Secret key generation method based on space filling curve mapping and nonlinear correlation matching

Abstract

The invention discloses a key generation method based on space filling curve mapping and nonlinear correlation matching, and relates to the technical field of physical layer security. According to the method, the key is generated by adopting the steps of channel detection and synchronous ciphertext transmission, distribution transformation of an acquired channel sample sequence, index mapping based on a space filling curve, segmented random nonlinear transformation and replacement, segmented matching based on nonlinear correlation measurement and the like; according to the channel detection and synchronous ciphertext transmission, a terminal exchanges a detection packet to collect a channel sample sequence, and encrypted data is synchronously transmitted to improve the communication efficiency; the distribution transformation is used for converting a normally-distributed channel sample sequence into a uniformly-distributed two-dimensional channel sample sequence, so that the distribution of channel samples is more dispersed, and more uniform index mapping is conveniently generated subsequently; segmented matching is carried out by measuring the nonlinear correlation among the index segments, so that the matching robustness is enhanced, and the key generation accuracy and generation rate are improved.

Description

Technical Field

[0001] The present application relates to the field of physical layer security technology, and in particular to a key generation method based on space filling curve mapping and nonlinear correlation matching. Background Art

[0002] With the rapid development and widespread deployment of new generation wireless communication technologies such as B5G (Beyond 5G), 6G and satellite communications, these technologies have become an important strategic support for promoting industrial control innovation, industrial transformation and national security. Although wireless networks provide the advantages of low cost and high bandwidth for data communication, the complex wireless environment brings complex coupling of spectrum, intelligent interference forms and diverse security threats, such as eavesdropping, signal interference, data injection, man-in-the-middle attacks, etc., which seriously threaten users' property safety and privacy protection. Therefore, with the widespread application of wireless communication technology in people's lives, facing the increasingly complex wireless environment and escalating security challenges, wireless communication security issues have become a key issue that needs to be solved urgently.

[0003] Traditional encryption schemes usually rely on pre-shared information to generate keys to prevent illegal access by malicious devices. However, the application of these methods in wireless environments is limited due to the inadequate key management infrastructure and limited mobile device resources. In particular, with the development of quantum computing technology, quantum algorithms pose a serious challenge to traditional public key encryption schemes. Therefore, in view of the limitations and potential threats of traditional encryption schemes, wireless communication security technology is urgently needed as an important support and effective supplement.

[0004] In order to overcome the shortcomings of traditional encryption schemes, in recent years, researchers have explored physical layer security technologies that use the inherent physical characteristics of wireless channels and wireless devices to ensure communication security. Physical layer security technology provides a new security guarantee for wireless communications by realizing functions such as information-theoretic security key generation, encrypted communication, and identity authentication. As a core component of this system, physical layer key generation uses the time-varying and reciprocal properties of wireless channels to generate shared keys between the communicating parties to support encrypted communication. Unlike traditional encryption methods, physical layer key generation relies on the channel itself, avoiding key distribution and management issues, and does not require a large amount of computing resources, thereby reducing the network burden. Therefore, physical layer key generation is particularly suitable for distributed, heterogeneous wireless networks, providing effective support for resource-constrained wireless devices and diverse network environments.

[0005] Traditional physical layer key generation methods usually use quantization algorithms to convert channel samples into initial key bits. However, due to the asynchrony of half-duplex devices during channel detection and the interference of environmental noise, the channel sample sequences of the communicating parties may lose correlation, resulting in inconsistent quantization. This problem has prompted researchers to propose matching-based key generation methods in recent years. These methods randomly permute the channel sample sequence, measure the similarity between channel samples to establish matching, and derive random permutation sequences for key generation based on the matching relationship. However, most matching-based key generation methods only rely on the single-dimensional characteristics of the channel sample sequence and measure the similarity of channel samples by distance measurement, which often leads to reduced robustness of sample matching, thereby affecting the performance of key generation in complex wireless environments. For example, in a quasi-static or slowly varying channel environment, the statistical characteristics of local channel samples may be highly similar, resulting in ambiguity in the matching process, which in turn affects the accuracy of key generation. In addition, in high-noise scenarios, outliers may appear in the channel sample sequence, which in turn damages the channel reciprocity on which the physical layer key generation relies, greatly affecting the reliability of the distance measurement, and ultimately leading to a decrease in the consistency of matching and key generation.

