(2026-04) Cryptanalysis of the Sharafi–Daghigh digital signature scheme
2026-04-18
This paper is devoted to the study of the Ring-LWE-based digital signature scheme proposed by Sharafi and Daghigh, especially, the cryptanalysis of this scheme. The Sharafi and Daghigh’s scheme is inspired by the Lindner–Peikert encryption paradigm and adopts a hash-and-sign approach via the Fiat–Shamir transformation. The security claims rely on the assumed hardness of the Ring LWE and Ring-SIS problems, whose definitions and properties are well studied in last two decades. We demonstrate that this scheme is not secure and generalise our analysis to the analogous scheme in the plain-LWE setting.