Rail transit sensor network-oriented mixed phase security key extraction method and device

Abstract

The invention discloses a mixed phase security key extraction method and device for a rail transit sensor network, and relates to the field of communication security. In the method, a first channel estimation sequence of a first terminal and a second channel estimation sequence of a second terminal are determined; respectively generating a first illustrative sequence and a second illustrative sequence according to the relationship between the channel amplitude and the amplitude threshold in the first channel estimation sequence and the second channel estimation sequence, and carrying out AND operation on the first illustrative sequence and the second illustrative sequence to obtain a final illustrative sequence; screening the phase of the channel estimation sequence according to the final illustrative sequence, generating a first fuzzy phase and a second fuzzy phase, and mapping the successfully decoded data into a first accurate phase and a second accurate phase; and generating an encryption security key according to the first accurate phase and the first fuzzy phase, and generating a decryption security key according to the second accurate phase and the second fuzzy phase. By implementing the technical scheme provided by the invention, the communication security is improved.

Description

Technical Field

[0001] The present application relates to the technical field of communication security, and in particular to a hybrid phase security key extraction method and device for a rail transit sensor network. Background Art

[0002] With the rapid development of rail transit and its increasing intelligence and informationization, rail transit sensor networks are playing an increasingly important role in ensuring train safety and improving operational efficiency. Sensor networks transmit large amounts of critical data, such as train speed, location, and equipment status. The security of this data is directly related to the stable operation of the rail transit system and the safety of passengers and property. Therefore, achieving efficient and secure key extraction in rail transit sensor networks has become a hot topic of research.

[0003] Among existing rail transit sensor network key extraction technologies, common methods include physical layer schemes based on channel feature extraction. In this scheme, noise can cause errors in the channel estimation sequences obtained by the communicating parties, often resulting in incomplete consistency in the binary bit sequences after feature quantization, necessitating repeated key negotiation to ensure consistency. However, repeated negotiation may result in the leakage of key information to eavesdroppers and reduce the rate of secure key generation. In addition, this scheme generally assumes that the channels of the eavesdropper and the legitimate receiver are uncorrelated. However, in complex communication scenarios, the eavesdropper's channel may be highly correlated with the legitimate receiver's channel, resulting in a certain degree of leakage of key information to the eavesdropper. Summary of the Invention

[0004] The present application provides a hybrid-phase security key extraction method and device for rail transit sensor networks, which abandons the quantization and key negotiation steps in traditional schemes, combines the key information extracted in the two stages, and encrypts the data at the symbol level; when the eavesdropping channel is highly correlated with the legitimate channel, the embodiment of the present application can still generate a large number of security keys, greatly increasing the number of keys; while reducing the receiving bit error rate of the legitimate receiving end, it can significantly improve the receiving bit error rate of the eavesdropping end, thereby enhancing the security and reliability of the system.

[0005] In a first aspect of the present application, a hybrid phase security key extraction method for a rail transit sensor network is provided, which is applied to a key extraction platform. The method comprises: Acquire pilot signals sent between a first terminal and a second terminal, determine a first channel estimation sequence for the first terminal and a second channel estimation sequence for the second terminal, and determine an amplitude threshold according to noise power of the pilot signals; generating a first indicative sequence based on a relationship between a channel amplitude in the first channel estimation sequence and the amplitude threshold, generating a second indicative sequence based on a relationship between a channel amplitude in the second channel estimation sequence and the amplitude threshold, and performing an AND operation on the first indicative sequence and the second indicative sequence to obtain a final indicative sequence; Filtering the phase of a channel estimation sequence according to the final indicative sequence to generate a first ambiguous phase and a second ambiguous phase, and mapping successfully decoded data of a retransmission request sent by the first terminal to the second terminal into a first accurate phase and a second accurate phase; An encryption security key is generated according to the first accurate phase and the first ambiguous phase, and a decryption security key is generated according to the second accurate phase and the second ambiguous phase.

[0006] Optionally, generating a first indicative sequence according to a relationship between the channel amplitude in the first channel estimation sequence and the amplitude threshold, and generating a second indicative sequence according to a relationship between the channel amplitude in the second channel estimation sequence and the amplitude threshold includes: The first exemplary sequence and the second exemplary sequence are generated by the following formula: ; Among them, S a Represents the first indicative sequence, S b represents the second indicative sequence, n∈[1,N], n is a positive integer, N represents the length of the first channel estimation sequence or the second channel estimation sequence, Indicates the first exemplary sequence or the second exemplary sequence n Indicative amplitude: ; in, represents the first channel estimation sequence or the second channel estimation sequence n The channel amplitude, Indicates the amplitude threshold.

[0007] Optionally, performing an AND operation on the first indicative sequence and the second indicative sequence to obtain a final indicative sequence includes: The final indicative sequence is generated by the following formula: W =[ W [1], W [2],......, W [ N ]], in, W represents the final indicative sequence, W [ n ] indicates the first nIndicative amplitude, n∈[1,N], n is a positive integer, N represents the length of the first channel estimation sequence or the second channel estimation sequence: ; in, S a [ n ] represents the first indicative sequence n An indicative amplitude, S b [ n ] represents the first n An indicative amplitude.

[0008] Optionally, the filtering the phase of the channel estimation sequence according to the final indicative sequence to generate a first ambiguous phase and a second ambiguous phase includes: The target phases of the first fuzzy phase and the second fuzzy phase are generated by the following formula: ; in, Indicates when W [ n ]=1, the corresponding phase value is retained, Indicates the first fuzzy phase or the second fuzzy phase k target phase, k ∈[1, N ], k is a positive integer, and the first fuzzy phase or the second fuzzy phase is generated according to a plurality of the target phases.

[0009] Optionally, mapping the successfully decoded data of the retransmission request sent by the first terminal to the second terminal into a first accurate phase and a second accurate phase includes: The first and second accurate phases are generated by the following equations: ; Where data represents the successfully decoded data, f(·) represents the mapping function, and boolBob represents the indicator of whether the second terminal has successfully decoded. If it is zero, it means that the second terminal has successfully decoded. represents the first fuzzy phase or the second fuzzy phase, Indicates the first accurate phase or the second accurate phase.