[0006] Therefore, how to extract the multidimensional features of the channel sample sequence and match the channel samples based on these features to enhance the reliability of channel sample matching has become the key to improving the consistency and robustness of key generation. In addition, relying solely on traditional matching methods based on distance metrics may not be able to effectively cope with complex wireless environments. To solve this problem, it is necessary to perform nonlinear transformations on the channel samples and use nonlinear correlation metrics to match the samples, thereby ensuring accurate and robust key generation in complex wireless environments. Summary of the invention

[0007] In response to the deficiencies in the prior art, the present application provides a key generation method based on space filling curve mapping and nonlinear correlation matching, which uses channel detection and synchronous ciphertext transmission, adaptive segmented rearrangement optimization, random segmented nonlinear transformation and permutation, segmented matching based on nonlinear correlation measurement and other steps to generate keys, so as to improve the accuracy and generation rate of key generation.

[0008] The technical solution adopted in this application is:

[0009] A key generation method based on space filling curve mapping and nonlinear correlation matching, the method comprising the following steps:

[0010] Step 1: Channel detection and synchronous ciphertext transmission;

[0011] Terminal A and terminal B sample the channel between them to obtain channel sample sequences of terminals A and B;

[0012] Terminal A generates a random permutation sequence as a secret key, encrypts the plaintext with the secret key, generates ciphertext, and transmits the ciphertext synchronously during channel detection;

[0013] Step 2: Terminal A / B performs distribution transformation on its channel sample sequence respectively;

[0014] Terminal A / B converts its channel sample sequence into a standard normal distribution to obtain a standardized channel sample sequence of terminal A / B;

[0015] Then, based on the inverse process of the selected distribution transformation algorithm that obeys the normal distribution, the standardized channel sample sequence of the terminal A / B is transformed into a uniform distribution, so as to obtain a two-dimensional channel sample sequence after the terminal A / B is transformed;

[0016] Step 3: Index mapping based on space-filling curve;

[0017] Terminal A / B converts the two-dimensional channel sample sequence converted by terminal A / B into a two-dimensional coordinate grid point sequence of terminal A based on the common space filling curve parameters, and then maps it to a one-dimensional space index to obtain a one-dimensional index sequence after A / B mapping;

[0018] Step 4: piecewise random nonlinear transformation and permutation;

[0019] Terminal A uses an equal-length segmentation method to perform fixed-length segmentation on the one-dimensional index sequence mapped by terminal A to obtain an index segment sequence of terminal A, and performs a random nonlinear transformation on each index segment to obtain an index segment sequence after nonlinear transformation of terminal A;

[0020] Terminal A randomly permutes its nonlinearly transformed index segment sequence based on the random permutation sequence generated in step 1, obtains the permuted index segment sequence of terminal A and sends it to terminal B;

[0021] Terminal B uses the same segment length as terminal A to perform fixed-length segmentation on the one-dimensional index sequence mapped by terminal B to obtain an index segment sequence of terminal B;

[0022] Step 5: Segment matching based on nonlinear correlation metrics;

[0023] Terminal B uses the nonlinear correlation coefficient as a metric to match the index segment sequence of terminal B with the index segment sequence after replacement by terminal A, and uses the obtained matching sequence as a key.

[0024] Furthermore, in step 1, terminal A and terminal B sample the channel between them, and the channel sample sequences of terminals A and B are generated respectively as follows:

[0025] Terminal A and terminal B sample the channel between them during the channel coherence time of terminal A and terminal B, and end when both terminal A and terminal B collect a specified number of channel samples; and the channel sample sequences collected by terminal A and terminal B are recorded as and ;in, is the channel sample sequence of terminal A, is the channel sample sequence of terminal B, , Respectively represent the first channel samples, and , N is the channel sample sequence length, that is, the specified number of channel samples.

[0026] Furthermore, in step 1, the random permutation sequence is a sequence from arrive A random permutation sequence of The length of the random permutation sequence is set.

[0027] Furthermore, in step 1, synchronously transmitting the ciphertext during the channel detection process specifically includes: embedding the ciphertext as a data payload into a data field of the channel detection packet, and transmitting it together with the pilot signal during the channel detection.

