Conference Paper

PAR: Payment for Anonymous Routing.

DOI: 10.1007/978-3-540-70630-4_14 Conference: Privacy Enhancing Technologies, 8th International Symposium, PETS 2008, Leuven, Belgium, July 23-25, 2008, Proceedings
Source: DBLP


Despite the growth of the Internet and the increasing con- cern for privacy of online communications, current deployments of anon- ymization networks depend on a very small set of nodes that volunteer their bandwidth. We believe that the main reason is not disbelief in their ability to protect anonymity, but rather the practical limitations in bandwidth and latency that stem from limited participation. This limited participation, in turn, is due to a lack of incentives to participate. We propose providing economic incentives, which historically have worked very well. In this paper, we demonstrate a payment scheme that can be used to compensate nodes which provide anonymity in Tor, an existing onion routing, anonymizing network. We show that current anonymous pay- ment schemes are not suitable and introduce a hybrid payment system based on a combination of the Peppercoin Micropayment system and a new type of "one use" electronic cash. Our system claims to maintain users' anonymity, although payment techniques mentioned previously - when adopted individually - provably fail.

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    • "In 2009, there were 1,500 Tor relays for approximately 100,000 simultaneously active Tor clients [22], whereas, in June 2011, there were 2,500 relays for 300,000 to 400,000 clients [1]. Among other incentives for acting as a relay in anonymity networks, several schemes propose to make use of micropayments to reward users relaying others' anonymous traffic [6], [8], [12] . These previous works have mainly contributed to the design of anonymous and secure micropayments. "
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    ABSTRACT: Scrip is a generic term for any substitute for real currency; it can be converted into goods or services sold by the issuer. In the classic scrip system model, one agent is helped by another in return for one unit of scrip. In this paper, we present an upgraded model, the one-to-n scrip system, where users need to find n agents to accomplish a single task. We provide a detailed analytical evaluation of this system based on a game-theoretic approach. We establish that a nontrivial Nash equilibrium exists in such systems under certain conditions. We study the effect of n on the equilibrium, on the distribution of scrip in the system and on its performance. Among other results, we show that the system designer should increase the average amount of scrip in the system when n increases in order to optimize its efficiency. We also explain how our new one-to-n scrip system can be applied to foster cooperation in two privacy-enhancing applications.
    Full-text · Article · Sep 2011
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    • "For example, even if the participation rate (i.e., the rate of users who decide to run routers as a result of Tortoise) is ten times higher for filesharers than it is for web browsing clients, the number of web browsing clients that decide to participate will still be three times that of filesharers. As with other incentive schemes that reward relay operators with additional bandwidth [2] [5] [14], Tortoise reduces anonymity by forcing a smaller sender anonymity set – the set of potential senders for a given anonymous connection. With both standard Tor and Tortoise , any Internet-connected device can use the anonymity system, and hence the sender anonymity set is quite large. "
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    ABSTRACT: Tor is a volunteer-operated network of application-layer relays that enables users to communicate privately and anonymously. Unfortunately, Tor often exhibits poor performance due to congestion caused by the unbalanced ratio of clients to available relays, as well as a disproportionately high consumption of network capacity by a small fraction of filesharing users. This paper argues the very counterintuitive notion that slowing down traffic on Tor will increase the bandwidth capacity of the network and consequently improve the experience of interactive web users. We introduce Tortoise, a system for rate limiting Tor at its ingress points. We demonstrate that Tortoise incurs little penalty for interactive web users, while significantly decreasing the throughput for filesharers. Our techniques provide incentives to filesharers to configure their Tor clients to also relay traffic, which in turn improves the network's overall performance. We present large-scale emulation results that indicate that interactive users will achieve a significant speedup if even a small fraction of clients opt to run relays.
    Preview · Conference Paper · Jan 2011
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    • "These e-cash protocols can also be used for payments in other systems that face free-riding problems, such as anonymous onion routing [27]. In such a system, routers would be paid for forwarding messages using e-cash, thus providing incentives to route traffic on behalf of others in a manner similar to that proposed by Androulaki et al. [2]. Since P2P systems like these require each user to perform many cryptographic exchanges, the need to provide high performance for repeated executions of these protocols is paramount. "
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    ABSTRACT: In recent years, many advances have been made in cryptography, as well as in the performance of communication networks and processors. As a result, many advanced cryptographic protocols are now efficient enough to be considered practical, yet research in the area re- mains largely theoretical and little work has been done to use these protocols in practice, despite a wealth of potential applications. This paper introduces a simple description language, ZKPDL, and an interpreter for this language. ZKPDL implements non-interactive zero-knowledge proofs of knowledge, a primitive which has received much atten- tion in recent years. Using our language, a single pro- gram may specify the computation required by both the prover and verifier of a zero-knowledge protocol, while our interpreter performs a number of optimizations to lower both computational and space overhead. Our motivating application for ZKPDL has been the efficient implementation of electronic cash. As such, we have used our language to develop a cryptographic library, Cashlib, that provides an interface for using e- cash and fair exchange protocols without requiring ex- pert knowledge from the programmer.
    Full-text · Conference Paper · Sep 2010
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