[0010] Optionally, generating an encryption security key according to the first accurate phase and the first fuzzy phase, and generating a decryption security key according to the second accurate phase and the second fuzzy phase includes: Generate an encryption security key or a decryption security key using the following formula: ; in, represents an encryption security key or a decryption security key, represents the first fuzzy phase or the second fuzzy phase, Indicates the first accurate phase or the second accurate phase.

[0011] Optionally, the method further includes: Sending, by the first terminal, a hash value of a preset number of digits of the encryption security key to the second terminal, and comparing, by the second terminal, the hash value of the preset number of digits with a hash value corresponding to the decryption security key; When the preset number of digits of the hash value matches the hash value corresponding to the decryption security key, it is determined that the encryption security key and the decryption security key are consistent.

[0012] In a second aspect of the present application, a hybrid phase security key extraction system for a rail transit sensor network is provided, comprising a channel module, an indicative module, a phase module, and a key module, wherein: a channel module configured to obtain pilot signals sent between a first terminal and a second terminal, determine a first channel estimation sequence for the first terminal and a second channel estimation sequence for the second terminal, and determine an amplitude threshold based on noise power of the pilot signals; an indicative module configured to generate a first indicative sequence based on a relationship between the channel amplitude in the first channel estimation sequence and the amplitude threshold, generate a second indicative sequence based on a relationship between the channel amplitude in the second channel estimation sequence and the amplitude threshold, and perform an AND operation on the first indicative sequence and the second indicative sequence to obtain a final indicative sequence; a phase module configured to filter the phase of the channel estimation sequence according to the final indicative sequence, generate a first ambiguous phase and a second ambiguous phase, and map successfully decoded data of a retransmission request sent by the first terminal to the second terminal into a first accurate phase and a second accurate phase; The key module is configured to generate an encryption security key according to the first accurate phase and the first fuzzy phase, and to generate a decryption security key according to the second accurate phase and the second fuzzy phase.

[0013] In the third aspect of the present application, an electronic device is provided, including a processor, a memory, a user interface and a network interface, the memory is used to store instructions, the user interface and the network interface are both used to communicate with other devices, and the processor is used to execute the instructions stored in the memory so that the electronic device performs any of the methods described above.

[0014] In a fourth aspect of the present application, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores instructions. When the instructions are executed, any one of the methods described above is executed.

[0015] In summary, one or more technical solutions provided in the embodiments of the present application have at least the following technical effects or advantages: 1. Utilize the pilot signals sent between the first and second terminals in the rail transit sensor network to determine the channel estimation sequence, thereby generating the fuzzy phase and accurate phase. Due to the complex rail transit environment, channel characteristics (such as channel amplitude and phase) are affected by multiple factors such as multipath effects, signal fading, and reflections from surrounding objects, resulting in a high degree of randomness and unpredictability. 2. Combine the fuzzy phase and the accurate phase to generate encryption and decryption security keys. The fuzzy phase is obtained by screening the relationship between the channel estimation sequence and the amplitude threshold, and the accurate phase is mapped from the successfully decoded data of the retransmission request sent by the first terminal to the second terminal. The fuzzy phase reflects the basic characteristics of the channel and has a certain degree of randomness; the accurate phase is based on the successfully decoded data, which further enhances the correlation between the key and the communication process. The security of the key generated by using the fuzzy phase or the accurate phase alone may have certain limitations. The mixed phase method allows the key to have both channel characteristics and communication data characteristics. Even if the attacker obtains part of the channel information or communication data, it is difficult to accurately infer the fuzzy phase and the accurate phase at the same time, making it difficult to crack the security key, which significantly improves the security of the key; 3. Some traditional key negotiation methods require the communicating parties to exchange a large amount of information on a public channel to reach a consensus on the key, which consumes a lot of communication bandwidth and time resources. However, the embodiment of the present application uses the existing pilot signal and the successfully decoded data of the retransmission request in the rail transit sensor network to generate the key, without the need for additional key negotiation steps; 4. Operations such as pilot signal acquisition, channel estimation sequence determination, and indicative sequence generation can all be completed in real time during the communication process. Successfully decoded data from retransmission requests can also be used to generate accurate phase information. The entire key generation process is tightly integrated with the rail transit communication process, eliminating cumbersome intermediate steps. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a flow chart of a hybrid phase security key extraction method for a rail transit sensor network disclosed in an embodiment of the present application; Figure 2 is a schematic diagram of the mapping function disclosed in the embodiment of this application; Figure 3 is a schematic diagram of generating a joint phase disclosed in an embodiment of the present application; Figure 4Schematic diagram of bit error rate curves of the receiving end and the eavesdropping end disclosed in the embodiment of the present application; Figure 5 Schematic diagram of bit generation rate curves under different modulation modes disclosed in the embodiments of this application; Figure 6 This is a module diagram of a hybrid phase security key extraction system for rail transit sensor networks disclosed in an embodiment of the present application; Figure 7 This is a structural diagram of an electronic device disclosed in an embodiment of the present application.

[0017] Explanation of the reference numerals: 601, channel module; 602, exemplary module; 603, phase module; 604, key module; 701, processor; 702, communication bus; 703, user interface; 704, network interface; 705, memory. DETAILED DESCRIPTION

[0018] In order to enable those skilled in the art to better understand the technical solutions in this specification, the technical solutions in the embodiments of this specification will be clearly and completely described below in conjunction with the drawings in the embodiments of this specification. Obviously, the described embodiments are only part of the embodiments of this application, not all of the embodiments.

[0019] In the description of the embodiments of this application, words such as "for example" or "for instance" are used to indicate examples, illustrations, or explanations. Any embodiment or design described as "for example" or "for instance" in the embodiments of this application should not be construed as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "for example" or "for instance" is intended to present the relevant concepts in a concrete manner.

[0020] In the description of the embodiments of the present application, the term "multiple" means two or more. For example, multiple systems refer to two or more systems, and multiple screen terminals refer to two or more screen terminals. In addition, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized.

