Information Leakage Problem in High-Capacity Quantum Secure Communication with Authentication Using Einstein-Podolsky-Rosen Pairs

The information leakage problem often exists in bidirectional quantum secure direct communication or quantum dialogue.In this work,we find that this problem also exists in the one-way quantum secure communication protocol[Chin.Phys.Lett.32(2015) 050301].Specifically,the first bit of every four-bit message block is leaked out without awareness.A way to improve the information leakage problem is given.     

Analyzing and Revising Quantum Dialogue Without Information Leakage Based on the Entanglement Swapping Between any Two Bell States and the Shared Secret Bell State

Information leakage in quantum dialogue (QD) or bidirectional quantum secure direct communication (BQSDC) was found ten years ago, but enough attention was not paid and even wrong conclusions were drawn. It is indeed necessary to emphasize the importance. Here, we find information leakage exists in the QD protocol based on entanglement swapping between any two Bell states and the shared secret Bell state. To be specific, half of the interchanged information is leaked out unconsciously. This is not allowed in a truly secure QD protocol. Afterward, this QD protocol is improved to the one without information leakage. Compared with the original one, there are some obvious advantages in the improved version.

     

Analysis and Improvement of Large Payload Bidirectional Quantum Secure Direct Communication Without Information Leakage

As we know, the information leakage problem should be avoided in a secure quantum communication protocol. Unfortunately, it is found that this problem does exist in the large payload bidirectional quantum secure direct communication (BQSDC) protocol (Ye Int. J. Quantum. Inf. 11(5), 1350051 2013) which is based on entanglement swapping between any two Greenberger-Horne-Zeilinger (GHZ) states. To be specific, one half of the information interchanged in this protocol is leaked out unconsciously without any active attack from an eavesdropper. Afterward, this BQSDC protocol is revised to the one without information leakage. It is shown that the improved BQSDC protocol is secure against the general individual attack and has some obvious features compared with the original one.     

基于Bell态粒子和单光子混合的量子安全直接通信方案的信息泄露问题

最近,一种基于Bell态粒子和单光子混合的量子安全直接通信方案[物理学报65 230301(2016)]被提出.文章宣称一个量子态可以编码3比特经典信息,从而使得协议具有很高的信息传输效率.不幸的是,该协议存在信息泄露问题:编码在单光子上的3比特经典信息有2比特被泄露,而编码在Bell态上的3比特经典信息有1比特被泄露,所以它不是一个安全的直接量子通信方案.在保留原协议思想且尽可能少地更改原协议的基础上,我们提出一种改进的消息编码规则,从而解决信息泄露问题,使之成为一个高效、安全的量子通信协议.衷心希望研究者能对量子安全通信协议中信息泄露问题引起足够重视,设计真正安全的量子通信协议.     

A Controller-Independent Quantum Dialogue Protocol with Four-Particle States

Controller-independent quantum dialogue (CIQD) is a significant topic in the research of quantum secure direct communication (QSDC). In this paper, we propose a new CIQD protocol with a special kind of four-particle entangled states. From our security analysis, it can be seen that the information leakage which is a serious problem in many CIQD protocols will be prevented in our protocol. Moreover, the presented protocol can resist many existing attacks, including intercept-and-resend attack, entangle-and-measure attack, fake entangled particles attack.

     

Bidirectional Quantum Secure Communication Based on One-Dimensional Four-Particle Cluster States

Using one-dimensional four-particle cluster states, we propose a bidirectional quantum secure communication protocol, in which the information leakage does not exist. In order to judge whether two sequences composed of cluster states are transmitted safely, two batches of decoy particles are used. Moreover, we show that this protocol is secure against eavesdropping.     

Efficient and Secure Authenticated Quantum Dialogue Protocols over Collective-Noise Channels

Based on the deterministic secure quantum communication,we present a novel quantum dialogue protocol without information leakage over the collective noise channel.The logical qubits and four-qubit decoherence-free states are introduced for resisting against collective-dephasing noise,collective-rotation noise and all kinds of unitary collective noise,respectively.Compared with the existing similar protocols,the analyses on security and information-theoretical efficiency show that the proposed protocol is more secure and efficient.     

