Quantum Secure Direct Communication Protocol Research Articles

Security proof of the two-way quantum secure direct communication with channel loss and noise

Quantum secure direct communication is one of the major branches of quantum cryptography, which sends secret information through a quantum channel directly without setting up a prior key. Over the past decade, numerous protocols have been proposed, and some of them have been experimentally demonstrated. The two-way protocol is seen as one of the most practical protocol; in this paper, we present the security proof of the two-way quantum secure direct communication protocol when the noisy and lossy channel is taken into account.

Efficient Quantum Secure Direct Communication Protocol Based on Quantum Channel Compression

The article presents the concept of quantum channel compression—decrease in the amount of qubits utilized in a protocol—which is achieved by means of data source encoding. It is also a report on an efficient quantum secure direct communication (QSDC) protocol, which is used for transferring predetermined cryptographic keys (e.g., keys that are generated by the algorithm of Advanced Encryption Standard). This type of quantum secure communication combines the ideas of dense coding process and quantum channel compression. It is justified that such a protocol obtains overall transfer efficiency over unity, i.e., over 100%.

Measurement-device-independent quantum secure direct communication

Quantum secure direct communication (QSDC) is a unique technique, which supports the secure transmission of confidential information directly through a quantum channel without the need for a secret key and for ciphertext. Hence this secure communication protocol fundamentally differs from its conventional counterparts. In this article, we report the first measurement-device-independent (MDI) QSDC protocol relying on sequences of entangled photon pairs and single photons. Explicitly, it eliminates the security loopholes associated with the measurement device. Additionally, this MDI technique is capable of doubling the communication distance of its conventional counterpart operating without using our MDI technique. We also conceive a protocol associated with linear optical Bell-basis measurements, where only two of the four Bell-basis states could be measured. When the number of qubits in a sequence reduces to 1, the MDI-QSDC protocol degenerates to a deterministic MDI quantum key distribution protocol.

The analysis of high-capacity quantum secure direct communication using polarization and orbital angular momentum of photons

Higher channel capacity and noise elimination are the key requirements for the implementation of long-distance quantum communication. As the additional degrees of freedom (DoF) of photons can be employed to achieve higher channel capacity and security beyond the polarizations DoF of photons, the photonic qubits are always employed as the flying qubits in quantum communication and quantum information processing. Here, exploiting the multiple DoFs of photons, we present an efficient quantum secure direct communication protocol based on the coding and manipulation of qubits on both the polarization and the orbital angular momentum of photons. Also, the numerical simulation is studied to further clarify the improvement of the channel capacity and the security. It is found that the channel capacity and the error rate (caused by eavesdropping) of the QSDC protocol which encoded on the polarization DoF and the OAM DoF is significantly higher than that of coding on only polarization DoF. We believe this work could provide more evidence for the applications of higher-dimensional qubits in quantum information science.

Device-independent quantum secure direct communication against collective attacks

“Device-independent” not only represents a relaxation of the security assumptions about the internal working of the quantum devices, but also can enhance the security of the quantum communication. In the paper, we put forward the first device-independent quantum secure direct communication (DI-QSDC) protocol and analyze its security and communication efficiency against collective attacks. Under practical noisy quantum channel condition, the photon transmission loss and photon state decoherence would reduce DI-QSDC’s communication quality and threaten its absolute security. For solving the photon transmission loss and decoherence problems, we adopt noiseless linear amplification (NLA) protocol and entanglement purification protocol (EPP) to modify the DI-QSDC protocol. With the help of the NLA and EPP, we can guarantee DI-QSDC’s absolute security and effectively improve its communication quality.

On the generalization and improvement of QSDC efficiency achieved through a quantum channel compression

The paper presents a complete and general representation of the overall efficiency expression for the quantum secure direct communication (QSDC) protocol that relies on quantum channel compression (QCC). For this purpose, (i) the encoding technique, respectively, QCC is generalized—QCCs of higher order are introduced; (ii) the data statistics of the messages to be transferred are incorporated into the overall efficiency expression. An analysis is made concerning the behavior and the extent of the overall efficiency. It is justified that QSDC protocols, which are based on high order of QCC, could achieve efficiencies that have never been reached before.