[0021] This embodiment discloses a hybrid phase security key extraction method for rail transit sensor networks, which is applied to a key extraction platform. Figure 1 This is a flow chart of a hybrid phase security key extraction method for a rail transit sensor network disclosed in an embodiment of the present application, such as Figure 1As shown, the method includes the following steps: S101. Acquire pilot signals sent between a first terminal and a second terminal, determine a first channel estimation sequence of the first terminal and a second channel estimation sequence of the second terminal, and determine an amplitude threshold according to noise power of the pilot signals; S102: Generate a first indicative sequence based on a relationship between the channel amplitude in the first channel estimation sequence and the amplitude threshold, generate a second indicative sequence based on a relationship between the channel amplitude in the second channel estimation sequence and the amplitude threshold, and perform an AND operation on the first indicative sequence and the second indicative sequence to obtain a final indicative sequence; S103: Filter the phase of the channel estimation sequence according to the final indicative sequence to generate a first ambiguous phase and a second ambiguous phase, and map successfully decoded data of a retransmission request sent by the first terminal to the second terminal into a first accurate phase and a second accurate phase; S104: Generate an encryption security key according to the first accurate phase and the first fuzzy phase, and generate a decryption security key according to the second accurate phase and the second fuzzy phase.

[0022] In the rail transit sensor network communication scenario, the first terminal (such as the communication equipment on the train) and the second terminal (such as the base station equipment next to the track) will send pilot signals to each other. In the embodiment of the present application, the first terminal is represented as Alice, and the second terminal is represented as Bob, where Alice and Bob can both serve as the sending end and the receiving end in the communication interaction. The pilot signal is a known signal with specific characteristics, and the position and format are usually pre-set in the frame structure of the communication system. Its function is to help the receiving end perform channel estimation, synchronization and other operations. For example, in an OFDM (orthogonal frequency division multiplexing) system, the pilot signal will be distributed on specific subcarriers, and the receiving end understands the channel characteristics by detecting changes in these pilot signals. After the first terminal receives the pilot signal sent by the second terminal, it will use the pilot signal to perform correlation operations with the known pilot sequence to estimate the channel characteristics. The purpose of channel estimation is to obtain the response of the channel at different frequencies or times, which is usually represented by a channel estimation sequence. The first terminal obtains the first channel estimation sequence by calculating the difference between the received value and the transmitted value of the pilot signal. h a =[ h a [1], h a [2],......, h a [ N ]],in h a [ n] (i=1, 2, ⋯, N) represents a specific frequency point or time point i The channel estimation value on N is the length of the first channel estimation sequence or the second channel estimation sequence, which is related to the number of sampling points or subcarriers of the pilot signal. Similarly, after the second terminal receives the pilot signal sent by the first terminal, it will also perform a similar channel estimation operation to obtain the second channel estimation sequence h b =[ h b [1], h b [2],......, h b [ N The noise in the communication environment will affect the pilot signal, thus affecting the accuracy of channel estimation. The amplitude threshold is determined according to the noise power of the pilot signal, for example, .in, represents the amplitude threshold, Represents the noise power. The noise power can be estimated by measuring the signal strength of the pilot signal receiving end when no signal is sent, or by using some known noise statistical characteristics to calculate it. The amplitude threshold is used to filter the valid information in the channel estimation sequence. The channel amplitude is compared with the threshold to distinguish the significant changes in the channel characteristics from the random fluctuations that may be caused by noise. For the first channel estimation sequence h a The amplitude of each channel in h a [ n ] (i=1, 2, ⋯, N), and compare it with the amplitude threshold. If the channel amplitude is greater than or equal to the amplitude threshold, it is considered that the channel characteristics of this point are more significant and may contain useful information. At this time, the first indicative sequence S aThe indicative amplitude at the corresponding position in the channel is set to 1. If the channel amplitude is less than the amplitude threshold, the channel characteristics at that point are considered to be caused by noise, and the indicative amplitude at the corresponding position is set to 0. The first indicative sequence is ultimately obtained. Similarly, for each channel amplitude in the second channel estimation sequence, the same method as for generating the first indicative sequence is used to compare it with the amplitude threshold to obtain the second indicative sequence. An AND operation is performed on the first and second indicative sequences, that is, an AND operation is performed on each corresponding position in the sequence. Only when both are 1 is the corresponding position in the final indicative sequence 1; otherwise, it is 0. The purpose of the final indicative sequence is to further filter out the parts of the channel characteristics of the communicating parties that are consistent. These parts are more likely to reflect true channel changes rather than noise interference. Based on the final indicative sequence, the phase information in the first and second channel estimation sequences is filtered. For positions in the final indicative sequence where the indicative amplitude is 1, the corresponding phase values are extracted from the first channel estimation sequence. These phase values constitute the first fuzzy phase sequence. Similarly, the corresponding phase values are extracted from the second channel estimation sequence to constitute the second fuzzy phase sequence. An ambiguous phase sequence reflects the consistent phase variations in the channel characteristics between communicating parties. However, due to factors such as noise, its accuracy is relatively low. When a first terminal sends data to a second terminal, data transmission errors may occur, necessitating retransmission. During the retransmission request process, if the second terminal successfully decodes the retransmission request data sent by the first terminal (decoding success can be determined using verification mechanisms such as a cyclic redundancy check (CRC)), the successfully decoded data is mapped to an accurate phase. The specific mapping method can be designed based on the communication protocol and actual needs. For example, the successfully decoded data can be mapped to phase values according to a certain encoding rule to generate a first accurate phase sequence and a second accurate phase sequence. The accurate phase sequence is generated based on the successfully decoded data and has high accuracy, reflecting the relatively stable phase relationship between the communicating parties during data transmission. The first terminal combines the first accurate phase sequence and the first ambiguous phase sequence to generate an encryption security key. The second terminal also combines the second accurate phase sequence and the second ambiguous phase sequence using the same processing method as the first terminal (e.g., the same cross-addition rule and weighting coefficients) to generate a decryption security key.

[0023] Optionally, generating a first indicative sequence according to a relationship between the channel amplitude in the first channel estimation sequence and the amplitude threshold, and generating a second indicative sequence according to a relationship between the channel amplitude in the second channel estimation sequence and the amplitude threshold includes: The first exemplary sequence and the second exemplary sequence are generated by the following formula: ; Among them, S a Represents the first indicative sequence, Sb represents the second indicative sequence, n∈[1,N], n is a positive integer, N represents the length of the first channel estimation sequence or the second channel estimation sequence, Indicates the first exemplary sequence or the second exemplary sequence n Indicative amplitude: ; in, represents the first channel estimation sequence or the second channel estimation sequence n The channel amplitude, Indicates the amplitude threshold.

