A privacy-preserving reputation system with user rewards

2013 IEEE International Conference on Communications (ICC), 2013

Reputation systems allow to estimate the trustworthiness of entities based on their past behavior. Electronic commerce, peer-to-peer routing and collaborative environments, just to cite a few, highly benefit from using reputation systems. To guarantee an accurate estimation, reputation systems typically rely on a central authority, on the identification and authentication of all the participants, or both. In this paper, we go a step further by presenting a distributed reputation mechanism which is robust against malicious behaviors and that preserves the privacy of its clients. Guaranteed error bounds on the estimation are provided.

Lecture Notes in Computer Science, 2004

Previous studies have been suggestive of the fact that reputation ratings may be provided in a strategic manner for reasons of reciprocation and retaliation, and therefore may not properly reflect the trustworthiness of rated parties. It thus appears that supporting privacy of feedback providers could improve the quality of their ratings. We argue that supporting perfect privacy in decentralized reputation systems is impossible, but as an alternative present three probabilistic schemes that support partial privacy. On the basis of these schemes, we offer three protocols that allow ratings to be privately provided with high probability in decentralized additive reputation systems. Ø is too limited or outdated, so that it cannot derive a meaningful reputation measure regarding the trustworthiness of the target agent.

Journal of Internet Services and Applications, 2011

Trust plays a key-role in enhancing user experience at service providers. Reputation management systems are used to quantify trust, based on some reputation metrics. Anonymity is an important requirement in these systems, since most individuals expect that they will not be profiled by participating in the feedback process. Anonymous Reputation management (ARM) systems allow individuals to submit their feedback anonymously. However, this solves part of the problem. Anonymous ratings by one individual can be linked to each other. This enables the system to easily build a profile of that individual. Data mining techniques can use the profile to re-identify that individual. We call this the linkability problem. This paper presents an anonymous reputation management system that avoids the linkability problem. This is achieved by constructing a system that empowers individuals to interact and rate service providers, securely and anonymously.

2010

A reputation protocol computes the reputation of an entity by aggregating the feedback provided by other entities in the system. Reputation makes entities accountable for their behavior. Honest feedback is clearly a pre-requisite for accurate reputation scores. However, it has been observed that entities often hesitate in providing honest feedback, mainly due to the fear of retaliation. We present a privacy preserving reputation protocol which enables entities to provide feedback in a private and thus uninhibited manner.

Computers & Security, 2012

Reputation systems make the users of a distributed application accountable for their behavior. The reputation of a user is computed as an aggregate of the feedback provided by other users in the system. Truthful feedback is clearly a prerequisite for computing a reputation score that accurately represents the behavior of a user. However, it has been observed that users often hesitate in providing truthful feedback, mainly due to the fear of retaliation. We present a decentralized privacy preserving reputation protocol that enables users to provide feedback in a private and thus uninhibited manner. The protocol has linear message complexity, which is an improvement over comparable decentralized reputation protocols. Moreover, the protocol allows users to quantify and maximize the probability that their privacy will be preserved.

Lecture Notes in Computer Science, 2009

Trust and Reputation systems in distributed environments attain widespread interest as online communities are becoming an inherent part of the daily routine of Internet users. Trust-based models enable safer operation within communities to which information exchange and peer to peer interaction are centric. Several models for trust based reputation have been suggested recently, among them the Knots model . In these models, the subjective reputation of a member is computed using information provided by a set of members trusted by the latter. The present paper discusses the computation of reputation in such models, while preserving members' private information. Three different schemes for the private computation of reputation are presented, and the advantages and disadvantages in terms of privacy and communication overhead are analyzed.

2019

We introduce updatable anonymous credential systems UACS and use them to construct a new privacy-preserving incentive system. In a UACS, a user holding a credential certifying some attributes can interact with the corresponding issuer to update his attributes. During this, the issuer knows which update function is run, but does not learn the user's previous attributes. Hence the update process preserves anonymity of the user. One example for a class of update functions are additive updates of integer attributes, where the issuer increments an unknown integer attribute value v by some known value k. This kind of update is motivated by an application of UACS to incentive systems. Users in an incentive system can anonymously accumulate points, e.g. in a shop at checkout, and spend them later, e.g. for a discount. In this paper, we (1) formally define UACS and their security, (2) give a generic construction for UACS supporting arbitrary update functions, and (3) construct a new incentive system using UACS that is efficient while offering offline double-spending protection and partial spending.

