Conference Paper

Simplified VSS and Fact-Track Multiparty Computations with Applications to Threshold Cryptography.

Source: DBLP
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    ABSTRACT: A private set intersection (PSI) protocol allows two parties to compute the intersection of their input sets privately. Most of the previous PSI protocols only output the result to one party and the other party gets nothing from running the protocols. However, a mutual PSI protocol in which both parties can get the output is highly desirable in many applications. A major obstacle in designing a mutual PSI protocol is how to ensure fairness. In this paper we present the first fair mutual PSI protocol which is efficient and secure. Fairness of the protocol is obtained in an optimistic fashion, i.e. by using an offline third party arbiter. In contrast to many optimistic protocols which require a fully trusted arbiter, in our protocol the arbiter is only required to be semi-trusted, in the sense that we consider it to be a potential threat to both parties’ privacy but believe it will follow the protocol. The arbiter can resolve disputes without knowing any private information belongs to the two parties. This feature is appealing for a PSI protocol in which privacy may be of ultimate importance.
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    ABSTRACT: Secure multiparty computation (SMC) has gained tremendous importance with the growth of the Internet and e-commerce, where mutually untrusted parties need to jointly compute a function of their private inputs. However, SMC protocols usually have very high computational complexities, rendering them practically unusable. In this paper, we tackle the problem of comparing two input values in a secure distributed fashion. We propose efficient secure comparison protocols for both the homomorphic encryption and secret sharing schemes. We also give experimental results to show their practical relevance.
    Database and Expert Systems Application, 2009. DEXA '09. 20th International Workshop on; 10/2009
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    ABSTRACT: At CHES 2011 Goubin and Martinelli described a new countermeasure against side-channel analysis for AES based on Shamir's secret-sharing scheme. In the present paper, we exhibit a flaw in this scheme and we show that it is always theoretically broken by a first-order side-channel analysis. As a consequence of this attack, only a slight adaptation of the scheme proposed by Ben-Or et STOC in 1988 can securely process multiplications on data shared with Shamir's technique. In the second part of this paper, we propose an improvement of this scheme that leads to a complexity ${\cal \tilde O}(d^2)$ instead of ${\cal O}(d^3)$, where d is the number of shares per data.
    Proceedings of the 11th international conference on Smart Card Research and Advanced Applications; 11/2012