An electronic contract is a contract signed by electronic means, which is widely used in electronic commerce activities. In recent years, with the rapid development of quantum cryptography technology, the quantum electronic contract has been widely studied by researchers. Supported by the basic principles of quantum mechanics, a quantum electronic contract scheme based on the single photon is proposed in this paper. In this scheme, two copies of the same contract are signed by both parties involved, and then a copy of each contract is sent to a trusted third party. The trusted third party verifies the signatures of both parties and compares the signed copies to determine whether the contract is valid. Compared with the previous scheme, this scheme is based on the quantum electronic contract signed by the single photon. Because the single photon is easy to prepare and operate, this scheme is simple and easy to implement. At the same time, the scheme does not need to exchange signatures between the two parties, which reduces the complexity of communication. Nevertheless, it requires both parties and the third party to be honest and trustworthy.
An electronic contract is a contract signed by electronic means, which is widely used in electronic commerce activities. In recent years, with the rapid development of quantum cryptography technology, the quantum electronic contract has been widely studied by researchers. Supported by the basic principles of quantum mechanics, a quantum electronic contract scheme based on the single photon is proposed in this paper. In this scheme, two copies of the same contract are signed by both parties involved, and then a copy of each contract is sent to a trusted third party. The trusted third party verifies the signatures of both parties and compares the signed copies to determine whether the contract is valid. Compared with the previous scheme, this scheme is based on the quantum electronic contract signed by the single photon. Because the single photon is easy to prepare and operate, this scheme is simple and easy to implement. At the same time, the scheme does not need to exchange signatures between the two parties, which reduces the complexity of communication. Nevertheless, it requires both parties and the third party to be honest and trustworthy.
To improve the security performance of blockchain smart contracts against quantum attacks, a smart contract based on light-weighted quantum blind signature is proposed here. Firstly, a smart contract architecture is built after the discussion of related researches, and information processing and information transmitting for quantum blind signature are analyzed. Secondly, the life cycle and signature rules of quantum blind signature for smart contracts are presented. Thirdly, a quantum blind signature protocol for single signer in light-weighted smart contract is put forward, where its algorithm design and business flow are introduced in detail before the security performance of the proposed algorithm is analyzed. Fourthly, based on the former single-person signature algorithm, a more complex multi-person quantum blind signature algorithm is proposed, and its security is also analyzed. Fifthly, related references are compared to verify the proposed method. The proposed quantum signature schemes based on quantum entanglement features can be used in single signer case or more, and will improve the security of blockchain smart contracts against quantum attacks, but with light-weighted structure and no need of any trusted third party or arbitrary institute. Finally, some suggestions for engineering applications and the research results are summarized and the future research is prospected.
We present a quantum scheme for signing contracts between two clients (Alice and Bob) using entangled states and the services of a third trusted party (Trent). The trusted party is only contacted for the initialization of the protocol, and possibly at the end, to verify clients’ honesty and deliver signed certificates. The protocol is fair, i.e., the probability that a client, say Bob, can obtain a signed copy of the contract, while Alice cannot, can be made arbitrarily small, and scales as N − 1 / 2 , where 4 N is the total number of rounds (communications between the two clients) of the protocol. Thus, the protocol is optimistic, as cheating is not successful, and the clients rarely have to contact Trent to confirm their honesty by delivering the actual signed certificates of the contract. Unlike the previous protocol (Paunković et al., Phys. Rev. A 84, 062331 (2011)), in the present proposal, a single client can obtain the signed contract alone, without the need for the other client’s presence. When first contacting Trent, the clients do not have to agree upon a definitive contract. Moreover, even upon terminating the protocol, the clients do not reveal the actual contract to Trent. Finally, the protocol is based on the laws of physics, rather than on mathematical conjectures and the exchange of a large number of signed authenticated messages during the actual contract signing process. Therefore, it is abuse-free, as Alice and Bob cannot prove they are involved in the contract signing process.
With the rapid spread of Internet technology, e-commerce is gradually becoming an integral part of the modern business models. The e-commerce transactions should obey integrity, authentication, nonrepudiation, traceability, and impartiality. Here, we propose and demonstrate a complete continuous-variable quantum e-commerce scheme, which involves subscription, payment, transport, and reception protocols among five parties. To this end, a simple, efficient quantum digital payment scheme is proposed. Furthermore, we streamline the entire e-commerce process by eliminating the private amplification step in the pre-distribution of keys. We achieve a contract signing rate of 1.51×10 3 times per second for a 33 kilobits contract, and a payment rate of 2.70×10 3 times per second over 80 km of single-mode fiber. Our results can support 411 times complete transactions per second, including three contract signings and two separate monetary payments. The proposed scheme takes into account the compatibility with existing e-commerce platforms to ensure a smooth transition and provides a practical solution for quantum e-commerce at metropolitan distances.
Electronic contract signing is an important issue in electronic commerce,while fair electronic contract signing protocol is an application model of fair exchange protocol,but there were defects in traditional fair electronic contract signing protocols.Presents a new fair electronic contract signing protocol based on the off-line trusted third party.The protocol effectively prevents all kinds of security attacks,and improves the efficiency of the implementation.The security of the newly devised scheme is also examined and proved.It is showed that fair processes of exchange activities are guaranteed in this protocol.
ABSTRACT We propose a novel quantum digital signature protocol that eliminates the need for a trusted third‐party, a common limitation in existing quantum signature schemes. While the concept of third‐party‐free quantum signatures has been discussed in earlier works, such as Gottesman and Chuang (2001), no concrete protocol with provable information‐theoretic security has been presented to date. Recent studies have explored computationally secure quantum signature schemes without trusted parties, but their security relies on assumptions about quantum computational hardness. In contrast, our protocol achieves information‐theoretic unforgeability based solely on the non‐cloning property of quantum states. It uses classical private keys and quantum public keys, and requires only single‐qubit operations. The scheme also satisfies key security properties, including asymmetry, undeniability, and expandability, making it suitable for implementation in near‐term quantum technologies.
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.