Wireless secure transmission method and system based on four-dimensional integer field chaotic system

Abstract

The invention discloses a wireless secure transmission method and system based on a four-dimensional integer domain chaotic system, and belongs to the field of communication, and the method comprises the steps: employing the four-dimensional integer domain chaotic system to obtain chaotic sequences 1-3; an original bit stream is subjected to XOR encryption through a chaos sequence 1, then is mapped into IQ two-path data through scrambling operation, channel coding and 16QAM, is subjected to encryption, up-sampling and cosine raising through chaos sequences 2 and 3, is subjected to up-conversion and then is subjected to radio frequency emission; a receiving end firstly performs down-conversion, symbol synchronization, frame synchronization, frequency offset compensation, phase correction and normalization on received data to obtain encrypted IQ two-path data, the encrypted IQ two-path data are decrypted through chaos sequences 2 and 3, the decrypted IQ two-path data are subjected to 16QAM demodulation, LDPC code removal and scrambling code removal, and then the decrypted IQ two-path data and a chaos sequence 1 are subjected to XOR decryption to recover an original bit stream. The method has high security under the condition that the bit error rate is low, and has high practicability in wireless secure communication.

Description

Technical Field

[0001] The present invention belongs to the field of communication technology, and in particular relates to a wireless secure transmission method and system based on a four-dimensional integer domain chaotic system. Background Art

[0002] With the rapid development of communication technology, wireless communication has become ubiquitous in our daily lives. However, due to the inherent broadcast nature of wireless communication, data transmission is susceptible to eavesdropping. Therefore, ensuring information security and ensuring the safe transmission of confidential information may even be more important than transmission speed.

[0003] Traditional encryption technologies, such as RSA (Rivest–Shamir–Adleman), DES (Data Encryption Standard), and AES (Advanced Encryption Standard), have long been effective. However, with the rapid development of modern computer technology and the continuous improvement of computing power, traditional encryption technologies have become less resilient to brute-force attacks due to their limited key space. Eavesdroppers can analyze and crack passwords through methods such as brute force attacks. Furthermore, in most practical applications, traditional encryption technologies sacrifice significant complexity to improve encryption performance, requiring significant computing power and processing time.

[0004] In recent years, the field of wireless secure communications has seen in-depth research focused on attack resistance and transmission performance. Chaotic systems, due to their random and dynamic properties, have become a core cryptographic tool. Chaotic cryptography is an information security technology based on the characteristics of nonlinear dynamic systems. Its theoretical core stems from chaos theory's description of the behavior of complex systems. Chaotic systems exhibit extreme sensitivity to initial conditions, long-term unpredictable trajectories, and inherent pseudo-randomness. These characteristics are highly consistent with cryptographic requirements for key sensitivity, plaintext obfuscation, and algorithmic irreversibility. In cryptographic applications, the deterministic equations of chaotic systems can generate complex nonlinear sequences through parameter manipulation. Their ergodic and mixing properties allow even small input differences to produce completely different output patterns after iteration. This quasi-random behavior effectively simulates the diffusion and obfuscation mechanisms required by cryptography. Chaotic cryptography overcomes the limitations of traditional cryptography, which relies on difficult mathematical problems, and has the potential to resist analytical and brute-force attacks. Its dynamic characteristics are particularly suitable for real-time data stream encryption.

