Cryptology ePrint Archive: Report 2014/640

Revocation in Publicly Verifiable Outsourced Computation

James Alderman and Carlos Cid and Jason Crampton and Christian Janson

Abstract: The combination of software-as-a-service and the increasing use of mobile devices gives rise to a considerable difference in computational power between servers and clients. Thus, there is a desire for clients to outsource the evaluation of complex functions to an external server. Servers providing such a service may be rewarded per computation, and as such have an incentive to cheat by returning garbage rather than devoting resources and time to compute a valid result.

In this work, we introduce the notion of Revocable Publicly Verifiable Computation (RPVC), where a cheating server is revoked and may not perform future computations (thus incurring a financial penalty). We introduce a Key Distribution Center (KDC) to efficiently handle the generation and distribution of the keys required to support RPVC. The KDC is an authority over entities in the system and enables revocation. We also introduce a notion of blind verification such that results are verifiable (and hence servers can be rewarded or punished) without learning the value. We present a rigorous definitional framework, define a number of new security models and present a construction of such a scheme built upon Key-Policy Attribute-based Encryption.

Category / Keywords: cryptographic protocols / Publicly Verifiable Outsourced Computation, Key Distribution Center, Key-policy Attribute-based Encryption, Revocation

Date: received 19 Aug 2014, last revised 19 Aug 2014

Contact author: james alderman 2011 at live rhul ac uk

Available format(s): PDF | BibTeX Citation

Note: This is the full version of the paper entitled "Publicly Verifiable Outsourced Computation with a Key Distribution Centre", available at http://arxiv.org/abs/1406.5720

Version: 20140827:071812 (All versions of this report)

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