[0024] In the above formula, represents the first channel estimation sequence or the second channel estimation sequence n The channel estimation sequence is obtained by processing the pilot signal at the receiving end, which reflects the response characteristics of the channel at different frequency points or time points. The size of the channel amplitude is affected by the characteristics of the channel itself (such as path loss, multipath effect, etc.) and noise. The amplitude threshold is a value pre-set based on factors such as the noise power of the pilot signal. The role of the amplitude threshold is to screen out the channel amplitudes with significant significance in the channel estimation sequence and exclude the random fluctuations that may be caused by noise. For each indicative amplitude in the indicative sequence S i [ n ], its value rules are as follows: hour, This means that at this position, the channel amplitude is large and exceeds the amplitude threshold. This may be due to significant changes caused by the characteristics of the channel itself (such as path attenuation, reflection, etc.), rather than random fluctuations dominated by noise. Therefore, the indicative amplitude of this position is set to 1, indicating that the information at this position may have practical significance and can be used for subsequent operations such as security key generation. When hour, This indicates that the channel amplitude at this location is small, below the amplitude threshold, and is likely a random fluctuation caused by noise, lacking actual channel characteristic information. Therefore, the indicative amplitude at this location is set to 0, and this information may be ignored in subsequent processing.

[0025] By comparing the channel amplitude with the amplitude threshold to generate an indicative sequence, the impact of noise on channel estimation can be effectively suppressed. In a communication environment, noise is inevitable and will interfere with the accuracy of channel estimation. The indicative sequence only retains the part of the channel amplitude that exceeds the threshold. These parts are more likely to reflect the true channel characteristics, thereby reducing the impact of noise on subsequent processing. The indicative sequence plays the role of information screening, extracting consistent and significant information from the channel estimation sequence. In rail transit sensor network communications, the communicating parties need to generate security keys based on consistent channel characteristics. The indicative sequence can help both parties screen out channel amplitude positions that may be consistent, laying the foundation for the subsequent generation of consistent security keys. For example, when the indicative amplitudes of the first and second indicative sequences of the communicating parties are both 1 at the corresponding positions, it means that the channel characteristics at that position are significant to both parties and may be used for further key generation.

[0026] Optionally, performing an AND operation on the first indicative sequence and the second indicative sequence to obtain a final indicative sequence includes: The final indicative sequence is generated by the following formula: W =[ W [1], W [2],......, W [ N ]], in, W represents the final indicative sequence, W [ n ] indicates the first n Indicative amplitude, n∈[1,N], n is a positive integer, N represents the length of the first channel estimation sequence or the second channel estimation sequence: ; in, S a [ n ] represents the first indicative sequence n An indicative amplitude, S b [ n ] represents the first n An indicative amplitude.

[0027] If and only if S a [ n ]=1 and S b [ n ]=1, W [ n]=1. This means that at the corresponding position of the first indicative sequence and the second indicative sequence of the communicating parties, both parties believe that the channel characteristics at that position are significant (i.e., the channel amplitude exceeds the amplitude threshold), so the indicative amplitude of the final indicative sequence at that position is set to 1, indicating that the channel characteristics at that position are consistent between both parties, which may reflect the actual channel changes. As long as S a [ n ]and S b [ n ] is 0, then W [ n ]=0. This indicates that in the indicative sequence of at least one party, the channel characteristics of this position are considered to be insignificant, which may be caused by noise interference or other factors, so it is ignored in the final indicative sequence. The core idea of the AND operation is to filter out the consistent parts of the channel characteristics of the communicating parties. In rail transit sensor network communications, since the environments in which the communicating parties are located may be different, the channel signals received by each party will be affected by different degrees of noise and interference. Through the AND operation, only those positions that are considered to have significant channel characteristics by both parties will be retained in the final indicative sequence, thereby eliminating inconsistent information caused by unilateral noise or interference, and improving the accuracy and reliability of the final indicative sequence.

[0028] The final indicative sequence obtained through the AND operation can better reflect the consistency of the channel characteristics between the communicating parties. In actual communications, channel characteristics may change due to various factors, such as train movement and reflections from surrounding objects. The AND operation can filter out random variations that occur only on one side, preserving the stable channel characteristics shared by both parties, ensuring consistent security key generation. The consistency of the final indicative sequence helps improve the security of the security key. If the security key is generated based on inconsistent channel characteristics between the two parties, key mismatches may occur during communication, leading to communication failure or information leakage. The final indicative sequence obtained through the AND operation ensures that both parties use the same channel characteristic information to generate the key, increasing the complexity and unpredictability of the key, thereby improving communication security. Because the AND operation excludes channel characteristic locations that one party considers insignificant, it effectively reduces the impact of noise on the final indicative sequence. Noise is inevitable in communication environments and can interfere with the accuracy of channel estimation. The AND operation only retains those channel characteristics that are considered significant by both parties, reducing the interference of noise on the subsequent security key generation process.

[0029] Optionally, the filtering the phase of the channel estimation sequence according to the final indicative sequence to generate a first ambiguous phase and a second ambiguous phase includes: The target phases of the first fuzzy phase and the second fuzzy phase are generated by the following formula: ; in, Indicates when W [ n ]=1, the corresponding phase value is retained, Indicates the first fuzzy phase or the second fuzzy phase k target phase, k ∈[1, N ], k is a positive integer, and the first fuzzy phase or the second fuzzy phase is generated according to a plurality of the target phases.

[0030] expression Used to extract the target phase from the channel estimation sequence. i = a When corresponding to the first terminal, i = b When corresponding to the second terminal; k is the index of the target phase sequence, n is the index of the channel estimation sequence and the final characteristic sequence. The core of this expression lies in the condition W [ n ] = 1. Only when the final characteristic sequence W Middle n Indicative amplitude W [ n ] is 1, the first channel estimation sequence or the second channel estimation sequence n Channel amplitude The corresponding phase value Extracted as the target phase This means that only those positions that are considered to have significant channel characteristics on both sides of the communication (as determined by the final characteristic sequence W The phase value corresponding to the marker will be retained. Indicates the calculation of channel amplitude The phase value can be obtained by calculating the inverse tangent function of the complex channel response (or other phase calculation methods). W All W [ n ]=1, and extract the corresponding phase values in turn , and obtain a series of target phases ,in k The value range depends on W [ n ] = 1. The collected multiple target phases are sorted in a certain order (for example,n The first fuzzy phase sequence (corresponding to the first terminal) or the second fuzzy phase sequence (corresponding to the second terminal) is constructed. W [1]=1, W [3]=1, W [5]=1, then the first fuzzy phase sequence .