[0005] Due to the characteristics of strong initial value sensitivity, significant quasi-randomness and complex nonlinear dynamic behavior, encryption technology based on chaotic systems has attracted much attention in the field of information security. Compared with the relatively limited key space of traditional encryption algorithms, chaotic systems can form more than 10 150At present, a large number of literatures have proved that this feature gives it unique advantages in scenarios such as secure communication. For example, the literature (B.Vaseghi, SSHashemi, S.Mobayen, and A.Fekih,"Finite Time Chaos Synchronization in Time-DelayChannel and Its Application to Satellite Image Encryption in OFDMCommunication Systems,"IEEE Access, vol.9, pp.21332-21344, 2021.) proposed a satellite image security communication method based on chaos synchronization, which aims to solve the security and reliability problems in satellite transmission and is suitable for conventional wireless or wired orthogonal frequency division multiplexing systems. The paper (X. Wang, C. Zhang, W. Zeng, and Y. Luo, "Data Center Secure Communication via DNA Hyperchaotic Encryption," Journal of Lightwave Technology, vol. 42, no. 16, pp. 5564-5572, 2024.) proposes a partial encryption scheme for satellite images based on dynamic chaotic isomorphic elliptic curves. The encryption and decryption speed is superior to existing schemes and is suitable for real-time satellite transmission. The paper (Y. Zhang, N. Jiang, S. Liu, A. Zhao, J. Peng, and K. Qiu, "Physical Layer Security Encryption in CO-OFDM based on Chaotic 3D Constellation Scrambling," 2021 Asia Communications and Photonics Conference (ACP), Shanghai, China, 2021, pp. 1-3.) proposes a three-step encryption strategy based on a five-dimensional hybrid hyperchaotic system and a novel three-dimensional regular hexagonal signal constellation. This strategy enhances security while improving transmission performance, providing a new solution for secure transmission. Although chaotic encryption technology provides a new solution for the field of information security due to its characteristics such as initial value sensitivity, pseudo-randomness and complex dynamic behavior, most of the current research on chaotic encryption technology is based on software simulation.When traditional chaotic systems are deployed on FPGA hardware platforms, the limited computational precision of digital devices causes the continuous state space of real-domain chaotic mapping to be discretized and truncated, leading to dynamic degradation in the iterative process. This is manifested in characteristics such as a sudden decrease in cycle length, uneven state distribution, and ergodic failure. This degradation not only violates the core definition of infinite aperiodicity in chaos theory but also significantly weakens the security of chaotic systems in scenarios such as secure communications. Summary of the Invention

[0006] To address the challenges of the existing technology, the present invention provides a wireless secure transmission method and system based on a four-dimensional integer domain chaotic system. Inspired by the relevant theories of integer domain chaos, the present invention utilizes a four-dimensional integer domain chaotic system to generate a key. A 16QAM transmit / receive module is built based on the AD9361+ZYNQ platform, and the key generated by the four-dimensional integer domain chaotic system is used to encrypt the signal. Analysis and field testing have verified that the present invention achieves high security while maintaining a low bit error rate, demonstrating its practicality in wireless secure communications.

[0007] The technical solutions adopted by the present invention to solve the technical problems are as follows:

[0008] The present invention provides a wireless secure transmission method based on a four-dimensional integer domain chaotic system, which specifically includes the following steps:

[0009] A four-dimensional integer domain chaotic system is used to obtain chaotic sequences 1-3. At the transmitting end, the original bit stream is first subjected to an XOR encryption operation by chaotic sequence 1, and then a scrambling operation and channel coding are performed. The encoded data is mapped into I and Q data through 16QAM, and then subjected to amplitude and phase encryption operations by chaotic sequences 2 and 3. After that, filtered data is obtained through upsampling and raised cosine, and then transmitted through radio frequency after up-conversion. At the receiving end, the received data is first subjected to down-conversion, symbol synchronization and frame synchronization, frequency offset compensation, phase correction, and normalization to obtain encrypted I and Q data. Then, it is decrypted by chaotic sequences 2 and 3. The decrypted I and Q data are subjected to 16QAM demodulation, LDPC code decoding, and scrambling, and then an XOR decryption operation is performed with chaotic sequence 1 to restore the original bit stream.

