Cryptology ePrint Archive: Report 2010/246

Quantifying Trust

Mariusz Jakubowski, Ramarathnam Venkatesan, Yacov Yacobi

Abstract: Trust is a central concept in public-key cryptography infrastruc- ture and in security in general. We study its initial quantification and its spread patterns. There is empirical evidence that in trust-based reputation model for virtual communities, it pays to restrict the clusters of agents to small sets with high mutual trust. We propose and motivate a mathematical model, where this phenomenon emerges naturally. In our model, we separate trust values from their weights. We motivate this separation using real examples, and show that in this model, trust converges to the extremes, agreeing with and accentuating the observed phenomenon. Specifically, in our model, cliques of agents of maximal mutual trust are formed, and the trust between any two agents that do not maximally trust each other, converges to zero. We offer initial practical relaxations to the model that preserve some of the theoretical flavor.

Category / Keywords: foundations / trust, collaboration, cryptography

Publication Info: This paper has not been published elsewhere.

Date: received 29 Apr 2010

Contact author: yacov at microsoft com

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Version: 20100502:165918 (All versions of this report)

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