Cryptology ePrint Archive: Report 2020/1343
Improved Cryptanalysis of UOV and Rainbow
Ward Beullens
Abstract: The contributions of this paper are twofold. First, we simplify the description of the Unbalanced Oil and Vinegar scheme (UOV) and its Rainbow variant, which makes it easier to understand the scheme and the existing attacks. We hope that this will make UOV and Rainbow more approachable for cryptanalysts. Secondly, we give two new attacks against the UOV and Rainbow signature schemes; the intersection attack that applies to both UOV and Rainbow and the rectangular MinRank attack that applies only to Rainbow. Our attacks are more powerful than existing attacks. In particular, we estimate that compared to previously known attacks, our new attacks reduce the cost of a key recovery by a factor of $2^{17}$, $2^{53}$, and $2^{73}$ for the parameter sets submitted to the second round of the NIST PQC standardization project targeting the security levels I, III, and V respectively. For the third round parameters, the cost is reduced by a factor of $2^{20}$, $2^{40}$, and $2^{55}$ respectively. This means all these parameter sets fall short of the security requirements set out by NIST.
Category / Keywords: public-key cryptography / post-quantum cryptography, digital signatures, cryptanalysis
Date: received 26 Oct 2020
Contact author: ward beullens at esat kuleuven be
Available format(s): PDF | BibTeX Citation
Version: 20201026:092828 (All versions of this report)
Short URL: ia.cr/2020/1343
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