[0031] By selecting phases based on the final indicative sequence, the phase values in both the first and second fuzzy phases are extracted from locations where the channel characteristics of both communicating parties are consistent. This helps improve the consistency of the fuzzy phases, reduces phase discrepancies caused by unilateral noise or interference, and facilitates the subsequent generation of consistent security keys. During communication, noise can affect the estimated channel phase, causing random fluctuations in the phase values. However, the final indicative sequence eliminates locations with insignificant channel characteristics that may be caused by noise. Therefore, the fuzzy phases selected based on this sequence better reflect actual channel phase variations and mitigate noise interference on phase information. Fuzzy phases are an important raw material for generating security keys. Further processing (such as quantization and encoding) of the first and second fuzzy phases, combined with accurate phase information, can generate highly secure encryption and decryption security keys, ensuring the security of rail transit sensor network communications.

[0032] Optionally, mapping the successfully decoded data of the retransmission request sent by the first terminal to the second terminal into a first accurate phase and a second accurate phase includes: The first and second accurate phases are generated by the following equations: ; Where data represents the successfully decoded data, f(·) represents the mapping function, and boolBob represents the indicator of whether the second terminal has successfully decoded. If it is zero, it means that the second terminal has successfully decoded. represents the first fuzzy phase or the second fuzzy phase, Indicates the first accurate phase or the second accurate phase.

[0033] When a first terminal sends data to a second terminal, the second terminal may not be able to correctly decode it the first time and will send a retransmission request to the first terminal. After receiving the retransmission request, the first terminal may process the original data (such as adding redundant information or adjusting the encoding method) and retransmit it. If the second terminal successfully decodes the retransmitted data, the successfully decoded data contains information that can be used to generate an accurate phase. f(·) represents a mapping function, which maps successfully decoded data to an accurate phase. Its specific form depends on the design requirements of the communication system and the key generation algorithm. The mapping function converts the information in the successfully decoded data (such as data bits, modulation symbols, etc.) into a phase value, which is used as the accurate phase for subsequent key generation. For example, the mapping function can generate a phase value based on the bit values of the data according to a certain rule (such as mapping bit 0 to phase 0 and bit 1 to phase π). Figure 2 This is a schematic diagram of the mapping function disclosed in the embodiment of this application. The mapping function converts a binary bit sequence into a discrete phase sequence based on a specific relationship. The input bit sequence is mapped to the coordinate axis through the constellation diagram, and each symbol determines the phase of the mapping. If the horizontal coordinate of the symbol point is x , the vertical coordinate is y , then the corresponding phase is arctan ( y / x ). Assuming the system adopts 8PSK modulation, the mapping relationship is as follows Figure 2 In the above formula, boolBob is a binary indicator used to identify whether the second terminal successfully decoded the retransmission request data sent by the first terminal. If boolBob = 0, it means that the second terminal successfully decoded the data; if boolBob = 1, it may indicate that the second terminal failed to decode the data. Only when boolBob = 0 is the accurate phase generated based on the successfully decoded data.

[0034] Due to factors such as quantization error, the fuzzy phases generated by the communicating parties may differ to some extent, resulting in inconsistent keys generated based on the fuzzy phases. Accurate phases, on the other hand, are generated based on successfully decoded data. When both communicating parties successfully decode the same data, the generated accurate phases are more consistent, thereby improving the consistency of the generated keys. Accurate phases can more accurately reflect the information during the communication process and reduce the predictability of keys caused by phase errors. By combining fuzzy and accurate phases to generate keys, the complexity and randomness of the keys are increased, improving the security of the keys and making it more difficult for attackers to crack the keys. In rail transit sensor network communications, accurate phase generation helps reduce the number of retransmissions caused by key mismatches, improving communication efficiency and reliability. Accurate phases can also be used for operations such as channel estimation optimization and adaptive modulation and coding, further improving the performance of communication systems.

[0035] Optionally, generating an encryption security key according to the first accurate phase and the first fuzzy phase, and generating a decryption security key according to the second accurate phase and the second fuzzy phase includes: Generate an encryption security key or a decryption security key using the following formula: ; in, represents an encryption security key or a decryption security key, represents the first fuzzy phase or the second fuzzy phase, Indicates the first accurate phase or the second accurate phase.

[0036] Represents the encryption security key, which is used to encrypt the symbol data modulated by the transmitter and to achieve the encryption effect by rotating the constellation points; Represents the decryption security key, which is used to decrypt the symbol data received by the receiving end, and reversely rotates the constellation points to achieve the decryption effect. The precise phase and fuzzy phase are combined into new phase information for key information encryption. The specific method is as follows Figure 3 shown.

[0037] Optionally, the method further includes: Sending, by the first terminal, a hash value of a preset number of digits of the encryption security key to the second terminal, and comparing, by the second terminal, the hash value of the preset number of digits with a hash value corresponding to the decryption security key; When the preset number of digits of the hash value matches the hash value corresponding to the decryption security key, it is determined that the encryption security key and the decryption security key are consistent.

[0038] A hash function maps input data of arbitrary length (here, the encryption security key) to an output of fixed length (a hash value). It exhibits properties such as one-way transmission (making it difficult to deducing the original data from the hash value) and collision resistance (making it difficult to find two different input data that produce the same hash value). To improve verification efficiency and reduce data transmission volume, the entire hash value of the encryption security key is typically not transmitted. Instead, the first few bits of the hash value (such as the first 8 or 16 bits) are selected as a preset-bit hash value. The selection of the preset bit count requires a balance between security and transmission efficiency. Too few bits may increase the probability of collisions, affecting verification accuracy; too many bits may increase data transmission volume and reduce efficiency. The second terminal uses the same hash function as the first terminal to hash the decryption security key it generates, obtaining the hash value corresponding to the decryption security key. Since both parties use the same hash function and key generation method (based on channel characteristics and successfully decoded data), the hash values corresponding to their keys should theoretically be consistent. The second terminal compares the preset-bit hash value of the encryption security key received from the first terminal with the hash value corresponding to its own decryption security key, bit by bit. This comparison can quickly determine whether the hash values of the two parties' keys are identical over a preset number of bits, thereby preliminarily determining whether the keys are consistent. After generating an encryption security key, the first terminal performs a hash operation on the encryption security key using a selected hash function to obtain a complete hash value. It then extracts a preset number of bits (e.g., the first 16 bits) from the complete hash value as the preset number of bits hash value and sends it to the second terminal via a communication link. After generating a decryption security key, the second terminal also performs a hash operation on the decryption security key using the same hash function to obtain a complete hash value corresponding to the decryption security key. It then extracts the hash value of the same number of bits as the first terminal (e.g., the first 16 bits) and compares it with the preset number of bits hash value received from the first terminal. If the preset number of bits hash value exactly matches the hash value corresponding to the decryption security key, it indicates that the hash values of the two parties' keys are identical over the preset number of bits, and a preliminary determination is made that the encryption security key and decryption security key are consistent. At this point, the communicating parties can use this key for subsequent encryption and decryption operations. If the preset number of bits hash value does not match the hash value corresponding to the decryption security key, it indicates that the two parties' keys may differ, and the communicating parties must re-generate and verify the key until key consistency verification is successful.

