Cryptology ePrint Archive: Report 2019/884

Cryptanalysis of Round-Reduced KECCAK using Non-Linear Structures

Mahesh Sreekumar Rajasree

Abstract: In this paper, we present new preimage attacks on KECCAK-384 and KECCAK-512 for 2, 3 and 4 rounds. The attacks are based on non-linear structures (structures that contain quadratic terms). These structures were studied by Guo et al. and Li et al. to give preimage attacks on round reduced KECCAK. We carefully construct non-linear structures such that the quadratic terms are not spread across the whole state. This allows us to create more linear equations between the variables and hash values, leading to better preimage attacks. As a result, we present the best theoretical preimage attack on KECCAK-384 and KECCAK-512 for 2 and 3-rounds and also KECCAK-384 for 4-rounds.

Category / Keywords: KECCAK, SHA-3, Hash function, Cryptanalysis, Preimage attack

Date: received 1 Aug 2019

Contact author: mahesr at iitk ac in

Available format(s): PDF | BibTeX Citation

Version: 20190801:132620 (All versions of this report)

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