Improvements on quantum designated verifier signature based on Bell states

<title>Abstract</title> <p>Quantum Designated Verifier Signature (QDVS) is a cryptographic scheme based on quantum mechanics in which a signature can be verified only by a specific designated verifier. Recently, Xin et al. (Quantum Information Processing, 2020, 19(3):79) proposed a QDVS scheme based on Bell states and claimed that it was secure. However, we demonstrate that their scheme is vulnerable to forgery attacks. To overcome this vulnerability, we propose an improved QDVS scheme utilizing single qubits and unitary operations. Compared with Xin et al.'s scheme, our scheme requires neither a trusted center (TC) nor quantum entanglement resources, thereby greatly reducing the implementation complexity. Our security analysis demonstrates that our scheme can resist common attacks, including inter-resending, forgery, and impersonation attacks.</p>