[0010] Furthermore, the iterative equation of the four-dimensional integer domain chaotic system is:

[0011]

[0012] Among them, the symbol · represents the bitwise AND, the symbol + represents the bitwise OR, and the symbol Represents bitwise exclusive OR; x nThe state variable value of the x sequence of the chaotic system at discrete time index n is the state of the x sequence at the current iteration step; x n-1 The state variable value representing the system's x sequence at discrete time index n-1 is the state of the x sequence at the previous iteration step; Represents the variable x n-1 Bitwise inversion; y n The state variable value of the y sequence of the chaotic system at discrete time index n is the state of the y sequence at the current iteration step; y n-1 The state variable value of the system's y sequence at discrete time index n-1 is the state of the y sequence in the previous iteration step; z n The state variable value of the z sequence of the chaotic system at discrete time index n is the state of the z sequence at the current iteration step; z n-1 The state variable value representing the system's z-sequence at discrete time index n-1 is the state of the z-sequence at the previous iteration step; Represents the variable z n-1 Bitwise inversion; t n The state variable value of the t sequence of the chaotic system at discrete time index n is the state of the t sequence at the current iteration step; t n-1 The state variable value representing the system's t sequence at discrete time index n-1 is the state of the t sequence at the previous iteration step; Represents the variable t n-1 Bitwise inversion; R n 、S n 、U n 、V n are pseudo-random sequences generated by m-sequences. Represents the variable R n Bitwise inversion, Represents the variable S n Bitwise inversion, Represents the variable U n Bitwise inversion, Represents the variable V n Bitwise inversion.

[0013] Furthermore, there are 3 groups of 12 key initial values ​​at the transmitting end and the receiving end respectively, and 12 key sequences are generated according to the key initial values, which are x n1 、y n1 、z n1 , t n1 、x n2 、y n2 、z n2 , t n2 、x n3 、y n3 、z n3 , tn3 ; Perform truncation and XOR operation on these 12 key sequences to obtain chaotic sequences 1-3.

[0014] Furthermore, the initial values ​​of the 12 keys are all 50-bit unsigned numbers in the range [0,2 50 -1]; When the initial key value is changed by 1 at random, the generated key sequence is completely different. The total key space of these 12 initial key values ​​is (2 50 ) 12 ≈4.15×10 180 .

[0015] Furthermore, the key sequence x n1 、y n1 、z n1 , t n1 The 50 bits of the key sequence x1, y1, z1, t1 are XORed together to generate the corresponding key sequence x1, y1, z1, t1; the key sequence x1, y1, z1, t1 is XORed bit by bit to obtain the chaotic sequence 1.

[0016] Furthermore, the key sequence x n2 、y n2 、z n2 , t n2 The 50 bits of the digits are XORed for every 10 bits in a group, and the four 5-bit numbers generated are XORed for each bit to form a 5-bit key, which is called chaotic sequence 2.

[0017] Furthermore, the key sequence x n3 、y n3 、z n3 , t n3 The 50 bits of the digits are XORed for every 10 bits in a group, and the four 5-bit numbers generated are XORed bit by bit to form a 5-bit key, which is called chaotic sequence 3.

[0018] Furthermore, the mathematical expression of the XOR encryption operation is:

[0019]

[0020] Among them, bit out Indicates the XOR encrypted data, bit in Represents the original bit stream data, key xor Represents chaotic sequence 1, symbol Represents bitwise exclusive OR.

[0021] Furthermore, the channel coding method is low-density parity-check code.

[0022] Furthermore, the constellation points are encrypted according to the chaotic sequence 2 and the chaotic sequence 3. The equation of the constellation points is: C=I+jQ; the equation of the encrypted constellation points is: C'=[I+key i ]+j[Q+key q ]; where I represents the amplitude of the in-phase component of the signal, j represents the imaginary unit, Q represents the amplitude of the quadrature component of the signal, and key i represents the chaotic sequence 2 used for I-way encryption, key q Represents the chaotic sequence 3 used for Q-path encryption.

[0023] The present invention provides a wireless secure transmission system based on a four-dimensional integer domain chaotic system, which is used to implement the wireless secure transmission method based on a four-dimensional integer domain chaotic system. The system is deployed on an AD9361+ZYNQ platform. The hardware architecture of the AD9361+ZYNQ platform includes a radio frequency part and a digital part. The radio frequency part is centered on the AD9361 and the radio frequency front end and is used for signal reception and transmission conversion. The digital part is centered on a ZYNQ processor and a clock management module. The ZYNQ processor integrates programmable logic and a processing system. The programmable logic part is used to implement 16QAM modulation and demodulation and signal processing functions. The processing system is used to implement high-level protocol processing and management tasks.

