Implementation method of communication system based on intelligent metasurface technology and chaotic encryption

Abstract

The invention discloses an implementation method of a communication system based on an intelligent metasurface and chaotic encryption. The implementation method comprises the steps of generating a chaotic sequence, selecting chaotic mapping and generating a highly unpredictable sequence. Key generation: applying the generated chaotic sequence to key generation; the reflection coefficient on the surface of the RIS is adjusted in real time by using a chaos sequence; frequency selection and spectrum expansion: realizing a frequency selection function on the RIS, and combining the frequency selection function with the spectrum expansion of the chaotic signal so as to improve the spectrum efficiency and resist spectrum sensing attack; data encryption: integrating a chaotic encryption module into a communication system to ensure that data is subjected to encryption protection in a transmission process; and data decryption: the receiver decrypts the encrypted data by using the same chaotic sequence (key). According to the method, the communication privacy can be enhanced, so that an eavesdropper is more difficult to obtain useful information. Meanwhile, channel interference is resisted, the communication quality is improved, spectrum resources can be utilized more effectively, and the spectrum efficiency of a communication system is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of data encryption and communication systems, and in particular to a method for realizing a communication system based on intelligent metasurface technology and chaotic encryption. Background Art

[0002] At present, traditional communication systems and data transmission systems face some challenges in terms of privacy protection, spectrum efficiency, anti-interference and security. In wireless communication, since the propagation of signals is limited by the environment and transmission medium, there is a risk of eavesdropping and interference to the communication. At the same time, spectrum resources are limited, and spectrum efficiency and energy efficiency become key issues in optimizing communication systems. As an emerging technology, smart metasurface technology provides more control means for communication systems by regulating the propagation path of electromagnetic waves. However, how to better use this technology to improve the privacy, spectrum efficiency and anti-interference of communication is still a problem that needs to be solved. On the other hand, chaotic encryption, as a very effective encryption method, uses the nonlinearity and unpredictability of chaotic dynamics to provide strong protection for information. However, existing communication systems may face challenges in algorithm complexity, real-time and system performance when integrating chaotic encryption. Therefore, it is necessary to provide a communication system that integrates smart metasurface and chaotic encryption to overcome the various limitations of traditional communication systems and improve the security, efficiency and adaptability of communication. In view of this, how to provide an encryption algorithm with higher security and lower complexity has become a problem that technicians in this field need to solve. Summary of the invention

[0003] The purpose of the present invention is to address the defects and shortcomings of the above-mentioned prior art and provide a method for implementing a communication system based on intelligent metasurface and chaotic encryption. The method can well solve the problem of low security in wireless communication transmission and improve the spectrum efficiency of the communication system.

[0004] The technical solution adopted by the present invention to solve the technical problem is: a method for realizing a communication system based on intelligent metasurface and chaotic encryption, the method comprising the following steps:

[0005] Chaotic sequence generation, selecting chaotic mapping to generate highly unpredictable sequences. The chaotic sequence is obtained by using a cascade chaotic system, connecting multiple chaotic systems in series, with the output of one system serving as the input of another system;

[0006] Key generation, applying the generated chaotic sequence to key generation;

[0007] Design a RIS control mechanism to adjust the reflection coefficient on the RIS surface in real time by using chaotic sequences;

[0008] Frequency selection and spectrum spreading: frequency selection function is implemented on RIS and combined with spectrum spreading of chaotic signals to improve spectrum efficiency and resist spectrum sensing attacks;

[0009] Data encryption, integrating the chaotic encryption module into the communication system to ensure that the data is encrypted and protected during transmission. The encryption method uses a block encryption algorithm to divide the plaintext into blocks of fixed length, and encrypts each block independently, using multiple rounds of iterations, with different key parts used in each round to process the data block;

[0010] Data decryption: The receiver uses the same chaotic sequence (key) to decrypt the encrypted data.