Quantum secure direct communication based on four-particle cluster state grouping

In this paper we present a quantum secure direct communication protocol based on four-particle cluster states. In our protocol both the sender and the receiver keep two particles of the cluster state, and we verify that our protocol can prevent the eavesdropper from intercepting valid messages. Meanwhile, we also analyze our protocol in a lossy channel under the attack of an eavesdropper. We show that both the communication efficiency and the qubit-utilization ratio are improved compared with other existing schemes.

Deterministic Quantum Secure Direct Communication Protocol Based on Hyper-Entangled State

A quantum secure direct communication (QSDC) protocol based on the hyper-entangled state is proposed to improve the efficiency of eavesdropping detection in an improved “ping-pong” protocol, in which we use the hyper-entangled state to detect eavesdropping during the quantum communication. In the security analysis, we use the entropy theory method to calculate the amount of information and compare the detection strategy of two QSDC protocols quantitatively by comparing the constraint between the maximal amount of information that the eavesdropper can get, and the probability that the eavesdropper is detected. The probability of being detected will be 50% in the original QSDC protocol which based on the Bell states if the eavesdropper attempts to get all the information, however, in the proposed protocol this probability can reach 75%, which indicates that the proposed protocol is more secure.

Hybrid M-Ary in Braided Single Stage Approach for Multiphoton Quantum Secure Direct Communication Protocol

Quantum secure direct communication (QSDC) is a branch of quantum cryptography which exploits laws of physics and was recently proposed for securing information transferred from sender to receiver without relying on computational complexity. Instead of an entangled photon, the quantum cryptography employs two other approaches, single photon and multiphoton for encoding the messages. The multiphoton was proposed to outperform the weaknesses of a single photon by introducing the multiplicity of a photon to perform data encryption tasks. Despite the advantages of multiphoton, the transmission time to transfer the encoded data is still regarded as a critical issue. Most of the multiphoton approaches require multiple photons to travel along a number of stages. Moreover, extra time is needed to change the polarization angle of the optical device for encoding purposes. These situations have resulted in an increase in source redundancy, which subsequently leads to an increase in the transmission time. In this paper, a compression message approach is proposed to mitigate the substantial increase in time used for the data transmission processes. The proposed compression approach, namely, hybrid M-ary in a braided single stage (HMBSS) is based on the lossless data encoding such that the number of photons is reduced in the data transmission stage. Extensive simulation experiments have been conducted to test the performance of the proposed approach against some selected multiphoton approaches. The results show that the proposed approach outperforms braided single-stage, M-ary three-stage and initialization vector in terms of reducing total average transmission time to encode the photon by about 75.9% and 91.7%, respectively. Furthermore, the HMBSS reduces the overhead on the transmission channel by minimizing the number of message's bits by about 45% in average even when the length of the message increases during the transmission as compared to others.

Deterministic Quantum Secure Direct Communication Protocol Based on Omega State

A quantum secure direct communication (QSDC) protocol is presented. In the proposed protocol, the omega state is introduced to detect the eavesdropping during the quantum communication, eavesdropping behaviors will change the state of the omega state, and the sender Alice and the receiver Bob detect eavesdropping through the state measurement results. The relationship between the amount of information that the eavesdropper gets and the probability of being detected is also given. Compared with the original QSDC protocol based on the Bell state, when the same amount of information is obtained, the eavesdropper must face a higher detection probability in the proposed protocol, and the eavesdropper mostly can obtain 0.676 (bit) of information. The security analysis is also given, and the result indicates that the proposed protocol is more secure. A simulation based on the law of large number and the Monte Carlo method is also given, and the mean square error is introduced to describe the similarity between the simulation data and the theoretical value. The simulation result indicates that the proposed security in an ideal environment and the security analysis are correct, and the proposed protocol is more secure by sending more quantum particles in detecting eavesdropping.

