Abstract For signing quantum messages, the arbitrated quantum signature (AQS) has been widely investigated to date. However, most of the existing AQS protocols are susceptible to different aspects of disavowal and forgery attacks due to the use of quantum one time pad (QOTP) encryption featuring the encryption manner with qubit by qubit and the commutative property of Pauli operations. We develop an AQS protocol with boson sampling-based random unitary encryption. The unique encryption is used to encrypt the message copy (ciphertext) to produce the signature, which can circumvent the drawbacks of the QOTP encryption and stand against the signer Alice’s disavowal and the verifier Bob’s forgery attacks including existential forgery under known message attacks. The employment of a random array via the public board can prevent Bob’s repudiation attacks on the receipt and the integrality of the signature. The quantum walk-based teleportation is applied to teleport the message copy from Alice to Bob, which can avoid preparing the essential entanglement resource beforehand. Security analyses and discussions show that our AQS protocol is with impossibility of disavowal from Alice and Bob and impossibility of forgery from anyone.
Abstract For signing quantum messages, the arbitrated quantum signature (AQS) has been widely investigated to date. However, most of the existing AQS protocols are susceptible to different aspects of disavowal and forgery attacks due to the use of quantum one time pad (QOTP) encryption featuring the encryption manner with qubit by qubit and the commutative property of Pauli operations. We develop an AQS protocol with boson sampling-based random unitary encryption. The unique encryption is used to encrypt the message copy (ciphertext) to produce the signature, which can circumvent the drawbacks of the QOTP encryption and stand against the signer Alice’s disavowal and the verifier Bob’s forgery attacks including existential forgery under known message attacks. The employment of a random array via the public board can prevent Bob’s repudiation attacks on the receipt and the integrality of the signature. The quantum walk-based teleportation is applied to teleport the message copy from Alice to Bob, which can avoid preparing the essential entanglement resource beforehand. Security analyses and discussions show that our AQS protocol is with impossibility of disavowal from Alice and Bob and impossibility of forgery from anyone.
As a new model for signing quantum messages, arbitrated quantum signature (AQS) has recently received a lot of attention. In this paper we study the cryptanalysis of previous AQS protocols from the aspects of forgery and disavowal. We show that in these protocols the receiver, Bob, can realize existential forgery of the sender's signature under known message attack. Bob can even achieve universal forgery when the protocols are used to sign a classical message. Furthermore, the sender, Alice, can successfully disavow any of her signatures by simple attack. The attack strategies are described in detail and some discussions about the potential improvements of the protocols are given. Finally we also present several interesting topics on AQS protocols that can be studied in future.
Arbitrated quantum signatures (AQS), for signing quantum message, have been proposed. It was claimed that the AQS schemes could guarantee unconditional security. However, in this paper, we show that all the presented AQS protocols are insecure if quantum one-time pad encryption is used where the signer Alice can always successfully acquire Bob's secret key and disavow any of her signatures. The detailed attack strategies and security analysis are described. Furthermore, the original version of the protocols is revised and accordingly the security of the AQS protocols are improved. And meanwhile we present a method to against Alice's disavowal proposed by Gao et al. (arXiv:1106.4398v1).
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 aim at ensuring the authenticity of a message with the help of an arbitrator. Moreover, they aim at preventing repudiation, both from a sender that denies the origin of a message, and from a receiver who disavows its reception. Such protocols use quantum communication and are often designed to protect quantum messages. In this paper, we study four recently submitted AQS schemes and propose attacks on their security.
Firstly, we look at Zhang, Sun, Zhang and Jia's AQS scheme which aims at signing quantum messages with chained CNOT encryption. We show that the sender can repudiate her messages and make false allegation of reception. Moreover, we show that a dishonest receiver can forge signatures.
Secondly, we analyse Ding, Xin, Yang and Sang's AQS protocol to sign classical messages based on GHZ states. We show that both the sender and the receiver have simple repudiation strategies.
Thirdly, we study Lu, Li, Yu and Han's AQS scheme that uses controlled teleportation to protect quantum messages. We expose forgeries, false allegation attacks and the possibility of repudiation by both parties.
Fourthly, we focus on the AQS scheme by Zhang, Xin, Sun, Li and Li designed to sign classical messages without entangled states. We show that one can disavow the reception of messages, and that information-theoretic security is not achieved for other security goals.
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.