This paper proposes the protocol of Quantum Secure Direct Communization (QSDC) based on the secret initial Bell states which are shared by two legitimate communicators. Then, we analyze the security of the protocol against the intercept-and-resend attack and individual attack. It is unnecessary for the scheme to make odd particles especially which is used for detection of eavesdropping. Instead, it extracts some particles for detection from the travel sequence carrying secret messages. The results show that this protocol is secure and the information will not be leaked out even if the communication is forced to interrupt for eavesdropping.
This paper proposes the protocol of Quantum Secure Direct Communization (QSDC) based on the secret initial Bell states which are shared by two legitimate communicators. Then, we analyze the security of the protocol against the intercept-and-resend attack and individual attack. It is unnecessary for the scheme to make odd particles especially which is used for detection of eavesdropping. Instead, it extracts some particles for detection from the travel sequence carrying secret messages. The results show that this protocol is secure and the information will not be leaked out even if the communication is forced to interrupt for eavesdropping.
Quantum secure direct communication (QSDC) can transmit secret messages directly from one user to another without first establishing a shared secret key, which is different from quantum key distribution. In this paper, we propose a novel quantum secure direct communication protocol based on signal photons and Bell states. Before the execution of the proposed protocol, two participants Alice and Bob exchange their corresponding identity IDA and IDB through quantum key distribution and keep them secret, respectively. Then the message sender, Alice, encodes each secret message bit into two single photons (| 01〉or|10〉) or a Bell state , and composes an ordered secret message sequence. To insure the security of communication, Alice also prepares the decoy photons and inserts them into secret message sequence on the basis of the values of IDA and IDB. By the secret identity IDA and IDB, both sides of the communication can check eavesdropping and identify each other. The proposed protocol not only completes secure direct communication, but also realizes the mutual authentication. The security analysis of the proposed protocol is presented in the paper. The analysis results show that this protocol is secure against some common attacks, and no secret message leaks even if the messages are broken. Compared with the two-way QSDC protocols, the presented protocol is a one-way quantum communication protocol which has the immunity to Trojan horse attack. Furthermore, our proposed protocol can be realized without quantum memory.
We present two novel quantum secure direct communication (QSDC) protocols over different collective-noise channels. Different from the previous QSDC schemes over collective-noise channels, which are all source-encrypting protocols, our two protocols are based on channel-encryption. In both schemes, two authorized users first share a sequence of EPR pairs as their reusable quantum key. Then they use their quantum key to encrypt and decrypt the secret message carried by the decoherence-free states over the collective-noise channel. In theory, the intrinsic efficiencies of both protocols are high since there is no need to consume any entangled states including both the quantum key and the information carriers except the ones used for eavesdropping checks. For checking eavesdropping, the two parties only need to perform two-particle measurements on the decoy states during each round. Finally, we make a security analysis of our two protocols and demonstrate that they are secure.
In this paper an efficient quantum secure direct communication (QSDC) scheme with authentication is presented, which is based on quantum entanglement and polarized single photons. The present protocol uses Einstein–Podolsky–Rosen (EPR) pairs and polarized single photons in batches. A particle of the EPR pairs is retained in the sender's station, and the other is transmitted forth and back between the sender and the receiver, similar to the ``ping–pong'' QSDC protocol. According to the shared information beforehand, these two kinds of quantum states are mixed and then transmitted via a quantum channel. The EPR pairs are used to transmit secret messages and the polarized single photons used for authentication and eavesdropping check. Consequently, because of the dual contributions of the polarized single photons, no classical information is needed. The intrinsic efficiency and total efficiency are both 1 in this scheme as almost all of the instances are useful and each EPR pair can be used to carry two bits of information.
To transmit secure message, a controlled quantum secure direct communication protocol is proposed based on five-particle cluster state and EPR pair entanglement swapping. The sender and the controller own their EPR pair sequences respectively. The sender sends one photon of the EPR pair he owns to controller. The controller performs local unitary operation randomly on one photon of the EPR pair he owns and sends it to the receiver as his permission. The sender encodes his secret message on the other photon of the EPR pair he owns and sends it to the receiver. Because of EPR pair entanglement swapping, the two photons in the receiver's hand entangled. Under the permission of the controller, the controller and the receiver measure their new EPR pairs in the Bell basis in turn. By comparing the measurement result of the receiver and the original state, the receiver can get the secret message. To ensure the security of the message transmitting, five photons of five-particle cluster state are all mixed in sending sequence to detect eavesdropping which can bring per qubit 88% eavesdropping detection probability. Compared with taking three photons of five-particle cluster state as detection photons, five photons in this paper will decrease the number of five-particle cluster state for detection greatly. The security of the present protocol is discussed: the detection probability of this protocol is more than 88%, and intercept-measure-resend attacks and correlation-elicitation (CE) attack can be defended effectively.
Quantum secure direct communication (QSDC) is a method of communication that transmits secret information directly through a quantum channel. This paper proposes a two-step QSDC scheme based on intermediate-basis, in which the intermediate-basis Einstein–Podolsky–Rosen (EPR) pairs can assist to detect channel security and help encode information. Specifically, the intermediate-basis EPR pairs reduce the probability of Eve choosing the correct measurement basis in the first step, enhancing the security of the system. Moreover, they encode information together with information EPR pairs to improve the transmission efficiency in the second step. We consider the security of the protocol under coherent attack when Eve takes different dimensions of the auxiliary system. The simulation results show that intermediate-basis EPR pairs can lower the upper limit of the amount of information that Eve can steal in both attack scenarios. Therefore, the proposed protocol can ensure that the legitimate parties get more confidential information and improve the transmission efficiency.
Abstract 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.