Resource Fairness and Composability of Cryptographic Protocols

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Resource Fairness and Composability of Cryptographic Protocols

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by Juan Garay , Philip Mackenzie , Manoj Prabhakaran , Ke Yang

Venue:	In Cryptology ePrint Archive, http://eprint.iacr.org/2005/370
Citations:	29 - 2 self

BibTeX

@INPROCEEDINGS{Garay_resourcefairness,
    author = {Juan Garay and Philip Mackenzie and Manoj Prabhakaran and Ke Yang},
    title = {Resource Fairness and Composability of Cryptographic Protocols},
    booktitle = {In Cryptology ePrint Archive, http://eprint.iacr.org/2005/370},
    year = {}
}

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Abstract

Abstract. We introduce the notion of resource-fair protocols. Informally, this property states that if one party learns the output of the protocol, then so can all other parties, as long as they expend roughly the same amount of resources. As opposed to similar previously proposed definitions, our definition follows the standard simulation paradigm and enjoys strong composability properties. In particular, our definition is similar to the security definition in the universal composability (UC) framework, but works in a model that allows any party to request additional resources from the environment to deal with dishonest parties that may prematurely abort. In this model we specify the ideally fair functionality as allowing parties to “invest resources ” in return for outputs, but in such an event offering all other parties a fair deal. (The formulation of fair dealings is kept independent of any particular functionality, by defining it using a “wrapper.”) Thus, by relaxing the notion of fairness, we avoid a well-known impossibility result for fair multi-party computation with corrupted majority; in particular, our definition admits constructions that tolerate arbitrary number of corruptions. We also show that, as in the UC framework, protocols in our framework may be arbitrarily and concurrently composed. Turning to constructions, we define a “commit-prove-fair-open ” functionality and design an efficient resource-fair protocol that securely realizes it, using a new variant of a cryptographic primitive known as “timelines.” With (the fairly wrapped version of) this functionality we show that some of the existing secure multi-party computation protocols can be easily transformed into resource-fair protocols while preserving their security. 1

Keyphrases

cryptographic protocol resource fairness resource-fair protocol fair deal security definition arbitrary number fair multi-party computation fair functionality new variant wrapped version commit-prove-fair-open functionality fair dealing corrupted majority uc framework additional resource strong composability property particular functionality efficient resource-fair protocol secure multi-party computation protocol standard simulation paradigm dishonest party universal composability well-known impossibility result

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