[0024] The beneficial effects of the present invention are:

[0025] 1. The present invention adopts a four-dimensional integer domain chaotic system to obtain a chaotic sequence, solving the problem of performance degradation caused by precision loss in the hardware system of the existing chaotic system.

[0026] 2. The present invention uses a four-dimensional integer domain chaotic system to generate keys and implements encrypted transmission of 16QAM signals in hardware boards, with low encryption complexity and extremely large key space.

[0027] 3. Through analysis, it is concluded that the key space of the present invention is 10 180 Order of magnitude.

[0028] 4. The actual test of the board card shows that the system can realize the safe transmission algorithm and has a low bit error rate. The bit error rate of normal transmission is 10 -9 The order of magnitude, while the error rate of abnormal reception is between 0.4 and 0.5, which fully proves that the present invention has strong practicality and good wireless security transmission performance in wireless security communication. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 These are chaotic sequence images. In the figure, (a) x sequence; (b) y sequence; (c) z sequence; (d) t sequence.

[0030] Figure 2 This is the flow chart of the transmitter.

[0031] Figure 3 This is the flow chart of the receiving end.

[0032] Figure 4 Chaotic sequence diagram generated for different initial key values.

[0033] Figure 5 It is the encrypted signal constellation diagram.

[0034] Figure 6 This is the structural block diagram of the AD9361+ZYNQ platform. DETAILED DESCRIPTION

[0035] The present invention is further described in detail below with reference to the accompanying drawings.

[0036] In a first aspect, the present invention provides a wireless secure transmission method based on a four-dimensional integer domain chaotic system.

[0037] The present invention provides a wireless secure transmission method based on a four-dimensional integer domain chaotic system, and its specific implementation process is as follows:

[0038] Step S1: construct a four-dimensional integer domain chaotic system;

[0039] The present invention adopts a four-dimensional integer domain chaotic system, and its iterative equation is expressed as follows:

[0040]

[0041] Among them, the symbol "·" represents the bitwise AND, the symbol "+" represents the bitwise OR, and the symbol Represents bitwise exclusive OR; x n The state variable value of the x sequence of the chaotic system at discrete time index n is the state of the x sequence at the current iteration step; x n -1 The state variable value representing the system's x sequence at discrete time index n-1 is the state of the x sequence at the previous iteration step; Represents the variable x n-1 Bitwise inversion; y n The state variable value of the y sequence of the chaotic system at discrete time index n is the state of the y sequence at the current iteration step; y n-1 The state variable value of the system's y sequence at discrete time index n-1 is the state of the y sequence in the previous iteration step; z n The state variable value of the z sequence of the chaotic system at discrete time index n is the state of the z sequence at the current iteration step; z n-1The state variable value representing the system's z-sequence at discrete time index n-1 is the state of the z-sequence at the previous iteration step; Represents the variable z n-1 Bitwise inversion; t n The state variable value of the t sequence of the chaotic system at discrete time index n is the state of the t sequence at the current iteration step; t n-1 The state variable value representing the system's t sequence at discrete time index n-1 is the state of the t sequence at the previous iteration step; Represents the variable t n-1 Bitwise inversion; R n 、S n 、U n 、V n are pseudo-random sequences generated by m-sequences. Represents the variable R n Bitwise inversion, Represents the variable S n Bitwise inversion, Represents the variable U n Bitwise inversion, Represents the variable V n Bitwise inversion.

[0042] Step S2: Obtaining a chaotic sequence;

[0043] There are 3 groups of 12 key initial values ​​at the transmitting end and the receiving end respectively. According to these key initial values, 3 groups of 12 key sequences are generated, which are x, n1 、y n1 、z n1 、y n1 and x for IQ encryption operations n2 、y n2 、z n2 , t n2 、x n3 、y n3 、z n3 , t n3 .

[0044] Each key sequence is 50 bits wide in the FPGA (Field-Programmable Gate Array). Due to the different bit widths required for encryption operations, these 12 key sequences are truncated and XORed.

