Quantum Secure Direct Communication Protocol Research Articles

Four-party quantum secure direct communication based on hyperentangled bell states

Quantum Secure Direct Communication (QSDC) is a promising approach for secure information exchange. This paper proposes an efficient and secure four-party QSDC scheme utilizing hyperentangled Bell states in the polarization degree of freedom, the first longitudinal momentum degree of freedom and the second longitudinal momentum degree of freedom. The four participants can perform different unitary operations to independently encode their secret messages onto photons in three degrees of freedom, subsequently transmitting them directly through the quantum channel. In this proposed protocol, each degree of freedom of the photon can effectively carry two bits of information. Each round of transmission by a photon enables the four legitimate participants to obtain six classical bits of information. Notably, when compared to other photons based single-degree-of-freedom QSDC network protocols, the capacity of proposed QSDC protocol is tripled. Therefore, it significantly enhances the information transmission capability. Furthermore, comprehensive security analysis shows that our QSDC network protocol can withstand various attacks from external eavesdroppers.

High-dimensional single photon based quantum secure direct communication using time and phase mode degrees

Quantum secure direct communication (QSDC) can guarantee security using the characteristics of quantum mechanics even when a message is directly transmitted through a quantum channel without using a secret key. However, the transmission rate of the QSDC is limited by the dead time of a single photon detector (SPD) as well as channel loss over the distance. To overcome this limited transmission rate, we propose a high-dimensional single photon-based QSDC protocol that applies two optical degrees of freedom: time and phase state. First, an N-dimensional time and phase state generation method that considers the dead time is proposed to minimize the measurement loss of a transmitted message. Second, among the two types of quantum states, the phase state with relatively low measurement efficiency is used only for eavesdropping detection, and the time state is used for sending messages with differential delay time bin-based encoding techniques. Lastly, we propose an efficient method for measuring N-dimensional time and phase-based quantum states and recovering classical bit information. This study performs security analysis against various attacks, and verifies the transmission rate improvement effect through simulation. The result indicates that our proposal can guarantee higher security and transmission rates compared to the conventional DL04 QSDC.

The hyperentanglement-based quantum secure direct communication protocol with single-photon measurement

The hyperentanglement-based quantum secure direct communication protocol with single-photon measurement

Efficient multiparty quantum secret sharing based on a novel structure and single qubits

Quantum secret sharing (QSS) is a significant branch of quantum cryptography and can be widely used in various applications. Quantum secret sharing schemes can be developed by utilizing different features of quantum mechanics, and quantum secure direct communication (QSDC) is an effective way to achieve secret sharing using single qubits. The utilization of QSDC offers certain benefits, such as low cost, high security, and great potential for implementation with current technologies. However, the purpose of QSDC is different from that of QSS, which causes some vulnerabilities, such as dishonest participant attacks. We discover two critical factors that affect the security of traditional protocols. Firstly, they skip a few steps from the QSDC protocol to the QSS protocol. Secondly, the participants have different privileges. This can lead to participants with more privileges engaging in potential attack behavior. In light of these issues, this study proposes a new multiparty QSS scheme to address these vulnerabilities. The proposed protocol ensures the independence of each participant and grants them equal privileges. Analysis results demonstrate that it can defend against malicious attackers, retain the advantages of the QSDC protocol, and further reduce transmission costs. It achieves an excellent balance between security and performance.

One-Sided Measurement-Device-Independent Practical Quantum Secure Direct Communication

Measurement-device-independent quantum secure direct communication (MDI-QSDC) protocol is capable of defending against attacks on detectors by illegal parties, and its security relies on the trustworthy preparation of quantum states. In this paper, we propose the one-sided measurement-device-independent quantum secure direct communication (1SMDI-QSDC) protocol, which not only has the advantage of being independent of detection loopholes but also weakens the requirement of MDI-QSDC for state preparation. We analyze the real-life secrecy capacity of this proposed protocol by using realistic experimental settings that contain the weak coherent pulse source, parametric down-conversion source, and customized decoy-state method. The results indicate that our protocols can achieve secure communication over a few hundred kilometers. Furthermore, we find that the coding technology of increasing capacity using masking (INCUM) can mitigate the degradation of the maximum distance of secure communication when the state preparation is highly untrustworthy.

