Paper 2021/192

Quantum Indifferentiability of SHA-3

Jan Czajkowski

Abstract

In this paper we prove quantum indifferentiability of the sponge construction instantiated with random (invertible) permutations. With this result we bring the post-quantum security of the standardized SHA-3 hash function to the level matching its security against classical adversaries. To achieve our result, we generalize the compressed-oracle technique of Zhandry (Crypto'19) by defining and proving correctness of a compressed permutation oracle. We believe our technique will find applications in many more cryptographic constructions.