[0011] Furthermore, the cascade chaotic system used in the chaotic sequence generation of the present invention uses a serial hybrid mapping. Since the one-dimensional chaotic mapping is very sensitive to the initial conditions, that is, a small initial change may lead to a huge difference between the system trajectories, and although the chaotic systems exhibit random behaviors, they are actually deterministic systems. In addition, in numerical calculations, one-dimensional chaotic mapping may sometimes be affected by numerical instability and other disadvantages, so a hybrid chaotic mapping is selected. Since the forms of the Logistic mapping and the Tent mapping are very simple, easy to understand and implement, and have obvious nonlinear characteristics, two commonly used one-dimensional chaotic mappings, the Logistic mapping and the Tent mapping, are selected, and their mathematical formulas are respectively

[0012] x n+1 =r*x n *(1-x n )

[0013]

[0014] x n is the output of the mapping at the nth moment, and r is the mapping parameter. The combined mapping has better chaotic dynamics characteristics, thus generating a chaotic sequence with better randomness.

[0015] Furthermore, the RIS control mechanism of the present invention mainly controls the adjustment of RIS parameters through chaotic sequences. The PID control algorithm is a classic feedback control algorithm. The algorithm is relatively simple and has good stability. It is easy to understand and implement. It only involves three basic parameters: proportional, integral and differential terms, making it relatively easy to adjust. Its mathematical formula is

[0016]

[0017] Among them, U(t) is the output of the controller, e(t) is the system error (the difference between the expected value and the actual value), K p ,Ki ,K d are the coefficients of the proportional, integral and differential terms respectively. The parameter proportion K is adjusted by the chaotic sequence p , integral K i , differential term K d , can monitor changes in the communication environment in real time.

[0018] Furthermore, the frequency selection and spectrum expansion of the present invention introduces a frequency selection and spectrum expansion module on the RIS, and realizes selective reflection or refraction of a specific frequency range by adjusting the reflection coefficient. Combined with chaotic signals, the spectrum characteristics of the signal are expanded to improve the spectrum utilization efficiency.

[0019] Among them, the reflection coefficient in RIS refers to the reflection intensity of each unit on the metasurface to the incident signal. Specifically, the reflection coefficient is usually expressed as a complex number, including amplitude and phase. The reflection coefficient in complex form can describe the change of the amplitude and phase of the signal during the reflection process. Each unit on the metasurface has certain electromagnetic properties, and by adjusting these properties, the reflection coefficient can be changed. This can be achieved by adjusting the capacitance, inductance or other parameters in the metasurface unit. By cleverly adjusting the reflection coefficient of each unit on the metasurface, directional reflection or refraction of signals in a specific direction can be achieved. This directionality can be used to optimize communication links or prevent signal interference. One of the advantages of RIS is its adaptability, that is, in different communication scenarios, it can dynamically adjust the reflection coefficient according to real-time communication needs and environmental changes. This adaptability enables RIS to flexibly adapt to diverse communication environments. The reflection coefficient in RIS is a key parameter that controls the reflection of the incident signal by the metasurface, and its adjustment can optimize the communication performance. Therefore, adjusting the reflection coefficient plays an important role in improving signal quality, enhancing the capacity of the system, and improving the performance of the communication link.

[0020] Furthermore, the present invention combines chaotic signals to expand the spectrum characteristics of signals because chaotic sequences have the property of spectrum expansion, that is, their spectrum covers a relatively wide frequency range. This spectrum expansion makes the chaotic signal show complex and irregular changes in the frequency domain, and its spectrum is more dispersed compared with traditional periodic signals. The chaotic sequence not only contains discrete frequency components in frequency, but also its spectrum is continuously distributed. This means that the chaotic signal has a higher component density in the frequency range, presenting a more continuous and dispersed spectrum form.

[0021] The encryption method used for data encryption and decryption is a block encryption algorithm, and its encryption and decryption formula is as follows

[0022]

[0023] R i =L i+1

[0024] represents XOR operation, F represents round function, K i is the i-th round subkey. In this framework, the F function is not required to be reversible, that is, there is no need to ensure the inverse operation of the F function during decryption. Decryption still requires the same iteration and round operation to obtain the original plaintext information. Only when the correct key is used can the plaintext be successfully restored, otherwise the relevant plaintext information cannot be obtained.

