Abstract Quantum key distribution (QKD) protocols are unconditionally secure, providing that quantum devices are truthful. Device-independent quantum key distribution (DI-QKD) protocols offer the prospect of distributing secret keys with minimal assumptions. The DI-QKD protocols are hard to implement using the current technologies as they require all the quantum devices to be uncharacterized. Measurement device independent quantum key distribution (MDI-QKD) protocols assume that the measurement devices are not truthful; the adversary might make them. MDI-QKD is secure but more challenging to implement. Receiver-device-independent quantum key distribution (RDI-QKD) protocols assume that the receiver's measurement devices can be viewed as a black box while the sender's device can be trusted. RDI-QKD relies on reasonable assumptions that make it easy to implement using the current state-of-the-art technology. We propose an RDI-QKD protocol, called DGL22. DGL22 is secure against all known attacks that are allowed by quantum mechanics. DGL22 provides several benefits over previous protocols, including the capability to attain high communication and sifting efficiency.
Abstract Quantum key distribution (QKD) protocols are unconditionally secure, providing that quantum devices are truthful. Device-independent quantum key distribution (DI-QKD) protocols offer the prospect of distributing secret keys with minimal assumptions. The DI-QKD protocols are hard to implement using the current technologies as they require all the quantum devices to be uncharacterized. Measurement device independent quantum key distribution (MDI-QKD) protocols assume that the measurement devices are not truthful; the adversary might make them. MDI-QKD is secure but more challenging to implement. Receiver-device-independent quantum key distribution (RDI-QKD) protocols assume that the receiver's measurement devices can be viewed as a black box while the sender's device can be trusted. RDI-QKD relies on reasonable assumptions that make it easy to implement using the current state-of-the-art technology. We propose an RDI-QKD protocol, called DGL22. DGL22 is secure against all known attacks that are allowed by quantum mechanics. DGL22 provides several benefits over previous protocols, including the capability to attain high communication and sifting efficiency.
Device-independent quantum key distribution (DI-QKD) is often seen as the ultimate key exchange protocol in terms of security, as it can be performed securely with uncharacterised black-box devices. The advent of DI-QKD closes several loopholes and side-channels that plague current QKD systems. While implementing DI-QKD protocols is technically challenging, there have been recent proof-of-principle demonstrations, resulting from the progress made in both theory and experiments. In this review, we will provide an introduction to DI-QKD, an overview of the related experiments performed, and the theory and techniques required to analyse its security. We conclude with an outlook on future DI-QKD research.
Abstract Device-independent quantum key distribution (DI-QKD) provides the gold standard for secure key exchange. Not only does it allow for information-theoretic security based on quantum mechanics, but it also relaxes the need to physically model the devices, thereby fundamentally ruling out many quantum hacking threats to which non-DI QKD systems are vulnerable. In practice though, DI-QKD is very challenging. It relies on the loophole-free violation of a Bell inequality, a task that requires high quality entanglement to be distributed between distant parties and close to perfect quantum measurements, which is hardly achievable with current technology. Notwithstanding, recent theoretical and experimental efforts have led to proof-of-principle DI-QKD implementations. In this article, we review the state-of-the-art of DI-QKD by highlighting its main theoretical and experimental achievements, discussing recent proof-of-principle demonstrations, and emphasizing the existing challenges in the field.
The security of practical quantum key distribution (QKD) systems is fundamentally constrained by vulnerabilities of single-photon detectors. Measurement-device-independent quantum key distribution (MDI-QKD) was proposed to remove this limitation by allowing all measurements to be performed by a completely untrusted party, under the assumption that the measurement node can be treated as adversarial but does not compromise the security guarantees of the protocol.
Here we show that this assumption is insufficient under realistic adversarial control of the measurement device. We present an attack in which an adversary exploits active control of the measurement node (Charlie) to obtain significant information about the secret key. The attack enables recovery of up to 70\% of the sifted key while introducing only 5.6\% quantum bit error rate. Unlike previously reported attacks targeting specific implementations of MDI-QKD, our results demonstrate a limitation of the standard security model underlying the protocol.
These findings indicate that additional constraints on the measurement-device independence assumption, or refined security analyses incorporating stronger adversarial capabilities, are required to ensure the security of MDI-QKD in realistic scenarios.
Quantum key distribution (QKD) can serve large numbers of users with unconditional secure communication, in which measurement-device-independent (MDI) QKD protocol can conveniently enhance realistic security by eliminating all detector side channels. In multi-user scenarios, MDI-QKD networks should meet the requirements of reliability and robustness. Around the issues, we complete a series of work on performance improvement, low-cost deployment, and robust networking. First is to answer how to change the trusted node to the untrusted node with low cost, here we propose and demonstrate an MDIQKD which is compatible with phase encoding BB84 networks, allowing for economical deployment of MDI-QKD networks and reconciliation between high key rate and high realistic security in the same network. Then we make the MDI networks more robust. We design an MDI-QKD networking scheme for multi-user access where more than two users can generate keys synchronously regardless of aligning reference frames and compensating channel disturbance on polarization. Third, we find a general method to distil secure keys from quantum discord, which is different to the previous entanglement-based frameworks of MDI-QKD, allowing imperfect preparation and measurement of quantum states. The series of work can help the practical application of MDI-QKD networks, and promote the development of quantum networks.
Quantum technologies promise to boost ICT further by extending its limits, even by promising more effective and secure communications due to the benefits of quantum physics. This leads to Quantum Key Distribution (QKD), a cryptographic primitive for securely exchanging a secret key between distant endpoints, leveraging an insecure communication channel due to potential eavesdroppers. The literature on QKD started with the BB84 protocol proposed in 1984 and continued with other protocols, each with its pros and cons. Still, they have been chiefly designed for static scenarios and do not consider the needs of dynamic networks. This paper presents a QKD solution for dynamic networks combining adaptive key management techniques and fault-tolerant routing, ensuring high security and efficiency even in variable network topologies. Using MDI-QKD (Measurement Device Independent QKD) and simulations with NetSquid, we provide a preliminary assessment of this solution's robustness against dynamic attacks and the improvement in quantum resource management. The work also compares the protocol's effectiveness with existing solutions, highlighting the advantages and potential practical applications.
Measurement-device-independent quantum key distribution (MDI-QKD) can remove all detection side-channels from quantum communication systems. The security proofs require, however, that certain assumptions on the sources are satisfied. This includes, for instance, the requirement that there is no information leakage from the transmitters of the senders, which unfortunately is very difficult to guarantee in practice. In this paper we relax this unrealistic assumption by presenting a general formalism to prove the security of MDI-QKD with leaky sources. With this formalism, we analyze the finite-key security of two prominent MDI-QKD schemes-a symmetric three-intensity decoy-state MDI-QKD protocol and a four-intensity decoy-state MDI-QKD protocol-and determine their robustness against information leakage from both the intensity modulator and the phase modulator of the transmitters. Our work shows that MDI-QKD is feasible within a reasonable time frame of signal transmission given that the sources are sufficiently isolated. Thus, it provides an essential reference for experimentalists to ensure the security of implementations of MDI-QKD in the presence of information leakage.