International Conference on Transparent Optical Networks
Quantum-assisted digital signature: a new service for future quantum-integrated optical networks
Gennaro Davide Paduanelli, Marco Ferrari, Alessio Giorgetti, Nicola Andriolli, Elisabetta Storelli, Antonino Cacicia, Rudi Paolo Paganelli, Alberto Tarable, Emilio Paolini, Giada Sajeva, Marco Brunero, Alessandro Gagliano, Paolo Martelli, Pietro Noviello, Giovanni Schmid, Alberto Gatto
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.
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.
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.
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.
Currently used digital signatures based on asymmetric cryptography will be vulnerable to quantum computers running Shor's algorithm. In this work, we propose a new quantum-assisted digital signature protocol based on symmetric keys generated by QKD, that allows signing and verifying messages in a simple way implementing an integration of currently available classical and quantum technologies. The protocol is described for a three-user scenario composed of one sender and two receivers. In contrast to previous schemes, it is independent of the message length. The security of the protocol has been analyzed, as well as its integrity, authenticity and non-repudiation properties.
Quantum digital signatures (QDSs), generating correlated bit strings among three remote parties for signatures through quantum law, can guarantee nonrepudiation, authenticity, and integrity of messages. Recently, a one-time universal-hashing QDS framework, exploiting the quantum asymmetric encryption and universal hash functions, has been proposed to significantly improve the signature rate and ensure unconditional security by directly signing the hash value of long messages. However, similar to quantum key distribution, this framework utilizes keys with perfect secrecy by performing privacy amplification that introduces cumbersome matrix operations, thereby consuming large computational resources, causing delays, and increasing failure probability. Here, we prove that, different from private communication, imperfect quantum keys with partial information leakage can be used for digital signatures and authentication without compromising the security while having eight orders of magnitude improvement on signature rate for signing a megabit message compared with conventional single-bit schemes. This study significantly reduces the delay for data postprocessing and is compatible with any quantum key generation protocols. In our simulation, taking two-photon twin-field key generation protocol as an example, QDS can be practically implemented over a fiber distance of 650 km between the signer and receiver. For the first time, this study offers a cryptographic application of quantum keys with imperfect secrecy and paves a way for the practical and agile implementation of digital signatures in a future quantum network.
Guaranteeing nonrepudiation, unforgeability as well as transferability of a signature is one of the most vital safeguards in today's e-commerce era. Based on fundamental laws of quantum physics, quantum digital signature (QDS) aims to provide information-theoretic security for this cryptographic task. However, up to date, the previously proposed QDS protocols are impractical due to various challenging problems and most importantly, the requirement of authenticated (secure) quantum channels between participants. Here, we present the first quantum digital signature protocol that removes the assumption of authenticated quantum channels while remaining secure against the collective attacks. Besides, our QDS protocol can be practically implemented over more than 100 km under current mature technology as used in quantum key distribution.