollo-Monedero

Forné

Pallarès

et al. 2013

Security Comm Networks

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Message encryption does not prevent eavesdroppers from unveiling who is communicating with whom, when, or how frequently, a privacy risk wireless networks are particularly vulnerable to. The Crowds protocol, a well-established anonymous communication system, capitalizes on user collaboration to enforce sender anonymity. This work formulates a mathematical model of a Crowd-like protocol for anonymous communication in a lossy network, establishes quantifiable metrics of anonymity and quality of service (QoS), and theoretically characterizes the trade-off between them. The anonymity metric chosen follows the principle of measuring privacy as an attacker's estimation error. By introducing losses, we extend the applicability of the protocol beyond its original proposal. We quantify the intuition that anonymity comes at the expense of both delay and end-to-end losses. Aside from introducing losses in our model, another main difference with respect to the traditional Crowds is the focus on networks with stringent QoS requirements, for best effort anonymity, and the consequent elimination of the initial forwarding step. Beyond the mathematical solution, we illustrate a systematic methodology in our analysis of the protocol. This methodology includes a series of formal steps, from the establishment of quantifiable metrics all the way to the theoretical study of the privacy QoS trade-off. Copyright © 2013 John Wiley & Sons, Ltd.Peer ReviewedPostprint (published version

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“…We briefly argue that model reduction such as bisimulation and SCC elimination [50] can be used to obtain even more compact counterexamples. Finally, we show the generation of counterexamples on the Crowds protocol [56], a protocol for anonymous Web browsing that has been adopted, among others, to Bluetooth [59] and wireless Internet [5].…”

Section: Introductionmentioning

confidence: 99%

Counterexample Generation in Probabilistic Model Checking

Han

Katoen

Berteun

2009

IIEEE Trans. Software Eng.

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Abstract-Providing evidence for the refutation of a property is an essential, if not the most important, feature of model checking. This paper considers algorithms for counterexample generation for probabilistic CTL formulas in discrete-time Markov chains. Finding the strongest evidence (i.e., the most probable path) violating a (bounded) until-formula is shown to be reducible to a single-source (hopconstrained) shortest path problem. Counterexamples of smallest size that deviate most from the required probability bound can be obtained by applying (small amendments to) k-shortest (hop-constrained) paths algorithms. These results can be extended to Markov chains with rewards, to LTL model checking, and are useful for Markov decision processes. Experimental results show that, typically, the size of a counterexample is excessive. To obtain much more compact representations, we present a simple algorithm to generate (minimal) regular expressions that can act as counterexamples. The feasibility of our approach is illustrated by means of two communication protocols: leader election in an anonymous ring network and the Crowds protocol.

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BT-Crowds: Crowds-Style Anonymity with Bluetooth and Java

Cited by 7 publications

References 3 publications

Regular Expressions for PCTL Counterexamples

Regular Expressions for PCTL Counterexamples

On collaborative anonymous communications in lossy networks

Counterexample Generation in Probabilistic Model Checking

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