[0045] Specifically, the key sequence x n1 The 50 bits of XOR are combined to generate a key sequence x1. Similarly, the key sequence y n1 The 50 bits of the key sequence z are XORed together to generate a key sequence y1.n1 The 50 bits of the key sequence z1 are XORed together to generate a key sequence z1. n1 The 50 bits of the key sequence x1, y1, z1 and t1 are XORed together to generate a key sequence t1; finally, the key sequence x1, y1, z1 and t1 are XORed bit by bit to obtain the chaotic sequence 1, which is used to perform XOR encryption operation on the original bit stream data.

[0046] The mathematical expression of this process is as follows:

[0047]

[0048] Among them, key xor Represents chaotic sequence 1.

[0049] Specifically, the key sequence x n2 Each 10 bits of the 50 bits are XORed as a group, and a total of five groups generate 5 bits. Similarly, the key sequence y n2 The 50 bits of the key sequence z are XORed for every 10 bits in a group, and a total of five groups generate 5 bits. n2 The 50 bits of the key sequence are XORed every 10 bits into a group, and a total of five groups generate 5 bits. n2 The 50 bits of the 50 bits are XORed in groups of 10, with a total of five groups generating 5 bits. Finally, the four 5-bit numbers generated above are XORed in bitwise order to form a 5-bit key, called chaotic sequence 2, which is used to encrypt the data amplitude and phase.

[0050] Similarly, according to the above operation, the key sequence x n3 The 50 bits of the key sequence y are XORed for every 10 bits in a group, and a total of five groups generate 5 bits. n3 The 50 bits of the key sequence z are XORed for every 10 bits in a group, and a total of five groups generate 5 bits. n3 The 50 bits of the key sequence are XORed every 10 bits into a group, and a total of five groups generate 5 bits. n3 The 50 bits of the 50 bits are XORed for every 10 bits in a group, and a total of five groups generate 5 bits. Finally, the four 5-bit numbers generated above are XORed bitwise to form a 5-bit key, called chaotic sequence 3, which is used to encrypt the data amplitude and phase.

[0051] The mathematical expression of this process is as follows:

[0052]

[0053] Among them, key i,q [4:0] represents the 5-bit key chaotic sequence 2 and chaotic sequence 3; x 2,3[4:0] represents the key sequence x n2 and key sequence x n3 The generated 5 bits, y 2,3 [4:0] represents the key sequence y n2 and key sequence y n3 Generated 5bit, z 2,3 [4:0] represents the key sequence z n2 and key sequence z n3 The generated 5 bits, t 2,3 [4:0] represents the key sequence t n2 and key sequence t n3 The generated 5 bits.

[0054] The four-dimensional chaotic sequence obtained by the present invention has chaotic characteristics and can be used for encryption operations. Figure 1 (n represents the iteration index, x(n) represents the state of the x sequence when the index is n, y(n) represents the state of the y sequence when the index is n; z(n) represents the state of the z sequence when the index is n; t(n) represents the state of the t sequence when the index is n).

[0055] In the present invention, the initial values ​​of the 12 keys of the chaotic system are all 50-bit unsigned numbers, that is, the range is 0, 2 50 -1]. When the initial key value is changed by 1, the generated key sequence is completely different, so the total key space of these 12 initial key value parameters is (2 50 ) 12 ≈4.15×10 180 .

[0056] The chaotic sequences generated by different initial key values ​​are as follows: Figure 4 As shown in the figure, x1 and x2 are different key sequences with the initial key value differing by only 1. It can be seen that when the initial key value changes, the generated key sequences are completely different.

[0057] In this paper, 12 key sequences were subjected to a comprehensive set of randomness statistical tests to ensure their sufficient randomness and statistical properties. NIST testing covered 15 core indicators, and all test items passed. The results showed that all p-values ​​were greater than 0.01, indicating that the key sequences exhibited excellent statistical randomness characteristics, with a uniform binary distribution and no significant discernible patterns, fully meeting the strict security requirements for key materials in cryptographic applications. This systematic verification confirmed that the key generation mechanism meets the randomness quality standards and is capable of resisting statistical attacks.