[0028] Furthermore, in step 2, the distribution transformation algorithm selected to obey the normal distribution is the Box-Muller algorithm.

[0029] Furthermore, step 3 specifically includes:

[0030] Step 3.1: Set the same order of space-filling curves for both terminal A and terminal B ;

[0031] Step 3.2: Terminal A is based on the order The two-dimensional channel sample sequence converted by terminal A Transformed into a two-dimensional coordinate grid sequence of terminal A , among which 2D coordinate grid points Specifically: ; Among them, the two-dimensional coordinate grid index satisfy , is the length of the two-dimensional channel sample sequence, and = ,symbol Indicates floor operation; , Represent the two-dimensional channel sample sequence The Two-dimensional channel samples;

[0032] Terminal B according to the order The two-dimensional channel sample sequence converted by terminal B Transformed into a two-dimensional coordinate grid sequence of terminal B , among which 2D coordinate grid points Specifically: ; , Represent the two-dimensional channel sample sequence The Two-dimensional channel samples;

[0033] Step 3.3: Terminal A uses the order The two-dimensional space-filling curve of terminal A is Mapped to the one-dimensional index sequence after terminal A is mapped , where each one-dimensional index All meet , ;

[0034] Terminal B uses the order The two-dimensional space-filling curve of terminal B is Mapped to the one-dimensional index sequence after terminal B mapping , where each one-dimensional index All meet , .

[0035] Furthermore, in step 3, a Hilbert curve is selected as the space filling curve.

[0036] Furthermore, in step 4, the random nonlinear transformation includes but is not limited to: exponential transformation, logarithmic transformation, sine-cosine transformation, hyperbolic tangent function (Tanh) transformation, etc.

[0037] Furthermore, in step 5, terminal B uses the nonlinear correlation coefficient as a metric to match the index segment sequence of terminal B with the index segment sequence after replacement of terminal A:

[0038] ;

[0039] in, The index segment sequence after the terminal A is replaced The Segments, is the index segment sequence of terminal B The Segments, represents the nonlinear correlation coefficient used, Indicates the matching order between index segments. The length of the random permutation sequence is set.

[0040] Furthermore, in step 5, the nonlinear correlation coefficient adopts the Chatterjee correlation coefficient.

[0041] The technical solution provided by this application brings at least the following beneficial effects:

[0042] (1) This application overcomes the limitation of using only one-dimensional sample features in traditional matching-based key generation methods by combining space filling curve mapping with nonlinear correlation matching, thereby achieving more accurate and efficient physical layer key generation;

[0043] (2) This application introduces a channel detection and synchronous ciphertext transmission mechanism to achieve synchronous transmission of encrypted data during the channel detection process, reducing the additional data packet exchange in confidential communication, thereby effectively improving communication efficiency;

[0044] (3) This application adopts a distribution transformation method based on the Box-Muller algorithm to convert the original normally distributed channel sample sequence into a uniformly distributed channel sample sequence, which overall enhances the differences between channel samples and promotes matching-based key generation. In this process, the distribution transformation can be completed without exchanging data between terminals, which significantly reduces the communication volume and potential data leakage risks during the key generation process.

[0045] (4) This application uses an index mapping method based on a space filling curve to map the channel sample sequence to a one-dimensional spatial index according to the construction method of the space filling curve, and avoids the limitation of relying only on the characteristics of a single-dimensional channel sample. This method also enhances the robustness of the index matching process under extreme channel sample conditions, and ensures the locality of the mapping between different dimensions by selecting an appropriate space filling curve (such as the Hilbert curve), thereby improving the reliability of the subsequent index segmentation and matching process.

[0046] (5) The present application performs index segment matching based on nonlinear correlation measurement. By adopting the method of piecewise random nonlinear transformation, the correlation between the index segments before and after the transformation is confused, thereby reducing the risk of leaking the key by publicly permuting the index segments. Compared with the traditional method of matching only by index segment distance measurement, the present application significantly enhances the robustness of the matching process by measuring nonlinear correlation, thereby ensuring the accuracy and generation rate of key generation in complex wireless environments. DETAILED DESCRIPTION

[0047] In order to enable those skilled in the art to better understand the technical solutions in this specification, the technical solutions of the present application will be described in detail and completely in conjunction with the embodiments of the present application.

