To transmit a message safely, five-particle cluster state particles are used to construct a bidirectional quantum secure direct communication protocol. Five-particle cluster state particles are used for both detecting eavesdroppers and transmitting secret messages. All of the five-particle cluster states' photons for detection are mixed to the sending sequence to detect eavesdroppers. The detection rate approaches 88% per qubit. The five-particle cluster states needed are only one fifth of the photons in the sending sequence. In this protocol, there is no photon carrying secret information transmitting in quantum channel, and the classical XOR operation which serves as a one-time-pad is used to ensure the security of the protocol. Compared with three photons of each five-particle cluster state as detection photons, the five photons in this study will decrease the five-particle cluster states needed for detection greatly.
To transmit a message safely, five-particle cluster state particles are used to construct a bidirectional quantum secure direct communication protocol. Five-particle cluster state particles are used for both detecting eavesdroppers and transmitting secret messages. All of the five-particle cluster states' photons for detection are mixed to the sending sequence to detect eavesdroppers. The detection rate approaches 88% per qubit. The five-particle cluster states needed are only one fifth of the photons in the sending sequence. In this protocol, there is no photon carrying secret information transmitting in quantum channel, and the classical XOR operation which serves as a one-time-pad is used to ensure the security of the protocol. Compared with three photons of each five-particle cluster state as detection photons, the five photons in this study will decrease the five-particle cluster states needed for detection greatly.
In order to transmit secure messages, a quantum secure direct communication protocol based on a five-particle cluster state and classical XOR operation is presented. The five-particle cluster state is used to detect eavesdroppers, and the classical XOR operation serving as a one-time-pad is used to ensure the security of the protocol. In the security analysis, the entropy theory method is introduced, and three detection strategies are compared quantitatively by using the constraint between the information that the eavesdroppers can obtain and the interference introduced. If the eavesdroppers intend to obtain all the information, the detection rate of the original ping-pong protocol is 50%; the second protocol, using two particles of the Einstein-Podolsky-Rosen pair as detection particles, is also 50%; while the presented protocol is 89%. Finally, the security of the proposed protocol is discussed, and the analysis results indicate that the protocol in this paper is more secure than the other two.
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.
A novel controlled quantum secure direct communication scheme by using five-particle cluster states is proposed.In this scheme,the quantum channel between the sender Alice,the controller Charlie and the receiver Bob consists of an ordered sequence of five-particle cluster states which are prepared by Alice.After determine the security of quantum channel,Alice prepares the encoded Bell-state sequences,and Alice and Bob perform Bell-state measurements on the particles at hand,respectively,and then Charlie may make a single-particle measurement.Then Alice and Charlie tell their result to Bob,Bob can get the secret information through the analysis of their results.In our scheme,the information-carrying particles do not need to be transmitted over the public channel.Moreover,we analyze the security of the controlled quantum secure direct communication protocol,and demonstrate that our scheme is determinate and secure.In the future,our scheme might be realizable based on present experimental technology.
Controllable quantum secure direct communication is an important branch of quantum communication. In this paper, we propose a controlled quantum secure direct communication protocol with channel capacity controllable based on a five-particle cluster state. To start with, the sender Alice prepares the five-particle cluster state sequence and inserts decoy photon randomly, and then sends two parts of the particle sequence to the receiver Bob and the controller Cindy, and meanwhile keeps one part of the particle sequence himself. After Bob and Cindy receive the particle sequence, Alice performs a Z-based single-particle measurement and publishes the measurement results and the position information of the decoy photon through the classical channel. According to the information published by Alice, Bob and Cindy remove the decoy photon and perform a Bell-state measurement to their own part particle sequence. Three sides of communication complete the first safety examination of the channel by checking the bit error rate of the measurement results. After that, the controller Cindy determines the channel capacity by selecting the measurement base (Z basis or X basis) to measure its own particle sequence, and then announces the measured results with classical channel. The sender Alice inserts decoy photon and codes the information by doing a unitary transformation to its own particle sequence and then sends the receiver Bob and tells him the position information of the decoy photon with classical channel. Combining the information published by Cindy with the information transmitted by Alice, Bob can complete the second safety examination of the channel and decode the information Alice has sent by removing decoy photon and performing a Bell-state measurement of his own two groups of particle with appropriate rules. Through an analysis of the entangled structural properties of the five-particle cluster state, it has been confirmed that this protocol is designed to make full use of the entanglement properties of the five-particle cluster in different entangled structures. Therefore the protocol can obviously be generalized into the two-way controlled quantum secure direct communication by simply changing the rules of the measurement and the particles used for unitary coding. Through analyzing the security of this protocol, it reveals that this protocol can effectively both prevent eavesdroppers from eavesdropping useful information and monitor this kind of act, and therefore the controlled quantum secure direct communication can theoretically be established in a certain noise environment.
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.
We present a new quantum secure direct communication protocol with three-particle entangled state. The communication parties utilize decoy photons to check eavesdropping. The sender encodes the secret message with unitary transformation, we can directly transmit secret message with Bell-basis measurement and Z-basis measurement. The protocol is efficient in that all entangled states are used to transmit the secret message and two bits message can be transmitted one time, the preparation of three-particle entangled state is realized technique, the protocol is feasible to operate. The protocol is also verified to be secure for a noise quantum channel.