Kripaka, IlliaFesenko, Andrii2026-02-252026-02-252025Kripaka, I. Bit-sliced Algorithm for the 512-point Number Theoretic Transform / Illia Kripaka, Andrii Fesenko // Theoretical and Applied Cybersecurity: scientific journal. – 2025. – Vol. 7, No. 2. – P. 5-12. – Bibliogr.: 22 ref.https://ela.kpi.ua/handle/123456789/79042A method for computing the 512-digit number theoretic transform used in the Vershyna digital signature scheme, employing bitwise digit operations, is proposed. The correctness of the developed algorithm and its efficient constant-time performance have been proven. The obtained results indicate that the proposed approach is adaptive and can be applied to computations with other polynomials. This enables its easy integration into various cryptosystems to ensure protection against side-channel attacks. The proposed method does not require changes to the digital signature scheme itself, introducing modifications only to the polynomial multiplication function.enArticleP. 5-12https://doi.org/10.20535/tacs.2664-29132025.2.343116003.26:519.6880000-0002-4489-3256