[0048] The embodiment of the present application provides a key generation method based on space filling curve mapping and nonlinear correlation matching, which uses channel detection and synchronous ciphertext transmission, distribution transformation based on Box-Muller algorithm, index mapping based on space filling curve, piecewise random nonlinear transformation and permutation, piecewise matching based on nonlinear correlation measurement and other steps to generate keys; wherein, channel detection and synchronous ciphertext transmission collect channel sample sequences by exchanging detection packets through terminals, and synchronously transmit encrypted data to improve communication efficiency; distribution transformation based on Box-Muller algorithm converts the normally distributed channel sample sequence into a uniformly distributed two-dimensional channel sample sequence by adopting the inverse process of Box-Muller algorithm, so that the distribution of its channel samples is more dispersed, The space-filling curve-based index mapping uses the space-filling curve to map the two-dimensional channel sample sequence to a one-dimensional space index. Compared with the traditional single coordinate mapping method, the space-filling curve can better combine the multi-dimensional characteristics of the channel sample and provide stronger discrimination, so that the generated index mapping is more consistent in the matching process. The segmented random nonlinear transformation and permutation segments the index, and the random nonlinear transformation is used to enhance the nonlinear characteristics of the index segmentation, further improving the anti-passive attack performance of the key generation. The segmented matching based on the nonlinear correlation metric measures the nonlinear correlation between each index segment for segmented matching, which can enhance the robustness of the segmented matching and effectively improve the accuracy and generation rate of the key generation.

[0049] As a possible implementation manner, a key generation method based on space filling curve mapping and nonlinear correlation matching provided in an embodiment of the present application includes the following steps:

[0050] Step 1: Channel detection and synchronous ciphertext transmission. Terminal A and terminal B sample the channel between them, and generate a channel sample sequence of terminal A and a channel sample sequence of terminal B respectively. At the same time, terminal A generates a random permutation sequence as a secret key, and encrypts the plaintext with the secret key to generate a ciphertext, and synchronously transmits the ciphertext during the channel detection process.

[0051] Step 2: Perform distribution transformation on the channel sample sequence obtained by sampling. Terminal A approximately transforms the channel sample sequence of terminal A into a standard normal distribution through standardization to obtain the standardized channel sample sequence of terminal A, and approximately transforms the standardized channel sample sequence of terminal A into a uniform distribution based on the inverse process of the selected distribution transformation algorithm that obeys the normal distribution (such as the Box-Muller algorithm) to obtain the two-dimensional channel sample sequence after transformation of terminal A; similarly, terminal B approximately transforms the channel sample sequence of terminal B into a standard normal distribution through standardization to obtain the standardized channel sample sequence of terminal B, and approximately transforms the standardized channel sample sequence of terminal B into a uniform distribution using the inverse process of the Box-Muller algorithm to obtain the two-dimensional channel sample sequence after transformation of terminal B;

[0052] Step 3: Based on the index mapping of the space filling curve, terminal A uses the common space filling curve parameters to convert the two-dimensional channel sample sequence converted by terminal A into a two-dimensional coordinate grid point sequence of terminal A, and uses the space filling curve to map the two-dimensional coordinate grid point sequence of terminal A to a one-dimensional spatial index, so as to obtain the one-dimensional index sequence mapped by terminal A; similarly, terminal B uses the common space filling curve parameters to convert the two-dimensional channel sample sequence converted by terminal B into a two-dimensional coordinate grid point sequence of terminal B, and uses the same space filling curve as terminal A to map the two-dimensional coordinate grid point sequence of terminal B to a one-dimensional spatial index, so as to obtain the one-dimensional index sequence mapped by terminal B;

[0053] Step 4: Segmented random nonlinear transformation and permutation. Terminal A uses an equal-length segmentation method to perform fixed-length segmentation on the one-dimensional index sequence mapped by terminal A to obtain the index segment sequence of terminal A, and performs random nonlinear transformation on each index segment in the index segment sequence of terminal A to obtain the index segment sequence after the nonlinear transformation of terminal A, and randomly permutes the index segment sequence after the nonlinear transformation of terminal A using the random permutation sequence generated in step 1 to obtain the permuted index segment sequence of terminal A; terminal A sends the permuted index segment sequence of terminal A to terminal B; terminal B uses the same segmentation length as terminal A to perform fixed-length segmentation on the one-dimensional index sequence mapped by terminal B to obtain the index segment sequence of terminal B;

[0054] Step 5: Segment matching based on nonlinear correlation measurement. Terminal B uses the nonlinear correlation coefficient as a measurement to match the index segment sequence of terminal B with the index segment sequence after replacement of terminal A, and obtains the matching sequence as the key.