[0025] The present invention includes round functions, and introduces obfuscation and diffusion. Obfuscation refers to making the relationship between the input and output of a cryptographic algorithm complex and unpredictable by adding nonlinear operations. The goal of obfuscation is to blur the statistical relationship between plaintext and ciphertext, making it more difficult for attackers to understand the cryptographic system. Diffusion refers to affecting each bit of the output by changing one or more bits of the input, ensuring that a change in a single bit will propagate to most bits of the output. Diffusion helps ensure that a small change in the input will result in a large change in the output, increasing the sensitivity of the cryptographic algorithm.

[0026] Beneficial effects:

[0027] 1. The present invention optimizes the signal transmission path by adjusting the reflection coefficient. The introduction of chaotic encryption increases the system's resistance to external interference, making it more difficult for communication signals to be illegally interfered with and decrypted.

[0028] 2. The present invention can improve the utilization efficiency of the spectrum through the adjustment of RIS frequency selection and spectrum expansion module. The introduction of chaotic sequence makes the signal spectrum wider, further increases the spectrum efficiency, and improves the data transmission rate and system capacity.

[0029] 3. Compared with traditional encryption methods, the introduction of chaotic encryption in the present invention improves the security of communication and prevents a series of potential security threats. The reflection coefficient and position are dynamically adjusted according to the real-time changes in the communication environment, so that the system can better adapt to different communication scenarios and network conditions. The use of RIS frequency selection and spectrum expansion modules, as well as the introduction of chaotic encryption, effectively resist spectrum sensing attacks. It is difficult for attackers to accurately perceive and interfere with the communication spectrum of the system, which improves the system's ability to resist spectrum attacks. The chaotic sequence in chaotic encryption can be used to generate dynamic keys, increasing the system's resistance to cryptanalysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly explain the technical solutions in the embodiments of the present invention, the following briefly introduces the prior art and the illustrations required for the embodiments. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained according to the following drawings without creative work.

[0031] Figure 1 It is a flow chart of a communication system based on intelligent metasurface technology and chaotic encryption provided by an embodiment of the present invention.

[0032] Figure 2 It is a schematic diagram of a RIS control mechanism process provided by an embodiment of the present invention.

[0033] Figure 3 The present invention is a schematic diagram of a chaotic signal spectrum expansion process provided by an embodiment of the present invention.

[0034] Figure 4 It is a schematic diagram of the structure of a block encryption algorithm provided by an embodiment of the present invention.

[0035] Figure 5 It is a schematic diagram of the internal structure of a round function provided by an embodiment of the present invention.

[0036] Figure 6 It is a schematic diagram of a decryption structure of a corresponding encryption algorithm provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0037] The present invention is described in detail below in conjunction with specific implementation modes.

[0038] like Figure 1 As shown, the present invention provides a communication system based on intelligent metasurface technology and chaotic encryption, the method comprising:

[0039] 1. Chaotic sequence generation, using cascade chaotic mapping at the transmitting end of the communication system

[0040] It should be noted that in the embodiment of the present invention, the output x mapped at the nth moment is first selected. n , the mapping parameter is r, and the following mapping is used

[0041] x n+1 =r*x n *(1-x n )

[0042]

[0043] The above two maps are combined to form a cascade chaotic map, and the output of the first chaotic map serves as the input of the second chaotic map.

[0044] The kinetic equation can be written as: n+1 =f(g(y n ))

[0045] f is the first mapping, g is the second mapping, y is n It is the output of the entire cascade chaotic system at the nth moment.

[0046] 2. Key Generation

[0047] Specifically, Ki = partial chaotic sequence

[0048] 3. Design RIS control mechanism: Use chaotic sequence as synchronization signal to ensure the synchronization between the adaptive adjustment process of RIS and the sending and receiving ends.

[0049] Specifically, the chaotic sequence generated in the first step is embedded into the communication signal to ensure that the synchronization signal is synchronized with the communication signal to the receiving end during transmission. Correspondingly, at the receiving end of the communication system, the same chaotic generator parameters are used to generate a chaotic sequence, which will be used to adjust the RIS of the synchronous receiving end.

