An Undeniable Signature Scheme Based on Approximate Trapdoors for Lattices

An undeniable signature is a type of digital signature in which the signer retains control over whether their signatures can be verified by others. Furthermore, it enables signatories to revoke their signatures in cases of significant compromise or disputes. Due to the great trend towards undeniable signatures based on lattices, the key and signature sizes are still large, which leads to concerns about efficiency. This work proposes a new undeniable signature scheme depending on approximate-ISIS problem, including signature verification, disavowal procedure, and key generation. We analyze the security of the proposed signature scheme against known cryptographic attacks on undeniable signatures. Also, we demonstrate that our scheme possesses completeness, soundness, and invisibility properties. Moreover, under the suppositions of the random oracle model, that propositioned signature is resistant to existential forgery. Our results demonstrate that it is possible to reduce both the public key and signature sizes by half compared to designs based on accurate trapdoors.