Natural Language Processing, 2021

This paper investigates the situation in which exists the unshared Internet in specific areas while users in there need instant advice from others nearby. Hence, a peer-to-peer network is necessary and established by connecting all neighbouring mobile devices so that they can exchange questions and recommendations. However, not all received recommendations are reliable as users may be unknown to each other. Therefore, the trustworthiness of advice is evaluated based on the advisor's reputation score. The reputation score is locally stored in the user’s mobile device. It is not completely guaranteed that the reputation score is trustful if its owner uses it for a wrong intention. In addition, another privacy problem is about honestly auditing the reputation score on the advising user by the questioning user. Therefore, this work proposes a security model, namely Crystal, for securely managing distributed reputation scores and for preserving user privacy. Crystal ensures that the ...

2004

Reputation systems have the potential of improving the quality of on-line markets by identifying fraudulent users and subsequently dealing with these users can be prevented. The behaviour of participants involved in e-commerce can be recorded and then this information made available to potential transaction partners to make decisions to choose a suitable counterpart. Unfortunately current reputation systems suffer from various vulnerabilities. Solutions for many of these problems will be discussed. One of the major threats is that of unfair feedback. A large number of negative or positive feedbacks could be submitted to a particular user with the aim to either downgrade or upgrade the user's reputation. As a result the produced reputation does not reflect the user's true trustworthiness. To overcome this threat a variation of Bayesian Reputation system is proposed. The proposed scheme is based on the subjective logic framework proposed Josang et al. [65]. The impact of unfair feedback is countered through some systematic approaches proposed in the scheme. Lack of anonymity for participants leads to reluctance to provide negative feedback. A novel solution for anonymity of feedback providers is proposed to allow participants to provide negative feedback when appropriate without fear of retaliation. The solution is based on several primitive cryptographic mechanisms; e-cash, designated verifier proof and knowledge proof. In some settings it is desirable for the reputation owner to control the distribution of its own reputation and to disclose this at its discretion to the intended parties. To realize this, a solution based on a certificate mechanism is proposed. This solution allows the reputation owner to keep the certificate and to distribute its reputation while not being able to alter that information without detection. The proposed solutions cater for two modes of reputation systems: centralised and decentralised. The provision of an off-line reputation system is discussed by proposing a new solution using certificates. This is achieved through the delegation concept and a variant of digital signature schemes known as proxy signatures. v The thesis presents a security architecture of reputation systems which consists of different elements to safeguard reputation systems from malicious activities. Elements incorporated into this architecture include privacy, verifiability and availability. The architecture also introduces Bayesian approach to counter security threat posed by reputation systems. This means the proposed security architecture in the thesis is a combination of two prominent approaches, namely, Bayesian and cryptographic, to provide security for reputation systems. The proposed security architecture can be used as a basic framework for further development in identifying and incorporating required elements so that a total security solution for reputation systems can be achieved. vi Declaration The work contained in this thesis has not been previously submitted for a degree or diploma at any higher education institution. To the best of my knowledge and belief, the thesis contains no material previously published or written by another person except where due reference is made.

Proceedings of the 2005 ACM symposium on Applied computing, 2005

In this paper we present a novel approach to enable untraceable communication between pseudonyms. Our work provides strong sender and recipient anonymity by eliminating the need to know of each other's address. We use a variation of Chaum mixes to achieve unlinkability between sender and recipient and introduce a concept called extended destination routing (EDR) which relies on routing headers constructed in multiple layers of encryption and published in a distributed hash table (DHT). In order to communicate, a sender requests from the DHT the recipient's routing header, which is extended and used for routing the message via a mix cascade to this recipient. This work was performed in the context of the UniTEC reputation system and describes the functionality of its anonymous communication layer, which is completely independent of the other UniTEC layers. Although trust and reputation systems in general are typical application areas for our contribution, the presented concepts are suitable for various other application areas as well. We have implemented a prototype of UniTEC and present the first results from an ongoing evaluation in our network emulation testbed.