Blind Quantum Signature with Blind Quantum Computation

Blind quantum computation allows a client without quantum abilities to interact with a quantum server to perform a unconditional secure computing protocol, while protecting client’s privacy. Motivated by confidentiality of blind quantum computation, a blind quantum signature scheme is designed with laconic structure. Different from the traditional signature schemes, the signing and verifying operations are performed through measurement-based quantum computation. Inputs of blind quantum computation are securely controlled with multi-qubit entangled states. The unique signature of the transmitted message is generated by the signer without leaking information in imperfect channels. Whereas, the receiver can verify the validity of the signature using the quantum matching algorithm. The security is guaranteed by entanglement of quantum system for blind quantum computation. It provides a potential practical application for e-commerce in the cloud computing and first-generation quantum computation.     

An Arbitrated Quantum Signature with Bell States

Entanglement is the main resource in quantum communication. The main aims of the arbitrated quantum signature (AQS) scheme are to present an application of the entanglement in cryptology and to prove the possibility of the quantum signature. More specifically, the main function of quantum entangled states in the existing AQS schemes is to assist the signatory to transfer quantum states to the receiver. However, teleportation and the Leung quantum one-time pad (L-QOTP) algorithm are not enough to design a secure AQS scheme. For example, Pauli operations commute or anticommute with each other, which makes the implementation of attacks easily from the aspects of forgery and disavowal. To conquer this shortcoming, we construct an improved AQS scheme using a new QOTP algorithm. This scheme has three advantages: it randomly uses the Hadamard operation in the new QOTP to resist attacks by using the anticommutativity of nontrivial Pauli operators and it preserves almost all merits in the existing AQS schemes; even in the process of handling disputes, no party has chance to change the message and its signature without being discovered; the receiver can verify the integrity of the signature and discover the disavow of the signatory even in the last step of verification.     

A Chaos-based Arbitrated Quantum Signature Scheme in Quantum Crypotosystem

An arbitrated quantum signature (AQS) scheme is demonstrated on a basis of an improved quantum chaotic encryption algorithm using the quantum one-time pad with a chaotic operation string. In this scheme, the signatory signs the message while the receiver verifies the signature’s validity with the aid of the trusty arbitrator who plays a crucial role when a possible dispute arises. Analysis shows that the signature can neither be forged nor disavowed by any malicious attackers.     

Security Analyses and Improvement of Arbitrated Quantum Signature with an Untrusted Arbitrator

Very recently, an arbitrated quantum signature (AQS) scheme of classical message with an untrusted arbitrator was presented (Yang et al. in Eur. Phys. J., D, At. Mol. Opt. Plasma Phys. 61(3):773–778, 2011). In this paper, the security of the AQS scheme with an untrusted arbitrator is analyzed. An AQS scheme with an untrusted arbitrator should satisfy the unforgeable property and undeniable property. In particular, the malicious verifier can not modify a message and its signature to produce a new message with a valid signature, and the dishonest signer who really has sent the message to the verifier which the verifier accepted as an authentic one cannot later deny having sent this message. However, we show that, in the AQS scheme with an untrusted arbitrator, the dishonest signer can successfully disavow his/her signature and the malicious verifier can counterfeit a valued signature for any message by known message attack when he has received a message-signature pair. Then, we suggest an improved AQS scheme of classical message with an untrusted arbitrator which can solve effectively the two problems raised above. Furthermore, we prove the security of the improved scheme.     

Arbitrated Quantum Signature Scheme with Continuous-Variable Coherent States

Motivated by the revealing features of the continuous-variable (CV) quantum cryptography, we suggest an arbitrated quantum signature (AQS) protocol with CV coherent states. It involves three participants, i.e., the signer Alice, the verifier Bob and the arbitrator Charlie who is trustworthy by Alice and Bob. Three phases initializing phase, signing phase and verifying phase are included in our protocol. The security of the signature scheme is guaranteed by the generation of the shared keys via the CV-based quantum key distribution (CV-QKD) and the implementation process of the CV-based quantum teleportation as well. Security analysis demonstrates that the signature can be neither forged by anyone nor disavowed by the receiver and signer. Moreover, the authenticity and integrality of the transmitted messages can be ensured. The paper shows that a potential high-speed quantum signature scheme with high detection efficiency and repetition rate can be realized when compared to the discrete-variable (DV) quantum signature scheme attributing to the well characteristics of CV-QKD.     