[0050] Furthermore, while the chaotic sequence is being generated and synchronized, the RIS is adaptively adjusted.

[0051] Specifically, the following control algorithm is used, which can adjust the parameters of RIS according to the value of the chaotic sequence and the result of communication environment monitoring, wherein the value of the chaotic sequence is used to adjust the proportional, integral and differential terms to more accurately control the change of the parameters.

[0052]

[0053] Among them, U(t) is the output of the controller, e(t) is the system error (the difference between the expected value and the actual value), K p ,K i ,K d are the coefficients of the proportional, integral, and differential terms respectively.

[0054] How it works: Measure the error, calculate the output using the above formula, apply the output, and repeat the feedback loop.

[0055] In one possible implementation of the above embodiment, assuming that the RIS has multiple units, each unit has an adjustable reflection coefficient, a mapping function is defined so that a positive value of the chaotic sequence corresponds to an increase in the reflection coefficient, and a negative value corresponds to a decrease in the reflection coefficient.

[0056] Specific steps are as follows Figure 2

[0057] 4. Frequency selection and spectrum expansion

[0058] The frequency selection function is implemented on RIS by adjusting the parameters of the metasurface to make it reflect or refract signals in a specific frequency range.

[0059] Specifically, a large number of adjustable reflection units are deployed on the RIS. By adjusting the capacitance values ​​of these units, signals of different frequencies can be reflected or refracted.

[0060] Furthermore, the signal generated by the chaotic sequence has a wide spectrum characteristic. Combining the chaotic signal with the traditional signal can expand the spectrum of the signal in the frequency domain and increase the utilization efficiency of the spectrum.

[0061] Specifically, the chaotic sequence is mixed with the digital signal by performing bit-by-bit XOR with the chaotic sequence. This step can be performed in the baseband part of the digital signal or other parts where the spectrum needs to be extended. Then, according to the requirements of the system design and the characteristics of the communication signal, a modulation technique such as amplitude modulation (AM), frequency modulation (FM) or phase modulation (PM) is applied to the mixed signal. The purpose of the modulation is to embed the chaotic sequence into the signal and ensure that the spectrum of the chaotic signal is extended. The signal generated by the chaotic signal modulation module is then merged with the original signal by simple superposition to ensure that the chaotic signal does not cause serious distortion to the original information. Finally, the chaotic modulated signal is output. This signal will contain a combination of the original signal and the chaotic sequence, and has an extended spectrum characteristic.

[0062] Specific steps are as follows Figure 3

[0063] 5. Data encryption, using block encryption algorithm

[0064] The packet length is a key parameter in the encryption algorithm, which directly affects the security and operating efficiency of the algorithm. Generally, the longer the packet length, the higher the security of the encryption algorithm, but it will also cause the algorithm to run slower. In the embodiment of the present invention, 32 bits are selected as the packet length of the encryption algorithm.

[0065] Specifically, the encryption algorithm uses the Feistel structure to divide the data into 16-bit blocks for operation. Inside the round function, the 16-bit data is further divided into 8-bit data for operation. Therefore, a 32-bit block length is used in the design to balance security and operation efficiency, while better adapting to the special needs of embedded processors.

[0066] In the encryption algorithm, the key length is another key parameter, which is directly related to the security and running speed of the algorithm. Generally speaking, the longer the key, the higher the security of the encryption algorithm, but it will also have a greater impact on the running speed of the algorithm. Therefore, in the embodiment of the present invention, in order to ensure the high security of the encryption algorithm, 128 bits are selected as the key length. Such a design is intended to balance the relationship between security and running efficiency, to meet the recommendations of current security standards, and to ensure that the encryption algorithm has sufficient anti-attack performance in practical applications.

[0067] Furthermore, each group of plaintext is divided into two parts, L0 and R0, where R0 and the key K are passed as parameters to the round function F, and the result of the F function is XORed with the other part of the plaintext L0 to obtain R1, and L1 is assigned to R0, that is, for each round

[0068] L i+1 =R i

[0069]

[0070] After n rounds of operations, the ciphertext (R n+1 ,L n+1 ).

[0071] represents XOR operation, F represents round function, K i is the i-th round subkey.

