ACAC Seminar Abstract

ACAC Seminar Abstract

ACAC Seminars

ACAC Seminar Abstract

Verifiable Rotation of Homomorphic Encryptions

Speaker: Berry Schoenmakers
Date, Time: Fri, 13 Feb 2009 15:00

Verifiable shuffling (or mixing) is a well-known primitive which allows a party to transform a given list of ciphertexts into a randomly permuted and re-blinded list of ciphertexts and prove in zero-knowledge that the multisets of plaintexts for both lists are identical. In this talk, we consider the same problem except that the random permutation is not arbitrary, but restricted to a rotation (cyclic shift).

We present two new, efficient protocols. Our first protocol is quite elegant and involves the use of the Discrete Fourier Transform (as well as the Fast Fourier Transform algorithm), and works under some reasonable conditions. Our second protocol is more general (requiring no further conditions) and is only slightly less efficient than the DFT-based protocol.

We also briefly address various applications of verifiable rotation, ranging from `fragile mixing' as introduced by Reiter and Wang at CCS'04 to applications in protocols for secure multiparty computation and voting.

This is joint work with Sebastiaan de Hoogh, Boris Skoric, and José Villegas, all from TU Eindhoven. To appear at PKC 2009.

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