Multiparty quantum secure direct communication immune to collective noise

In this paper, the N-particle GHZ states are used as quantum resources for multiparty quantum secure direct communication. Three new multiparty quantum secure direct communication protocols are proposed, which are based on the ideal quantum channels, the collective–dephasing noise channels and the collective–rotation noise channels, respectively. With the help of logical quantum states, the latter two protocols can be immune to the collective–dephasing noise and the collective–rotation noise, respectively. The security analysis shows that the Trojan horse attacks and the teleportation attack are automatically resisted because of the one-way transmission of quantum states in quantum channels. The use of the decoy states (or decoy logical qubits) also makes the three protocols secure against other kinds of attacks. Moreover, all of them have no information leakage problem.

Controlled Quantum Secure Direct Communication Protocol Based on Huffman Compression Coding

The invention discloses a controlled quantum secure direct communication method based on Huffman compression coding, which is characterized in that a sender Alice and a receiver Bob design the same sequence generator, a control party Charlie enables the two communication parties to generate the same pseudo-random sequence through sending the initial state of the sequence generators; the sender Alice performs compression on the original information by using Huffman compression coding, and carries out an exclusive-or operation on the compressed sequence and the pseudo-random sequence to form a sequence S1; the sender Alice sends a sequence SB to the receiver Bob to detect the channel security, if the channel is secure, the sender Alice divides the sequence S1 into an odd sequence and an even sequence, and the odd sequence the even sequence are differently coded, then loaded to remaining particles SA and sent to the receiver Bob; and if not, the communication is abandoned. The receiver Bob measures decoding and recovers the sequence S1 after detecting the channel security, and performs an exclusive-or operation on the sequence S1 and the pseudo-random sequence to obtain a compressed sequence, and the receiver Bob decompresses the compressed sequence to acquire the original information. The transmission efficiency of quantum secure direct communication can be effectively improved according to the method disclosed by the invention.

Measurement-device-independent quantum communication without encryption

Security in communication is vital in modern life. At present, security is realized by an encryption process in cryptography. It is unbelievable if a secure communication is achievable without encryption. In quantum cryptography, there is a unique form of quantum communication, quantum secure direct communication, where secret information is transmitted directly over a quantum channel. Quantum secure direct communication is drastically distinct from our conventional concept of secure communication, because it does not require key distribution, key storage and ciphertext transmission, and eliminates the encryption procedure completely. Hence it avoids in principle all the security loopholes associated with key and ciphertext in traditional secure communications. For practical implementation, defects always exist in real devices and it may downgrade the security. Among the various device imperfections, those with the measurement devices are the most prominent and serious ones. Here we report a measurement-device-independent quantum secure direct communication protocol using Einstein-Podolsky-Rosen pairs. This protocol eradicates the security vulnerabilities associated with the measurement device, and greatly enhances the practical security of quantum secure direct communication. In addition to the security advantage, this protocol has an extended communication distance, and a high communication capacity.

Three-step three-party quantum secure direct communication

We propose a three-party quantum secure direct communication (QSDC) protocol with hyperentanglement in both spatial-mode and polarization degrees of freedom. The secret message can be encoded independently with desired unitary operations in two degrees of freedom. In this protocol, a party can synchronously obtain the other two parties messages. Compared with previous three-party QSDC protocols, our protocol has several advantages. First, the single photons in our protocol are only required to transmit for three times. This advantage makes this protocol simple and useful. Second, Alice and Bob can send different secret messages to Charlie, respectively. Finally, with hyperentanglement, this protocol has a higher information capacity than other protocols.

Six-Qubit Decoherence-Free State Measurement Method and its Application to Development of Authenticated Quantum Secure Direct Communication Protocol

This paper proposes a measurement method capable of distinguishing six-qubit decoherence-free states. In addition, based on this measurement method, the paper presents an authenticated quantum secure direct communication (AQSDC) protocol that is simultaneously robust against both collective dephasing noise and collective rotation noise. This AQSDC protocol enables a sender to transmit secure and authenticated messages to a receiver via one-step quantum transmission without using classical channels. The new measurement method enables the qubit efficiency of the AQSDC protocol to be superior to those of existing AQSDC protocols. The analyses presented herein demonstrate that the AQSDC protocol is secure and effective.

