An Efficient Mix-Net

We describe an efficient mix-net. Its efficiency is based on a novel method, double encryption. We use a variant of "repetitive robustness", introduced by Jakobsson, to achieve robustness. The notion of double encryption enables us to avoid the large number of proofs of knowledge required in most mix-net constructions. For a large number n of senders each mix-center in our mix-net computes approximately 25n exponentiations in real time, which also gives the approximate execution time of the mix-net. Thus, our mix-net is faster than any known mix-net and the first mix-net in which the number of exponentiations computed by a mix-center is essentially independent of the number of mix-centers. Currently there exist no security proofs of our construction, but we describe the underlying ideas of the design.

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