Permutation-Based Hashing Beyond the Birthday Bound

ePrint Report: Permutation-Based Hashing Beyond the Birthday Bound

Charlotte Lefevre, Bart Mennink

It is known that the sponge construction is tightly indifferentiable from a random oracle up to around $2^{c/2}$ queries, where $c$ is the capacity. In particular, it cannot provide generic security better than half of the underlying permutation size. In this paper, we aim to achieve hash function security beating this barrier. We present a hashing mode based on two $b$-bit permutations named the double sponge. The double …

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