Single-Photon-Memory Measurement-Device-Independent Quantum Secure Direct Communication—Part II: A Practical Protocol and its Secrecy Capacity

In Part I of this two-part letter on single-photon-memory measurement-device-independent quantum secure direct communication (SPMQC), we reviewed the fundamentals and evolution of quantum secure direct communication (QSDC). In this Part II, we propose a practical protocol and analyze its secrecy capacity. In order to eliminate the security loopholes resulting from practical detectors, the measurement-device-independent (MDI) QSDC protocol has been proposed. However, block-based transmission of quantum states is utilized in MDI-QSDC, which requires practical quantum memory that is still unavailable at the time of writing. For circumventing this impediment, we propose the SPMQC protocol for dispensing with high-performance quantum memory. The performance of the proposed protocol is characterized by simulations considering realistic experimental parameters, and the results show that it is feasible to implement SPMQC by relying on existing technology.

Measurement-device-independent one-step quantum secure direct communication

The one-step quantum secure direct communication (QSDC) (Sci. Bull. 67, 367 (2022)) can effectively simplify QSDC’s operation and reduce message loss. For enhancing its security under practical experimental condition, we propose two measurement-device-independent (MDI) one-step QSDC protocols, which can resist all possible attacks from imperfect measurement devices. In both protocols, the communication parties prepare identical polarization-spatial-mode two-photon hyperentangled states and construct the hyperentanglement channel by hyperentanglement swapping. The first MDI one-step QSDC protocol adopts the nonlinear-optical complete hyperentanglement Bell state measurement (HBSM) to construct the hyperentanglement channel, while the second protocol adopts the linear-optical partial HBSM. Then, the parties encode the photons in the polarization degree of freedom and send them to the third party for the hyperentanglement-assisted complete polarization Bell state measurement. Both protocols are unconditionally secure in theory. The simulation results show the MDI one-step QSDC protocol with complete HBSM attains the maximal communication distance of about 354 km. Our MDI one-step QSDC protocols may have potential applications in the future quantum secure communication field.

The analysis of efficiency for high-dimensional quantum secure direct communications under atmospheric turbulence

Recently, there is a tremendous attention on the high-dimensional quantum information processing using the orbital angular momentum (OAM) of photons. It provides an efficient method to increase the capacity of quantum channel. However, OAM is very vulnerable to atmospheric turbulence, resulting in phase distortion and, therefore, leading to information leakage during quantum communications. On the other hand, quantum secure direct communications (QSDC) define an efficient way of information exchange through quantum channels directly. Here in this work, by combining the applications of OAM states of photons as the information carrier with the QSDC, we analyze the performance of the high-dimensional quantum secure direct communication protocol based on encoding the information on the single photon OAM state under the condition of free space channel. Numerically, we discussed the performance of OAM states QSDC under atmospheric turbulence, and mainly calculated the influence of cross-talk caused by phase fluctuation on the system. We draw the conclusion that under the weak turbulence, when the beam waist and the Fried parameter r become comparable, the information capacity will decrease sharply.

Controlled Quantum Secure Direct Communication Based on Four-Qubit Cluster States and Quantum Search Algorithm

A controlled quantum secure direct communication protocol based on four-qubit cluster states and quantum search algorithm is put forward, in which four users, a sender, a receiver and two controllers, are involved in achieving the secure transmission of secret message. The four-qubit cluster state can ensure the feasibility and security of the protocol because of its large persistency of entanglement. Meanwhile, the idea of quantum search algorithm is used to accomplish the task of encoding and decoding secret message. The proposed protocol can successfully avoid the information leakage problem and resist some common attacks including the outsider attacks and the internal attacks, and its qubit efficiency is up to 20%. Furthermore, compared with the previous quantum secure direct communication protocols, it can effectively resist the attacks from the dishonest receiver.

