We propose a new quantum-assisted digital signature (Q-DS) protocol based on the composite of truly random symmetric keys generated by quantum key distribution with secure standardized hash functions, which allows for high parameterization to provide different security levels. The protocol is demonstrated to be secure, it is implemented, and its performance is tested for several system configurations. A comparative evaluation of the results obtained for Q-DS is carried out with 6 pre-quantum and 12 post-quantum digital signature algorithms. The results show that the Q-DS overperforms during the signature generation and verification processes, while its performance is affected by the key generation process. However, using more efficient QKD devices, this process can be highly improved, making the Q-DS protocol comparable to the most efficient post-quantum solution, i.e., CRYSTALS-Dilithium.
We propose a new quantum-assisted digital signature (Q-DS) protocol based on the composite of truly random symmetric keys generated by quantum key distribution with secure standardized hash functions, which allows for high parameterization to provide different security levels. The protocol is demonstrated to be secure, it is implemented, and its performance is tested for several system configurations. A comparative evaluation of the results obtained for Q-DS is carried out with 6 pre-quantum and 12 post-quantum digital signature algorithms. The results show that the Q-DS overperforms during the signature generation and verification processes, while its performance is affected by the key generation process. However, using more efficient QKD devices, this process can be highly improved, making the Q-DS protocol comparable to the most efficient post-quantum solution, i.e., CRYSTALS-Dilithium.
One of the most important applications of cryptography is digital signature (DS), which aims to certify the provenance of a message as well as its authenticity, ensuring the nonrepudiation, unforgeability, and transferability of messages. However, the forthcoming advent of quantum computers poses a significant threat to classical signature schemes. In this work, an improved version of a novel quantum-assisted digital signature (QADS) solution will be presented, in which quantum keys generated by quantum key distribution (QKD) are used together with standard classical cryptographic functions to provide a hybrid system that integrates quantum and classical cryptography. The quantum keys enhance the security of the DS, allowing to sign messages with arbitrary lengths while maintaining a suitable DS length. The proposed solution could push the practical exploitation of QKD in a new application domain, leading to a more pervasive integration of quantum technology in realistic scenarios.
Digital signature (DS) is an essential application of cryptography, used to certify the provenance of a message and its authenticity, guaranteeing the non-repudiation, unforgeability, and transferability of messages. However, the forthcoming advent of quantum computation poses a significant threat to classical signature schemes. A possible solution could be the introduction of novel DS schemes based on the fundamental laws of quantum physics. Recently, several quantum DS (QDS) protocols have been proposed, even relying on the exploitation of off-the-shelf quantum key distribution (QKD) solutions. However, their efficiency and large signature size, uncorrelated to the size of the message to sign, represent the main limitation in their employment in a practical scenario. A trade-off solution could be a quantum-assisted DS (QADS), where the QKD technology is exploited together with classical cryptographic functions to achieve a stronger DS scheme, more resistant even to quantum attacks. We propose a generalized quantum-assisted digital signature (G-QADS) protocol based on a hybrid system, composed by the standard Wegman-Carter Message Authentication Code (WG-MAC) together with symmetric QKD keys, to enhance the security of the DS, allowing messages with arbitrary lengths to be signed while maintaining a suitable DS length. In this work, the G-QADS process is proposed for a three-party configuration (one signer and two verifiers), where the third participant is involved in the procedure just in the case of contention between the other two parties. The G-QADS protocol is then experimentally tested to prove its resilience to forging and non-repudiation attacks, demonstrating its capability in securing the message signature (with a success probability of the attacks <10 −18 ). The performance is experimentally tested exploiting QKD prototypes based on standard BB84 protocol with decoy states and polarization encoding, in a software-defined network (SDN) infrastructure supervised by a single SDN controller, which provides the management of both classical and quantum communication channels. The proposed solution could push the practical exploitation of QKD into a new application domain, leading to a more pervasive integration of quantum technology in realistic scenarios.