A Protocol for Bidirectional Quantum Secure Communication Based on Genuine Four-Particle Entangled States

By swapping the entanglement of genuine four-particle entangled states, we propose a bidirectional quantum secure communication protocol. The biggest merit of this protocol is that the information leakage does not exist. In addition, the ideas of the ``two-step" transmission and the block transmission are employed in this protocol. In order to analyze the security of the second sequence transmission, decoy states are used.     

An Novel Protocol for the Quantum Secure Multi-Party Summation Based on Two-Particle Bell States

A protocol for the quantum secure multi-party summation based on two-particle Bell states is proposed. In this protocol, two-particle Bell states are used as private information carriers. Without using the entangled character of Bell states, we also use Pauli matrices operations to encode information and Hadamard matrix to extract information. The proposed protocol can also resist various attacks and overcomes the problem of information leakage with acceptable efficiency. In theory, our protocol can be used to build complex secure protocols for other multiparty computations and also lots of other important applications in distributed networks.     

Quantum secure direct communication and deterministic secure quantum communication

In this review article, we review the recent development of quantum secure direct communication (QSDC) and deterministic secure quantum communication (DSQC) which both are used to transmit secret message, including the criteria for QSDC, some interesting QSDC protocols, the DSQC protocols and QSDC network, etc. The difference between these two branches of quantum communication is that DSQC requires the two parties exchange at least one bit of classical information for reading out the message in each qubit, and QSDC does not. They are attractive because they are deterministic, in particular, the QSDC protocol is fully quantum mechanical. With sophisticated quantum technology in the future, the QSDC may become more and more popular. For ensuring the safety of QSDC with single photons and quantum information sharing of single qubit in a noisy channel, a quantum privacy amplification protocol has been proposed. It involves very simple CHC operations and reduces the information leakage to a negligible small level. Moreover, with the one-party quantum error correction, a relation has been established between classical linear codes and quantum one-party codes, hence it is convenient to transfer many good classical error correction codes to the quantum world. The one-party quantum error correction codes are especially designed for quantum dense coding and related QSDC protocols based on dense coding.      

Enhanced Multiparty Controlled QSDC Using GHZ State

Recently, Gao et al. [Opt. Commun. 283 (2010) 192] pointed out that Wang et al.'s multiparty controlled quantum secure directcommunication (CQSDC) protocol [Opt. Commun. 266 (2006)732] has the information leakage problem and proposed an improvedprotocol. However, in the improved protocol, due to the introductionof an additional random sampling to avoid the weakness, the qubitefficiency is decreased. By introducing the base changing techniqueto the random sampling in Wang et al.'s protocol, this study overcomesthe information leakage problem and provides a better qubit efficiency.     

Information Leakage in Efficient Bidirectional Quantum Secure Direct Communication with Single Photons in Both Polarization and Spatial-Mode Degrees of Freedom

Recently, Wang et al. presented a bidirectional quantum secure direct communication protocol with single photons in both polarization and spatial-mode degrees of freedom (Int. J. Theor. Phys. 54(10): 3443-3453, 2015). They claimed that their protocol was efficient and removed the drawback of information leakage. However, we found that the information leakage actually exists in their protocol. In this paper, we analyze Wang et al.’s protocol in detail. In addition, we propose an improvement to avoid the information leakage. The security of the improved protocol has also been discussed.     

High-Efficient Syndrome-Based LDPC Reconciliation for Quantum Key Distribution

Quantum key distribution (QKD) is a promising technique to share unconditionally secure keys between remote parties. As an essential part of a practical QKD system, reconciliation is responsible for correcting the errors due to the quantum channel noise by exchanging information through a public classical channel. In the present work, we propose a novel syndrome-based low-density parity-check (LDPC) reconciliation protocol to reduce the information leakage of reconciliation by fully utilizing the syndrome information that was previously wasted. Both theoretical analysis and simulation results show that our protocol can evidently reduce the information leakage as well as the number of communication rounds.     

Quantum Protocol for Millionaire Problem

A quantum protocol for millionaire problem based on commutative encryption is proposed. In our protocol, Alice and Bob don’t have to use the entangled character, joint measurement of quantum states. They encrypt their private information and privately get the result of their private information with the help of a third party (TP). Correctness analysis shows that the proposed protocol can be used to get the result of their private information correctly. The proposed protocol can also resist various attacks and overcomes the problem of information leakage with acceptable efficiency. In theory, our protocol can be used to build complex secure protocols for other multiparty computation problems and also have lots of other important applications in distributed networks.

