Cryptology ePrint Archive: Report 2014/778

Anonymous IBE from Quadratic Residuosity with Improved Performance

Michael Clear and Hitesh Tewari and Ciarán McGoldrick

Abstract: Identity Based Encryption (IBE) has been constructed from bilinear pairings, lattices and quadratic residuosity. The latter is an attractive basis for an IBE owing to the fact that it is a well-understood hard problem from number theory. Cocks constructed the first such scheme, and subsequent improvements have been made to achieve anonymity and improve space efficiency. However, the anonymous variants of Cocks' scheme thus far are all less efficient than the original. In this paper, we present a new universally-anonymous IBE scheme based on the quadratic residuosity problem. Our scheme has better performance than the universally anonymous scheme from Ateniese and Gasti (CT-RSA 2009) at the expense of more ciphertext expansion. Another contribution of this paper is a modification to a variant of the space-efficient scheme by Boneh, Gentry and Hamburg (FOCS 07) that results in an IND-ID-CPA secure IBE scheme with comparable efficiency to Cocks, but with reduced ciphertext expansion.

Category / Keywords: public-key cryptography / Anonymous IBE, Cocks, Quadratic Residuosity

Original Publication (with minor differences): Africacrypt 2014

Date: received 1 Oct 2014

Contact author: clearm at scss tcd ie

Available format(s): PDF | BibTeX Citation

Note: Minor extension to Africacrypt 2014 paper.

Version: 20141005:042101 (All versions of this report)

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