Method of Security Evaluation of the LBlock-like Ciphers against Differential Cryptanalysis
ะะฐะฝัะฐะถะธัััั...
ะคะฐะนะปะธ
ะะฐัะฐ
2025
ะะฒัะพัะธ
Yakymchuk, Oleksii
Lopatetskyi, Mykhailo
ะะฐัะบะพะฒะธะน ะบะตััะฒะฝะธะบ
ะะฐะทะฒะฐ ะถััะฝะฐะปั
ะะพะผะตั ISSN
ะะฐะทะฒะฐ ัะพะผั
ะะธะดะฐะฒะตัั
Igor Sikorsky Kyiv Polytechnic Institute
ะะฝะพัะฐััั
This paper considers the problem of estimating the security of the lightweight block cipher LBlockagainst differential cryptanalysis. We formalize the process and present two algorithms of computingupper bounds for differential probabilities. The baseline algorithm provides approximate estimatesbased on the number of active๐-boxes, while the refined algorithm incorporates the full probabilitydistributions of๐-box differentials, yielding significantly better bounds.To illustrate the efficiency of the proposed methodology, we introduce a modified version of LBlockwith8ร8๐-boxes, which has lower computational complexity and allows experimental evaluationon our resources. We consider different linear permutations of encryption round, analyzing affect theestimates produced by both algorithms. The results demonstrate that the refined algorithm achievesmuch smaller maximum bounds (below2โ40in the best cases) compared to the baseline approach andprovides a more accurate characterization of security against differential cryptanalysis.Overall, the proposed algorithms make it possible to efficiently evaluate the provable security ofLBlock-like ciphers against differential cryptanalysis
ะะฟะธั
ะะปััะพะฒั ัะปะพะฒะฐ
symmetric cryptography, block cipher, differential cryptanalysis, LBlock
ะัะฑะปัะพะณัะฐัััะฝะธะน ะพะฟะธั
Yakymchuk, O. Method of Security Evaluation of the LBlock-like Ciphers against Differential Cryptanalysis / Oleksii Yakymchuk, Mykhailo Lopatetskyi // Theoretical and Applied Cybersecurity: scientific journal. โ 2025. โ Vol. 7, No. 2. โ P. 13-23. โ Bibliogr.: 17 ref.