A Novel Quantum Group Proxy Blind Signature Scheme Based on Five-Qubit Entangled State

A novel quantum group proxy blind signature scheme based on five-qubit entangled state is proposed. The quantum key distribution, quantum encryption algorithm and some laws of quantum mechanics (such as quantum no-cloning theorem and Heisenberg uncertainty principle) are used to guarantee the unconditional security of this scheme. Analysis result shows that the signature can neither be forged nor disavowed by any malicious attackers and our scheme satisfies all the characteristics of group signature and proxy signature. This protocol can be applied in real life such as E-commerce transaction.

     

The Security Problems in Some Novel Arbitrated Quantum Signature Protocols

With the development of quantum signature, two improved arbitrated quantum signature(AQS) protocols have been presented with different quantum encryptions. In this paper, some security loopholes during the two AQS protocols are proposed. In the enhanced arbitrated quantum signature(EAQS) protocol, though the signer is not able to deny his signature, the receiver can still forge some valid signatures. In the chaos-based arbitrated quantum signature(CAQS) protocol, the receiver can forge a valid signature without being caught, and the signer can also deny her signature after the signing phase. Finally, some potential improved ideas are discussed.     

A Quantum Proxy Blind Signature Scheme Based on Genuine Five-Qubit Entangled State

In this paper, a quantum proxy blind signature scheme based on controlled quantum teleportation is proposed. This scheme uses a genuine five-qubit entangled state as quantum channel and adopts the classical Vernam algorithm to blind message. We use the physical characteristics of quantum mechanics to implement delegation, signature and verification. Security analysis shows that our scheme is valid and satisfy the properties of a proxy blind signature, such as blindness, verifiability, unforgeability, undeniability.     

Multiparty Quantum Blind Signature Scheme Based on Graph States

A multiparty quantum blind signature scheme is proposed based on the principle of graph state, in which the unitary operations of graph state particles can be applied to generate the quantum blind signature and achieve verification. Different from the classical blind signature based on the mathematical difficulty, the scheme could guarantee not only the anonymity but also the unconditionally security. The analysis shows that the length of the signature generated in our scheme does not become longer as the number of signers increases, and it is easy to increase or decrease the number of signers.     

A Novel Quantum Broadcasting Multiple Blind Signature Scheme Based on Multi-Particle Partial Entanglement

Recently, a quantum broadcasting multiple blind signature scheme has been proposed by using GHZ entanglement, which is claimed to have foreseeable application in E-bank system. However, its security is promised by the utilized hash function. In this paper, we have designed a novel quantum broadcasting multiple blind signature scheme by utilizing a three-particle partial entanglement state. In existed quantum broadcasting multiple blind signature schemes, the collector Charlie has to verify the individual signatures before aggregating them into a multi-signature. In this new scheme, Charlie is only acting as a signature collector. Specifically, Charlie only needs to collect all the individual signatures and aggregating them into a multi-signature, which indicates that Charlie has no need to verify the individual signature any more. All the verification are executed by the receiver Bob himself. Meanwhile, the signature is generated by quantum entanglement swapping rather than using hash function, which make its security is only based on quantum physics. It is showed that multi-particle partially entangled state can be efficiently used as a resource in quantum information processing with perfect performance.

     

Security Weaknesses in Arbitrated Quantum Signature Protocols

Arbitrated quantum signature (AQS) is a cryptographic scenario in which the sender (signer), Alice, generates the signature of a message and then a receiver (verifier), Bob, can verify the signature with the help of a trusted arbitrator, Trent. In this paper, we point out there exist some security weaknesses in two AQS protocols. Our analysis shows Alice can successfully disavow any of her signatures by a simple attack in the first protocol. Furthermore, we study the security weaknesses of the second protocol from the aspects of forgery and disavowal. Some potential improvements of this kind of protocols are given. We also design a new method to authenticate a signature or a message, which makes AQS protocols immune to Alice’s disavowal attack and Bob’s forgery attack effectively.     

