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A Total Break of the Scrap Digital Signature Scheme



Daniel Smith-Tone


Recently a completely new post-quantum digital signature scheme was proposed using the so called ''scrap automorphisms''. The structure is inherently multivariate, but differs significantly from most of the multivariate literature in that it relies on sparsity and rings containing zero divisors. In this article, we derive a complete and total break of Scrap, performing a key recovery in not much more time than verifying a signature. We also generalize the result, breaking unrealistic instances of the scheme for which there is no particularly efficient signing algorithm and key sizes are unmanageable.
Cryptology Eprint Archive


Multivariate Cryptography, Scrap, Cryptanalysis, Gr\"obner basis


Smith-Tone, D. (2023), A Total Break of the Scrap Digital Signature Scheme, Cryptology Eprint Archive, [online],, (Accessed June 23, 2024)


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Created October 2, 2023, Updated October 13, 2023