Efficient private multi-party computations of trust in the presence of curious and malicious users

• Published in: Journal of trust management 2014-06, Vol.1 (1), p.8
• Main Authors: Dolev, Shlomi, Gilboa, Niv, Kopeetsky, Marina
• Format: Article
• Language: English
• Subjects: Algorithms; Coding and Information Theory; Communication; Community; Computer Science; Data Structures and Information Theory; Licenses; Privacy; Protocol; Public Key Infrastructure; Reputations; Software Engineering/Programming and Operating Systems; Systems and Data Security; Trust
• ISSN: 2196-064X; 2196-064X
• DOI: 10.1186/2196-064X-1-8

Schemes for multi-party trust computation are presented. The schemes do not make use of a Trusted Authority. The schemes are more ein a completely distributed manner, where each user calculates its trust value privately and independently. Given a community C and its members (users) U 1 ,…, U n , we present computationally secure schemes for trust computation. The first scheme, Accumulated Protocol AP computes the average trust attributed to a specific user, U t following a trust evaluation request initiated by a user U n . The exact trust values of each queried user are not disclosed to U n . The next scheme, Weighted Accumulated Protocol WAP generates the average weighted trust in a specific user U t taking into consideration the unrevealed trust that U n has in each user participating in the trust evaluation process. The Public Key Encryption Protocol PKEP outputs a set of the exact trust values given by the users without linking the user that contributed a specific trust value to the trust this user contributed. The obtained vector of trust values assists in removing outliers. Given the set of trust values, the outliers that provide extremely low or high trust values can be removed from the trust evaluation process. We extend our schemes to the case when the initiator, U n , can be compromised by the adversary, and we introduce the Multiple Private Keys and the Weighted protocols ( MPKP and MPWP ) for computing average unweighted and weighted trust, respectively. Moreover, the Csed Protocol ( CEBP ) extends the PKEBP in this case. The computation of all our algorithms requires the transmission of O ( n ) (possibly large) messages.