Extending device-independent (DI) quantum cryptography to composably support all fundamental information security objectives is crucial for secure quantum networks. Achieving this goal requires composable quantum digital signatures (QDSs), which support integrity, authenticity, and nonrepudiation when integrated into quantum networks. Yet existing QDS protocols generally rely on assumptions about the underlying quantum devices, while their security analyses remain largely restricted to stand-alone settings, leaving related-key attacks on the underlying linear feedback shift register (LFSR)-based Toeplitz authentication unaddressed. Here, we establish the first composable security framework for QDS within constructive cryptography, and realize the corresponding ideal QDS resource by developing a DI-QDS protocol employing one-time universal hashing and multi-channel multiplexing. We further derive a related-key security bound for the underlying LFSR-based Toeplitz authentication, thereby establishing unforgeability while extending the forgery boundary considered in previous QDS security analyses. We also demonstrate the practical feasibility of our DI-QDS protocol under realistic quantum network conditions in the finite-size regime, with numerical simulations showing that it enables efficient signing of multibit documents over metropolitan-scale distances. Our results establish QDS as a composable cryptographic primitive and extend DI quantum cryptography to support the full range of information security objectives with composable security guarantees in future quantum networks.
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The paper addresses composable security for quantum digital signatures (QDS), including device-independent (DI) key generation and attacks that jointly modify signed documents and verification-key shares. It defines an ideal QDS resource in constructive cryptography as a transferable authenticated repository with prescribed direction $A\to B\to C$, and constructs a protocol intended to realize it.
The construction combines two bipartite DI key-generation links, XOR-correlated three-party keys, and one-time universal hashing using LFSR-based Toeplitz matrices. Security is established by replacing authenticated communication and key generation with ideal resources, then analyzing the remaining messaging protocol. A related-key analysis bounds the messaging distinguishing error by $\varepsilon_{\rm msg}\leq\min\{1,\sqrt{7n\lceil L_{\rm Doc}/n\rceil/2^n}\}$ for $n\geq12$, where $L_{\rm Doc}$ is the maximum encoded document length. The total error adds authentication and both key-generation errors. For simulated $10^3$-bit documents, $n=82$ gives the stated total target $\varepsilon_{\rm QDS}=10^{-10}$.
Finite-size key security uses entropy accumulation against general attacks. Numerical modeling combines quantum-dot photon sources with multiplexed, adaptive entanglement swapping; simulations using $10^{12}$ photon-pair generation attempts per side find positive signature rates over metropolitan-scale pairwise distances.
The security model permits either Alice or Bob to be corrupted, but keeps Charlie honest, and the messaging construction is analyzed for a single successfully prepared signature instance. Cross-instance memory attacks are excluded by isolating or destroying used devices and employing fresh ones. Feasibility results are simulations, including an idealized QND success probability of $1/2$, rather than an experimental demonstration.
Some signs of AI-generated textOverclaimsStrong assumptions
Central claim may not hold: Distribution-stage Step 3 flips both testing inputs for Φ− outcomes, yielding an ideal honest CHSH winning probability of approximately 0.6768, below the classical threshold, so the specified implementation does not establish the claimed DI key generation or positive signature rates.
The composable signature construction is proved only for successfully prepared single instances with prescribed A→B→C transfer and corruption patterns ∅, {A}, and {B}, while Charlie and setup remain honest, limiting the breadth of the abstract's resource claim.
Written by gpt-6.1-sol from the paper's full text. Automated: it can be wrong.
Extending device-independent (DI) quantum cryptography to composably support all fundamental information security objectives is crucial for secure quantum networks. Achieving this goal requires composable quantum digital signatures (QDSs), which support integrity, authenticity, and nonrepudiation when integrated into quantum networks. Yet existing QDS protocols generally rely on assumptions about the underlying quantum devices, while their security analyses remain largely restricted to stand-alone settings, leaving related-key attacks on the underlying linear feedback shift register (LFSR)-based Toeplitz authentication unaddressed. Here, we establish the first composable security framework for QDS within constructive cryptography, and realize the corresponding ideal QDS resource by developing a DI-QDS protocol employing one-time universal hashing and multi-channel multiplexing. We further derive a related-key security bound for the underlying LFSR-based Toeplitz authentication, thereby establishing unforgeability while extending the forgery boundary considered in previous QDS security analyses. We also demonstrate the practical feasibility of our DI-QDS protocol under realistic quantum network conditions in the finite-size regime, with numerical simulations showing that it enables efficient signing of multibit documents over metropolitan-scale distances. Our results establish QDS as a composable cryptographic primitive and extend DI quantum cryptography to support the full range of information security objectives with composable security guarantees in future quantum networks.
The paper addresses composable security for quantum digital signatures (QDS), including device-independent (DI) key generation and attacks that jointly modify signed documents and verification-key shares. It defines an ideal QDS resource in constructive cryptography as a transferable authenticated repository with prescribed direction A→B→C, and constructs a protocol intended to realize it.