[0058] Step S3: encryption operation;

[0059] like Figure 2As shown, first, chaotic sequence 1 is used to perform XOR encryption operation on the original bit stream data.

[0060] The mathematical expression of this process is as follows:

[0061]

[0062] Among them, bit out Indicates the XOR encrypted data, bit in Represents raw bitstream data.

[0063] Then, the XOR-encrypted data is scrambled and channel-coded using a low-density parity-check code (LDPC) with an encoding scheme of (8160, 7136). The coded data is then mapped into I and Q data using 16QAM.

[0064] Finally, the amplitude and phase of the I-channel data are encrypted using chaotic sequence 2, and the amplitude and phase of the Q-channel data are encrypted using chaotic sequence 3.

[0065] Step S4: encrypting constellation points;

[0066] In the present invention, the constellation points are defined as follows:

[0067] C=I+jQ (5)

[0068] According to the extracted chaotic sequence 2 and chaotic sequence 3, the encrypted constellation points are:

[0069] C'=[I+key i ]+j[Q+key q ] (6)

[0070] Among them, C' represents the encrypted constellation point, I represents the amplitude of the in-phase component of the signal, j represents the imaginary unit, Q represents the amplitude of the orthogonal component of the signal, key i represents the chaotic sequence 2 used for I-way encryption, key q Represents the chaotic sequence 3 used for Q-path encryption.

[0071] The encrypted signal constellation diagram is as follows Figure 5As shown. The image is converted into bit stream data for transmission, and the original image and the encrypted image show significant differences in multiple indicators. The variance of the encrypted data histogram is orders of magnitude lower than that of the original data, indicating that the pixel value distribution tends to be uniformly discrete from a high concentration, which is consistent with the characteristics of the ideal encryption algorithm to eliminate statistical preferences. The correlation coefficients in the horizontal, vertical and diagonal dimensions all drop sharply from a strong correlation state close to 1 to a value close to 0, reflecting that the encryption process effectively breaks the spatial correlation between adjacent pixels, making the encrypted data present a non-directional random distribution. The entropy value after encryption approaches the theoretical maximum value, indicating that the information randomness of the encrypted data is close to the ideal state, and the probability of occurrence of each symbol is highly balanced, which significantly improves the uncertainty of the information. Overall, the encrypted image performs well in terms of pixel distribution balance, spatial correlation elimination and information randomness, which shows that the encryption method adopted by the present invention has strong security and resistance to statistical analysis.

[0072] Step S5: filtering and transmitting the encrypted data;

[0073] First, the encrypted data is upsampled and raised cosine operated, and the filtered data is obtained through interpolation filtering;

[0074] Then, after performing an up-conversion operation on the filtered data, the transmitter transmits it to the receiver via radio frequency.

[0075] Step S6: decryption operation;

[0076] After receiving the data, the receiving end performs a decryption operation (the inverse operation of encryption) to restore the original bit stream data.

[0077] Specifically, if Figure 3 As shown in the figure, first, the received data is subjected to down-conversion, symbol synchronization and frame synchronization, frequency offset compensation, phase correction, normalization and other operations in sequence to obtain encrypted I-channel and Q-channel data; then, the I-channel data is decrypted using chaotic sequence 2, and the Q-channel data is decrypted using chaotic sequence 3; then, the decrypted data is demodulated using 16QAM, and the bit stream obtained after 16QAM demodulation is decoded and descrambled, and then the original bit stream data is restored by performing an XOR decryption operation using chaotic sequence 1.

[0078] In the present invention, the frame format uses a 176-bit training sequence for bit synchronization, frame synchronization, frequency and phase correction, amplitude normalization, and signal-to-noise ratio estimation. This is followed by a 510-bit 16QAM signal as the data segment. The bit rate is 15.36 MHz, the symbol rate is 3.84 MHz, and the data rate after interpolation filtering is 30.72 MHz.

