Motivated by the dense coding and teleportation of two-mode squeezed vacuum (TMSV) state, a continuous-variable arbitrated quantum signature (CV-AQS) scheme is proposed. The signer Alice generates the signature by the dense coding and sends it to the verifier Bob. The measurement results of two quadrature components serve for the recovery of the secret message. With the help of the arbitrator Charlie, Bob verifies the validity of the signature. The security of the presented protocol is protected by the calculation of the fidelity parameter and the implementation process of two-mode squeezed vacuum (TMSV) state teleportation. Moreover, the proposed scheme can be correctly implemented in the lossy and lossless transmission with a higher capacity.
Motivated by the dense coding and teleportation of two-mode squeezed vacuum (TMSV) state, a continuous-variable arbitrated quantum signature (CV-AQS) scheme is proposed. The signer Alice generates the signature by the dense coding and sends it to the verifier Bob. The measurement results of two quadrature components serve for the recovery of the secret message. With the help of the arbitrator Charlie, Bob verifies the validity of the signature. The security of the presented protocol is protected by the calculation of the fidelity parameter and the implementation process of two-mode squeezed vacuum (TMSV) state teleportation. Moreover, the proposed scheme can be correctly implemented in the lossy and lossless transmission with a higher capacity.
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.
A quantum message signature scheme based on quantum teleportation is presented. In this scheme, Alice prepares N-pair particles m and m' in the same states which carry the quantum information while Bob generates N-pair particles a and b in EPR states, to each triplet composed of particles ai,bi and mi, Alice performs Bell-state measurement on mi and ai, to get signature, Bob compares the state of m'i and bi can verify the signature. This scheme does not rely on an arbitrator to verify the signature; however it has unconditional security and provides a higher efficiency in transmission.
Quantum signature is quantum counterpart of classical digital signature, which has been widely applied to modern communication, such as electronic payment, electronic voting and electronic medical, owing to its great implication in ensuring the authenticity and the integrity of the message and the non-repudiation. Arbitrated quantum signature (AQS) is an important and practical type of quantum signature. The AQS algorithm is a symmetric key cryptography-based quantum signature algorithm, and its implementation requires the trusted arbitrator to be directly involved. In this paper, employing the key-controlled chained CNOT (KCCC) operation as the appropriate encryption (decryption) algorithm, we suggest an AQS scheme based on teleportation of quantum walks with two coins on a four-vertex cycle, which is used to transfer the message copy from the sender to the receiver. In light of the model of teleportation of quantum walks, the sender encodes the message to be signed into her or his coin state, and the necessary entangled states can be created as a result of the conditional shift between the coin state and the position state. The measurements performed on the generated entangled states are the bases of signature production and message recovery. Then according to the classical measurement results from the sender, the receiver performs the appropriate local unitary operations (i.e., Pauli operations) on his own coin state to recover the original message and further verifies the validity of the completed signature by using the appropriate verification algorithms under the aid of the trustworthy arbitrator. The suggested AQS scheme makes the following contributions: 1) the necessary entangled states for quantum teleportation of message copy do not need preparing in advance, and they can be produced automatically by the first step of quantum walks; 2) the scheme satisfies the features of non-repudiation, un-forgeability and non-disavowal due to the use of the KCCC operation; 3) the scheme may be achieved by linear optical elements such as beam splitters, wave plates, etc., because quantum walks have proven to be realizable in different physical systems and experiments. Analysis and discussion show that the proposed AQS scheme possesses the impossibility of disavowals by the signer and the receiver and impossibility of forgeries by anyone. Comparisons reveal that the designed AQS protocol is favorable. Furthermore, it provides an idea by employing the quantum computing model into quantum communication protocols with a possible improvement with respect to its favorable properties, for example, the automatic generation of entangled states via the first step of quantum walks on different models. In the near future, we will further investigate the production of entanglement by quantum walks and its applications with some improvements in designing the quantum communication protocols.
Arbitrated quantum signature (AQS) schemes use quantum cryptography to ensure their security, and the schemes provide that the signature receiver verifies the signature with the arbitrator's assistance.Very recently, Gao and Choi found in some previous AQS schemes, the receiver, Bob can counterfeit the signer's signature under known message.Additionally, the paper gives the security analysis of the AQS scheme, and results show that not only the receiver, but also the attacker can forge the signature in the AQS scheme.Furthermore, the signer can successfully disavow any message she ever signed.To conquer these shortcomings, this paper gives a new AQS scheme without quantum entangled state; it uses special quantum logic gate and new quantum one-time pads to ensure its security.Compares with other previous AQS schemes, the new scheme has following advantages: (1) the new scheme guarantees the receiver and the attacker cannot forge the signature; (2) Because the new scheme does not use quantum entangled states, so it can reduce the complexity of implementation and provides a higher efficiency in transmission; (3) The receiver, Bob has verified the signature's integrity, so Alice cannot disavow her having signed message.
In the most arbitrated quantum signatures (AQSs), the signers and verifiers need to perform the quantum key distribution protocols or some other protocols to share secret keys before signing a signature. In some schemes, the entangle states, which are not easily implemented, have to be prepared and distributed among the partners. Based on single photon and one-way functions, a new AQS scheme without entangled states is proposed. In our scheme, the signer generates a quantum signature on the classical message with his/her private key and the one-way function. The arbitrator communicates with the signer through a classical unencrypted channel. The signer and verifier need not perform the key distribution protocol before signing a message. On the other hand, without entangled states, our scheme can reduce the complexity of implementation. Then, our scheme is more efficient than the similar schemes. At the same time, our scheme is secure against forgery attack and disavowal attack.
Quantum dense coding of continuous variables via a two-mode squeezed vacuum state is considered for a noisy quantum channel. Classical information is encoded in the two quadrature components of one mode of a two-mode squeezed vacuum state and the encoded mode is sent through a noisy quantum channel which is assumed to be linearly dissipative. Decoding at the receiver side is performed by simultaneous measurement of two quadrature components of the two-mode state. By calculating the error probability of a binary communication system, we examine whether the dense coding is effective or not when a quantum channel is noisy.