# Rotational Cryptanalysis of Round-Reduced Keccak

## Abstract

In this paper we attack round-reduced Keccak hash function with a technique called rotational cryptanalysis. We focus on Keccak variants proposed as SHA-3 candidates in the NIST’s contest for a new standard of cryptographic hash function. Our main result is a preimage attack on 4-round Keccak and a 5-round distinguisher on Keccak-\(f\)[1600] permutation — the main building block of Keccak hash function.

### Keywords

Preimage attack Keccak Rotational cryptanalysis SHA-3## Notes

### Acknowledgement

We would like to thank the Keccak Team for useful comments and discussion. We also thank Dmitry Khovratovich, Thomas Peyrin and anonymous reviewers for improving the quality of the paper. The research was cofounded by the European Union from resources of the European Social Fund, Project PO KL Information technologies: Research and their interdisciplinary applications, Agreement UDA-POKL.04.01.01-00-051/10-00. Josef Pieprzyk was supported by the Australian Research Council grant DP0987734.

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