Deterministic Quantum Secure Direct Communication and Authentication Protocol Based on W‐Class State

A Quantum secure direct communication (QSDC) and authentication protocol based on the W-class state is presented to enhance the efficiency of eavesdropping detection. In this protocol, the W-class state is used to transmission the checking sequence and detect eavesdroppers. In the security analysis, the method of entropy theory is introduced, and two detection strategies are compared quantitatively by using the constraint between the information that eavesdroppers can obtain and a normalized difference parameter is introduced. To obtain the same amount of information, the eavesdropper must face a higher detection probability in the proposed protocol than in the comparison. The security of the proposed protocol is also discussed. The analysis results indicate that the proposed protocol is more secure, but it must send more particles.

Impersonation attack on a quantum secure direct communication and authentication protocol with improvement

We analyze the security of a quantum secure direct communication and authentication protocol based on single photons. We first give an impersonation attack on the protocol. The cryptanalysis shows that there is a gap in the authentication procedure of the protocol so that an opponent can reveal the secret information by an undetectable attempt. We then propose an improvement for the protocol and show it closes the gap by applying a mutual authentication procedure. In the improved protocol single photons are transmitted once in a session, so it is easy to implement as the primary protocol. Furthermore, we use a novel technique for secret order rearrangement of photons by which not only quantum storage is eliminated also a secret key can be reused securely. So the new protocol is applicable in practical approaches like embedded system devices.

Analysis and Improvement of an Efficient Controlled Quantum Secure Direct Communication and Authentication Protocol

The controlled quantum secure direct communication (CQSDC) with authentication protocol based on four particle cluster states via quantum one-time pad and local unitary operations is cryptanalyzed. It is found that there are some serious security issues in this protocol. An eavesdropper (Eve) can eavesdrop on some information of the identity strings of the receiver and the controller without being detected by the selective-CNOT-operation (SCNO) attack. By the same attack, Eve can also steal some information of the secret message that the sender transmits. In addition, the receiver can take the same kind of attack to eavesdrop on some information of the secret message out of the control of the controller. This means that the requirements of CQSDC are not satisfied. At last, we improve the original CQSDC protocol to a secure one.

Measurement device-independent quantum dialogue

Very recently, the experimental demonstration of quantum secure direct communication (QSDC) with state-of-the-art atomic quantum memory has been reported (Zhang et al. in Phys Rev Lett 118:220501, 2017). Quantum dialogue (QD) falls under QSDC where the secrete messages are communicated simultaneously between two legitimate parties. The successful experimental demonstration of QSDC opens up the possibilities for practical implementation of QD protocols. Thus, it is necessary to analyze the practical security issues of QD protocols for future implementation. Since the very first proposal for QD by Nguyen (Phys Lett A 328:6---10, 2004), a large number of variants and extensions have been presented till date. However, all of those leak half of the secret bits to the adversary through classical communications of the measurement results. In this direction, motivated by the idea of Lo et al. (Phys Rev Lett 108:130503, 2012), we propose a measurement device-independent quantum dialogue scheme which is resistant to such information leakage as well as side-channel attacks. In the proposed protocol, Alice and Bob, two legitimate parties, are allowed to prepare the states only. The states are measured by an untrusted third party who may himself behave as an adversary. We show that our protocol is secure under this adversarial model. The current protocol does not require any quantum memory, and thus, it is inherently robust against memory attacks. Such robustness might not be guaranteed in the QSDC protocol with quantum memory (Zhang et al. 2017).

High-capacity quantum secure direct communication with two-photon six-qubit hyperentangled states

This study proposes the first high-capacity quantum secure direct communication (QSDC) with two-photon six-qubit hyper-entangled Bell states in two longitudinal momentum and polarization degrees of freedom (DOFs) of photon pairs, which can be generated using two 0.5 mm-thick type-I β barium borate crystal slabs aligned one behind the other and an eight-hole screen. The secret message can be independently encoded on the photon pairs with 64 unitary operations in all three DOFs. This protocol has a higher capacity than previous QSDC protocols because each photon pair can carry 6 bits of information, not just 2 or 4 bits. Our QSDC protocol decreases the influence of decoherence from environment noise by exploiting the decoy photons to check the security of the transmission of the first photon sequence. Compared with two-way QSDC protocols, our QSDC protocol is immune to an attack by an eavesdropper using Trojan horse attack strategies because it is a one-way quantum communication. The QSDC protocol has good applications in the future quantum communication because of all these features.