[0072] The encryption process is as follows Figure 4 shown.

[0073] The design of the round function is crucial to the security of the entire cryptographic system. The following is the design of the round function of the embodiment of the present invention:

[0074] Specifically, the input of the round function F is 16 bits of data, which is divided into two parts, each of which is 8 bits. The right half is added modulo 2^8 with the subkey K i2 The left half is combined with the subkey K i1 Then, the XOR operation is performed on the XOR result and the intermediate result of the right half again. In order to enhance the obfuscation effect, the left and right parts of the data are shifted 3 bits to the left and 5 bits to the right respectively after the S-box table lookup operation, and then XOR calculation is performed. Then, the left half of the data is XORed with the subkey K i3 Perform a modulo 2^8 addition operation, and the right half of the data is sequentially combined with the subkey K i4 XOR operation is performed with the intermediate result of the left half.

[0075] Furthermore, a P-box is introduced. The main purpose of the P-box is to improve the overall security through diffusion. In the embodiments of the present invention, a conventional P-box architecture is adopted. The input is 16-bit data after confusion processing, and the output is 16-bit data with the order scrambled. For example, S1 is located at the position of S14 after permutation, and S2 is located at the position of S11 after permutation. In implementation, we only need to perform simple position replacement, with a low algorithm complexity and simple and rapid operation.

[0076] The internal structure of the round function is as Figure 5 , The symbol represents the exclusive OR operation, The symbol represents the modulo 2^8 addition operation, K i1 ,K i2 ,K i3 , K i4 is the i-th round sub-key generated by the key expansion algorithm, <<<n represents a circular left shift of n bits.

[0077] 6. Data decryption, perform the entire encryption operation in reverse order.

[0078] Specifically, the data decryption is the reverse of the data encryption steps and uses the same key, that is, for each round there is

[0079]

[0080] Ri = L i+1

[0081] After n rounds of operations, the plaintext (L0, R0) can be obtained.

[0082] The decryption process is as Figure 5 shown.

[0083] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for implementing a communication system based on intelligent metasurface technology and chaotic encryption, characterized in that: The following steps are involved: Chaotic sequence generation, selecting chaotic mapping to generate highly unpredictable sequences, wherein the chaotic sequence is obtained by using a cascade chaotic system, which connects multiple chaotic systems in series, with the output of one system serving as the input of another system; Key generation, applying the generated chaotic sequence to key generation; Design a RIS control mechanism to adjust the reflection coefficient on the RIS surface in real time by using chaotic sequences; Frequency selection and spectrum spreading: frequency selection function is implemented on RIS and combined with spectrum spreading of chaotic signals to improve spectrum efficiency and resist spectrum sensing attacks; Data encryption, integrating the chaotic encryption module into the communication system to ensure that the data is encrypted and protected during transmission. The encryption method uses a block encryption algorithm to divide the plaintext into blocks of fixed length and encrypt each block independently. It adopts a multi-round iteration method, and each round uses a different key part to process the data block; Data decryption: The receiver uses the same chaotic sequence (key) to decrypt the encrypted data.

2. According to claim 1, a method for implementing a communication system based on intelligent metasurface technology and chaotic encryption is characterized in that: A series hybrid map is used. Since the one-dimensional chaotic map is very sensitive to the initial conditions, that is, a small initial change may lead to a huge difference between the system trajectories, and although chaotic systems exhibit random behavior, they are actually deterministic systems. In addition, in numerical calculations, one-dimensional chaotic maps may sometimes be affected by numerical instability and other shortcomings. Therefore, a hybrid chaotic map is selected. Since the forms of the Logistic map and the Tent map are very simple, easy to understand and implement, and have obvious nonlinear characteristics, two commonly used one-dimensional chaotic maps are selected: the Logistic map and the Tent map. Their mathematical formulas are respectively x n+1 =r*x n *(1-x n ) x n is the output of the mapping at the nth moment, x n+1 is the output of the mapping at the n+1th moment, r is the mapping parameter, and the combined mapping has better chaotic dynamic characteristics, thereby generating a chaotic sequence with better randomness.

