Abstract In the last decades, Quantum Cryptography has become one of the most important branches of Quantum Communications with a particular projection over the future Quantum Internet. It is precisely in Quantum Cryptography where two techniques stand out above all others: Quantum key Distribution (QKD), and Quantum Secure Direct Communication (QSDC). The first one has four loopholes relating to the exposure of the key at all points in the communication system, while the second has clear practical implementation problems in all its variants currently in use. Here, we present an alternative to QKD and QSDC techniques called quantum key secure communication (QKSC) protocol with a successful implementation on two free access quantum platforms.
Abstract In the last decades, Quantum Cryptography has become one of the most important branches of Quantum Communications with a particular projection over the future Quantum Internet. It is precisely in Quantum Cryptography where two techniques stand out above all others: Quantum key Distribution (QKD), and Quantum Secure Direct Communication (QSDC). The first one has four loopholes relating to the exposure of the key at all points in the communication system, while the second has clear practical implementation problems in all its variants currently in use. Here, we present an alternative to QKD and QSDC techniques called quantum key secure communication (QKSC) protocol with a successful implementation on two free access quantum platforms.
In the last decades, Quantum Cryptography has become one of the most important branches of Quantum Communications with a particular projection over the future Quantum Internet. It is precisely in Quantum Cryptography where two techniques stand out above all others: Quantum Key Distribution (QKD), and Quantum Secure Direct Communication (QSDC). The first one has four loopholes relating to the exposure of the key at all points in the communication system, while the second has clear practical implementation problems in all its variants currently in use. Here, we present an alternative to QKD and QSDC techniques called quantum key secure communication (QKSC) protocol with a successful implementation on two free access quantum platforms.
Quantum secure direct communication (QSDC) is one of the most important branches of quantum communication. In contrast to the quantum key distribution (QKD) which distributes a secure key between distant parties, QSDC directly transmits secret message instead of sharing key in advance. To establish a secure QSDC protocol, on the one hand, the security of the quantum channel should be confirmed before the exchange of the secret message. On the other hand, the quantum state should be transmitted in a quantum data block since the security of QSDC is based on the error rate analysis in the theories on statistics. Compared with the deterministic quantum key distribution (DQKD) which can also be used to transmit deterministic information, QSDC schemes do not need extra classical bits to read the secret message except for public discussion. In this article, we introduce the basic principles of QSDC and review the development in this field by introducing typical QSDC protocols chronologically. The first QSDC protocol was proposed by Long and Liu, which can be used to establish a common key between distant parties. In their scheme, the method for transmitting quantum states in a block by block way and in multiple steps was proposed and the information leakage before eavesdropping detection was solved. Subsequently, Deng et al. presented two pioneering QSDC schemes, an entangled-state-based two-step QSDC scheme and a single-photon-state-based quantum one-time pad scheme, in which the basic principle and criteria for QSDC were pointed out. From then on, many interesting QSDC schemes have been proposed, including the high-dimension QSDC scheme based on quantum superdense coding, multi-step QSDC scheme based on Greenberger-Horne-Zeilinger states, QSDC scheme based on quantum encryption with practical non-maximally entangled quantum channel, and so on. We also introduce the anti-noise QSDC schemes which were designed for coping with the collective-dephasing noise and the collective-rotation noise, respectively. In 2011, Wang et al. presented the first QSDC which exploited the hyperentangled state as the information carrier and several QSDC schemes based on the spatial degree of freedom (DOF) of photon, single-photon multi-DOF state and hyperentanglement were proposed subsequently. In addition to the point-to-point QSDC schemes, we also review the QSDC networks. Finally, a perspective of QSDC research is given in the last section.
The development of modern computer technologies endangers the confidentiality of information, which is usually ensured by traditional cryptographic means. This circumstance forces us to look for new methods of protection. In view of modern trends, quantum cryptography methods can become such alternatives, which allow solving a number of important cryptographic problems, for which the impossibility of solving using only classical (that is, non-quantum) communication has been proven. Quantum cryptography is a branch of quantum informatics that studies methods of protecting information by using quantum carriers. The possibility of such protection is ensured by the fundamental laws of quantum mechanics. One of the promising directions of quantum cryptography is Quantum Secure Direct Communication (QSDC) that offers secure communication without any shared key. A characteristic feature of this method is the absence of cryptographic transformations, accordingly, there is no key distribution problem. The purpose of this work is a general overview of quantum cryptography protocols, finding their weak points for further development and improvement, as well as identifying vulnerabilities to different attacks. The article analyzes new methods and protocols, as well as presents their advantages and disadvantages. Based on partial generalizations of theoretical provisions and practical achievements in the field of quantum cryptography, a generalized classification was developed. By comparing various factors of the protocols, and their resistance to certain cyberattacks, we have the opportunity to identify several problems in this field and expand the possibilities for choosing appropriate methods for building modern quantum information protection systems. In accordance with this, conclusions were presented regarding the use of protocols and increasing the level of their effectiveness.
Quantum cryptography represents a revolutionary approach to securing communications by harnessing the principles of quantum mechanics. This paper provides an overview of the state-of-the-art techniques in quantum cryptography, focusing on key areas such as Quantum Key Distribution (QKD), quantum secure direct communication (QSDC), and quantum digital signatures. We explore the advancements in QKD protocols, including BB84, E91, and the recently proposed measurement-device-independent QKD (MDI-QKD), which aim to counteract practical threats such as detector loopholes. Additionally, we discuss the integration of quantum cryptography with classical systems, the challenges in implementing quantum-safe protocols, and the efforts towards achieving large-scale quantum networks. Finally, we examine the future directions of quantum cryptography, addressing emerging technologies such as quantum repeaters, quantum memory, and hybrid quantum-classical encryption schemes, which are expected to enhance the security and scalability of quantum communication systems. The paper concludes with insights into the practical deployment of quantum cryptography and its potential to reshape the landscape of global cybersecurity in the coming decades.
Quantum secure direct communication is one of the major branches of quantum cryptography. In quantum secure direct communication, secret information can be transmitted directly through a quantum channel without the use of a private key. Quantum secure direct communication(QSDC) offers higher security and instantaneousness in communication. Because it does not use private key, key management is dispensed with. Unlike quantum key distribution where key is transferred from quantum terminal to the classical terminal at the user's site, the coding operations are solely in the quantum terminal, it further provides security in the user's site. QSDC is also a powerful basic cryptographic primitive to build other quantum communication protocols, such as quantum bidding, quantum signature and quantum dialogue and so on. Here, we briefly introduce the basic ideas of QSDC, describe the major protocols, report current status, and give a perspective.
Communication security has to evolve to a higher plane in the face of the threat from the massive computing power of the emerging quantum computers. Quantum secure direct communication (QSDC) constitutes a promising branch of quantum communication, which is provably secure and overcomes the threat of quantum computing, whilst conveying secret messages directly via the quantum channel. In this survey, we highlight the motivation and the status of QSDC research with special emphasis on its theoretical basis and experimental verification. We will detail the associated point-to-point communication protocols and show how information is protected and transmitted. Finally, we discuss the open challenges as well as the future trends of QSDC networks, emphasizing again that QSDC is not a pure quantum key distribution (QKD) protocol, but a fully-fledged secure communication scheme.