Quantum secure direct communication is the direct communication of secret messages without first producing a shared secret key. It may be used in some urgent circumstances. Here we propose a quantum secure direct communication protocol using single photons. The protocol uses batches of single photons prepared randomly in one of four different states. These single photons serve as a one-time pad which is used directly to encode the secret messages in one communication process. We also show that it is unconditionally secure. The protocol is feasible with present-day technique.
Quantum secure direct communication is the direct communication of secret messages without first producing a shared secret key. It may be used in some urgent circumstances. Here we propose a quantum secure direct communication protocol using single photons. The protocol uses batches of single photons prepared randomly in one of four different states. These single photons serve as a one-time pad which is used directly to encode the secret messages in one communication process. We also show that it is unconditionally secure. The protocol is feasible with present-day technique.
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.
A quantum high secure direct communication with authentication protocol is proposed by using single photons. The high security of the protocol is achieved on levels. The first level involves the verification of the quantum channel security by using fake photons. The authentication process is also ensured by the fake photons. The second level of security is given by the use of multiple polarization bases. The secret message is encoded in groups of photons; each single character of the message is associated with m (m≥7) photons. Thus, at least 27(128) characters will be encoded. In order to defeat the quantum teleportation attack, the string of bits associated to the secret message is encrypted with a secret string of bits by using XOR operator. Encryption of the sender's identity string and the receiver's identity string by the XOR operator with a random string of fake photons defends quantum man-in-the-middle attack efficiently. Quantum memory is required to implement our protocol. Storage of quantum information is a key element in quantum information processing and provides a more flexible, effective and efficient communication. Our protocol is feasible with current technologies.
Abstract Quantum secure direct communication (QSDC) enables the direct transmission of secret messages over a quantum channel without prior key sharing. QSDC implemented in the continuous-variable (CV) regime allows high-capacity information transmission using simple optical communication technologies. In this work, we propose a novel CV-QSDC protocol with a quantum one-time pad, which achieves secure message transmission based on coherent states and unitary operations, and the receiver can directly obtain the secret messages after measuring the coherent states. The security of this protocol is jointly guaranteed by one-time pad encryption and a CV quantum key distribution (QKD) protocol. Performance analysis shows that the proposed scheme can achieve a quantum bit error rate (QBER) lower than 1% by adjusting the modulation variance and unitary operation parameters. With the optimal modulation variance, the secure transmission distance of the proposed protocol can exceed 150 km.
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.
Quantum key distribution (QKD) is considered as an ideal method to make secret message unreadable to eaves-dropper but intelligible to the two authorized parties of the communication [1][2][3][4][5][6].In the research of experimental quantum key distribution, single photons and entangled photon pairs are used as the carriers.In quantum key distribution, secret keys are generated first between the communication parties.The security of quantum key distribution is guaranteed by the laws of quantum mechanics.After the quantum key distribution is completed, the communication parties should share secret keys, then the sender encrypts the secret message using the secret keys to form the ciphertext and transmits the ciphertext through a classical channel.The receiver receives the ciphertext and then decrypt the ciphertext to get the secret message.Altogether there are four steps in a secret communication process with QKD: key generation, encryption, transmission and decryption.Here in this review, we review some new development in quantum communication, quantum direct communication (QDC).Quantum direct communication is a form of quantum communication where secret messages can be transmitted through a quantum channel with or without additional classical communications.There are two forms of quantum direct communication, quantum secure direct communication (QSDC) [7{9] and deterministic secure quantum communication (DSQC) [10,11].In QSDC, secret messages are transmitted directly between the communication parties, from sender Alice to receiver Bob, without additional classical communication except those for the necessary eavesdropping check.In other words, the quantum key distribution process and the classical communication of ciphertext are condensed into one single quantum communication procedure in QSDC.Deterministic secure quantum communication is another type of quantum direct communication, such as those proposed in Ref. [10,11], where classical communication is required in order to read out the secret message.As mentioned earlier, to complete a secure communication with the help of QKD, one usually encodes the secret message with an encryption scheme, and the ciphered text is transmitted through a classical channel.With a quantum channel, this procedure can be varied.
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.