A Linear Superposition Carrier Chaotic Watermark Communication Security Authentication Method

Abstract

The present invention discloses a linear superposition carrier chaotic watermark communication security authentication method, which comprises: the legal transmitter performs XOR on the chaotic watermark sequence and the orthogonal random sequence to obtain a spread spectrum watermark sequence, the spread spectrum watermark sequence forms a transmission baseband waveform through a shaping filter, performs carrier modulation on it and linearly superimposes it with the original communication signal sent by the legal transmitter to complete the watermark embedding and original communication signal; the legal transmitter and the illegal transmitter both send communication signals to the legal receiver; wherein the communication signal sent by the legal transmitter contains watermark information, and the communication signal sent by the illegal transmitter does not contain watermark information; the legal receiver performs coherent demodulation, matched filtering and watermark detection on the received communication signal to perform security authentication on the identity of the unknown transmitter. The present invention improves the concealment of watermark information and the accuracy of authentication of legal persons.

Description

Technical Field

[0001] The invention relates to the field of communication technology, and in particular to a linear superposition carrier chaotic watermark communication security authentication method. Background Art

[0002] With the continuous increase of wireless mobile users, wireless communication security faces huge challenges. Due to the openness and broadcasting of wireless networks, it is easier for unauthorized users to disguise themselves as legitimate users to launch deception attacks, which will lead to malicious users inserting information or stealing information in the communication channel. In addition, if the upper-layer communication protocol is loaded by relying solely on a specific cryptographic algorithm, it is difficult to cope with high-intensity and high-computing power password cracking capabilities, and it will also increase the waste of high-level resources. In order to ensure communication security and prevent communication signals from being intercepted, a mechanism that can be closely integrated with the upper-layer communication protocol to enhance encrypted secure communication is urgently needed. Secret communication can hide secret information in carrier information. This method uses embedded watermarks to realize physical layer identity authentication. By transmitting watermark information and carrier information together, business data can be transmitted secretly, and identity authentication can be completed without occupying additional frequency band resources of the system. Since it is difficult for eavesdroppers and deceptive attackers to obtain watermark information at the physical carrier layer, the system can further enhance information security. Therefore, linear superposition carrier chaotic watermark communication security authentication technology is of great significance. Summary of the invention

[0003] In order to solve the problem of how to ensure secure communication between legitimate communicating parties in a radio electromagnetic environment with interference and malicious attacks, the present invention provides a linear superposition carrier chaotic watermark communication security authentication method to achieve hidden identity tagging of the legitimate transmitter, which can be applied to both single-antenna communication systems and multi-antenna communication systems. In particular, the method can be applied to covert communication systems to improve their defense capabilities against interference and malicious deception attacks.

[0004] The invention discloses that a legitimate transmitter performs XOR on a chaotic watermark sequence and an orthogonal random sequence to obtain a spread spectrum watermark sequence, the spread spectrum watermark sequence forms a transmission baseband waveform through a shaping filter, performs carrier modulation on the waveform and linearly superimposes the waveform with the original communication signal sent by the legitimate transmitter to complete the watermark embedding and the original communication signal;

[0005] Both the legal transmitter and the illegal transmitter send communication signals to the legal receiver; the communication signal sent by the legal transmitter contains watermark information, while the communication signal sent by the illegal transmitter does not contain watermark information;

[0006] The legitimate receiver performs coherent demodulation, matched filtering and watermark detection on the received communication signal to securely authenticate the identity of the unknown transmitter.

[0007] Furthermore, a chaotic watermark sequence is generated under negotiation between two legitimate communication parties; the two legitimate communication parties include a legitimate transmitter and a legitimate receiver.

[0008] Furthermore, the method for obtaining the chaotic watermark sequence includes:

[0009] The chaotic system function Tent is used to generate a series of initial watermark information seeds. Based on the initial watermark information seeds, watermark information seeds are generated. A fixed threshold value η1 is set, and the watermark information, i.e., the chaotic watermark sequence, is obtained by comparing each sequence in the watermark information seeds with the fixed threshold value η1.