[0039] Key consistency verification ensures that both communicating parties use the same key for encryption and decryption operations, preventing data decryption failure or information leakage due to key inconsistency. In rail transit sensor network communications, data transmission between trains and base stations involves sensitive information such as the train's operating status and control instructions. Key consistency verification is a critical step in ensuring communication security. Compared to transmitting the entire key for comparison, transmitting a hash value with a preset number of bits can significantly reduce the amount of data transmitted and improve verification efficiency. In rail transit communications, data transmission requires high real-time performance. Reducing the amount of data transmitted can reduce communication latency and improve communication efficiency. Key consistency verification can promptly detect key generation errors caused by communication interference, equipment failure, and other reasons, avoiding the use of incorrect keys for encryption and decryption operations, thereby enhancing the reliability of rail transit sensor network communication systems.

[0040] In order to verify the effect of the embodiment of the present application, a key extraction scheme based on channel characteristics is used as a comparison and compared with the embodiment of the present application. h AE and legal channels h AB There is a certain correlation, and the eavesdropping channel can be modeled as follows: ; in, Represents the correlation between the eavesdropping channel and the legitimate channel, between [0, 1], w represents a parameter that follows N (0, 1) distribution and is unrelated to the legitimate channel, n e represents the equivalent receiver noise at the eavesdropping end.

[0041] The comparison scheme uses a key extraction scheme based on channel characteristics. When the eavesdropped channel and the legitimate channel are highly correlated, the channel estimation sequences obtained by the two are almost identical. Therefore, the key obtained by the eavesdropper is not much different from the real key, posing a certain threat to system security. In the simulation, the correlation between the channels is set to 0.9, the modulation method is QPSK, the channel is a Rayleigh channel, the signal-to-noise ratio range is 0 to 30dB, and the maximum number of retransmissions is 5.

[0042] The performance metrics include the following: 1. The bit error rate of the legitimate receiving end and the bit error rate of the eavesdropping end. This indicator can directly reflect the reliability and security of the system; 2. Bit Generation Rate (BGR): This indicator is defined as the average number of keys that can be generated per channel, where N is the length of the first channel estimation sequence or the second channel estimation sequence. In this solution, the equivalent BGR is defined as follows: ; Where Lf represents the length of the fuzzy phase key, Lp represents the length of the accurate phase key, M is the system modulation order, and boolBob is an indicator indicating whether the legitimate receiving end has successfully decoded. If it is zero, it means that Bob's end has successfully decoded.

[0043] Figure 4 is a schematic diagram of the bit error rate curve of the receiving end and the eavesdropping end disclosed in the embodiment of this application, such as Figure 4 As shown, the bit error rate of the embodiment of the present application at the legitimate receiving end is reduced compared to the baseline solution at all signal-to-noise ratios, resulting in a performance gain of approximately 4dB, enhancing system reliability. The bit error rate at the eavesdropping end is increased compared to the baseline solution at all signal-to-noise ratios. When the signal-to-noise ratio is greater than 9dB, the bit error rate at the eavesdropping end is approximately 0.26, a 20-fold improvement compared to the baseline solution, resulting in a security gain of approximately 15dB, enhancing system security.

[0044] Figure 5 Schematic diagram of bit generation rate curves under different modulation modes disclosed in the embodiments of this application, such as Figure 5 As shown, the BGR curves for PSK and QAM modulation schemes of the same order follow the same trend: 8PSK and 8QAM ultimately approach 2 bits / symbol, and 16PSK and 16QAM ultimately approach 3 bits / symbol. When the signal-to-noise ratio (SNR) is poor, the number of retransmissions reaches its upper limit, the legitimate receiver fails to successfully decode, the system cannot extract accurate phase information, and the bit rate is limited. When the SNR improves, the legitimate receiver successfully decodes, and the system combines accurate and ambiguous phase information for encrypted transmission. The system's bit rate increases, eventually approaching a constant value.

[0045] This embodiment also discloses a hybrid phase security key extraction system for rail transit sensor networks. Figure 6 This is a module diagram of a hybrid phase security key extraction system for rail transit sensor network disclosed in an embodiment of the present application, such as Figure 6 As shown, the system includes a channel module 601, an exemplary module 602, a phase module 603 and a key module 604, wherein: a channel module 601 configured to obtain pilot signals sent between a first terminal and a second terminal, determine a first channel estimation sequence for the first terminal and a second channel estimation sequence for the second terminal, and determine an amplitude threshold based on noise power of the pilot signals; an indicative module 602 configured to generate a first indicative sequence based on a relationship between the channel amplitude in the first channel estimation sequence and the amplitude threshold, generate a second indicative sequence based on a relationship between the channel amplitude in the second channel estimation sequence and the amplitude threshold, and perform an AND operation on the first indicative sequence and the second indicative sequence to obtain a final indicative sequence; a phase module 603 configured to filter the phase of the channel estimation sequence according to the final indicative sequence, generate a first ambiguous phase and a second ambiguous phase, and map successfully decoded data of a retransmission request sent by the first terminal to the second terminal into a first accurate phase and a second accurate phase; The key module 604 is configured to generate an encryption security key according to the first accurate phase and the first fuzzy phase, and to generate a decryption security key according to the second accurate phase and the second fuzzy phase.

