Cryptanalysis with Countermeasure on the SIS Based Signature Scheme

Digital signatures are widely used in various applications, including email security, document authentication, and electronic transactions. They play an essential role in ensuring the non-repudiation and integrity of digital transactions and communication. Motivated by the progress of developments in quantum computers, researchers are dynamically proposing digital signature schemes that can withstand quantum attacks. Recently, Soni et al. presented a digital signature protocol that relies on the difficulty of the shortest integer solution challenge in lattices. This protocol has significantly smaller key and signature sizes than previously proposed lattice-based protocols. The design is also compact, simple and elegant. Hence, it is crucial to analyse the security of this protocol. Thus, we perform cryptanalysis on the Soni et al. scheme, which indicates that the availability of one valid message-signature pair can enable an attacker to extract the signer’s secret key. It is a significant flaw as the singing key is not a one-time key and the one-time use of this key will lead to its leakage. To overcome this flaw, we suggest a countermeasure in which the signing key can’t be achieved using any number of valid message-signature pairs.