In this work we implemented and evaluated the performance of the most relevant pre-quantum, post-quantum (PQC) and quantum digital signature (Q-DS) algorithms during the key generation, signature generation and signature verification processes. The aim is to help in the selection of possible candidates during the migration process from current cryptographic systems to quantum-resistant ones. As a result, for a security level of 256 bits, RSA is the pre-quantum algorithm that presents the worst performance together with the “small” variant of SPHINCS+ sphincsshake256ssimple in PQC. The Q-DS is the most efficient solution during the signature generation and verification, but its performance is strongly impacted in the key generation process that is carried out through Quantum Key Distribution. The out-performer within the pre-quantum algorithms, for a security level of 256 bits, is the elliptic curve secp521r1 and within PQC solutions the CRYSTALS-Dilithium DSA Dilithium5 stands out.
With the quantum computational paradigm rapidly developing across the world, new vulnerabilities on currently deployed cryptography protocols are to be taken in consideration. A possible answer to said vulnerabilities is using quantum technologies on cryptography. For a quantum-assisted cryptography protocol, key pairs can be generated via quantum state measurements. This protocol is known as quantum key distribution, of extended use for providing security against any algorithm-based attack to the keys. Ensured the key protection against eavesdroppers, a QKD-assisted protocol can focus its security analysis on party behaviour. Depending on the protocol rules and steps to follow, users can attempt attacks on it with the purpose of causing disagreement or misunderstanding between parties. In this work, we present a simulation environment for a hybrid, quantum-assisted digital signature (QDS) protocol. The configurations available for the simulated network as well as the digital signature protocol make it possible to design specific communication scenarios, such as attacks on the message integrity, forging and repudiation attempts or noisy communication across the quantum channels.
The paper offers a novel digital signature scheme that integrates ElGamal cryptographic principles with the Short Integer Solution (SIS) problem, specifically designed to ensure post-quantum security. As quantum computers advance and present significant risks to traditional cryptographic systems, this scheme offers an interesting alternative for securing digital signatures against potential quantum threats. The scheme uses only basic secure principles. The offered approach offers key generation, where parameters and random matrices are selected, and signature generation, which involves creating signatures based on hashed messages and matrix computations. Verification ensures the authenticity and integrity of signatures. We provide experimental evaluations detailing key generation, signature creation, and verification times across different matrix dimensions and message sizes. Key generation takes between 2.5–10.2 seconds, while signature generation ranges from 0.20 to 9.30 milliseconds and verification from 0.18 to 8.90 milliseconds, depending on message size and matrix dimension. The scheme maintains a consistent signature size of 1.7 KB, independent of message length due to a hash-and-sign strategy. These results demonstrate that the scheme balances post-quantum security with practical performance, especially in high-security contexts. A comparison with traditional ElGamal encryption reveals the trade-offs between security and efficiency. While the SIS-based scheme delivers enhanced protection against quantum threats, it also entails increased computational complexity and larger signature sizes compared to conventional schemes. Overall, our proposed digital signature scheme stands as an excellent option for safe communications in a post-quantum world, representing a crucial step in protecting the authenticity and integrity of digital exchanges against changing technological risks. We believe that as quantum computing continues to develop, research into robust cryptographic alternatives will become increasingly important for safeguarding sensitive information across various sectors.
Digital signature is a key technique in information security, especially for identity authentications. Compared to classical correspondence, quantum digital signatures (QDSs) provide a considerably higher level of security. At present, its performance is limited by key generation protocols, which are fundamentally limited in terms of channel capacity. Based on the idea of twin-field quantum key distribution, this Letter presents a twin-field QDS protocol and details a corresponding security analysis. In its distribution stage, a specific key generation protocol, the sending-or-not-sending twin-field protocol, has been adopted. Besides, we present a systematic model to evaluate the performance of a QDS protocol and compare the performance of our protocol to other typical QDS protocols. Numerical simulation results show that the new protocol exhibits outstanding security and practicality compared to other existing protocols. Therefore, our protocol paves the way toward real-world applications of QDSs.