The construction combines two bipartite DI key-generation links, XOR-correlated three-party keys, and one-time universal hashing using LFSR-based Toeplitz matrices. Security is established by replacing authenticated communication and key generation with ideal resources, then analyzing the remaining messaging protocol. A related-key analysis bounds the messaging distinguishing error by εmsg≤min{1,7n⌈LDoc/n⌉/2n} for n≥12, where LDoc is the maximum encoded document length. The total error adds authentication and both key-generation errors. For simulated 103-bit documents, n=82 gives the stated total target εQDS=10−10.
Finite-size key security uses entropy accumulation against general attacks. Numerical modeling combines quantum-dot photon sources with multiplexed, adaptive entanglement swapping; simulations using 1012 photon-pair generation attempts per side find positive signature rates over metropolitan-scale pairwise distances.
The security model permits either Alice or Bob to be corrupted, but keeps Charlie honest, and the messaging construction is analyzed for a single successfully prepared signature instance. Cross-instance memory attacks are excluded by isolating or destroying used devices and employing fresh ones. Feasibility results are simulations, including an idealized QND success probability of 1/2, rather than an experimental demonstration.
Digital signatures play an important role in software distribution, modern communication, and financial transactions, where it is important to detect forgery and tampering. Signatures are a cryptographic technique for validating the authenticity and integrity of messages, software, or digital documents. The security of currently used classical schemes relies on computational assumptions. Quantum digital signatures (QDS), on the other hand, provide information-theoretic security based on the laws of quantum physics. Recent work on QDS Amiri et al., Phys. Rev. A 93, 032325 (2016); Yin, Fu, and Zeng-Bing, Phys. Rev. A 93, 032316 (2016) shows that such schemes do not require trusted quantum channels and are unconditionally secure against general coherent attacks. However, in practical QDS, just as in quantum key distribution (QKD), the detectors can be subjected to side-channel attacks, which can make the actual implementations insecure. Motivated by the idea of measurement-device-independent quantum key distribution (MDI-QKD), we present a measurement-device-independent QDS (MDI-QDS) scheme, which is secure against all detector side-channel attacks. Based on the rapid development of practical MDI-QKD, our MDI-QDS protocol could also be experimentally implemented, since it requires a similar experimental setup.
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.
Quantum digital signatures (QDSs), which distribute and measure quantum states by key generation protocols and then sign messages via classical data processing, are a key area of interest in quantum cryptography. However, the practical implementation of a QDS network has many challenges, including complex interference technical requirements, linear channel loss of quantum state transmission, and potential side-channel attacks on detectors. Here, we propose an asynchronous measurement-device-independent (MDI) QDS protocol with asynchronous two-photon interference strategy and one-time universal hashing method. The two-photon interference approach protects our protocol against all detector side-channel attacks and relaxes the difficulty of experiment implementation, while the asynchronous strategy effectively reduces the equivalent channel loss to its square root. Compared to previous MDI-QDS schemes, our protocol shows several orders of magnitude performance improvements and doubling of transmission distance when processing multibit messages. Our findings present an efficient and practical MDI-QDS scheme, paving the way for large-scale data processing with nonrepudiation in quantum networks.
Quantum digital signatures (QDSs) provide a means for signing electronic communications with information-theoretic security. However, all previous demonstrations of quantum digital signatures assume trusted measurement devices. This renders them vulnerable against detector side-channel attacks, just like quantum key distribution. Here we exploit a measurement-device-independent (MDI) quantum network, over a metropolitan area, to perform a field test of a three-party MDI QDS scheme that is secure against any detector side-channel attack. In so doing, we are able to successfully sign a binary message with a security level of about ${10}^{\ensuremath{-}7}$. Remarkably, our work demonstrates the feasibility of MDI QDSs for practical applications.
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.
Abstract Cryptography promises four information security objectives, namely, confidentiality, integrity, authenticity and non-repudiation, to support trillions of transactions annually in the digital economy. Efficient digital signatures, ensuring integrity, authenticity and non-repudiation of data with information-theoretical security are highly urgent and intractable open problems in cryptography. Here, we propose a high-efficiency quantum digital signature (QDS) protocol using asymmetric quantum keys acquired via secret sharing, one-time universal2 hashing and a one-time pad. We just need to use a 384-bit key to sign documents of lengths up to 264 with a security bound of 10−19. If a one-megabit document is signed, the signature efficiency is improved by more than 108 times compared with previous QDS protocols. Furthermore, we build the first all-in-one quantum secure network integrating information-theoretically secure communication, digital signatures, secret sharing and conference key agreement and experimentally demonstrate this signature efficiency advantage. Our work completes the cryptography toolbox of the four information security objectives.