CN103248628A - Quantum safety communication eavesdropping detection method based on four-particle W state - Google Patents

Abstract

A quantum safety communication eavesdropping detection method based on a four-particle W state can improve the eavesdropping detection efficiency to 69 percent, and adopts the technical scheme that during transmitting of quantum safety communication, particles to be detected which are in the four-particle W state are randomly inserted into a transmission particle sequence by a sender, and after receiving the transmitted particle sequence, a receiver extracts the particles to be detected, performs four-particle W state measuring, and analyzes the safety in a communication process through a measurement result. By the security analysis, the eavesdropping detection efficiency of the method can reach 69 percent, so that high safety requirements on the quantum safety communication can be met well.

Description

A kind of safe quantum communication eavesdropping detection method based on four particle W attitudes

Technical field

The present invention relates to the eavesdropping detection method in a kind of safe quantum communication, adopt four particle W attitudes the eavesdropping detection efficiency can be brought up to 69% as detecting particle.

Background technology

Through practice and theoretical proof, attacks such as the safety problem that the safe quantum communication field exists all the time such as eavesdropping, Denial of Service attack, man-in-the-middle attack, these attack meetings cause confidential information to be eavesdropped or can not pass to the recipient exactly, especially by the eavesdropping to confidential information such as " tangling " method, can do a lot of damage to communication process.In the safe quantum communication field, the eavesdropping detection efficiency of existing communication protocol is not very high, proposed a kind of based on two right step quantum direct communication agreements [1] of EPR as people such as Deng Fuguo in 2003 in quantum direct communication and the ultra dense basis of coding of quantum, this detection efficiency can only reach 50%, can not satisfy the requirement of secure communication far away.

Summary of the invention

In order to guarantee better fail safe and efficiency of transmission in the safe quantum communication process, accelerate the paces of the physics realization of safe quantum communication, the present invention is in conjunction with the theoretical research of safe quantum communication and the latest Progress in this field, fully use the characteristic of tangling of four particle W attitudes, proposed a kind of safe quantum communication eavesdropping detection method based on four particle W attitudes.This method can not only be kept the big advantage of ultra dense coding transmission amount, and the eavesdropping detection efficiency can be brought up to 69%, and the existing important theoretical research meaning of this method also has actual application value.

The technical solution adopted for the present invention to solve the technical problems is: recipient Bob inserts at random in the transmission particle that has prepared and is in the four particle W attitudes that maximum is tangled, the throughput subchannel sends to transmit leg Alice then, after transmit leg Alice acknowledged receipt of these transmission particles, recipient Bob told the particle of which position of transmit leg Alice can form maximum four particle W attitudes of tangling.Transmit leg Alice extracts these and detects particle from the transmission particle, and it is carried out four particle W attitudes measure.Four particle W attitudes are a kind of attitudes of tangling, and are not understanding under the prerequisite of tangling between its constituent particle, no matter how the physical location of particle distributes, as long as one of them changes, then all the other particles also all can be done corresponding variation.If the listener-in carries out certain operation at tenth of the twelve Earthly Branches to this any particle that tangles attitude or measures, make and be in the particle group solution of tangling attitude and tangle, validated user will be found listener-in's existence in follow-up W attitude is measured, this invention just is based on four particle W attitudes, and this characteristic of tangling is carried out the fail safe detection.Therefore under the situation that has the listener-in to exist, the measurement result of transmit leg Alice is not four particle W attitudes entirely, interrupt communication.Under the situation that does not have the listener-in to exist, measurement result all should be four particle W attitudes, and communication continues.The transmit leg Alice information that will send adopts ultra dense coding to act in the particle flux that she has subsequently, and the four particle W attitudes that some prepare are inserted in this particle flux again, then this particle flux is sent to recipient Bob.Recipient Bob at first extracts the detection particle and carries out the detection of four particle W attitudes after receiving the particle flux of encryption, if no listener-in exists then residual particles is measured carrying out Bell, obtains transmit leg Alice information transmitted; Otherwise the code message of abandoning transmitting, and interrupt communication.

The invention has the beneficial effects as follows that the introducing of four particle W attitudes makes the eavesdropping detection efficiency in the safe quantum communication process bring up to 69%.

Description of drawings

In order being illustrated more clearly in the safe quantum communication process proposed by the invention based on the technical scheme of the eavesdropping detection method of four particle W attitudes and the fail safe proof procedure of this method, will to do simply the accompanying drawing of required use in the method below and introduce.For the researcher in this field, under the prerequisite of not paying creative research, can and prove that flow process acquires other accompanying drawing by these accompanying drawings according to the scheme concrete steps.

