A short packet covert communication method against change point detection-based jamming attacks

Abstract

A short packet covert communication method for countering change-point detection-based interference attacks includes information sensing, key generation and codebook sharing, information encoding, information transmission, and decoding of the decrypted signal using a shared Gaussian codebook. The method includes a sending node, a receiving node, and a detection node. The detection node uses Shewhart change-point detection, meaning it makes a judgment each time it observes channel usage. Once the detection node detects a transmission from the sending node, it launches an interference attack to fully disrupt information transmission. Therefore, when a transmission is detected by the detection node and subjected to an interference attack, the destination node cannot successfully decode the data. To successfully transmit information, the sending node uses any moment during the interference gap to randomly transmit private data encoded with a finite block length with a priori transmission probability, thereby enhancing the concealment of the transmission.

Description

Technical Field

[0001] The present invention belongs to the technical field of wireless secure transmission, and in particular relates to a short packet covert communication method for resisting interference attacks based on change point detection. Background Art

[0002] The development of wireless communications has greatly improved the quality of our daily lives. However, due to the broadcast nature of wireless signals, malicious attackers can illegally eavesdrop through public channels, exposing private data to serious security risks during transmission and significantly compromising its confidentiality. To ensure the security of private data, researchers have developed physical layer security technologies based on traditional security techniques. These technologies leverage the fading characteristics of wireless channels to achieve absolute security under Shannon's information theory. However, while physical layer security technologies can protect private information from being decrypted by monitoring nodes, they cannot guarantee that the transmission of private information will remain undetected. If a monitor detects suspicious communication activity, it can interfere with the target's communications. Clearly, simply protecting the content of private data cannot meet higher security requirements. Meanwhile, with the advancement of information technology, jamming attack technologies are also continuously advancing. These include traditional jamming techniques such as single-tone jamming and blocking jamming, as well as intelligent jamming techniques such as tracking jamming and cognitive jamming. In response to these advancements in jamming technology, achieving higher levels of security in the defense and industrial sectors has become a key focus for researchers. Currently, anti-jamming technologies can be categorized as traditional and intelligent. Traditional anti-jamming methods utilize a larger signal bandwidth to evade jamming attacks. Intelligent anti-interference technology uses reinforcement learning and deep reinforcement learning to optimize anti-interference strategies such as channel selection, access control, and power allocation. However, given the simple structures and limited resources of battlefield IoT devices and individual soldier equipment, many demanding anti-interference technologies are difficult to implement. Furthermore, existing anti-interference technologies rely on strategy adjustments after a jamming attack occurs. Therefore, if covert wireless transmission can be concealed, the likelihood of wireless communications being eavesdropped on would be greatly reduced, and the damage caused by jamming attacks would be extremely limited.

[0003] In recent years, covert communication technology has attracted widespread attention from researchers because it can ensure that communication behavior is detected by unauthorized detection nodes with an extremely low probability. This technology primarily exploits the randomness of the environment to conceal communication behavior. Since private communication is not always transmitted, detection nodes are required to determine whether transmission is occurring. However, when communication uses finite-length coding to transmit data packets, the detection node is limited in the number of observation samples it collects, which increases its uncertainty about the existence of transmission behavior. The paper "Age of Information for Short-Packet Covert Communication" develops a new framework to jointly describe the concealment and timeliness of wireless communications. This research demonstrates that finite-block-length coding can enhance the concealment of communication. However, this research fails to consider that detection nodes not only detect communication but also interfere with it, making this approach unsuitable for practical security scenarios.

[0004] To conserve resources, detection nodes only initiate artificial interference to disrupt information transmission upon detecting wireless transmission activity. To counter these detection-jamming attacks, transmitting nodes design covert wireless communication schemes based on the limited length of data packet codes. These schemes simultaneously optimize transmit power and code length to achieve the optimal compromise between stealth and reliability. However, no relevant research in this area has yet been published. Summary of the Invention

[0005] The purpose of the present invention is to solve the problem when communication detection and interference attacks exist at the same time, and to provide a short packet covert communication method to counter interference attacks based on change point detection. This strategy realizes a covert communication scheme that is resistant to detection and interference attacks by optimizing the transmission power and coding length, thereby improving the effective transmission rate of the system.

[0006] A short packet covert communication method for countering a change point detection-based interference attack comprises the following steps:

[0007] Step 1: The information-sensing sending node uses the information-sensing module to obtain the private data packet and stores the perceived private data. When a gap in the jamming attack is detected, the sending node prepares to send the private data packet at any time during the gap with a prior probability ρ1. The prior probability ρ1 satisfies: 0 ≤ ρ1 < 1.

[0008] Step 2: Key Generation and Codebook Sharing Before private data transmission, the sending node and the destination node generate a random sequence of encryption keys by leveraging the reciprocity, time-varying, and spatial uniqueness of the wireless channel. The Gaussian coding codebook is encrypted with this key and then shared with the legitimate destination node.