[0010] Furthermore, the chaotic system function Tent is used to generate a series of initial watermark information seeds through the following formula:

[0011]

[0012] Among them, 0 <a<1,0<x1≤1,x k+1 is the k+1th initial watermark information seed;

[0013] The watermark information seed w = {w m =x k},m=1,2,...,M,0 <w m <1From the chaotic sequence x={x k},k=1,2,...,M,0 <x m <1Generate;w m is the mth watermark information seed;

[0014] Set a fixed threshold value η1, that is, set the chaotic value greater than the threshold value η1 in the watermark information seed w to 1, and set the other chaotic values ​​to 0, and get the watermark information is the mth watermark information.

[0015] Furthermore, performing XOR operation on the chaotic watermark sequence and the orthogonal random sequence to obtain a spread spectrum watermark sequence includes:

[0016] The Hadamard matrix H is used to iteratively generate two mutually orthogonal sequences c1 and c2 of length l and two Wlash sequences, and the length of the Wlash sequence is l = 2 r , c i =[c1,c2,...,c i ],c i ∈{-1,1};

[0017] The recursive relationship of the Hadamard matrix is ​​as follows:

[0018]

[0019] Select H r Any two columns or any two rows in are taken as c1 and c2;

[0020] Using two orthogonal sequences c1 and c2 to perform direct sequence spread spectrum on the watermark information w, the spread spectrum watermark sequence w' = {w 22 (i)},w 22 (i)∈{0,1}:

[0021]

[0022] in, Represents the direct sequence spread spectrum process. The watermark information before watermark spread is w 21 (i) The signal after watermark information spread is w 22 (i).

[0023] Furthermore, the spread spectrum watermark sequence w' is shaped and filtered to form a transmission baseband waveform. After the transmission baseband waveform is modulated by the carrier, it is linearly superimposed with the original communication signal s to form the final transmission signal r:

[0024] r=s+ρw

[0025] Where ρ represents the watermark amplitude coefficient.

[0026] Furthermore, the starting position of the linear superposition of the watermark is located in the middle section of the original carrier signal; assuming that the length of the original carrier is l1, the length of the watermark information is l2, the starting position of the linear superposition of the watermark is:

[0027]

[0028] Among them, l3 is the starting position of the watermark linear superposition.

[0029] Furthermore, after receiving the unknown signal, the legitimate receiver performs carrier demodulation, matched filtering, and then watermark detection. If the watermark detection passes, it is judged to be a legitimate transmitter, the watermark is extracted and removed, and then sampling judgment, demapping and restoration of the baseband signal are performed; otherwise, the authentication fails and the reception is terminated.

[0030] Furthermore, the watermark detection process uses despreading and coherent detection to distinguish the similarity between the watermark information to be detected and the known watermark.

[0031] Due to the adoption of the above technical solution, the present invention has the following advantages:

[0032] 1. Linear superposition carrier chaotic watermark communication security authentication technology loads chaotic watermark information on the legitimate transmitter. The chaotic watermark information is non-periodic and sensitive to initial conditions. Therefore, the watermark information has real-time and confidentiality.

[0033] 2. The present invention generates a chaotic watermark sequence through a chaotic system function to ensure the randomness and uniqueness of the watermark sequence, and then XORs two different orthogonal sequences according to the characteristics of the watermark sequence. On the one hand, it improves the concealment of the watermark information, and on the other hand, it effectively improves the accuracy of authentication of the legitimate person. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the embodiments of the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0035] Figure 1 A schematic diagram of a wireless communication security authentication scenario according to an embodiment of the present invention;

[0036] Figure 2 The figure is a schematic diagram showing the linear superposition carrier chaotic watermark embedding and authentication process according to an embodiment of the present invention. DETAILED DESCRIPTION

[0037] The present invention is further described in conjunction with the accompanying drawings and embodiments, and the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by ordinary technicians in this field should fall within the scope of protection of the embodiments of the present invention.

