In order to improve the communication efficiency and security of Quantum Secure Direct Communication, a new Quantum Secure Direct Communication scheme based on d-dimension Bell entangled state is proposed. In the scheme, the receiver and the sender transport the d-dimensional Bell particles as secure test particles to ensure the security of communication. The receiver can calculate the security of the channel according to the measurement of d-dimensional Bell state particles, which is based on the entanglement properties of the d-dimensional Bell state. Secret information is transmitted through the other d-dimensional Bell state particles by dense coding technique. Then, the receiver can determine the security of the channel by comparing the measurements of the particles and makes a joint measurement of the transmitted particles to obtain secret information. Finally, the entropy theory is used to analyze the security of the protocol. Under the four dimensional Bell state, the transmission efficiency of the protocol is 90.90% and the efficiency of the quantum bit is 45.45%. The results show that the proposed scheme is safe and reliable and has high transmission efficiency.
In order to improve the communication efficiency and security of Quantum Secure Direct Communication, a new Quantum Secure Direct Communication scheme based on d-dimension Bell entangled state is proposed. In the scheme, the receiver and the sender transport the d-dimensional Bell particles as secure test particles to ensure the security of communication. The receiver can calculate the security of the channel according to the measurement of d-dimensional Bell state particles, which is based on the entanglement properties of the d-dimensional Bell state. Secret information is transmitted through the other d-dimensional Bell state particles by dense coding technique. Then, the receiver can determine the security of the channel by comparing the measurements of the particles and makes a joint measurement of the transmitted particles to obtain secret information. Finally, the entropy theory is used to analyze the security of the protocol. Under the four dimensional Bell state, the transmission efficiency of the protocol is 90.90% and the efficiency of the quantum bit is 45.45%. The results show that the proposed scheme is safe and reliable and has high transmission efficiency.
According to the characteristics of a class of three-particle W-states and the quantum dense coding,a new quantum secure direct communication scheme is presented.All particles,which are transmitted,are used to encode secret information except for the particles for testing security,which can greatly improve the communication efficiency.In order to ensure the security of the scheme,the channel is tested two times using the entanglement correlation between particles of W-states in particle distribution phase.It can improve the detection rate for eavesdropper and the reduce information leakage by inserting decoy photons into particles and rearranging the order of particles in information transfer phase.Security analysis shows that the scheme can ensure information transfer security and improve communication efficiency.
By studying the properties of the mixture of Bell state particles and single photons,in the paper we design a quantum code scheme with high coding capacity,and propose a novel quantum secure direct communication protocol with high transmission efficiency.Alice prepares Bell state particles and single photons,and divides Bell state particles into two sequences SA and SB.SB is sent to Bob for the first security check through using quantum correlation properties of particles.When the check result shows that the quantum channel is safe,by using the designed quantum code scheme, Alice encodes her classical message on the mixed quantum state sequence of Bell sequence SA and single photon sequence SS.Then,some single photons that are used for security check are re-inserted randomly into the encoded sequence,and the order of particles is rearranged to ensure checking Eve's attack.Alice sends the new sequence to Bob.Bob delays and receives it.And then,the quantum channel conducts the second-time security check.The transmission error rate is calculated,and if the error rate is lower than the tolerance threshold,the channel is safe.Bob decodes and reads Alice's message.The first security check is to determine whether quantum channel is safe.The second security check is to test whether there are eavesdroppers during information transmission.Safety analysis is done by applying the quantum information theory for the proposed protocol.The error rate introduced by Eve and the amount of information by Eve are calculated.It is shown that this pro-tocol can effectively resist measurement-resend attack,intercept-resend attack, auxiliary particle attack,denial of service attack and Trojan attack.Among them,auxiliary particle attack is analyzed in detail.The transmission efficiency and coding capacity are also analyzed.The transmission efficiency is 2,the quantum bit rate is 1,and the coding capacity is that a quantum state can encode three bits of classical messages.We also compare the proposed protocol with many existing popular protocols in the sense of efficiency,e.g.,Ping-Pong protocol, Deng F G et al.'s two-step and one-pad-time quantum secure direct communication protocol,Wang J et al.'s quantum secure direct communication protocol based on entanglement swapping and Quan D X et al.'s one-way quantum secure direct communication protocol based on single photon.It is proved that this proposed protocol has higher transmission efficiency.In addition,neither complex U operation nor entanglement swapping is used,and implementation process is simplified.However,this protocol is devoted to theoretical research of quantum secure direct communication.There are still some difficulties in the practical application.For example,the storage technology of quantum states is not mature at present.It is not easy to prepare and measure Bell state particles nor to combine them with single photons,and so on.The implementation of this protocol depends on the development of quantum technology in the future.
