CN108400865A - One kind being based on DCSK chaos encrypting methods - Google Patents

Abstract

The invention discloses one kind being based on DCSK chaos encrypting methods, includes the following steps：1) bipolar signal is randomly generated in transmitting terminal；2) bipolar signal in step 1) is input in second order inverse time chaos system and generates chaotic signal；3) signal after the bipolar signal in step 1) being multiplied with the chaotic signal in step 2)；4) binary signal of transmitting terminal is become into bipolar signal；5) signal after being multiplied in the bipolar signal and step 3) in step 4) is multiplied again as transmission signal；6) it receives signal and is integrated in a neighborhood at each reception each integer point moment intermediate value of signal, then its binaryzation is obtained into the bipolar signal of receiving terminal；7) binary signal of transmitting terminal can be recovered by the bipolar signal of receiving terminal being become binary signal.The present invention generates chaotic signal using second order inverse time chaos system and carries out keyed cryptographic to the binary signal to be sent.

Description

A Chaotic Encryption Method Based on DCSK

technical field

The invention belongs to the field of secure communication, and in particular relates to a DCSK-based chaotic encryption method.

Background technique

Although the structure of the chaotic signal is relatively complex, the composition of the chaotic system is relatively simple. The research phase of chaos communication mainly includes the following aspects: using chaos technology for encryption processing; using chaos for spread spectrum communication and chaos modulation technology. At present, there are mainly two kinds of encryption schemes of Chaotic Modulation Method (DCSK). A method that uses coherent demodulation, which requires the receiving end to know the information of the sending end to recover the sent signal, so it is very dependent on chaotic synchronization and is sensitive to noise. The non-coherent demodulation method does not need to use chaos synchronization, and has strong anti-interference ability to noise, so it is widely used.

Contents of the invention

The object of the present invention is to provide a DCSK-based chaotic encryption method, which uses a second-order reverse time chaotic system to generate chaotic signals to perform keying and encryption on binary signals to be sent.

The present invention adopts following technical scheme to realize:

A kind of encryption method based on DCSK chaos, comprises the following steps:

1) Randomly generate a series of bipolar signals;

2) The bipolar signal in step 1) is used as the input of the second-order reverse time chaotic system to generate the chaotic signal;

3) Multiply the bipolar sequence in step 1) and the chaotic signal in step 2) in each corresponding symbol period to obtain the multiplied chaotic signal, so as to ensure that the In a neighborhood, the value of the chaotic signal is greater than 0;

4) Convert the binary signal to be sent into a bipolar signal;

5) Multiply the bipolar signal in step 5) and the multiplied chaotic signal in step 4) again as the sending signal;

6) Receive the signal from the channel, then integrate the received signal in a neighborhood of the median value at each integer point time, and then binarize it to obtain the bipolar signal at the receiving end;

7) Change the bipolar signal at the receiving end into a binary signal to obtain a binary signal at the sending end.

The further improvement of the present invention is, step 3) in, second-order reverse time chaotic system, its mathematical expression is:

Among them, u is the reverse time chaotic signal to be generated, is the second order differential of u, is the first-order differential of u, β and ω are the control parameters of the system, and ω is the angular frequency;

The activation function s(t) is described as:

s(t)=s _n ,n<t≤n+1 (2)

where s _n is a bipolar sequence.

The further improvement of the present invention is that in step 4), the bipolar signal s(t) and the reverse time chaotic signal u(t) are multiplied to obtain the multiplied chaotic signal y(t), namely:

y(t)=u(t)×s(t) (3).

A further improvement of the present invention is that in step 6), the multiplied chaotic signal and the binary signal m(t) to be sent are multiplied to obtain the sent signal r(t), namely:

r(t)=m(t)×y(t) (4)

Add noise w(t) to the transmitted signal to obtain the received signal R(t), namely:

R(t)=r(t)+w(t) (5).

A further improvement of the present invention is that in step 7), the received signal is integrated in a neighborhood of its integer point time median:

Among them, l is the length of the neighborhood of the integral, and then binarize st _n to get k _n , namely:

A further improvement of the present invention is that in step 8), the bipolar sequence after the integration is changed into a binary signal to obtain the binary signal at the sending end:

The present invention has following beneficial technical benefit:

1) Good encryption effect

The bipolar signal for generating the chaotic signal of the present invention is randomly generated, and has absolutely no correlation with the binary signal to be sent.

2) Low bit error rate

The receiving end uses integration to restore the binary signal at the sending end. In theory, the bit error rate of this scheme tends to zero.

3) High transmission efficiency

Traditional DCSK modulates a binary signal within two symbol periods, but the scheme proposed in this paper modulates a binary signal within one symbol period.

Description of drawings

Fig. 1 is a bipolar signal diagram generated randomly;

Figure 2 is a diagram of the reverse time chaotic signal produced by a random bipolar signal;

Fig. 3 is the chaotic signal diagram after multiplying the bipolar sequence and the reverse time chaotic signal;

Fig. 4 is a binary signal diagram to be sent;

Fig. 5 is the chaotic signal diagram after the binary signal sent and the chaos are multiplied;

Fig. 6 is a transmission signal superimposed noise diagram;

Fig. 7 is a signal diagram obtained by integrating the receiving end in the neighborhood of the output signal integer moment;

FIG. 8 is a binary signal diagram of the sending end obtained by binarizing the integrated signal.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and embodiments.