[0038] The linear superposition carrier chaotic watermark communication security authentication technology loads chaotic watermark information on the legitimate transmitter. The chaotic watermark information is non-periodic and sensitive to initial conditions. Therefore, the watermark information has real-time and confidentiality. The method of the present invention can be applied to both single-antenna communication systems and multi-antenna communication systems. In particular, the method can be applied to covert communication systems to improve their defense capabilities against interference and malicious deception attacks. Figure 1 The present invention provides an embodiment of a linear superposition carrier chaotic watermark communication security authentication method, which includes:

[0039] In this embodiment, the scenario targeted is that a legitimate receiver performs watermark identity authentication on different transmitters. Figure 1 shown.

[0040] The implementation process and software flow of the present invention are as follows: Figure 2 The specific description process is as follows:

[0041] The legal communication parties are {S k}, k = 1, 2, ..., K where S1 is the legal receiver, S2 is the legal transmitter, and the illegal transmitter {Eve k}, k = 1, 2, ..., K, the legal transmitter S2 and the illegal transmitter Eve simultaneously transmit communication signals to the legal receiver S1, wherein the signal sent by the legal transmitter contains watermark information, while the signal sent by the illegal transmitter does not contain watermark information.

[0042] S1 is the legal receiver, and S2 is the legal transmitter. The two parties negotiate to generate watermark information based on the chaotic system.

[0043] The chaotic system function Tent is used to generate a series of initial watermark information seeds. Based on the initial watermark information seeds, watermark information seeds are generated. A fixed threshold value η1 is set, and the watermark information, i.e., the chaotic watermark sequence, is obtained by comparing each sequence in the watermark information seeds with the fixed threshold value η1.

[0044] The first step is to initialize a and x k , the range is 0 <a<1,0<x1≤1;

[0045] In the second step, the chaotic system function Tent is used to generate a series of initial watermark information seeds through the following formula:

[0046]

[0047] The watermark information seed w = {w m =x k},m=1,2,...,M,0 <w m <1From the chaotic sequence x={x k},k=1,2,...,M,0 <x m <1Generate;w m is the mth watermark information seed;

[0048] Set a fixed threshold value η1, that is, set the chaotic value greater than the threshold value η1 in the watermark information seed w to 1, and set the other chaotic values ​​to 0, and get the watermark information is the mth watermark information.

[0049] In one embodiment of the present application, performing XOR operation on the chaotic watermark sequence and the orthogonal random sequence to obtain the spread spectrum watermark sequence includes:

[0050] The Hadamard matrix H is used to iteratively generate two mutually orthogonal sequences c1 and c2 of length l, two Wlash sequences, and the sequence length is l = 2 r , c i =[c1,c2,...,c i ],c i ∈{-1,1}.

[0051] The recursive relationship of the Hadamard matrix is ​​as follows:

[0052]

[0053] Take H r Any two columns or any two rows are used as c1 and c2 to form two Wlash sequences with sequence lengths of l and c. i =[c1,c2,...,c i ],c i ∈{-1,1}.

[0054] Initialize the Hadamard matrix H1 and set the sequence length of the two mutually orthogonal sequences to l = 2 r .

[0055]

[0056] According to l = 2 r , get the r value, and generate H through the Hadamard matrix recursion relationship r for:

[0057]

[0058] Take H3 as an example:

[0059]

[0060] According to any two columns or any two rows, as c1 and c2, two Wlash sequences are formed, and the sequence length is l and c i =[c1,c2,...,c i ],c i ∈{-1,1}, taking H3 as an example, by splitting each row or column of the matrix, 8 Wlash sequences of length 8 can be obtained, and the two sequences have high autocorrelation and low cross-correlation.