[0009] Step 3: Information Encoding The sending node performs Gaussian encoding on the privacy data packet to be transmitted, where the length used for encoding is N D , indicating that the transmission of the privacy data packet needs to utilize N D Secondary channel usage. Considering both stealth and reliability, the optimal expression of the system's code length is as follows:

[0010]

[0011] in, Indicates the maximum encoding length of the sending node, represents the noise of the destination node, R represents the information coding rate, P represents the transmission power, N D It represents the optimal encoding length when the encoding length is not constrained by the range of values. Its expression is as follows:

[0012]

[0013] Where η represents the effective transmission rate of the system, and the expression of t is as follows:

[0014]

[0015] in, L represents the length of the average false alarm interval used by the detection node in Shewhart change point detection.

[0016] Step 4: When only the concealment performance of communication is considered in information transmission, the transmission power P of the sending node should satisfy:

[0017]

[0018] in, It indicates the optimal encoding length.

[0019] Step 5: Information Decoding: During each transmission cycle, the destination node first decrypts the information and then decodes the decrypted signal using a shared Gaussian codebook. A transmission is considered valid only if it is not detected or interfered with by the detection node. Furthermore, due to the limited code length of information, decoding errors are inevitable during transmission. Therefore, the effective transmission rate of the system is expressed as follows:

[0020] η=P c (1-δ)R, (9)

[0021] Among them, δ represents the packet error rate of the destination node, P c Indicates the probability of not being detected by the detection node during the transmission process. With the goal of maximizing the effective transmission rate of the system, the optimal transmission power P of the system is *It can be calculated according to the following equation:

[0022]

[0023] Among them, L represents the average false alarm interval length used by the detection node. Finally, the optimal value of the transmission power P can be obtained through one-dimensional search * .

[0024] The communication system of the present invention includes a sending node, a receiving node and a detection node. The sending node wants to transmit a private data packet to the destination node in a covert manner, while the detection node hopes to disrupt the transmission. In order to save resources and make timely judgments on the transmission behavior, the detection node adopts Shewhart change point detection, that is, the detection node makes a judgment every time it observes the use of the channel. Once the detection node detects the existence of the transmission behavior of the sending node, it will send an interference attack to fully destroy the transmission of information. Therefore, when the transmission behavior is detected by the detection node and is attacked by interference, the destination node cannot decode successfully. In order to successfully transmit information, the sending node will use any moment of the interference gap to randomly send private data encoded with a finite block length with a priori transmission probability, thereby enhancing the concealment of the transmission; by designing the transmission power size and the coding length of the information, the concealment and reliability of the transmission of private information are improved.

[0025] The present invention discloses a short packet covert communication method for countering interference attacks based on change point detection. In specific operation, the sending node sends a short data packet encoded with a finite block length to the destination node at any time during the interference gap with a shorter data packet encoding length and lower power, thereby achieving the effect of resisting detection-interference attacks. Unlike the currently existing anti-interference methods, the present invention has many advantages: First, the currently existing anti-interference attack methods all achieve anti-interference by adjusting the strategy after the attack occurs, making the secure transmission have a lag. The method proposed in this article can deal with potential interference attacks very well, so that the destructiveness of interference attacks is greatly alleviated. Secondly, the short data packet encoded with a finite block length sent can reduce a lot of transmission time and reduce the probability of detection by the detection node. Finally, the method of the present invention is simple to operate and does not require a large amount of information about the detection node to be analyzed, making it easier to implement in engineering and suitable for scenarios with high security requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of a model of a short packet covert communication system for counteracting interference attacks based on change point detection involved in the present invention.

[0027] Figure 2 It is a structural diagram of frames sent by a sending node and a detecting node involved in the present invention.

[0028] Figure 3 This is a simulation diagram of the effective transmission rate that can be achieved by the system corresponding to different transmission powers when the strategy proposed by the present invention is adopted in the application of the method embodiment of the present invention.

[0029] Figure 4 This is a simulation diagram of the maximum effective transmission rate that can be achieved by the system corresponding to different average false alarm lengths at the detection node when the strategy proposed by the present invention is adopted in the application of the method embodiment of the present invention. DETAILED DESCRIPTION

[0030] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0031] like Figure 1 The figure shows a short packet covert communication method to counter the interference attack based on change point detection. The system includes a sending node, a destination node and a detection node. The sending node wants to transmit the privacy data packet to the destination node in a covert manner, while the detection node hopes to destroy the transmission. In order to save resources and make timely judgments on the transmission behavior, the detection node adopts Shewhart change point detection, that is, the detection node makes a judgment every time it observes the use of the channel. Once the detection node detects the existence of the transmission behavior of the sending node, it will send an interference attack to fully destroy the transmission of information. Therefore, when the transmission behavior is detected by the detection node and is attacked by interference, the destination node cannot successfully decode it. The frame structure of the sending node sending privacy information and the detection node sending interference attack is as follows: Figure 2 As shown in the figure, we can see that in order to successfully transmit information, the sending node will use any moment during the interference gap to randomly send private data encoded with a finite block length with a priori probability ρ1 to enhance the confidentiality of the transmission. The method of the present invention includes the following steps:

