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U. Toulouse

Bio: U. Toulouse is an academic researcher. The author has contributed to research in topics: Reputation system & Secret sharing. The author has an hindex of 1, co-authored 1 publications receiving 18 citations.

Papers
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Dissertation
01 Jan 2010
TL;DR: Wang et al. as mentioned in this paper proposed privacy-preserving reputation protocols, which compute reputation such that the individual feedback of any user is not revealed, and use trust awareness, data perturbation, secret sharing, secure multi-party computation, additive homomorphic cryptosystems, and zero-knowledge proofs.
Abstract: It has been observed that users in a reputation system often hesitate in providing negative feedback due to the fear of retaliation. A solution to this issue is privacy preserving reputation systems, which compute reputation such that the individual feedback of any user is not revealed. In this thesis, we present privacy preserving reputation protocols, that are decentralized, do not require specialized platforms nor trusted third parties, protect privacy under a range of adversarial models (semi-honest, non-disruptive malicious, disruptive malicious), and are more efficient than comparable protocols (the most expensive protocol requires O(n) + O(log N) messages, where n and N are the number of feedback providers and the total number of users respectively). The techniques that we utilize include trust awareness, data perturbation, secret sharing, secure multi-party computation, additive homomorphic cryptosystems, and zero-knowledge proofs. We also address some issues related to trust recommendation and propagation. In particular, we present a solution to the problem of subjectivity in trust recommendation. Experimental results indicate the effectiveness of the proposed strategies.

18 citations


Cited by
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Book ChapterDOI
04 Oct 2019
TL;DR: Permission to copy without fee all or part of this material is granted provided that the copies arc not made or distributed for direct commercial advantage.
Abstract: Usually, a proof of a theorem contains more knowledge than the mere fact that the theorem is true. For instance, to prove that a graph is Hamiltonian it suffices to exhibit a Hamiltonian tour in it; however, this seems to contain more knowledge than the single bit Hamiltonian/non-Hamiltonian.In this paper a computational complexity theory of the “knowledge” contained in a proof is developed. Zero-knowledge proofs are defined as those proofs that convey no additional knowledge other than the correctness of the proposition in question. Examples of zero-knowledge proof systems are given for the languages of quadratic residuosity and 'quadratic nonresiduosity. These are the first examples of zero-knowledge proofs for languages not known to be efficiently recognizable.

1,962 citations

Journal ArticleDOI
TL;DR: This survey presents a study and analysis of existing trust systems in participatory sensing applications, and identifies many trust problems that have not been solved and many attacks that have been addressed yet in the literature.

102 citations

Journal ArticleDOI
TL;DR: This work presents a decentralized privacy preserving reputation protocol that enables users to provide feedback in a private and thus uninhibited manner and allows users to quantify and maximize the probability that their privacy will be preserved.

57 citations

Journal Article
TL;DR: This work ties ratings to actual interactions to force users to also deposit their negative ratings at the reputation server and enhances users' anonymity by limiting timing attacks through the use of transferable-eCash-based payment systems.
Abstract: Privacy-respecting reputation systems have been constructed based on anonymous payment systems in order to implement raters' anonymity. To the best of our knowledge, all these systems suffer from the problem of having a "final state", i. e., a system state in which users have no incentive anymore to behave honestly because they reached a maximum reputation or they can no longer be rated. Thus the reputation is in fact no longer lively. We propose a novel approach to address the problem of liveliness by the employment of negative ratings. We tie ratings to actual interactions to force users to also deposit their negative ratings at the reputation server. Otherwise they would not be able to interact any more. Additionally we enhance users' anonymity by limiting timing attacks through the use of transferable-eCash-based payment systems.

23 citations

Proceedings ArticleDOI
09 Sep 2012
TL;DR: This article proposes an evolution of trust-based recommender systems that only relies on local information and can be deployed on top of existing social networks, and takes into account friends' similarity and confidence on ratings, but limits data exchange to direct friends, in order to prevent ratings from being globally known.
Abstract: In this article, we propose an evolution of trust-based recommender systems that only relies on local information and can be deployed on top of existing social networks. Our approach takes into account friends' similarity and confidence on ratings, but limits data exchange to direct friends, in order to prevent ratings from being globally known. Therefore, calculations are limited to locally processed algorithms, privacy concerns can be taken into account and algorithms are suitable for decentralized or peer-to-peer architectures.We have implemented and evaluated our approach against five others, using the Epinions trust network. We show that local information with good default scoring strategies are sufficient to cover more users than classical collaborative filtering and trust-based recommender systems. Regarding accuracy, our approach performs better than most others, specially for cold start users, despite using less information.

15 citations