[0055] In one embodiment, the channel detection and synchronization ciphertext transmission in step 1 of the embodiment of the present application includes:

[0056] Step 1.1: Terminal A and terminal B sample the channel between them within the channel coherence time of terminal A and terminal B, and end when both terminal A and terminal B have collected a certain number of channel samples, and the channel sample sequences collected by terminal A and terminal B are recorded as and ;in, is the channel sample sequence of terminal A, is the channel sample sequence of terminal B, , Respectively represent the first channel samples, N is the channel sample sequence length;

[0057] Step 1.2: Terminal A generates a slave arrive Random permutation sequence As a secret key shared between terminal A and terminal B, Corresponding to the length of the index segment sequence of terminal A in step 4.1, and using the secret key to encrypt the plaintext of terminal A, to obtain the ciphertext of terminal A;

[0058] Step 1.3: Terminal A embeds the ciphertext of terminal A as a data payload in the channel detection packet and transmits it together with the pilot signal in the channel detection to reduce the data packet exchange for confidential communication.

[0059] In one embodiment, step 2 of the embodiment of the present application specifically includes:

[0060] Step 2.1: Terminal A obtains the channel sample sequence from terminal A Estimate the sample mean of the channel sample sequence of terminal A and the sample standard deviation , respectively:

[0061] ;

[0062] ;

[0063] And according to the sample mean of the channel sample sequence of terminal A and the sample standard deviation Channel sample sequence for terminal A Standardize and obtain the standardized channel sample sequence of terminal A , where each element ( ) is as follows:

[0064] ;

[0065] The obtained channel sample sequence after normalization of terminal A Approximately follows the standard normal distribution Similarly, terminal B obtains the channel sample sequence from terminal B Estimate the sample mean of the channel sample sequence of terminal B and the sample standard deviation , respectively:

[0066] ;

[0067] ;

[0068] And according to the sample mean of the channel sample sequence of terminal B and the sample standard deviation Channel sample sequence for terminal B Standardize to obtain the standardized channel sample sequence of terminal B , where each element ( ) The standardization process is:

[0069] ;

[0070] The obtained channel sample sequence after normalization of terminal B It also approximately follows the standard normal distribution ;

[0071] Step 2.2: Terminal A normalizes the channel sample sequence of terminal A Perform dimension splitting to obtain the two-dimensional channel sample sequence of terminal A ,in = ,symbol Represents a round-down operation; similarly, terminal B normalizes the channel sample sequence of terminal B Perform dimension splitting to obtain the two-dimensional channel sample sequence of terminal B ;

[0072] Step 2.3: Terminal A uses the inverse process of the Box-Muller algorithm to convert the two-dimensional channel sample sequence of terminal A into Approximately converted into a uniform distribution, the two-dimensional channel sample sequence after terminal A conversion is obtained Specifically, for the two-dimensional channel sample sequence of terminal A The ( ) two-dimensional channel sample pairs , terminal A calculates the auxiliary quantity , and based on this auxiliary Calculate the two-dimensional channel sample sequence after terminal A conversion , among which ( ) two-dimensional channel sample pairs are :

[0073]

[0074]

[0075] in, For the value range defined in The arc tangent function of e is the natural base; similarly, terminal B also converts the two-dimensional channel sample sequence of terminal B into Approximately converted into a uniform distribution, the two-dimensional channel sample sequence after terminal B conversion is obtained .