[0046] Optionally, the exemplary module 602 is configured to: The first exemplary sequence and the second exemplary sequence are generated by the following formula: ; Among them, S a Represents the first indicative sequence, S b represents the second indicative sequence, n∈[1,N], n is a positive integer, N represents the length of the first channel estimation sequence or the second channel estimation sequence, Indicates the first exemplary sequence or the second exemplary sequence n Indicative amplitude: ; in, represents the first channel estimation sequence or the second channel estimation sequence n The channel amplitude, Indicates the amplitude threshold.

[0047] Optionally, the exemplary module 602 is configured to: The final indicative sequence is generated by the following formula: W =[ W [1], W [2],......, W [ N ]], in, W represents the final indicative sequence, W [ n ] indicates the first n Indicative amplitude, n∈[1,N], n is a positive integer, N represents the length of the first channel estimation sequence or the second channel estimation sequence: ; in, S a [ n ] represents the first indicative sequence n An indicative amplitude, S b [ n ] represents the first n An indicative amplitude.

[0048] Optionally, the phase module 603 is configured to: The target phases of the first fuzzy phase and the second fuzzy phase are generated by the following formula: ; in, Indicates when W [ n ]=1, the corresponding phase value is retained, Indicates the first fuzzy phase or the second fuzzy phase k target phase, k ∈[1, N ], k is a positive integer, and the first fuzzy phase or the second fuzzy phase is generated according to a plurality of the target phases.

[0049] Optionally, the phase module 603 is configured to: The first and second accurate phases are generated by the following equations: ; Where data represents the successfully decoded data, f(·) represents the mapping function, and boolBob represents the indicator of whether the second terminal has successfully decoded. If it is zero, it means that the second terminal has successfully decoded. represents the first fuzzy phase or the second fuzzy phase, Indicates the first accurate phase or the second accurate phase.

[0050] Optionally, the key module 604 is configured to: Generate an encryption security key or a decryption security key using the following formula: ; in, represents an encryption security key or a decryption security key, represents the first fuzzy phase or the second fuzzy phase, Indicates the first accurate phase or the second accurate phase.

[0051] Optionally, the system further includes a verification module configured to: Sending, by the first terminal, a hash value of a preset number of digits of the encryption security key to the second terminal, and comparing, by the second terminal, the hash value of the preset number of digits with a hash value corresponding to the decryption security key; When the preset number of digits of the hash value matches the hash value corresponding to the decryption security key, it is determined that the encryption security key and the decryption security key are consistent.

[0052] It should be noted that the above embodiments provide devices that implement their functions using only the division of the above functional modules as examples. In actual applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above. In addition, the device and method embodiments provided in the above embodiments are based on the same concept. The specific implementation process is detailed in the method embodiment and will not be repeated here.

[0053] This embodiment also discloses an electronic device, referring to Figure 7 The electronic device may include: at least one processor 701 , at least one communication bus 702 , a user interface 703 , a network interface 704 , and at least one memory 705 .

[0054] The communication bus 702 is used to implement the connection and communication between these components.

[0055] The user interface 703 may include a display screen (Display) and a camera (Camera). Optionally, the user interface 703 may also include a standard wired interface and a wireless interface.

[0056] The network interface 704 may optionally include a standard wired interface or a wireless interface (such as a WI-FI interface).

[0057] The processor 701 may include one or more processing cores. Using various interfaces and circuits, the processor 701 connects to various components within the server. It executes instructions, programs, code sets, or instruction sets stored in the memory 705, as well as accesses data stored in the memory 705, to perform various server functions and process data. Optionally, the processor 701 may be implemented using at least one of the following hardware forms: a digital signal processing (DSP), a field-programmable gate array (FPGA), or a programmable logic array (PLA). The processor 701 may integrate one or a combination of a central processing unit (CPU), a graphics processing unit (GPU), and a modem. The CPU primarily processes the operating system, user interface, and application programs; the GPU is responsible for rendering and drawing content displayed on the display screen; and the modem handles wireless communications. It is understood that the modem may also be implemented independently of the processor 701 and implemented on a separate chip.

[0058] Among them, the memory 705 may include a random access memory (RAM) or a read-only memory (Read-Only Memory). Optionally, the memory 705 includes a non-transitory computer-readable storage medium. The memory 705 can be used to store instructions, programs, codes, code sets or instruction sets. The memory 705 may include a program storage area and a data storage area, wherein the program storage area may store instructions for implementing an operating system, instructions for at least one function (such as a touch function, a sound playback function, an image playback function, etc.), instructions for implementing the above-mentioned various method embodiments, etc.; the data storage area may store data involved in the above-mentioned various method embodiments, etc. The memory 705 may also be optionally at least one storage device located away from the aforementioned processor 701. As Figure 7 As shown, the memory 705 as a computer storage medium may include an operating system, a network communication module, a user interface module, and an application program of a hybrid phase security key extraction method for a rail transit sensor network.

[0059] exist Figure 7In the electronic device shown, the user interface 703 is mainly used to provide an input interface for the user and obtain the data input by the user; and the processor 701 can be used to call an application stored in the memory 705 for a hybrid phase security key extraction method for a rail transit sensor network. When executed by one or more processors 701, the electronic device executes one or more methods in the above embodiments.

[0060] It should be noted that for the aforementioned method embodiments, for simplicity of description, they are all expressed as a series of action combinations, but those skilled in the art should be aware that this application is not limited by the order of the actions described, because according to this application, certain steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily required for this application.

[0061] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0062] In the several embodiments provided in this application, it should be understood that the disclosed devices can be implemented in other ways. For example, the device embodiments described above are merely schematic, such as the division of units, which is only a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some service interface, and the indirect coupling or communication connection of devices or units can be electrical or other forms.

[0063] Units described as separate components may or may not be physically separate, and components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0064] In addition, the functional units in the various embodiments of the present application may be integrated into a single processing unit, or each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0065] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable memory. Based on this understanding, the technical solution of this application, or the portion that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a memory 705 and includes several instructions for causing a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the various embodiments of the method of this application. The aforementioned memory 705 includes various media that can store program code, such as a USB flash drive, a mobile hard drive, a magnetic disk, or an optical disk.

[0066] The above is only an exemplary embodiment of the present disclosure and cannot be used to limit the scope of the present disclosure. That is, any equivalent changes and modifications made according to the teachings of the present disclosure are still within the scope of the present disclosure. After considering the disclosure of the specification, those skilled in the art will easily think of other embodiments of the present disclosure. This application is intended to cover any variations, uses or adaptive changes of the present disclosure, which follow the general principles of the present disclosure and include common knowledge or customary technical means in the technical field that are not recorded in the present disclosure. The description and examples are to be regarded as exemplary only, and the scope and spirit of the present disclosure are defined by the claims.

