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Semiquantum secure direct communication with single photons in both polarization and spatial-mode degrees of freedom

Tian-Yu Ye, Mao-Jie Geng, Tian-Jie Xu, Ying Chen

Published Oct 6, 2021• 0 citations
OpenAlex

Abstract

In this paper, we propose the first semiquantum secure direct communication (SQSDC) protocol which is based on single photons in both polarization and spatial-mode degrees of freedom. This protocol doesn't require both communicants to possess quantum capabilities, and is feasible for the direct communication circumstance where one communicant is quantum and the other is classical. We validate the complete robustness of the transmissions of single photons between two communicants in Steps 1 and 2 of this protocol in detail. It turns out that during these transmissions, if Eve wants not to be detected by two communicants, she will obtain nothing useful. The security of the whole protocol is guaranteed by the complete robustness of the transmissions of single photons between two communicants in Steps 1 and 2 of this protocol and the subsequent classical one-time pad encryption process. In this protocol, one single photon with two degrees of freedom can carry two private bits from the message owner, so compared with the existing SQSDC protocols based on single photons in one degree of freedom, its quantum communication capacity is doubled.

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In this paper, we propose the first semiquantum secure direct communication (SQSDC) protocol which is based on single photons in both polarization and spatial-mode degrees of freedom. This protocol doesn't require both communicants to possess quantum capabilities, and is feasible for the direct communication circumstance where one communicant is quantum and the other is classical. We validate the complete robustness of the transmissions of single photons between two communicants in Steps 1 and 2 of this protocol in detail. It turns out that during these transmissions, if Eve wants not to be detected by two communicants, she will obtain nothing useful. The security of the whole protocol is guaranteed by the complete robustness of the transmissions of single photons between two communicants in Steps 1 and 2 of this protocol and the subsequent classical one-time pad encryption process. In this protocol, one single photon with two degrees of freedom can carry two private bits from the message owner, so compared with the existing SQSDC protocols based on single photons in one degree of freedom, its quantum communication capacity is doubled.
Semiquantum cryptography has drawn much attention in recent years since it simplifies the implementation of quantum cryptographic protocols. In this paper, we study semiquantum secure direct communication (SQSDC). Based on single-photons, we propose a two-step SQSDC protocol with identity authentication, which can be used to prevent impersonation and the man-in-the-middle attack. Different from previous protocols based on quantum entanglement or quantum memory, our protocol removes there restrictions for simplifying its physical implementation. We prove that our two-step SQSDC protocol is completely robust. That is, any adversarial attempting to learn some information on the secure message or identity strings will inevitably induce some errors that can be detected by communicators.
Semiquantum secure direct communication (SQSDC) allows a quantum user and a classical user to exchange confidential messages without preshared keys. However, existing SQSDC protocols are predominantly unidirectional, and those supporting bidirectional transmission often lack rigorous security checking in both directions. Here, we propose a bidirectional SQSDC protocol utilizing four‐photon states composed of two Bell states. The first Bell state facilitates forward transmission via Z‐basis encoding and decoding, while the second Bell state enables reverse transmission through bit‐flip operations. Security is ensured by Bell‐state measurements on checking photon pairs prior to each decoding phase, with photon reordering eliminating the need for preshared keys. Security analysis confirms robustness against intercept‐resend, entanglement‐measurement, and Trojan horse attacks. The protocol achieves a transmission efficiency of 30% and requires only currently available technologies, making it experimentally feasible for practical semiquantum communication networks.
In this paper, we propose a new controlled quantum secure direct communication (CQSDC) protocol with single photons in both polarization and spatial-mode degrees of freedom. Based on the defined local collective unitary operations, the sender’s secret messages can be transmitted directly to the receiver through encoding secret messages on the particles. Only with the help of the third side, the receiver can reconstruct the secret messages. Each single photon in two degrees of freedom can carry two bits of information, so the cost of our protocol is less than others using entangled qubits. Moreover, the security of our QSDC network protocol is discussed comprehensively. It is shown that our new CQSDC protocol cannot only defend the outsider eavesdroppers’ several sorts of attacks but also the inside attacks. Besides, our protocol is feasible since the preparation and the measurement of single photon quantum states in both the polarization and the spatial-mode degrees of freedom are available with current quantum techniques.
Abstract In this paper, a novel authenticated bidirectional quantum secure direct communication (ABQSDC) scheme is constructed by using single photons in both polarization and spatial-mode degrees of freedom, which is able to simultaneously exchange the private bit sequences between two remote users while authenticating their identifications. This scheme is verified to have no information leakage problem and be immune to the outside active attacks. This scheme only needs single photons in two degrees of freedom as quantum resource and single-photon measurements, and has a qubit efficiency of 2 / 3 . This scheme has a quantum communication capacity of four classical bits carried by one single photon in two degrees of freedom, and does not need to generate the initial quantum resource specially. This scheme has good practical feasibility with current quantum technologies.
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.
Semi-quantum protocol is a hot topic in quantum cryptography. One of the original motivational reasons to study semi-quantum protocol is to better understand “how quantum” a protocol needs to be in order to gain an advantage over its classical counterpart. Semi-quantum secure direct communication (SQSDC) is an important branch of the semi-quantum protocol, which makes it possible to directly transfer large amounts of data between quantum participant and classical participant without need to share the secret key in advance. In this paper, we propose two new SQSDC protocols based on single photons to study how to reduce the quantum resource requirements of both quantum participant and classical participant. In both protocols, the classical participant requires neither quantum memory or quantum delay lines. We first propose in the first protocol that the quantum participant only need to prepare single-state qubits in the preparation phase, which is different from previous SQSDC protocols. Then we propose in the second protocol that quantum participant can accomplish the same work as the first one even without quantum memory. Efficiency analysis shows that the first protocol is more efficient than some protocol, and the second one can save more quantum resources at the expense of some efficiency. Compared with the existing SQSDC protocols based on single photons, both protocols can use fewer quantum states or quantum resource requirements than other protocols. Finally, we analyze the security of both protocols.