Fig. 1 is concrete operations step of the present invention;

Fig. 2 is the attack process of listener-in Eve;

Fig. 3 is the fail safe detection efficiency comparison diagram of the present invention and existing program;

Fig. 4 is the probability graph of listener-in's success steal information behind employing the present invention.

Embodiment

Bell attitude mentioned among Fig. 1 is

$|{\mathrm{\ψ}}^{+}\⟩=\frac{1}{\sqrt{2}}\left(\right|00\⟩+|11\⟩),---\left(1\right)$

Four particle W attitudes are

Recipient Bob and transmit leg Alice are the legitimate correspondence both sides, and Eve is the listener-in.The communication process of whole proposal is as follows:

The first step: recipient Bob generates N Bell attitude that is used for message transfer, extracts first particle and form transfer sequence S1 according to the order of sequence from each Bell attitude, and remaining particle is formed reservation queue S2 according to the order of sequence in each Bell attitude.And generate

The detection particle S3 of individual four particle W attitudes is used for detecting eavesdropping, wherein comprises in the S3 sequence

Individual particle.

Second step: recipient Bob is inserted into the S3 sequence in the S1 sequence randomly, so just obtains a new sequence S4, and recipient Bob notes the position of particle in the S4 sequence in the S3 sequence.Recipient Bob keeps the S2 sequence, and the S4 sequence is sent to transmit leg Alice.

The 3rd step: after recipient Bob acknowledged Alice receives whole S4 sequences, tell transmit leg Alice to detect the position of particle sequence S3 in S4 by classical channel.

The 4th step: transmit leg Alice extracts the detection particle from the S4 sequence, and it is carried out four particle W attitudes measure.

The 5th step: by to detecting the measurement of particle, if measurement result all is not in four particle W attitudes, the existence that the listener-in is arranged in this communication process is described, transmit leg Alice interrupts this communication; If measurement result is in four particle W attitudes entirely, illustrate that this communication process is safe, communication continues.

The 6th step: transmit leg Alice abandons the detection particle, and the single quantum bit of N remaining Bell attitude is carried out ultra dense coding, i.e. operation at the tenth of the twelve Earthly Branches, and the sequence definition after will encoding is S5.

The 7th step: transmit leg Alice generates

The individual detection particle sequence S6 that is in four particle W attitudes, and S6 is inserted among the sequence S5 at random, a new sequence S7 obtained like this.Transmit leg Alice notes the position of S6 particle in S7, and the S7 sequence is sent to recipient Bob.

The 8th step: after transmit leg Alice confirms that recipient Bob receives whole S7 sequences, tell recipient Bob to detect the position of particle sequence S6 in S7 by classical channel.

The 9th step: recipient Bob extracts the detection particle from the S7 sequence, and it is carried out four particle W attitudes measure.

The tenth step: by to detecting the measurement of particle, if measurement result all is not in four particle W attitudes, the existence that the listener-in is arranged in this communication process is described, recipient Bob interrupts this communication; If measurement result is in four particle W attitudes entirely, illustrate that this communication process is safe, communication continues.

The 11 step: recipient Bob abandons the detection particle, the corresponding particle with reservation queue S2 in of each particle in the residual particles sequence is combined and does Bell measurement, deciphers transmit leg Alice to the confidential information of its transmission with this.So far once communication is finished.

Reservation particle owing to recipient Bob among Fig. 2 transmits in quantum channel, Eve can't obtain any information of the reservation quantum bit of recipient Bob, therefore, all attack operation of Eve can only be at the quantum bit that transmits in quantum channel, and its attack process is as follows:

The first step: according to the character of quantum mechanics and quantum information, can not clone principle etc. as quantum uncertainty principle and quantum, Eve at first adds one to whole system and belongs to attitude in order to obtain the information that relevant transmit leg Alice operates

Second step: listener-in Eve must implement a unitary attack operation to whole system before the quantum bit of transmit leg Alice is encoded

The 3rd step: carry out encoding operation at the transmission of quantum bit of transmit leg Alice

After, listener-in Eve measures whole system again, finishes the attack process to whole system.