[0061] The watermark information w is directly spread by using the two orthogonal sequences c1 and c2 to obtain the spread spectrum watermark sequence w = {w 22 (i)},w 22 (i)∈{0,1}:

[0062]

[0063] in, Represents the direct sequence spread spectrum process. The watermark information before watermark spread is w 21 (t), the signal after watermark information spread is w 22 (i).

[0064] Retrieve the watermark information w(i), where i represents the symbol position in the sequence. When w(i) = 0, use c1 to spread the watermark information bit 0. Continue to spread the sequence in sequence until all watermark information is spread;

[0065] Retrieve watermark information w(i), where i represents the symbol position in the sequence. When w(i) = 1, use c2 to spread the watermark information bit 1. Continue to spread the sequence in sequence until all watermark information is spread.

[0066] All the spread spectrum sequences obtained by retrieving the watermark information w(i) form a spread spectrum watermark sequence w" = {w 22 (i)},w 22 (i)∈{0,1}.

[0067] In one embodiment of the present application, for the spread spectrum watermark sequence w″={w 22 (i)},w 22 (i)∈{0,1} shaping filter to form a transmission waveform, which is then modulated by the carrier and linearly superimposed with the baseband signal s to form the final transmission signal r:

[0068] r=s+ρw

[0069] Among them, ρ represents the watermark embedding amplitude coefficient. Considering that the length of the original carrier is longer than the watermark information, the watermark linear superposition start position is actually selected in the middle of the original carrier information data. Assuming the length of the original carrier data is l1 and the length of the watermark information is l2, the watermark linear superposition start position is:

[0070]

[0071] According to the original carrier data length l1 and the watermark information length l2, the watermark linear superposition start bit l3 is initialized and the watermark embedding amplitude coefficient ρ.

[0072] The spread spectrum watermark sequence is linearly superimposed and embedded with the original carrier through shaping filter and carrier modulation to generate the r transmission signal.

[0073] In one embodiment of the present application, after receiving the unknown signal r, the legal receiver performs carrier demodulation, matched filtering, and then watermark detection. If the watermark detection is passed, it is judged as a legal transmitter, and the watermark is further extracted and removed, and then sampling judgment, demapping and restoration of the baseband signal are performed. Otherwise, the authentication fails and the reception is terminated.

[0074] In one embodiment of the present application, the legitimate receiver first demodulates the carrier of the received signal r, and then performs matched filtering to complete the preprocessing of the received signal. The correlation coefficients of the segments are calculated with c1 and c2 respectively, and the watermark information is extracted according to the size of the correlation coefficients. The legal receiver initializes the watermark similarity threshold detection threshold η2 and pre-processes the signal Perform watermark detection process, when preprocessing signal When the watermarked signal is transmitted by the legitimate transmitter, the legitimate receiver obtains the watermark information of the receiving end through correlation detection. At this time, the watermark similarity is greater than the threshold η2; when the preprocessed signal When the signal transmitted by the illegal transmitter does not contain a watermark, the legal receiver extracts the watermark information through correlation detection, and the watermark similarity is less than the threshold η2. The legal receiver removes the watermark of the signal of the legal transmitter that has passed the authentication and demodulates the communication normally, and refuses to receive the signal that has not passed the authentication.

[0075] The present invention performs secure identity authentication on both parties of legitimate communication, generates unique watermark information through chaotic sequence, and directly spreads the specific watermark sequence through two specific mutually orthogonal sequences, so that the watermark has robustness, and then embeds the signal modulated by the original signal carrier through linear superposition, so that the embedding of the watermark does not affect the availability of the carrier signal. In other words, in a complex electromagnetic environment with interference and malicious attacks, the legitimate parties can achieve identity authentication through the carrier watermark information, thereby preventing malicious deception attacks and completing covert communication.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A linear superposition carrier chaotic watermark communication security authentication method, characterized in that: include: The legitimate transmitter performs XOR on the chaotic watermark sequence and the orthogonal random sequence to obtain a spread spectrum watermark sequence. The spread spectrum watermark sequence is formed into a transmission baseband waveform through a shaping filter, which is then carrier modulated and linearly superimposed with the original communication signal sent by the legitimate transmitter to complete the watermark embedding and original communication signal. Both legal transmitters and illegal transmitters send communication signals to legal receivers; The communication signal sent by the legal transmitter contains watermark information, while the communication signal sent by the illegal transmitter does not contain watermark information; The legitimate receiver performs coherent demodulation, matched filtering and watermark detection on the received communication signal to securely authenticate the identity of the unknown transmitter.