Claims

1. A hybrid phase security key extraction method for rail transit sensor network, characterized in that: Applied to a key extraction platform, the method includes: Acquire pilot signals sent between a first terminal and a second terminal, determine a first channel estimation sequence for the first terminal and a second channel estimation sequence for the second terminal, and determine an amplitude threshold according to noise power of the pilot signals; generating a first indicative sequence based on a relationship between a channel amplitude in the first channel estimation sequence and the amplitude threshold, generating a second indicative sequence based on a relationship between a channel amplitude in the second channel estimation sequence and the amplitude threshold, and performing an AND operation on the first indicative sequence and the second indicative sequence to obtain a final indicative sequence; Filtering the phase of a channel estimation sequence according to the final indicative sequence to generate a first ambiguous phase and a second ambiguous phase, and mapping successfully decoded data of a retransmission request sent by the first terminal to the second terminal into a first accurate phase and a second accurate phase; An encryption security key is generated according to the first accurate phase and the first ambiguous phase, and a decryption security key is generated according to the second accurate phase and the second ambiguous phase.

2. The hybrid phase security key extraction method for rail transit sensor network according to claim 1 is characterized in that: Generating a first indicative sequence according to a relationship between the channel amplitude in the first channel estimation sequence and the amplitude threshold, and generating a second indicative sequence according to a relationship between the channel amplitude in the second channel estimation sequence and the amplitude threshold comprises: The first exemplary sequence and the second exemplary sequence are generated by the following formula: ； Among them, S a Represents the first indicative sequence, S b represents the second indicative sequence, n∈[1,N], n is a positive integer, N represents the length of the first channel estimation sequence or the second channel estimation sequence, Indicates the first exemplary sequence or the second exemplary sequence n An indicative amplitude, ； in, represents the first channel estimation sequence or the second channel estimation sequence n The channel amplitude, Indicates the amplitude threshold.

3. The hybrid phase security key extraction method for rail transit sensor network according to claim 1 is characterized in that: The performing an AND operation on the first indicative sequence and the second indicative sequence to obtain a final indicative sequence includes: The final indicative sequence is generated by the following formula: W =[ W [1]， W [2]，......， W [ N ]]， in, W represents the final indicative sequence, W [ n ] indicates the first n Indicative amplitude, n∈[1,N], n is a positive integer, N represents the length of the first channel estimation sequence or the second channel estimation sequence, ； in, S a [ n ] represents the first indicative sequence n An indicative amplitude, S b [ n ] represents the first n An indicative amplitude.

4. The hybrid phase security key extraction method for rail transit sensor network according to claim 3 is characterized in that: The step of screening the phase of the channel estimation sequence according to the final indicative sequence to generate a first ambiguous phase and a second ambiguous phase comprises: The target phases of the first fuzzy phase and the second fuzzy phase are generated by the following formula: ； in, Indicates when W [ n ]=1, the corresponding phase value is retained, Indicates the first fuzzy phase or the second fuzzy phase k target phase, k ∈[1, N ], k is a positive integer, The first ambiguous phase or the second ambiguous phase is generated according to a plurality of the target phases.

5. The hybrid phase security key extraction method for rail transit sensor network according to claim 4 is characterized in that: Mapping the successfully decoded data of the retransmission request sent by the first terminal to the second terminal into a first accurate phase and a second accurate phase includes: The first and second accurate phases are generated by the following equations: ； Where data represents the successfully decoded data, f(·) represents the mapping function, and boolBob represents the indicator of whether the second terminal has successfully decoded. If it is zero, it means that the second terminal has successfully decoded. represents the first fuzzy phase or the second fuzzy phase, Indicates the first accurate phase or the second accurate phase.

6. The hybrid phase security key extraction method for rail transit sensor network according to claim 5 is characterized in that: Generating an encryption security key according to the first accurate phase and the first fuzzy phase, and generating a decryption security key according to the second accurate phase and the second fuzzy phase includes: Generate an encryption security key or a decryption security key using the following formula: ； in, represents an encryption security key or a decryption security key, represents the first fuzzy phase or the second fuzzy phase, Indicates the first accurate phase or the second accurate phase.

7. The hybrid phase security key extraction method for rail transit sensor network according to claim 1 is characterized in that: The method further comprises: Sending, by the first terminal, a hash value of a preset number of digits of the encryption security key to the second terminal, and comparing, by the second terminal, the hash value of the preset number of digits with a hash value corresponding to the decryption security key; When the preset number of digits of the hash value matches the hash value corresponding to the decryption security key, it is determined that the encryption security key and the decryption security key are consistent.

8. A hybrid phase security key extraction system for rail transit sensor networks, characterized in that: It includes a channel module, a characteristic module, a phase module and a key module, wherein: a channel module configured to obtain pilot signals sent between a first terminal and a second terminal, determine a first channel estimation sequence for the first terminal and a second channel estimation sequence for the second terminal, and determine an amplitude threshold based on noise power of the pilot signals; an indicative module configured to generate a first indicative sequence based on a relationship between the channel amplitude in the first channel estimation sequence and the amplitude threshold, generate a second indicative sequence based on a relationship between the channel amplitude in the second channel estimation sequence and the amplitude threshold, and perform an AND operation on the first indicative sequence and the second indicative sequence to obtain a final indicative sequence; a phase module configured to filter the phase of the channel estimation sequence according to the final indicative sequence, generate a first ambiguous phase and a second ambiguous phase, and map successfully decoded data of a retransmission request sent by the first terminal to the second terminal into a first accurate phase and a second accurate phase; The key module is configured to generate an encryption security key according to the first accurate phase and the first fuzzy phase, and to generate a decryption security key according to the second accurate phase and the second fuzzy phase.

9. An electronic device, characterized in that: The electronic device comprises a processor, a memory, a user interface and a network interface, wherein the memory is used to store instructions, the user interface and the network interface are both used to communicate with other devices, and the processor is used to execute the instructions stored in the memory so that the electronic device executes the method according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that The computer-readable storage medium stores instructions, and when the instructions are executed, the method according to any one of claims 1 to 7 is executed.

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