DPP among Fig. 3 refers to the detection efficiency of the scheme that people such as Deng Fuguo proposes, and WPP is the detection efficiency of the eavesdropping detection method that proposes of the present invention.Its fail safe proof procedure is as follows:

The first step: belong to attitude because the whole system of listener-in Eve is added one

So quantum bit changes, namely

Second step: because eavesdropping Eve has implemented a unitary attack operation to whole system before the quantum of transmit leg Alice is encoded

The state of whole system changes, and detection particle wherein also changes, namely

Wherein | α | ²+ | β | ²=1, | m| ²+ | n| ²=1, parameter alpha, β, m, n is determined by Eve.

The 3rd step: transmit leg Alice measures detecting particle, will obtain four particle W attitudes by probability, then the detection probability d that draws eavesdropping Eve about α, β, m, the expression formula of m.

The 4th step: transmit leg Alice calculates the apposition that detects particle, according to

Obtain density operator ρ '.

The 5th step: transmit leg Alice is according to formula ${\mathrm{\&rho;}}^{\&prime;\&prime;}=p_{0}I\&CircleTimes;...\&CircleTimes;I{\mathrm{\&rho;}}^{\&prime;}I\&CircleTimes;...\&CircleTimes;I+{\mathrm{<figure-callout\; id="1"\; label="p"\; filenames="HDA00003190344900022.png"\; state="\{\{state\}\}">p</figure-callout>}}_1{\mathrm{\&sigma;}}_Z\&CircleTimes;...\&CircleTimes;{\mathrm{\&sigma;}}_Z{\mathrm{\&rho;}}^{\&prime;}{\mathrm{\&sigma;}}_Z\&CircleTimes;$ $...\&CircleTimes;{\mathrm{\&sigma;}}_Z,$ The density operator is changed into the form ρ ' ' of density matrix.

The 6th step: transmit leg Alice obtains the eigenvalue of this density matrix _i

The 7th step: combining information entropy theory

Analyze, transmit leg Alice tries to achieve maximum fault information I that Eve can obtain in the S4 sequence about α, β, m, the expression formula of n.

The 8th step: transmit leg Alice simultaneous the 3rd step and the 7th step obtain detection probability d and two functions of maximum fault information I, draw the corresponding functional relation of eavesdropping the detection probability d that the retrievable maximum fault information I of Eve and Eve be detected.

Can sum up by Fig. 3 and to draw, the detection efficiency of the eavesdropping detection method that the present invention proposes will exceed 19% than the detection efficiency of the scheme that people such as Deng Fuguo propose.

Fig. 4 is the safety analysis figure of the safety detecting method of the present invention's proposition.Wherein s successfully obtains the probability of I bit information for the listener-in.In following analytic process, c is the probability of control model, and 1-c is the probability of massage pattern, and therefore, not found possibility is if Eve wants to steal a message transmitting procedure

$s(c,d)=(1-c)+c(1-d)(1-c)+c^2{(1-d)}^2(1-c)+\&CenterDot;\&CenterDot;\&CenterDot;=\frac{1-c}{1-c(1-d)}.---\left(3\right)$

The probability of then successfully stealing I=nI (d) bit information be s (I, c, d)=s (c, d) ^{I/I (d)}Therefore,

$s(I,c,d)=s{\left(\frac{1-c}{1-c(1-d)}\right)}^{I/I\left(d\right)},$ Wherein $I\left(d\right)=1+H\left(\frac{{\sin }^{-1}(d/0.6875)}{\mathrm{\&pi;}}\right).---\left(4\right)$

When I → ∞, s → 0 that is to say that this method is progressive safe.For example, when c=0.5, when getting different d, effect such as Fig. 4.

List of references

[1]DENG?F?G,LONG?G?L,LIU?X?S.Two-step?Quantum?direct?Communication?Protocol?Using?the?Einstein-Podolsky-Rosen?Pair?Block[J].Physical?Review?A,2003,68:042317.

Claims (2)

1. the safe quantum communication based on four particle W attitudes is eavesdropped detection method, in the transmission particle sequence of safe quantum communication, insert the detection particle that is in four particle W attitudes at random, by the measurement that is in four particle W attitudes detection particle being come the fail safe of analyzing and testing communication process, it is characterized in that: detect particle and need be inserted at random in the transmission particle sequence.

2. the safe quantum communication based on four particle W attitudes according to claim 1 is eavesdropped detection method, it is characterized in that the detection particle that is in four particle W attitudes will be inserted in the transmission particle sequence randomly, will insert the detection particle at random in the particle sequence that recipient Bob sends for transmit leg Alice, transmit leg Alice gives in the particle sequence after recipient Bob sends coding also will insert the detection particle at random.

Images