Multi-proxy Strong Blind Quantum Signature Scheme

A multi-proxy strong blind quantum signature scheme is proposed in this paper. An original signatory Alice delegates her signing authority to a group of proxy signatories by using a classical warrant. A blind factor is introduced by a sender U to blind a message, and the proxy signatories sign the message blindly via applying appropriate unitary operators. A receiver Bob verifies the generated signature with the help of an arbitrator Trent. The security of this scheme is based on a quantum key distribution protocol, a quantum one-time pad and other quantum properties. It is proved that our scheme has the properties of non-disavowal, non-counterfeit, multi-proxy, blindness, untraceability and can resist some common attacks.     

Cryptanalysis of a Batch Proxy Quantum Blind Signature Scheme

The security analysis of a batch proxy quantum blind signature scheme is given, which shows it does not satisfy the verifiability of proxy blind signature. Furthermore, a malicious signature receiver can forge valid batch proxy blind signatures. Therefore, this scheme also does not satisfy the unforgeability of proxy blind signature in the sense. A feasible method to deal with these problems is also discussed in the end.     

A Quantum Proxy Weak Blind Signature Scheme

We present a weak blind signature scheme based on a genuinely entangled six qubits state. Different from classical blind signature schemes and current quantum signature schemes, our quantum weak blind signature scheme could guarantee not only the unconditionally security but also the anonymity of the message owner. To achieve that, quantum key distribution and one-time pad are adopted in our scheme. Our scheme has the characteristics of classical security and quantum security.     

A Secure Quantum Voting Scheme Based on Quantum Group Blind Signature

International Journal of Theoretical Physics - We proposed a secure quantum voting scheme employing five-qubit cluster state as quantum channel. It is based on quantum group blind signature. With...     

Quantum group blind signature scheme without entanglement

In this paper we propose a quantum group blind signature scheme designed for distributed e-voting system. Our scheme combines the properties of group signature and blind signature to provide anonymity of voters in an e-voting system. The unconditional security of our scheme is ensured by quantum mechanics. Without employing entanglement, the proposed scheme is easier to be realized comparing with other quantum signature schemes.     

Blind Quantum Signature with Controlled Four-Particle Cluster States

A novel blind quantum signature scheme based on cluster states is introduced. Cluster states are a type of multi-qubit entangled states and it is more immune to decoherence than other entangled states. The controlled four-particle cluster states are created by acting controlled-Z gate on particles of four-particle cluster states. The presented scheme utilizes the above entangled states and simplifies the measurement basis to generate and verify the signature. Security analysis demonstrates that the scheme is unconditional secure. It can be employed to E-commerce systems in quantum scenario.     

A Quantum Multi-Proxy Blind Signature Scheme Based on Entangled Four-Qubit Cluster State

In this paper, a multi-proxy blind signature scheme based on controlled quantum teleportation is proposed. Entangled four-qubit Cluster state functions as quantum channel, which needs less resource to complete the quantum multi-proxy blind signature. The scheme uses the physical characteristics of quantum mechanics to guarantee its blindness, unforgeability, and undeniability. The eavesdropping check is used to ensure the security. Our scheme has a foreseeable application to the E-business, E-governments, and etc.     

A Quantum Multi-Proxy Blind Signature Scheme Based on Entangled Four-Qubit Cluster State

In this paper, a multi-proxy blind signature scheme based on controlled quantum teleportation is proposed.Entangled four-qubit Cluster state functions as quantum channel, which needs less resource to complete the quantum multi-proxy blind signature. The scheme uses the physical characteristics of quantum mechanics to guarantee its blindness, unforgeability, and undeniability. The eavesdropping check is used to ensure the security. Our scheme has a foreseeable application to the E-business, E-governments, and etc.     

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.