Arbitrated quantum signature scheme with continuous-variable squeezed vacuum states

We propose an arbitrated quantum signature （AQS） scheme with continuous variable （CV） squeezed vacuum states, which requires three parties, i.e., the signer Alice, the verifier Bob and the arbitrator Charlie trusted by Alice and Bob, and three phases consisting of the initial phase, the signature phase and the verification phase. We evaluate and compare the original state and the teleported state by using the fidelity and the beam splitter （BS） strategy. The security is ensured by the CV-based quantum key distribution （CV-QKD） and quantum teleportation of squeezed states. Security analyses show that the generated signature can be neither disavowed by the signer and the receiver nor counterfeited by anyone with the shared keys. Furthermore, the scheme can also detect other manners of potential attack although they may be successful. Also, the integrality and authenticity of the transmitted messages can be guaranteed. Compared to the signature scheme of CV-based coherent states, our scheme has better encoding efficiency and performance. It is a potential high-speed quantum signature scheme with high repetition rate and detection efficiency which can be achieved by using the standard off-the-shelf components when compared to the discrete-variable （DV） quantum signature scheme.

Enhanced arbitrated quantum signature scheme using Bell states

We investigate the existing arbitrated quantum signature schemes as well as their cryptanalysis, including intercept- resend attack and denial-of-service attack. By exploring the loopholes of these schemes, a malicious signatory may success- fully disavow signed messages, or the receiver may actively negate the signature from the signatory without being detected. By modifying the existing schemes, we develop counter-measures to these attacks using Bell states. The newly proposed scheme puts forward the security of arbitrated quantum signature. Furthermore, several valuable topics are also presented for further research of the quantum signature scheme.

An Arbitrated Quantum Signature Scheme without Entanglement

Several quantum signature schemes are recently proposed to realize secure signatures of quantum or classical messages. Arbitrated quantum signature as one nontriviai scheme has attracted great interests because o~ its usefulness and efficiency. Unfortunately, previous schemes cannot against Trojan horse attack and DoS attack and lack of the unforgeability and the non-repudiation. In this paper, we propose an improved arbitrated quantum signature to address these secure issues with the honesty arbitrator. Our scheme takes use of qubit states not entanglements. More importantly, the qubit scheme can achieve the unforgeability and the non-repudiation. Our scheme is also secure for other known quantum attacks.