Cryptology ePrint Archive: Report 2014/829

Additively Homomorphic UC commitments with Optimal Amortized Overhead

Ignacio Cascudo and Ivan Damgård and Bernardo David and Irene Giacomelli and Jesper Buus Nielsen and Roberto Trifiletti

Abstract: We propose the first UC secure commitment scheme with (amortized) computational complexity linear in the size of the string committed to. After a preprocessing phase based on oblivious transfer, that only needs to be done once and for all, our scheme only requires a pseudorandom generator and a linear code with efficient encoding. We also construct an additively homomorphic version of our basic scheme using VSS. Furthermore we evaluate the concrete efficiency of our schemes and show that the amortized computational overhead is significantly lower than in the previous best constructions. In fact, our basic scheme has amortised concrete efficiency comparable with previous protocols in the Random Oracle Model even though it is constructed in the plain model.

Category / Keywords: cryptographic protocols / universal composability, commitment, VSS, secret sharing, coding, asymptotics

Original Publication (in the same form): IACR-PKC-2015

Date: received 12 Oct 2014, last revised 11 Jan 2015

Contact author: giacomelli at cs au dk

Available format(s): PDF | BibTeX Citation

Note: Full version of the paper appeared in PKC2015

Version: 20150111:135506 (All versions of this report)

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