Cryptanalysis of quantum secure direct communication protocol with mutual authentication based on single photons and Bell states

Recently, Yan et al. proposed a quantum secure direct communication (QSDC) protocol with authentication using single photons and Einstein-Podolsky-Rosen (EPR) pairs (Yan L. et al., Comput. Mater. Contin., 63 (2020) 1297). In this work, we show that the above QSDC protocol is secure neither against intercept-and-resend attack, nor against impersonation attack. With any of these two types of attacks, an eavesdropper can recover the full secret message. We also propose a suitable modification of this protocol, which not only defeats the above attacks, but also resists all other common attacks. Thus, our modified protocol provides an improvement over the existing one in terms of security.

The transmission efficiency analysis for quantum secure direct communications over noisy channels

The concept of quantum secure direct communication (QSDC) is to distribute secure message directly between distant users securely, which is an important branch of quantum information science. The purpose of QSDC is to investigate the large capacity of quantum channels and fast speed of information transmission. However, the fidelity of qubits and the efficiency of QSDC will inevitably be affected by the channel noise and the decoherence of the quantum system. In this work, we focus on the performance of QSDC under different noisy channels, and investigate the evolution of quantum states. By numerically studying the performance for two QSDC protocols, we show the efficiency of information transmission over different noisy channel models.

Three-Party Quantum Secure Direct Communication Protocol with Adaptive Capacity

Three-Party Quantum Secure Direct Communication Protocol with Adaptive Capacity

Bi-directional semi-quantum secure direct communication protocol based on high-dimensional single-particle states

Semi-quantum secure direct communication allows the quantum party and the classical party to transmit secure messages directly, but does not need sharing a secret key in advance. To increase the information transmission efficiency and practicability of semi-quantum secure direct communication, a bidirectional semi-quantum secure direct communication protocol with high-dimensional single-particle states is designed. The proposed protocol involves quantum party Alice and classical party Bob. Each participant can receive a secret message while sending a secret message. Unlike most of existing quantum secure direct communication protocols, it is not necessary for the classical party Bob in the proposed protocol to possess the capability of measuring quantum states, which greatly enhances the feasibility of the protocol. The protocol allows the classical party Bob to implement the unitary operations on particles and reorder the quantum sequence. Furthermore, the quantum party Alice and the classical party Bob can verify the correctness of the received secret message with the Hash function. Security analysis indicates that without being discovered by the legitimate participants, Eve cannot obtain the secret message with common attack, such as intercept-resend attack, measure-resend attack, tampering attack and entanglement-measure attack. Compared with the typical semi-quantum secure direct communication protocols, the proposed protocol has a high qubit efficiency of about 28.6%. In addition, the transmission efficiency of secret message is greatly enhanced, since the proposed protocol utilizes the high-dimensional single-particle states as the carrier of secret message.

Bidirectional Quantum Secure Direct Communication Using Dense Coding of Four Qubit Cluster States

We are introducing an efficient bidirectional quantum secure direct communication protocol that employs the four qubit cluster states, creating a novel quantum channel based on dense coding between the transmitter and receiver. By dense coding, after a conventional announcement, two legitimate users can simultaneously exchange their messages. Two safety checking measures are taken to ensure safe transmission. Information leaking is not an issue in this protocol, and it is secure against some well-known eavesdropping assaults. It is also accessible with cutting-edge technology.

Efficient quantum secure direct communication with complete Bell‐state measurement

Quantum secure direct communication (QSDC) is a powerful technique of transmitting confidential information directly and securely based on the pre-established secure quantum channel and block transmission. Here we propose an efficient QSDC protocol using the complete Bell-state measurement (CBSM) resorting to linear optical elements and temporal-polarization hyperentanglement. In this protocol, the polarized entangled photons are utilized as the information carrier, and all the detection events of CBSM can be identified with common single-photon detectors instead of photon number resolving detectors due to the introduction of temporal degree of freedom (DOF). Moreover, since all the two-photon detection events in CBSM are effective and can be preserved with the efficiency of 100% rather than 50% in the previous QSDC, the quantum efficiency of QSDC can be doubled by encoding more messages on entangled photon pairs.