     

Three-party Quantum Secure Direct Communication with Single Photons in both Polarization and Spatial-mode Degrees of Freedom

We present an efficient three-party quantum secure direct communication (QSDC) protocol with single photos in both polarization and spatial-mode degrees of freedom. The three legal parties’ messages can be encoded on the polarization and the spatial-mode states of single photons independently with desired unitary operations. A party can obtain the other two parties’ messages simultaneously through a quantum channel. Because no extra public information is transmitted in the classical channels, the drawback of information leakage or classical correlation does not exist in the proposed scheme. Moreover, the comprehensive security analysis shows that the presented QSDC network protocol can defend the outsider eavesdropper’s several sorts of attacks. Compared with the single photons with only one degree of freedom, our protocol based on the single photons in two degrees of freedom has higher capacity. Since the preparation and the measurement of single photon quantum states in both the polarization and the spatial-mode degrees of freedom are available with current quantum techniques, the proposed protocol is practical.     

Three-step semiquantum secure direct communication protocol

Quantum secure direct communication is the direct communication of secret messages without need for establishing a shared secret key first. In the existing schemes, quantum secure direct communication is possible only when both parties are quantum. In this paper, we construct a three-step semiquantum secure direct communication (SQSDC) protocol based on single photon sources in which the sender Alice is classical. In a semiquantum protocol, a person is termed classical if he (she) can measure, prepare and send quantum states only with the fixed orthogonal quantum basis {|0〉, |1〉}. The security of the proposed SQSDC protocol is guaranteed by the complete robustness of semiquantum key distribution protocols and the unconditional security of classical one-time pad encryption. Therefore, the proposed SQSDC protocol is also completely robust. Complete robustness indicates that nonzero information acquired by an eavesdropper Eve on the secret message implies the nonzero probability that the legitimate participants can find errors on the bits tested by this protocol. In the proposed protocol, we suggest a method to check Eves disturbing in the doves returning phase such that Alice does not need to announce publicly any position or their coded bits value after the photons transmission is completed. Moreover, the proposed SQSDC protocol can be implemented with the existing techniques. Compared with many quantum secure direct communication protocols, the proposed SQSDC protocol has two merits: firstly the sender only needs classical capabilities; secondly to check Eves disturbing after the transmission of quantum states, no additional classical information is needed.     

Quantum Dialogue Without Information Leakage Using a Single Quantum Entangled State

At present, a lot of quantum dialogue protocols have the problem of information leakage, especially the ones merely using a single quantum state as the quantum resource. In this paper, the author successfully puts forward a novel kind of information leakage resistant quantum dialogue protocol merely using a single quantum entangled state. This kind of quantum dialogue protocol uses the measurement correlation property of a single quantum entangled state to prevent the information leakage problem. Its Bell state version is illustrated in detail at first in this paper, then it is generalized to the cases of three-particle, four-particle and five-particle quantum entangled states. Different from those previous information leakage resistant quantum dialogue protocols, the proposed protocol needs neither the auxiliary quantum state nor the entanglement swapping technology of quantum state.     

Quantum secure dialogue by using single photons

By combining the idea of quantum secure direct communication (QSDC) and BB84 quantum key distribution (QKD), we propose a secure quantum dialogue protocol via single photons. Comparing with the previous bidirectional quantum secure communication scheme [24] in which the EPR pairs are used, our protocol is not only feasible in practice but also can overcome the drawback “information leakage” or “classical correlation”. Our scheme possesses the characters of security and high efficiency.     

Bidirectional quantum secure communication based on a shared private Bell state

We propose a secure bidirectional quantum communication protocol, which is based on a shared private quantum entangled channel, the highlight of our protocol is that the drawback “information leakage” is eliminated. Our protocol is similar but more efficient than a bidirectional quantum communication based on QKD & OTP (One-time pad).     

Single-Photon Secure Quantum Dialogue Protocol Without Information Leakage

Combining the idea of ping-pong protocol with Controlled-NOT operation, we propose a secure quantum dialogue protocol based on single-photonss. Bob obtains the information of the encrypted quantum state by performing Controlled-NOT operation on the auxiliary particle and the encrypted single-photonss. Unlike the previous quantum dialogue protocols based on single-photonss, the proposed protocol not only overcomes information leakage but also possesses an acceptable efficiency.