2. The method according to claim 1, characterized in that A chaotic watermark sequence is generated under negotiation between two legal communication parties; the two legal communication parties include a legal transmitter and a legal receiver.

3. The method according to claim 1, characterized in that The method for obtaining the chaotic watermark sequence includes: The chaotic system function Tent is used to generate a series of initial watermark information seeds. Based on the initial watermark information seeds, watermark information seeds are generated. A fixed threshold value η1 is set, and the watermark information, i.e., the chaotic watermark sequence, is obtained by comparing each sequence in the watermark information seeds with the fixed threshold value η1.

4. The method according to claim 3, characterized in that Using the chaotic system function Tent, a series of initial watermark information seeds are generated through the following formula: Among them, 0 <a<1,0<x1≤1,x k+1 is the k+1th initial watermark information seed; The obtained watermark information seed w = {w m = x k}, m = 1, 2,..., M, 0 < w m <1 is generated by the chaotic sequence x = {xk}, k = 1, 2,..., M, 0 < xm < 1; w m is the m-th watermark information seed; Set a fixed threshold value η1, that is, set the chaotic value greater than the threshold value η1 in the watermark information seed w to 1, and set the other chaotic values ​​to 0, and get the watermark information is the mth watermark information.

5. The method according to claim 1, characterized in that The method of performing XOR operation on the chaotic watermark sequence and the orthogonal random sequence to obtain a spread spectrum watermark sequence includes: The Hadamard matrix H is used to iteratively generate two mutually orthogonal sequences c1 and c2 of length l and two Wlash sequences, and the length of the Wlash sequence is l = 2 r , c i =[c1,c2,...,c i ],c i ∈{-1,1}; The recursive relationship of the Hadamard matrix is ​​as follows: Select H r Any two columns or any two rows in are taken as c1 and c2; Using two orthogonal sequences c1 and c2 to perform direct sequence spread spectrum on the watermark information w, the spread spectrum watermark sequence w' = {w 22 (i)},w 22 (i)∈{0,1}: in, Represents the direct sequence spread spectrum process. The watermark information before watermark spread is w 21 (i) The signal after watermark information spread is w 22 (i).

6. The method according to claim 5, characterized in that The spread spectrum watermark sequence w' is shaped and filtered to form a transmission baseband waveform. After the transmission baseband waveform is modulated by the carrier, it is linearly superimposed with the original communication signal s to form the final transmission signal r: r=s+ρw Where ρ represents the watermark amplitude coefficient.

7. The method according to claim 6, characterized in that The starting position of the linear superposition of the watermark is located in the middle of the original carrier signal; assuming that the length of the original carrier is l1, the length of the watermark information is l2, the starting position of the linear superposition of the watermark is: Among them, l3 is the starting position of the watermark linear superposition.

8. The method according to claim 1, characterized in that: After the legal receiver receives the unknown signal, it performs carrier demodulation, matched filtering, and then watermark detection. If the watermark detection passes, it is judged as a legal transmitter, the watermark is extracted and removed, and then sampling judgment, demapping and restoration of the baseband signal are performed; otherwise, the authentication fails and the reception is terminated.

9. The method according to claim 8, characterized in that The watermark detection process uses despreading and coherent detection to distinguish the similarity between the watermark information to be tested and the known watermark.

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