A quantum secure direct communication scheme using dense coding is proposed. At first, the sender (Alice) prepares four-particle genuine entangled states and shares them with the receiver (Bob) by sending two particles in each entangled state to him. Secondly, Alice encodes secret information by performing the unitary transformations on her particles and transmits them to Bob. Finally, Bob performs the joint measurements on his particles to decode the secret information. The two-step security test guarantees the security of communication.
In the paper, a protocol of quantum secure direct communication (QSDC) based on EPR entangled state and a quantum state of one particle is presented. The proposed protocol of QSDC uses the idea of one time pad of classical cryptology. The concept of data block and the method of split-step transmission are introduced into the proposed protocol of QSDC. According to the property of quantum, the eavesdropper can get nothing from quantum communication system, so the security of whole QSDC system is ensured. A part of secret message which will be transmitted is loaded on entangled states by processing quantum dense encoding operation on entangled particles. A nonorthogonal mixed state of single particle is introduced into the proposed protocol in order to improve the transmission efficiency, hence another part of secret message which will be transmitted is loaded on states of single particle. The private key and secret message are transmitted directly at the same time on quantum channel. So the proposed scheme of QSDC shall gain higher efficiency as well as complexity increase, and the system be proved the security by performance analysis.
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.
In response to the demand for identity authentication in quantum secure direct communication, this paper proposes a quantum secure direct communication scheme based on a mixture of single photon and Bell state, by combining the bidirectional identity authentication. Before communication begins, both parties share a series of secret information to prepare a series of single photon and Bell state particles. Encoding four single photons and four Bell states yields eight types of encoded information, followed by identity authentication. The first step in identity authentication is to use a single photon to verify the legitimacy of the receiver. If the error exceeds the given threshold, it indicates the presence of eavesdropping. Otherwise, the channel is safe. Then, Bell state particles are used to verify the legitimacy of the sender, and the threshold is also used to determine whether there is eavesdropping. The present method is the same as previous one. If the error rate is higher than the given threshold, it indicates the existence of third-party eavesdropping. Otherwise, it indicates that the channel is secure. As for the specific verification method, it will be explained in detail in the article. Afterwards, Bell state particles are mixed with a single photon as a transmission carrier, and eavesdropping detection particles are added whenever the quantum state is sent. However, once the eavesdropper intercepts the transmitted particles, owing to incomplete information obtained, the eavesdropper is unable to recover the original information, and the eavesdropping behavior will be immediately detected, thus terminating communication. In this scheme, single photon and Bell states are fully utilized, and hybrid communication can effectively improve transmission efficiency, encoding capability, and quantum bit utilization. Security analysis shows that this scheme can resist common external and internal attacks such as interception/measurement replay attacks, auxiliary particle attacks, and identity impersonation attacks. The analysis of efficiency and encoding capacity shows that the transmission efficiency of this scheme is 1, the encoding capacity is 3 bits per state, and the quantum bit utilization rate is 1. Compared with other schemes, this scheme has significant advantages because it uses different particles for bidirectional authentication, making it more difficult for attackers to crack, and thus it has higher security than traditional schemes.