[0076] In one embodiment, step 3 of the embodiment of the present application specifically includes:

[0077] Step 3.1: Terminal A and Terminal B select the two-dimensional Hilbert curve as the space filling curve and set the same curve parameter order , which means the number of iterations required in the construction process of the Hilbert curve is times (similarly, Hilbert curves or other space-filling curves of other dimensions and orders can also be selected for index mapping);

[0078] Step 3.2: Terminal A is based on the order The two-dimensional channel sample sequence converted by terminal A Transformed into a two-dimensional coordinate grid sequence of terminal A , among which ( ) two-dimensional coordinate grid points are Similarly, terminal B uses the order The two-dimensional channel sample sequence converted by terminal B Transformed into a two-dimensional coordinate grid sequence of terminal B , among which ( ) two-dimensional coordinate grid points are ;

[0079] Step 3.3: Terminal A uses the order The two-dimensional Hilbert curve of terminal A is the two-dimensional coordinate grid sequence Mapped to the one-dimensional index sequence after terminal A is mapped , where each one-dimensional index ( ) are satisfied Similarly, terminal B uses the order The two-dimensional Hilbert curve of terminal B is the two-dimensional coordinate grid sequence Mapped to the one-dimensional index sequence after terminal B mapping , where each one-dimensional index ( ) are satisfied .

[0080] In one embodiment, step 4 of the embodiment of the present application specifically includes:

[0081] Step 4.1: Terminal A follows a fixed length One-dimensional index sequence after mapping terminal A Perform fixed-length segmentation to obtain the index segment sequence of terminal A ,in , ( ) is the index segments, each of which has a length of Similarly, terminal B has a fixed length One-dimensional index sequence after mapping terminal B Perform fixed-length segmentation to obtain the index segment sequence of terminal B ,in ( ) is the segments, and the length of each index segment is ;

[0082] Step 4.2: Terminal A to Terminal A Index Segment Sequence Each segment in ( ) Using random nonlinear transformation , get the index segment sequence after nonlinear transformation of terminal A ,in ( ) is the index segment sequence of terminal A No. Index segments After nonlinear transformation After the index segmentation, these nonlinear transformations can be selected from exponential transformation, logarithmic transformation, sine-cosine transformation, Tanh transformation, etc.

[0083] Step 4.3: Terminal A uses the random permutation sequence described in step 1.2 Index segment sequence after nonlinear transformation of terminal A Perform random permutation to obtain the index segment sequence after terminal A is permuted , among which Index segments ( ) is the index segment sequence after nonlinear transformation of terminal A The ( ) index segments;

[0084] Step 4.4: Terminal A replaces the index segment sequence of the terminal A Send to terminal B.

[0085] In one embodiment, step 5 of the embodiment of the present application specifically includes:

[0086] Step 5.1: Terminal B establishes the index segment sequence of terminal B based on the nonlinear correlation metric Index segment sequence after replacement with terminal A Specifically, terminal B selects the Chatterjee correlation coefficient as the nonlinear correlation measure between index segments and calculates the index segment sequence of terminal B. Index segment sequence after replacement with terminal A Matching order between index segments , so that the matching error is minimized, and the matching order As the key of terminal B:

[0087] ;

[0088] in, ( ) is the index segment sequence after terminal A is replaced The Segments, ( ) is the index segment sequence of terminal B The Segments, For segmentation and The Chatterjee correlation coefficient between them is calculated as follows:

[0089] set up and For two segments of equal length, In For sample values , arranged in increasing order, so that ;set up exist The order in is ,Right now of The number of, Chatterjee correlation coefficient is defined as:

[0090] .

