Jinjing Shi

Batch proxy quantum blind signature scheme

Motivated by proxy signature and blind signature for the secure communications, the batch signature is proposed to create a novel quantum cryptosystem. It is based on three-dimensional two-particle-entangled quantum system which is used to distribute the quantum keys and create strings of quantum-trits (qutrits) for messages. All of the messages, which are expected to be signed, are encrypted by the private key of the message owner during communications. Different from the classical blind signature, an authenticity verification of signatures and an arbitrator’s efficient batch proxy signature are simultaneously applied in the present scheme. Analysis of security and efficiency shows that it enables us to achieve a large number of quantum blind signatures for quantities of messages with a high efficiency with the arbitrator’s secure batch proxy blind signature.

A multiparty quantum proxy group signature scheme for the entangled-state message with quantum Fourier transform

A novel multiparty quantum proxy group signature scheme is proposed based on the discrete quantum Fourier transform in order to improve the efficiency and the security of quantum signature for an n-dimensional quantum message, in which the generation and verification of the signature can be successfully conducted only if all the n participants cooperate with each other and with the message owner’s, the receiver’s and the arbitrator’s help. The quantum parallel algorithm is applied to efficiently compare the restored quantum message to the original quantum message both of which contain a large amount of information. All the operations in signing and verifying phase can be executed in quantum circuits. The analysis shows that our scheme is more efficient than other traditional quantum signature schemes, and a secure quantum proxy group signature can be achieved effectively for a contract that needs the cosigner of multi participants. It has a wide application to E-payment system, Online contract, Online notarization and etc.

Multiparty Quantum Group Signature Scheme with Quantum Parallel Computation

A novel (n, n) scheme of multiparty quantum group signature of classical or quantum message is proposed based on the discrete quantum Fourier transform. The generation and verification of the signature can be processed only if all the n participants work in concert. Moreover, a new verification manner, in which the message owner and the signing group separately verify the signature on both side by using the entangled state of EPR sequence, is involved in this paper. Security analysis shows that it is feasible to achieve a secure quantum group signature with the secure quantum computation.

Quantum blind dual-signature scheme without arbitrator

Motivated by the elegant features of a bind signature, we suggest the design of a quantum blind dual-signature scheme with three phases, i.e., initial phase, signing phase and verification phase. Different from conventional schemes, legal messages are signed not only by the blind signatory but also by the sender in the signing phase. It does not rely much on an arbitrator in the verification phase as the previous quantum signature schemes usually do. The security is guaranteed by entanglement in quantum information processing. Security analysis demonstrates that the signature can be neither forged nor disavowed by illegal participants or attacker. It provides a potential application for e-commerce or e-payment systems with the current technology.

Continuous-variable quantum key distribution under the local oscillator intensity attack with noiseless linear amplifier

An improved continuous-variable quantum key distribution (CVQKD) protocol is proposed to improve the performance of CVQKD system under the local oscillator intensity attack by using a suitable noiseless linear amplifier (NLA) at the destination. This method can enhance the efficiency of the CVQKD scheme in terms of the maximum transmission distance, no matter whether the direct or reverse reconciliation is used. Simulation results show that there is a considerable increase in the transmission distance for the NLA-based CVQKD by adjusting the values of the parameters.

Quantum dual signature scheme based on coherent states with entanglement swapping

A novel quantum dual signature scheme, which combines two signed messages expected to be sent to two diverse receivers Bob and Charlie, is designed by applying entanglement swapping with coherent states. The signatory Alice signs two different messages with unitary operations (corresponding to the secret keys) and applies entanglement swapping to generate a quantum dual signature. The dual signature is firstly sent to the verifier Bob who extracts and verifies the signature of one message and transmits the rest of the dual signature to the verifier Charlie who verifies the signature of the other message. The transmission of the dual signature is realized with quantum teleportation of coherent states. The analysis shows that the security of secret keys and the security criteria of the signature protocol can be greatly guaranteed. An extensional multi-party quantum dual signature scheme which considers the case with more than three participants is also proposed in this paper and this scheme can remain secure. The proposed schemes are completely suited for the quantum communication network including multiple participants and can be applied to the e-commerce system which requires a secure payment among the customer, business and bank.

Improving continuous-variable quantum key distribution under local oscillator intensity attack using entanglement in the middle*

A modified continuous-variable quantum key distribution (CVQKD) protocol is proposed by originating the entangled source from a malicious third party Eve in the middle instead of generating it from the trustworthy Alice or Bob. This method is able to enhance the efficiency of the CVQKD scheme attacked by local oscillator (LO) intensity attack in terms of the generated secret key rate in quantum communication. The other indication of the improvement is that the maximum transmission distance and the maximum loss tolerance can be increased significantly, especially for CVQKD schemes based on homodyne detection.

Anonymous voting for multi-dimensional CV quantum system*

We investigate the design of anonymous voting protocols, CV-based binary-valued ballot and CV-based multi-valued ballot with continuous variables (CV) in a multi-dimensional quantum cryptosystem to ensure the security of voting procedure and data privacy. The quantum entangled states are employed in the continuous variable quantum system to carry the voting information and assist information transmission, which takes the advantage of the GHZ-like states in terms of improving the utilization of quantum states by decreasing the number of required quantum states. It provides a potential approach to achieve the efficient quantum anonymous voting with high transmission security, especially in large-scale votes.

Quantum states sharing in the relay system with teleportation of non-maximally entanglement

A novel scheme for multi-quantum-state sharing is proposed based on the relay system with teleportation in the non-maximally-entangled channel in order to improve the efficiency of secure distribution of quantum states for communications. Multi quantum states are encoded as quantum packets and teleported from the source to the destination with assistance of the relay. It demonstrates that secure multi quantum states sharing can be achieved and meanwhile the range of quantum communication can be increased and approximately doubled. It provides a valuable application prospect in long distance reliable communications and a wide application to quantum networks.

A Quantum TITO Diversity Transmission Scheme with Quantum Teleportation of Non-maximally Entangled Bell State

A quantum TITO (Two-Input-Two-Output) diversity transmission scheme for the entangled-state message is proposed by generalizing the wireless transmission technique to the quantum field. The TITO quantum teleportation can be implemented with non-maximally entangled Bell states in order to enhance the security and fidelity of the quantum channel, in which a quantum signal sequence with n entangled quantum states can be transmitted through the TITO quantum channel by applying the diversity technology. The analysis shows that the quantum TITO transmission can be achieved securely and with an expected fidelity.