[0032] Step 1: Key generation and codebook sharing: Before private data transmission, the sending node and the destination node generate a random sequence of encryption keys by leveraging the reciprocity, time-varying, and spatial uniqueness of the wireless channel. The key is used to encrypt the Gaussian encoding codebook, which is then shared with the legitimate destination node.

[0033] Step 2: Information Perception: The sending node uses the information perception module to continuously obtain private data packets and stores the perceived private data. When a gap in the jamming attack is detected, the sending node prepares to send the private data packet at any time during the gap with a prior probability ρ1. The prior probability ρ1 satisfies: 0 ≤ ρ1 < 1.

[0034] Step 3: Information encoding: The sending node performs Gaussian encoding on the privacy data packet to be transmitted, where the encoding length is N D, indicating that the transmission of the privacy data packet needs to utilize N D Secondary channel usage. Considering both confidentiality and reliability, the optimal expression for the coding length is as follows:

[0035]

[0036] in, Indicates the maximum encoding length of the sending node, represents the noise of the destination node, R represents the information coding rate, P represents the transmission power, N D It represents the optimal code length when the code length is not constrained by the value range. Its expression is as follows:

[0037]

[0038] Where η represents the effective transmission rate of the system, and the expression of t is as follows:

[0039]

[0040] in, L represents the length of the average false alarm interval used to detect the false alarm frequency of a node in Shewhart change point detection.

[0041] Step 4: Information transmission: When considering the concealment performance of communication, the transmission power P of the sending node should satisfy:

[0042]

[0043] in, It indicates the optimal encoding length.

[0044] Step 5: Information Decoding In each transmission cycle, the destination node uses the shared Gaussian codebook to decode the received signal. The expression of the private data received by the destination node is as follows:

[0045]

[0046] Where i = 1, 2, L, m represents the channel usage index; s A [i] is a complex Gaussian random variable with mean zero and variance 1, representing the symbol sent by the sending node during the i-th channel use; n J [i] satisfies the mean of zero and the variance of The complex Gaussian random variable represents the noise observed by the destination node when the sending node uses the channel for the i-th time. The received signal-to-noise ratio of the destination node is:

[0047]

[0048] In the transmission method mentioned in the present invention, the probability that the sending node is not detected by the detection node during the process of transmitting private information can be expressed as:

[0049]

[0050] The use of finite block length coding inevitably results in decoding errors at the destination node Bob. The packet error rate at the destination node can be expressed as:

[0051]

[0052] in is the standard Gaussian Q function; R is a fixed constant representing the data packet encoding transmission rate. For the convenience of calculation, we use the following linear function to approximate the packet error rate of the destination node

[0053]

[0054] Where θ = exp(R)-1,

[0055] The effective transmission rate of the system can be expressed as:

[0056] η c =P c (1-δ)R (5)

[0057] The higher the transmission power, the more reliable the privacy packet transmission, but the greater the probability of exposure. Similarly, the longer the code length, the greater the reliability of privacy packet transmission, but also reduces the concealment performance. With the goal of maximizing the system's effective transmission rate, the optimal transmission probability P of the system can be calculated according to the following equation:

[0058]

[0059] The effective transmission rate η in the transmission method of the present invention is different in the packet coding length N D The simulation results are as follows: Figure 3 As shown, the noise variance of the detection node and the destination node is set to The maximum transmission power of the sending node is set to P max =0dBm, the maximum value of the code length is set to Channel usage, the coding rate of the sending node is set to R = 0.05, and the average false alarm interval length at the detection node is L = 100. At the same time, under a given packet coding length, the effective transmission rate first increases and then decreases with the increase of transmission power, indicating that there is an optimal transmission power that maximizes the effective transmission rate. This is because while the transmission power can enhance the reliability of transmission, it also increases the risk of transmission exposure and interference attacks. At the same time, for a given transmission power, different coding lengths correspond to different effective transmission rates, and the effective transmission rate does not show a monotonic change with the increase of power, indicating that there is an optimal transmission power that maximizes the system's effective transmission rate.

