Fair exchange is essential in E-commerce, and concurrent signature realizes the fair exchange of digital signatures with removing the requirement of a trusted third party. Multi-party concurrent signature is an extension to the multi-user scenario. The security of existing multi-party concurrent signatures is mostly based on traditional hard problems that could be solved efficiently with quantum algorithms in a post-quantum world. Meanwhile, the lattice-based cryptography is considered to be resistant to quantum attack. Wang et al. proposed a lattice-based multi-party concurrent signature. We give the analysis of their proposed signature scheme and find that it is not secure since an inside adversary can forge the signature. Moreover, the initial signer can produce any signatures, instead of a signature on the original messages, if he is malicious.
Fair exchange is essential in E-commerce, and concurrent signature realizes the fair exchange of digital signatures with removing the requirement of a trusted third party. Multi-party concurrent signature is an extension to the multi-user scenario. The security of existing multi-party concurrent signatures is mostly based on traditional hard problems that could be solved efficiently with quantum algorithms in a post-quantum world. Meanwhile, the lattice-based cryptography is considered to be resistant to quantum attack. Wang et al. proposed a lattice-based multi-party concurrent signature. We give the analysis of their proposed signature scheme and find that it is not secure since an inside adversary can forge the signature. Moreover, the initial signer can produce any signatures, instead of a signature on the original messages, if he is malicious.
Concurrent signatures scheme is an effective way to solve the problem of fair exchange without the help of any trusted third party. Until now, all concurrent signatures are based on traditional cryptosystems, but the emergence of quantum computing poses a severe threat to the security of classic public–key cryptosystems. More and more attentions are being paid to lattice–based cryptosystems, which is one of the candidate cryptosystems against the attacks from quantum computing. In this paper, we present a new formal model of multi–party concurrent signatures scheme and a lattice–based multi–party concurrent signatures scheme. The scheme has comparative advantages in both efficiency and security over the existing concurrent signatures schemes based on traditional cryptosystem. In particular, our scheme is constructed based on constant–size ring signatures, and thus we have solved the open problem: how to construct a multi–party concurrent signatures scheme based on constant–size ring signatures, which was proposed by Tonien et al. (2006).
Concurrent Signatures scheme is an effective way to solve the problem of fair exchange without the help of any trusted third party, it has the advantage of efficiency. Until now, all concurrent signatures are based on traditional cryptosystems, but the emergence of quantum computing poses a severe threat to the security of classic public-key cryptosystems. More and more attentions are being paid to lattice-based cryptosystems, which is one of the candidate cryptosystems against the attacks from quantum computing. In this paper we present a new formal model of multi-party concurrent signatures scheme which is constructed based on constant-size ring signatures, and a lattice-based multi-party concurrent signatures scheme. The scheme has comparative advantages in both efficiency and security over the existing concurrent signatures schemes based on traditional cryptosystems. In particular, our scheme is constructed based on constant-size ring signatures, and thus we have solved the open problem: how to construct a multi-party concurrent signatures scheme based on constant-size ring signatures, which was proposed by Dongvu Tonien, Willy Susilo and Reihaneh Safavi-Naini in 2006.
When using digital signatures, we need to deal with the problem of fairness of information exchange. To solve this problem, Chen, etc. introduced a new conception which is named concurrent signatures in Eurocrypt'04. Using concurrent signatures scheme, two entities in the scheme can generate two ambiguous signatures until one of the entities releases additional information which is called keystone. After the keystone is released, the two ambiguous signatures will be bound to their real signers at the same time. In order to provide a method to solve the fairness problem of quantum digital signatures, we propose a new quantum concurrent signature scheme. The scheme we proposed does not use a trusted third party in a quantum computing environment, and has such advantages as no need to conduct complex quantum operations and easy to implement by a quantum circuit. Quantum concurrent signature improves the theory of quantum cryptography, and it also provides broad prospects for the specific applications of quantum cryptography.
We present a lattice-based concurrent signature construction as a post-quantum solution to fair exchange of digital signatures. Our construction has the following two desirable features: (1) it is adaptively secure in the standard model, that is, its security does not rely on the random oracle assumption, and (2) it achieves anonymity, a stronger security notion than ambiguity. That is, before the release of the keystone, from a third party's point of view, a signature in our construction could be generated by anyone, not just limited to two parties involved in the exchange. We obtain these results by applying a novel idea to the lattice-based signatures due to Boyen.
With the advancement of quantum computing, the utilization of quantum algorithms such as Shor’s algorithm enables the efficient resolution of problems that are intractable in classical computing paradigms, posing a significant threat to traditional signature schemes. Lattice-based cryptography is considered one of the most promising post-quantum cryptographic algorithms due to its computational advantages and potential resistance to quantum attacks. Proxy signature is an authorization mechanism that allows the original signer to delegate the signing power to a proxy. The security of existing proxy signature schemes is mostly based on classical hard problems, which cannot guarantee security under quantum attacks. Therefore, this paper combines lattice-based cryptography with proxy signatures to propose a new lattice-based proxy signature scheme (NLBPS). NLBPS constructs signatures using lattice-based trapdoor sampling algorithms and preimage sampling algorithms. Comparative analysis shows that the proposed scheme has relatively smaller key and signature sizes compared to some existing lattice-based proxy signature schemes, and it also offers a certain improvement in computational efficiency.
The security of digital signatures depends significantly on the signature key. Therefore, to reduce the impact of leaked keys upon existing signatures and subsequent ones, a digital signature scheme with strong forward security could be an effective solution. Most existing strong forward-secure digital signature schemes rely on traditional cryptosystems, which cannot effectively resist quantum attacks. By introducing lattice-based delegation technology into the key-iteration process, a two-direction and lattice-based key-iteration algorithm with strong forward security is proposed. In the proposed algorithm, a unique key pair is assigned to the signer in every period. Based on the proposed algorithm, a strong forward-secure signature scheme is further put forward, which achieves resistance to quantum attacks. Performance analysis shows that under the security assumption of the SIS problem on the lattice, the proposed strong forward-secure signature scheme is existentially unforgeable under the random oracle model. Ultimately, based on the proposed strong forward-secure signature scheme, a remote identity-authentication scheme that is resistant to quantum attacks is proposed, ensuring post-quantum security in the user-authentication process.