3. The method for implementing a communication system based on intelligent metasurface technology and chaotic encryption according to claim 1 is characterized in that: The RIS control mechanism is to control the RIS parameter adjustment through a chaotic sequence. The PID control algorithm is a classic feedback control algorithm. The algorithm is relatively simple and has good stability. It is easy to understand and implement. It only involves three basic parameters: proportional, integral and differential terms, making the adjustment relatively easy. Its mathematical formula is: Among them, U(t) is the output of the controller, e(t) is the system error (the difference between the expected value and the actual value), K p ,K i ,K d are the coefficients of the proportional, integral and differential terms respectively. The parameter ratio K is adjusted by the chaotic sequence. p , integral K i , differential term K d , can monitor changes in the communication environment in real time.

4. The method for implementing a communication system based on intelligent metasurface technology and chaotic encryption according to claim 1, characterized in that: The frequency selection and spectrum expansion module is introduced on the RIS to achieve selective reflection or refraction of a specific frequency range by adjusting the reflection coefficient, and the spectrum characteristics of the signal are expanded by combining the chaotic signal to improve the spectrum utilization efficiency; Among them, the reflection coefficient in RIS refers to the reflection intensity of each unit on the metasurface to the incident signal. Specifically, the reflection coefficient is usually expressed as a complex number, including amplitude and phase. The complex form of the reflection coefficient can describe the change of the amplitude and phase of the signal during the reflection process. Each unit on the metasurface has certain electromagnetic properties. By adjusting these properties, the reflection coefficient can be changed, which can be achieved by adjusting the capacitance, inductance or other parameters in the metasurface unit. By cleverly adjusting the reflection coefficient of each unit on the metasurface, directional reflection or refraction of signals in a specific direction can be achieved. This directionality can be used to optimize communication links or prevent signal interference. One of the advantages of RIS is its adaptability, that is, in different communication scenarios, it can dynamically adjust the reflection coefficient according to real-time communication needs and environmental changes. This adaptability enables RIS to flexibly adapt to diverse communication environments. The reflection coefficient in RIS is the key parameter that controls the reflection of the incident signal by the metasurface. Its adjustment can optimize the communication performance. Therefore, adjusting the reflection coefficient plays an important role in improving signal quality, enhancing the capacity of the system and improving the performance of the communication link. The spectral characteristics of the signal combined with the chaotic signal are extended because the chaotic sequence has the property of spectrum extension, that is, its spectrum covers a relatively wide frequency range. This spectrum extension makes the chaotic signal show complex and irregular changes in the frequency domain. Compared with the traditional periodic signal, its spectrum is more dispersed. The chaotic sequence not only contains discrete frequency components in frequency, but also its spectrum is continuously distributed, which means that the chaotic signal has a higher component density in the frequency range and presents a more continuous and dispersed spectrum form.

5. The method for implementing a communication system based on intelligent metasurface technology and chaotic encryption according to claim 1, characterized in that: The encryption method used for data encryption and decryption is a block encryption algorithm, and its encryption and decryption formula is as follows R i =L i+1 represents XOR operation, F represents round function, K i is the i-th round subkey. In this framework, the F function is not required to be reversible, that is, there is no need to ensure the inverse operation of the F function during the decryption process. Decryption still requires the same iteration and round operations to obtain the original plaintext information. Only when the correct key is used can the plaintext be successfully restored, otherwise the relevant plaintext information cannot be obtained.

6. The method for implementing a communication system based on intelligent metasurface technology and chaotic encryption according to claim 1, characterized in that: The method includes a round function, and introduces obfuscation and diffusion. Obfuscation refers to making the relationship between the input and output of the cryptographic algorithm complex and unpredictable by adding nonlinear operations. The goal of obfuscation is to blur the statistical relationship between plaintext and ciphertext, and increase the difficulty for attackers to understand the cryptographic system. Diffusion refers to affecting each bit of the output by changing one or more bits of the input, ensuring that changes in a single bit will propagate to most bits of the output. Diffusion helps to ensure that a small change in the input will result in a large change in the output, thereby increasing the sensitivity of the cryptographic algorithm.

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