[0079] In a second aspect, the present invention provides a wireless secure transmission system based on a four-dimensional integer domain chaotic system, which is used to implement a wireless secure transmission method based on a four-dimensional integer domain chaotic system provided in the first aspect of the present invention.

[0080] The present invention provides a wireless secure transmission system based on a four-dimensional integer domain chaotic system, which mainly includes the following modules:

[0081] The AD9361+ZYNQ platform consists of the RF part and the digital part. Its structural block diagram is as follows Figure 6 shown.

[0082] Specifically, the RF part is centered around the AD9361 (Analog Devices AD9361, RF transceiver chip) and the RF front end, responsible for signal reception and transmission conversion.

[0083] Specifically, the digital part is centered around the ZYNQ (fully programmable system-on-chip) processor and clock management module.

[0084] Among them, the ZYNQ processor integrates programmable logic (PL) and processing system (PS). The programmable logic part mainly implements 16QAM modulation and demodulation and signal processing functions, and the processing system part is mainly responsible for high-level protocol processing and management tasks.

[0085] The present invention proposes a secure wireless transmission system based on a four-dimensional integer domain chaotic system, which can be implemented in a hardware architecture. The hardware architecture utilizes the AD9361+ZYNQ platform, implementing functions such as scrambling, LDPC encoding and decoding, 16QAM modulation and demodulation, encryption and decryption, and radio frequency transmission and reception. The transmitter encrypts and transmits information such as text and images, which the receiver can correctly receive and decrypt.

[0086] The present invention uses Xilinx board xc7z035ffv676-2 to carry out performance test. During the test, a thousand pictures are sent cyclically at the transmitting end, and the calculated bit error rate is less than 10 -9 If the receiving end does not decrypt or uses the wrong key to decrypt, each image will be garbled, with a bit error rate of about 44%, indicating that no valid information can be recovered. The above tests show that the present invention has strong practicality and good wireless security transmission performance in wireless secure communication.

[0087] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A wireless secure transmission method based on a four-dimensional integer domain chaotic system, characterized in that: The following steps are involved: The chaotic sequences 1-3 are obtained using a four-dimensional integer domain chaotic system; At the transmitting end, the original bit stream is first subjected to an XOR encryption operation using chaotic sequence 1, followed by a scrambling operation and channel coding. The encoded data is mapped into I and Q data using 16QAM, and then subjected to amplitude and phase encryption operations using chaotic sequences 2 and 3. The filtered data is obtained through upsampling and raised cosine, and then transmitted through RF after upconversion. At the receiving end, the received data is first subjected to downconversion, symbol synchronization and frame synchronization, frequency offset compensation, phase correction, and normalization to obtain the encrypted I and Q data. The data is then decrypted using chaotic sequences 2 and 3, and the decrypted I and Q data are subjected to 16QAM demodulation, LDPC code decoding, and descrambling, and then XOR decryption operation with chaotic sequence 1 to restore the original bit stream.

2. A wireless secure transmission method based on a four-dimensional integer domain chaotic system according to claim 1, characterized in that: The iterative equation of the four-dimensional integer domain chaotic system is: Among them, the symbol · represents the bitwise AND, the symbol + represents the bitwise OR, and the symbol Represents bitwise exclusive OR; x n The state variable value of the x sequence of the chaotic system at discrete time index n is the state of the x sequence at the current iteration step; x n-1 The state variable value representing the system's x sequence at discrete time index n-1 is the state of the x sequence at the previous iteration step; Represents the variable x n-1 Bitwise inversion; y n The state variable value of the y sequence of the chaotic system at discrete time index n is the state of the y sequence at the current iteration step; y n-1 The state variable value of the system's y sequence at discrete time index n-1 is the state of the y sequence in the previous iteration step; z n The state variable value of the z sequence of the chaotic system at discrete time index n is the state of the z sequence at the current iteration step; z n-1 The state variable value representing the system's z-sequence at discrete time index n-1 is the state of the z-sequence at the previous iteration step; Represents the variable z n-1 Bitwise inversion; t n The state variable value of the t sequence of the chaotic system at discrete time index n is the state of the t sequence at the current iteration step; t n-1 The state variable value representing the system's t sequence at discrete time index n-1 is the state of the t sequence at the previous iteration step; Represents the variable t n-1 Bitwise inversion; R n 、S n 、U n 、V n are pseudo-random sequences generated by m-sequences. Represents the variable R n Bitwise inversion, Represents the variable S n Bitwise inversion, Represents the variable U n Bitwise inversion, Represents the variable V n Bitwise inversion.