[0060] The maximum effective transmission rate η of the present invention * The simulation results of different coding rates R with the change of average false alarm interval length L are as follows Figure 4 As shown in Figure 1, both the packet coding length and transmit power are optimal within the feasible domain. As can be seen from the figure, as the average false alarm interval length increases, the maximum effective transmission rate also increases. This is because increasing the average false alarm interval length reduces the false alarm probability at the detection node, increases the decision threshold, and thus increases the probability of missed detection, thereby improving the maximum effective transmission rate. Furthermore, the figure also shows that increasing the coding rate does not lead to a continuous increase in the maximum effective transmission rate, as this decreases transmission reliability.

[0061] The description of the above embodiment is relatively specific and detailed, but it only expresses a feasible implementation method of the present invention and does not limit the scope of the patent of the present invention. It should be pointed out that researchers and engineers in this field can add several variations or improvements based on this embodiment within the framework of the present invention, but these are all within the scope of protection of the patent of the present invention. The scope of protection of the patent of the present invention shall be based on the claims.

Claims

1. A short packet covert communication method against change point detection-based interference attacks, characterized in that The following steps are involved: Step 1: Information perception: The sending node uses the information perception module to obtain the private data packet and stores the perceived private data. When a gap in the interference attack is found, the sending node prepares to send the private data packet at any time during the gap with a prior probability of ρ1. The prior probability ρ1 satisfies: 0≤ρ1<1; Step 2: Key Generation and Codebook Sharing: Before private data transmission, the sending node and the destination node generate a random sequence of encryption keys by leveraging the reciprocity, time-varying, and spatial uniqueness of the wireless channel. This key is used to encrypt the Gaussian codebook, which is then shared with the legitimate destination node. Step 3: Information encoding: The sending node performs Gaussian encoding on the privacy data packet to be transmitted, where the length of the Gaussian encoding is N D , indicating that the transmission of the privacy data packet needs to utilize N D Secondary channel usage; considering both concealment and reliability, the optimal expression of the system's code length is as follows: in, Indicates the maximum encoding length of the sending node, represents the noise of the destination node, R represents the information coding rate, P represents the transmission power, It represents the optimal encoding length when the encoding length is not constrained by the range of values. Its expression is as follows: Where η represents the effective transmission rate of the system, and the expression of t is as follows: in, L represents the length of the average false alarm interval used by the detection node in Shewhart change point detection; represents the noise of the detection node; Step 4: Information transmission: When only the concealment performance of communication is considered, the transmission power P of the sending node satisfies: in, represents the noise of the destination node, R represents the information coding rate, Indicates the optimal coding length given; Step 5: Information decoding: In each transmission cycle, the destination node first decrypts the information and then decodes the decrypted signal using the shared Gaussian codebook.

2. The short packet covert communication method for resisting change point detection interference attack according to claim 1 is characterized in that The optimal expression for the coding length of the system in step 3 above is: in, Indicates the maximum encoding length of the sending node, represents the noise of the destination node, R represents the information coding rate, P represents the transmission power, It represents the optimal encoding length when the encoding length is not constrained by the range of values. Its expression is as follows: Where η represents the effective transmission rate of the system, and the expression of t is as follows: Where A and B represent the parameters in the formula, L represents the length of the average false alarm interval used by the detection node in Shewhart change point detection; Represents the noise of the detection node.

3. The short packet covert communication method for resisting interference attacks based on change point detection according to claim 2 is characterized in that In step 5 above, the expression for the destination node to receive private data is as follows: Where i = 1, 2, ..., m represents the channel usage index; s A [i] is a complex Gaussian random variable with mean zero and variance 1, representing the symbol sent by the sending node during the i-th channel use; n J [i] satisfies the mean of zero and the variance of The complex Gaussian random variable represents the noise observed by the destination node when the sending node uses the channel for the i-th time; P represents the sending power of the sending node; the received signal-to-noise ratio of the destination node is: When the sending node is transmitting private information, the probability of not being detected by the detection node is expressed as: Where L represents the length of the average false alarm interval used by the detection node in Shewhart change point detection; represents the noise of the detection node; N D Represents the length of Gaussian coding, indicating that the transmission of the privacy data packet requires the use of N D Secondary channel usage; The use of finite block length coding inevitably results in decoding errors at the destination node Bob. The packet error rate at the destination node is expressed as: in is the standard Gaussian Q function; R represents the information coding rate, and the following linear function is used to approximate the packet error rate of the destination node Among them, θ and k are parameters in the formula, θ=exp(R)-1, The effective transmission rate of the system is expressed as: or c =P c (1-δ)R (13) Among them, δ represents the packet error rate of the destination node, P c It represents the probability of not being detected by the detection node during the transmission process; the goal is to maximize the effective transmission rate of the system; the optimal transmission probability of the system P * Calculated according to the following equation: Where L represents the average false alarm interval length used by the detection node in Shewhart change point detection; P max Represents the maximum transmit power of the sending node; represents the noise of the detection node; represents the noise of the destination node; Indicates the optimal code length given; Finally, the optimal value of the transmission power P can be obtained through one-dimensional search * .

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