Quantum Secure Direct Communication with Mutual Authentication using a Single Basis

In this paper, we propose a new theoretical scheme for quantum secure direct communication (QSDC) with user authentication. Different from the previous QSDC protocols, the present protocol uses only one orthogonal basis of single-qubit states to encode the secret message. Moreover, this is a one-time and one-way communication protocol, which uses qubits prepared in a randomly chosen arbitrary basis, to transmit the secret message. We discuss the security of the proposed protocol against some common attacks and show that no eaves-dropper can get any information from the quantum and classical channels. We have also studied the performance of this protocol under realistic device noise. We have executed the protocol in IBMQ Armonk device and proposed a repetition code based protection scheme that requires minimal overhead.

One-step quantum secure direct communication

Quantum secure direct communication (QSDC) attracts much attention for it can transmit secret messages directly without sharing a key. In this article, we propose a one-step QSDC protocol, which only requires to distribute polarization-spatial-mode hyperentanglement for one round. In this QSDC protocol, the eavesdropper cannot obtain any message, so that this protocol is unconditionally secure in principle. This protocol is a two-way quantum communication and has high capacity for it can transmit two bits of secret messages with one pair of hyperentanglement. With entanglement fidelities of both polarization and spatial-mode degrees of freedom being 0.98, the maximal communication distance of this one-step QSDC can reach about 216 km. QSDC can also be used to generate the key. In this regard, the key generation rate is estimated about 2.5 times of that in the entanglement-based QKD with the communication distance of 150 km. With the help of future quantum repeaters, this QSDC protocol can provide unconditionally secure communication over arbitrarily long distance.

Quantum secure data transfer with pulse shape encoded optical qubits

Quantum secure data transfer is an important topic for quantum cyber security. We propose a scheme to realize quantum secure data transfer in the basis of quantum secure direct communication (QSDC). In this proposal, the transmitted data is encoded in the pulse shape of a single optical qubit, which is emitted from a trapped atom owned by the sender and received by the receiver with another trapped atom. The encoding process can be implemented with high fidelity by controlling the time-dependent driving pulse on the trapped atom to manipulate the Rabi frequency in accordance with the target pulse shape of the emitted photons. In the receiving process, we prove that, the single photon can be absorbed with arbitrary probability by selecting appropriate driving pulse. We also show that, based on the QSDC protocol, the data transfer process is immune to the individual attacks.

Continuous-Variable Quantum Secure Direct Communication Based on Gaussian Mapping

Quantum secure direct communication (QSDC) realizes the transmission of secret messages directly in a quantum channel. A continuous-variable- (CV) based quantum-communication system allows high-speed, large-capacity information transmission in optical telecommunication systems. In this work, we propose a QSDC protocol based on Gaussian mapping. As for Gaussian modulation, the designed Gaussian-mapping scheme effectively solves the problem, which results from the nonuniformity of the secret-message bitstream, and is applicable to different modulation variances. The system performance analysis shows that the proposed scheme can realize inerrant Gaussian modulation of secret messages, and secure transmission of messages under information theory. Moreover, our work hopes to stimulate discussion on experimental realization and practical advance of CV-QSDC protocol.

Advances in quantum secure direct communication

The practical implementation of quantum secure direct communication (QSDC) will undoubtedly be a milestone in the development of quantum cryptography. Research is in its final phase and focuses on developing secure protocols that consider realistic constraints and are feasible within the current state of technology. Three well-known protocols ae compared, Ping-Pong, Two-Step and Deng-Long, in the context of the level of security offered and the challenges related to their implementation. This work explains how the evolution of QSDC protocols from a purely quantum formulation to hybrid classical-quantum solutions based on the Wyner wiretap channel model can solve most problems encountered. The work aims to inform scientists in other fields of quantum information processing about the latest advances in QSDC. The attached appendix introduces basic concepts for readers unfamiliar with this research area.