3. The wireless secure transmission method based on a four-dimensional integer domain chaotic system according to claim 1 is characterized in that: There are 3 groups of 12 key initial values ​​at the transmitting end and the receiving end respectively. 12 key sequences are generated according to the key initial values, which are x n1 、y n1 、z n1 , t n1 、x n2 、y n2 、z n2 , t n2 、x n3 、y n3 、z n3 , t n3 ; Perform truncation and XOR operations on these 12 key sequences to obtain chaotic sequences 1-3.

4. The wireless secure transmission method based on a four-dimensional integer domain chaotic system according to claim 3 is characterized in that: The initial values ​​of the 12 keys are all 50-bit unsigned numbers in the range [0,2 50 -1]; When the initial key value is changed by 1 at random, the generated key sequence is completely different. The total key space of these 12 initial key values ​​is (2 50 ) 12 ≈4.15×10 180 .

5. The wireless secure transmission method based on a four-dimensional integer domain chaotic system according to claim 3 is characterized in that: The key sequence x n1 、y n1 、z n1 , t n1 The 50 bits of the key sequence x1, y1, z1, t1 are XORed together to generate the corresponding key sequence x1, y1, z1, t1; the key sequence x1, y1, z1, t1 is XORed bitwise to obtain the chaotic sequence 1; the key sequence x n2 、y n2 、z n2 , t n2 The 50 bits of the 50 bits are XORed for every 10 bits in a group, and the four 5-bit numbers are XORed bit by bit to form a 5-bit key, called chaotic sequence 2; the key sequence x n3 、y n3 、z n3 , t n3 The 50 bits of the digits are XORed for every 10 bits in a group, and the four 5-bit numbers generated are XORed bit by bit to form a 5-bit key, which is called chaotic sequence 3.

6. The wireless secure transmission method based on a four-dimensional integer domain chaotic system according to claim 1, characterized in that: The mathematical expression of the XOR encryption operation is: Among them, bit out Indicates the XOR encrypted data, bit in Represents the original bit stream data, key xor Represents chaotic sequence 1, symbol Represents bitwise exclusive OR.

7. The wireless secure transmission method based on a four-dimensional integer domain chaotic system according to claim 1, characterized in that: The channel coding method is low density parity check code.

8. The wireless secure transmission method based on a four-dimensional integer domain chaotic system according to claim 1, characterized in that: The constellation points are encrypted according to the chaotic sequence 2 and the chaotic sequence 3. The equation of the constellation points is: C=I+jQ; the equation of the encrypted constellation points is: C'=[I+key i ]+j[Q+key q ]; where I represents the amplitude of the in-phase component of the signal, j represents the imaginary unit, Q represents the amplitude of the quadrature component of the signal, and key i represents the chaotic sequence 2 used for I-way encryption, key q Represents the chaotic sequence 3 used for Q-path encryption.

9. A wireless secure transmission system based on a four-dimensional integer domain chaotic system, characterized in that: A wireless secure transmission method based on a four-dimensional integer domain chaotic system is used to implement any one of claims 1-8, the system being deployed on an AD9361+ZYNQ platform, the hardware architecture of the AD9361+ZYNQ platform including an RF part and a digital part; the RF part is centered around AD9361 and an RF front end, and is used for signal reception and transmission conversion; the digital part is centered around a ZYNQ processor and a clock management module, the ZYNQ processor integrates programmable logic and a processing system, the programmable logic part is used to implement 16QAM modulation and demodulation and signal processing functions, and the processing system is used to implement high-level protocol processing and management tasks.

Images