[0091] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A key generation method based on space filling curve mapping and nonlinear correlation matching, characterized in that: The following steps are involved: Step 1: Channel detection and synchronous ciphertext transmission; Terminals A and B sample the channel between them respectively to obtain channel sample sequences of terminals A and B; Terminal A generates a random permutation sequence as a secret key, and uses it to encrypt plaintext to generate ciphertext, and transmits the ciphertext synchronously during channel detection; Step 2: Terminal A / B performs distribution transformation on its channel sample sequence respectively; After the terminal A / B converts its channel sample sequence into a standard normal distribution, based on the inverse process of the selected distribution transformation algorithm that obeys the normal distribution, the standardized channel sample sequence of the terminal A / B is converted into a uniform distribution to obtain a two-dimensional channel sample sequence after the terminal A / B is converted; Step 3: Index mapping based on space-filling curve; Terminal A / B converts the converted two-dimensional channel sample sequence into a two-dimensional coordinate grid point sequence based on the common space filling curve parameters, and then maps it to a one-dimensional space index to obtain a one-dimensional index sequence mapped by terminal A / B; Step 4: piecewise random nonlinear transformation and permutation; Terminal A segments the mapped one-dimensional index sequence with a fixed length based on the set segment length to obtain the index segment sequence of terminal A, and performs a random nonlinear transformation on each index segment to obtain the index segment sequence after the nonlinear transformation of terminal A; then, the index segment sequence is randomly permuted based on the random permutation sequence generated in step 1 to obtain the permuted index segment sequence of terminal A and send it to terminal B; Terminal B uses the same segment length as terminal A to perform fixed-length segmentation on the one-dimensional index sequence mapped by terminal B to obtain an index segment sequence of terminal B; Step 5: Segment matching based on nonlinear correlation metrics; Terminal B uses the nonlinear correlation coefficient as a metric to match the index segment sequence of terminal B with the index segment sequence after replacement by terminal A, and uses the obtained matching sequence as a key.

2. The key generation method based on space filling curve mapping and nonlinear correlation matching according to claim 1, characterized in that: In step 1, the random permutation sequence is a sequence from arrive A random permutation sequence of The length of the random permutation sequence is set.

3. The key generation method based on space filling curve mapping and nonlinear correlation matching according to claim 1, characterized in that: In step 1, synchronously transmitting the ciphertext during the channel detection process specifically includes: embedding the ciphertext as a data payload into the data field of the channel detection packet, and transmitting it together with the pilot signal during the channel detection.

4. The key generation method based on space filling curve mapping and nonlinear correlation matching according to claim 1, characterized in that: In step 2, the distribution transformation algorithm selected to obey the normal distribution is the Box-Muller algorithm.

5. The key generation method based on space filling curve mapping and nonlinear correlation matching as claimed in claim 1, characterized in that: Step 3 specifically includes: Step 3.1: Set the same order of space-filling curves for both terminal A and terminal B ; Step 3.2: Terminal A is based on the order The two-dimensional channel sample sequence converted by terminal A Transformed into a two-dimensional coordinate grid sequence of terminal A , among which 2D coordinate grid points Specifically: ; Among them, the two-dimensional coordinate grid index satisfy , is the length of the two-dimensional channel sample sequence, and = ,symbol Indicates floor operation; , Represent the two-dimensional channel sample sequence The Two-dimensional channel samples; Terminal B according to the order The two-dimensional channel sample sequence converted by terminal B Transformed into a two-dimensional coordinate grid sequence of terminal B , among which 2D coordinate grid points Specifically: ; , Represent the two-dimensional channel sample sequence The Two-dimensional channel samples; Step 3.3: Terminal A uses the order The two-dimensional space-filling curve of terminal A is Mapped to the one-dimensional index sequence after terminal A is mapped , where each one-dimensional index All meet , ; Terminal B uses the order The two-dimensional space-filling curve of terminal B is Mapped to the one-dimensional index sequence after terminal B mapping , where each one-dimensional index All meet , .

6. The key generation method based on space filling curve mapping and nonlinear correlation matching as claimed in claim 5, characterized in that: In step 3, the Hilbert curve is selected as the space filling curve.

7. The key generation method based on space filling curve mapping and nonlinear correlation matching according to claim 1, characterized in that: In step 4, the random nonlinear transformation is an exponential transformation, a logarithmic transformation, a sine-cosine transformation or a hyperbolic tangent function.

8. The key generation method based on space filling curve mapping and nonlinear correlation matching as claimed in claim 1, characterized in that: In step 5, terminal B uses the nonlinear correlation coefficient as a metric to match the index segment sequence of terminal B with the index segment sequence after replacement of terminal A: ； in, The index segment sequence after the terminal A is replaced The Segments, is the index segment sequence of terminal B The Segments, represents the nonlinear correlation coefficient used, Indicates the matching order between index segments. The length of the random permutation sequence is set.

9. The key generation method based on space filling curve mapping and nonlinear correlation matching as claimed in claim 8, characterized in that: In step 5, the nonlinear correlation coefficient adopts the Chatterjee correlation coefficient.

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