The present invention utilizes the second-order reverse time chaotic system, and the expression is as follows:

Among them, u is the reverse time chaotic signal to be generated, is the second order differential of u, is the first-order differential of u, β and ω are the control parameters of the system, and ω is the angular frequency;

The activation function s(t) is described as:

s(t)=s _n ,n<t≤n+1 (2)

where s _n is a bipolar signal.

Randomly generate a series of bipolar signals as shown in Figure 1: s _n = [-1 -1 -1 1 -1 1 1 -1 1 1 -1-1 -1 1 -1 1 1 -1 1 -1 1 -1 -1 1 -1 1 -1 -1 1 1 -1 -1 1 -1 1 1 -1 1 -1 -1 -11 -1 -1 1 -1 1 1-1 1 -1 -1 1 -1 1 -1 -1 1 -1 1 1 -1 -1 1 -1 -1 -1 1 -1 1 1 -11 1 -1 -1 -1 1 -1 1];

Substituting the above-generated s _n into the formula (1) generates the corresponding chaotic signal u(t) as shown in Figure 2;

Multiply s(t) and u(t) to obtain the modulated chaotic signal y(t) at the sending end, as shown in Figure 3, namely:

y(t)=s(t)×u(t) (3)

Multiply the binary signal m(t) to be sent by the modulated chaotic signal y(t) as shown in Figure 4 to obtain the transmitted signal as shown in Figure 5:

r(t)=m(t)×y(t) (4)

Add noise w(t) to the transmitted signal to obtain the received signal R(t) as shown in Figure 6, namely:

R(t)=r(t)+w(t) (5)

Integrate the received signal in a neighborhood of the median value at its integer point time to obtain st _n as shown in Figure 7, l=0.25:

Among them, l is the half-length of the neighborhood of the integral, and then binarize st _n to get k _n , namely:

Turn the integrated bipolar sequence into a binary signal as shown in Figure 8, and then the binary signal at the sending end can be obtained.

Example

Taking a specific signal as an example, the present invention is verified, wherein Fig. 6 is the transmitted signal, Fig. 7 is the signal actually transmitted in the channel, Fig. 8 is the binary signal finally recovered, and the simulated noise in the channel is Gaussian white Noise, signal-to-noise ratio SNR=0dB, the feasibility of the method can be seen from the sent binary signal and the restored binary signal.

Claims (6)

1. a kind of encryption method based on DCSK chaos, is characterized in that, comprises the following steps: 1) Randomly generate a series of bipolar signals; 2) The bipolar signal in step 1) is used as the input of the second-order reverse time chaotic system to generate the chaotic signal; 3) Multiply the bipolar sequence in step 1) and the chaotic signal in step 2) in each corresponding symbol period to obtain the multiplied chaotic signal, so as to ensure that the In a neighborhood, the value of the chaotic signal is greater than 0; 4) Convert the binary signal to be sent into a bipolar signal; 5) Multiply the bipolar signal in step 5) and the multiplied chaotic signal in step 4) again as the sending signal; 6) Receive the signal from the channel, then integrate the received signal in a neighborhood of the median value at each integer point time, and then binarize it to obtain the bipolar signal at the receiving end; 7) Change the bipolar signal at the receiving end into a binary signal to obtain a binary signal at the sending end. 2. a kind of encryption method based on DCSK chaos according to claim 1, is characterized in that, step 3) in, second-order reverse time chaotic system, its mathematical expression is: Among them, u is the reverse time chaotic signal to be generated, is the second order differential of u, is the first-order differential of u, β and ω are the control parameters of the system, and ω is the angular frequency; The activation function s(t) is described as: s(t)=s _n ,n<t≤n+1 (2) where s _n is a bipolar sequence. 3. a kind of encryption method based on DCSK chaos according to claim 2, it is characterized in that, step 4) in, bipolar signal s (t) and reverse time chaotic signal u (t) are multiplied to obtain multiplication The chaotic signal y(t) after that is: y(t)=u(t)×s(t) (3). 4. a kind of encryption method based on DCSK chaos according to claim 3, it is characterized in that, in step 6), the multiplied chaos signal and the binary signal m (t) to be sent are multiplied to obtain sending signal r ( t), namely: r(t)=m(t)×y(t) (4) Add noise w(t) to the transmitted signal to obtain the received signal R(t), namely: R(t)=r(t)+w(t) (5). 5. a kind of encryption method based on DCSK chaos according to claim 4, it is characterized in that, in step 7), receive signal is integrated in a neighborhood at its integer point moment median value place: Among them, l is the length of the neighborhood of the integral, and then binarize st _n to get k _n , namely: 6. a kind of encryption method based on DCSK chaos according to claim 5, it is characterized in that, step 8) in, the bipolar sequence after integral becomes binary signal and can obtain the binary signal of sending end: