Millimeter wave-based mechanical disk covert channel implementation method and device

Abstract

The invention discloses a mechanical disk covert channel implementation method and device based on millimeter waves, and realizes the mechanical disk covert channel implementation method based on the millimeter waves by utilizing the characteristic that the vibration state of a disk can be influenced by normal channel seeking operation of the disk. Through an information coding mode, a track seeking operation serving as a conventional activity of a disk can be used for high-bit-rate information transmission, and through a vibration signal guided beam forming technology, a beam can be accurately directed to an optimal direction for sensing the vibration of the disk, so that the signal-to-noise ratio of a vibration signal is effectively improved, the sensing range is expanded, and meanwhile, the sensing efficiency is improved. Due to the fact that the formed wave beam is concentrated in energy and has high directivity, the wave beam can be reflected by an object in the environment, then the wave beam direction is adjusted, sensing of magnetic disk vibration in a non-line-of-sight scene is achieved, the signal-to-noise ratio of a vibration signal can be further enhanced through a multi-antenna phase coherent integration algorithm, and the magnetic disk vibration sensing accuracy is improved. Therefore, the system has a very strong long-distance sensing capability.

Description

Technical Field

[0001] The present invention relates to a novel covert channel implementation method, in particular to a millimeter wave-based mechanical disk covert channel implementation method and device. Background Art

[0002] With the rapid development of information technology, the importance of information security has become increasingly prominent, and covert channels, as an important part of it, have attracted much attention. In a covert channel, the content of communication is limited to the intended recipient, and third parties can neither detect the existence of the communication nor eavesdrop or intercept the information, thereby ensuring the confidentiality of the communication and effectively resisting interference and attacks. In this context, out-of-band covert channels, as a new type of covert channel technology, show unique advantages. It transmits information through media outside the system or network (such as electromagnetic waves, sound waves, light, etc.), does not rely on traditional network protocols and transport layers, but uses the characteristics or vulnerabilities in the physical environment to achieve covert communication, thereby significantly improving the security and concealment of information transmission.

[0003] However, existing out-of-band covert channels still have some limitations. For example, many covert channels (such as optical signals) have high requirements for transmission conditions and must be carried out in a line-of-sight environment. Any physical obstacles may cause channel interruption. In addition, since the signal is easily attenuated, most covert channels are only effective at close range or within contact range, which limits their practicality. Summary of the invention

[0004] The present invention aims at the problems existing in the existing out-of-band covert channel technology and proposes a new type of covert channel, namely, a millimeter-wave based mechanical disk covert channel, which utilizes the frequent and short conventional seek operations of the disk to achieve covert and high-bit-rate information transmission, and utilizes the vibration signal guided beamforming technology and multi-antenna phase coherent integration algorithm to enhance the vibration signal to meet the performance requirements of detecting tiny disk vibrations in long-distance and non-line-of-sight scenarios.

[0005] Specifically, this method uses the beamforming technology guided by the vibration signal to determine the optimal beam direction for the radar to capture the vibration state of the disk, then encodes the sensitive information encapsulated into the data packet into the vibration state of the disk, and uses the millimeter-wave radar to continuously capture the signal containing the vibration state of the disk along the above-mentioned optimal beam direction, then extracts the vibration signal from the above-mentioned signal and uses the multi-antenna phase coherent integration algorithm to enhance the signal, and finally decodes the enhanced signal to restore the sensitive information.

[0006] The present invention is achieved through the following technical solutions:

[0007] The present invention discloses a method for realizing a mechanical disk covert channel based on millimeter waves, which is characterized in that:

[0008] S1. Determine the optimal beam direction for capturing the disk vibration state through the millimeter wave radar through the beamforming technology guided by the vibration signal, and record the distance bin where the disk is located;

[0009] S2. Encapsulate sensitive information into data packets according to the data packet design method;

[0010] S3. Encode the data packet into the vibration of the disk according to the information encoding method;

[0011] S4. obtaining a signal including the vibration state of the disk by continuously detecting the optimal beam direction through the millimeter wave radar;

[0012] S5. Extract the vibration signal by using the time-frequency spectrum and obtaining a signal including the vibration state of the disk and the distance bin where the disk is located;

[0013] S6. According to the multi-antenna phase coherent integration algorithm, the vibration signal is enhanced to obtain a high-quality vibration signal;

[0014] S7. According to the data packet design method, the high-quality vibration signal is divided into a vibration signal of the data packet header and a vibration signal of the data packet payload;

[0015] S8. Calculate the decoding threshold by the vibration signal of the data packet header;

[0016] S9. Decode the vibration signal of the data packet payload according to the decoding algorithm and the decoding threshold to obtain sensitive information.

[0017] As a further improvement, in S1 of the present invention, the beamforming technology guided by the vibration signal is specifically: the transmitting antenna scans the space through the beamforming technology, that is, sends beams in all directions, and calculates each direction θ i The corresponding SNR v′(t) , in all directions, SNR v′(t) The highest direction will be considered the best perceived beam direction, and the SNR in that direction will be recorded. v′(t) Highest distance bin.

[0018] As a further improvement, the calculation SNR of the present invention v′(t) There are three steps involved:

[0019] 1) Perform fast Fourier transform on the received millimeter wave signal and extract each range bin R j The phase signal

[0020] 2) According to φ(t)=4πf c R(t) / c, from the phase signal Extracting vibration signals

[0021] 3) According to the inherent idling vibration frequency f of the perceived target 0 , for vibration signal The application cut-off frequency is f 0 The bandpass filter BPF is used to calculate the signal-to-noise ratio of the detected vibration signal by the following formula:

[0022]

[0023] As a further improvement, in S2 described in the present invention, the data packet design method is specifically as follows: the data packet consists of two parts: a header and a payload, the header mode is fixed, which is a "101" sequence, the payload length is fixed, and its content is sensitive information presented in the form of a binary sequence.

[0024] As a further improvement, in S3 described in the present invention, the information encoding method is on-off keying modulation. Specifically, the duration T1 of the seek vibration caused by the movement of the read / write head represents bit '1', and the duration T0 of the idling vibration caused by the read / write head not moving and only the disk rotating represents bit '0'. The source address and destination address of the seek are two fixed files in the disk respectively. When the bit '1' is transmitted, the read / write head moves repeatedly between the source address and the destination address, and when the bit '0' is transmitted, the read / write head remains stationary.

[0025] As a further improvement, in S5 of the present invention, the vibration signal is extracted by obtaining a signal including the vibration state of the disk and the distance bin where the disk is located through the time-frequency spectrum diagram, specifically including:

[0026] 4) By SNR v′(t) The first two steps and the distance bin where the disk is located, extract the vibration signal from the received millimeter wave signal;

[0027] 5) Set the time window w based on the packet header duration t , and slide along the vibration signal with a fixed step size. In each slide, the time domain signal is converted into a time-frequency spectrum through wavelet transform, and the frequency window w is set f ;

[0028] 6) Cumulative w f The internal frequency energy value is obtained, and the correlation ρ between the vibration signal and the packet header pattern "101" is calculated by matched filtering;

[0029] 7) Repeat step 3) for each slide, and the correlation ρ forms an m×n matrix P, where m is the number of slide steps and n is the number of frequency windows. If P ij Exceeding the threshold value header, then the i-th step is taken as the starting point of the packet header, the j-th frequency window is taken as the frequency range of the disk seek vibration, a vibration signal of a fixed length is taken after the starting point of the packet header, and it is filtered according to the frequency range of the seek vibration.

[0030] As a further improvement, in S6 described in the present invention, the multi-antenna phase coherent integration algorithm is specifically: accumulating the vibration signals extracted from the millimeter wave signals captured by multiple receiving antennas.

[0031] As a further improvement, in S8 of the present invention, the process of calculating the decoding threshold value by the vibration signal of the packet header is specifically as follows: according to the vibration amplitude A of the bit '1' bit1 and the vibration amplitude A of bit '0' bit0 Set the decoding threshold A = (A bit1 +A bit0 ) / 2.

[0032] The present invention also discloses a millimeter wave-based mechanical disk covert channel implementation device, which is characterized by comprising:

[0033] Beam Steering Module: It is used to determine the best beam direction for capturing the vibration state of the disk through the millimeter-wave radar by using the beamforming technology guided by the vibration signal, and record the distance bin where the disk is located;

[0034] Information encapsulation module: used to encapsulate sensitive information into data packets according to the data packet design method;

[0035] Information encoding and transmission module: used to encode data packets into the vibration of the disk according to the information encoding method;

[0036] Signal acquisition module: used to continuously detect the optimal beam direction through the millimeter wave radar to obtain a signal containing the vibration status of the disk;

[0037] Vibration signal extraction module: used to extract vibration signals through the time-frequency spectrum and the signals including the vibration state of the disk and the distance bin where the disk is located;

[0038] Vibration signal enhancement module: used to enhance the vibration signal according to the multi-antenna phase coherent integration algorithm to obtain a high-quality vibration signal;

[0039] Information extraction module: used for separating the high-quality vibration signal into the vibration signal of the data packet header and the vibration signal of the data packet payload according to the data packet design method;

[0040] Threshold calculation module: used to calculate the decoding threshold through the vibration signal of the data packet header;

[0041] Information decoding module: used to decode the vibration signal of the data packet payload according to the decoding algorithm and decoding threshold to obtain sensitive information.

[0042] The beneficial effects of the present invention are as follows:

[0043] The present invention utilizes the characteristic that the normal seek operation of the disk can affect the vibration state of the disk, and realizes a mechanical disk covert channel method based on millimeter waves. Through the information encoding method, the seek operation as a normal activity of the disk can be used for high-bit rate information transmission. Through the beamforming technology guided by the vibration signal, the beam can be accurately pointed to the best direction for sensing the vibration of the disk, thereby effectively improving the signal-to-noise ratio of the vibration signal and expanding the sensing range. At the same time, since the formed beam energy is concentrated and has strong directionality, it can be reflected by objects in the environment, and then the beam direction is adjusted to realize the perception of the disk vibration in the non-line-of-sight scenario. Through the multi-antenna phase coherent integration algorithm, the signal-to-noise ratio of the vibration signal can be further enhanced, so that the present invention has a strong long-distance sensing ability. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a schematic flow chart of the method of the present invention. DETAILED DESCRIPTION

[0045] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, characteristics and results of the present invention.

[0046] The purpose of the present invention is to propose a mechanical disk covert channel based on millimeter waves in order to solve the problem that the existing out-of-band covert channel technology cannot normally transmit information in a long-distance and non-line-of-sight environment. Figure 1 It is a schematic flow chart of the method of the present invention.

[0047] The specific implementation method of the present invention is as follows:

[0048] Step 1: Based on the beamforming technology guided by the vibration signal, the millimeter wave radar scans in the spatial range of [-90 degrees, 90 degrees] at intervals of 2 degrees, and then determines the optimal beam direction for the millimeter wave radar to capture the vibration state of the disk, and records the distance bin where the disk is located to achieve the purpose of long-distance perception. Specifically, since the seek vibration can be detected by the phase change Δφ of the millimeter wave signal reflected by the vibrating target: Therefore, the key to accurately perceive the seek vibration is to ensure that the signal-to-noise ratio (SNR) of the detected vibration signal v′(t) is v′(t) High enough. Signal-to-noise ratio SNR v′(t) It can be calculated by the ratio of the power of the detected vibration signal v′(t) to the noise power, that is,

[0049]

[0050] Where the noise power P(noise)=P(N S(t) )+P(N other ) consists of two parts. S(t) represents the noise caused by the channel noise of the mmWave signal used to sense vibration. other represents other noise that is not related to the channel, such as the noise caused by imperfect phase estimation due to the finite resolution of the Fourier transform.

[0051] Vibration signal-guided beamforming technology aims to reduce noise N S(t) To improve SNR v′(t) . Improve SNR v′(t) The most intuitive method is to use traditional transmit beamforming technology. In order to determine the best beam direction, the traditional method scans in space to find the reflected signal strength SNR S(t) However, this traditional method cannot be directly applied to enhance SNR v′(t) , because the millimeter wave sensing direction and the sensing target vibration direction are not necessarily consistent. Therefore, the present invention proposes a transmitting end beamforming technology based on vibration signal guidance. This method considers both P(v′(t)) and P(N S(t) ) for SNR v′(t) The specific technology is that the transmitting antenna scans the space through beamforming technology, that is, sends beams in all directions and calculates the θ in each direction. i The corresponding SNR v′(t) , in all directions, SNR v′(t) The highest direction will be considered the best perceived beam direction, and the SNR in that direction will be recorded. v′(t) The highest range bin. Calculate SNR v′(t) There are three steps involved:

[0052] 8) Perform fast Fourier transform on the received millimeter wave signal and extract each range bin R j The phase signal

[0053] 9) According to φ(t)=4πf c R(t) / c, from the phase signal Extracting vibration signals

[0054] 10) According to the inherent idling vibration frequency f of the perceived target 0 , for vibration signal The application cut-off frequency is f 0The bandpass filter BPF is used to calculate the signal-to-noise ratio of the detected vibration signal by the following formula:

[0055]

[0056] Step 2: Encapsulate sensitive information into a data packet according to the data packet design method. The data packet consists of two parts: a header and a payload. The data packet consists of two parts: a header and a payload. The header has three functions: marking the start of the transmission, determining the seek vibration frequency f 1 , and provide a decoding threshold. The header pattern is fixed, which is a "101" sequence. In order to avoid the problem of mistaking the "101" sequence in the payload as a header, the duration of bit '1' and bit '0' in the header is set to a non-integer multiple of T1 and T0. The payload length is fixed, and its content is sensitive information presented in the form of a binary sequence.

[0057] Step three, according to the information encoding method, encode the data packet into the vibration of the disk. The information encoding method is on-off keying modulation. Specifically, the duration T1 of the seek vibration caused by the movement of the read / write head represents the bit '1', and the duration T0 of the idling vibration caused by the read / write head not moving and only the disk rotating represents the bit '0'. The source address and destination address of the seek are two fixed files in the disk. When the bit '1' is transmitted, the read / write head moves repeatedly between the source address and the destination address. When the bit '0' is transmitted, the read / write head remains stationary. In order to ensure accurate control of the disk state, the present invention disables the disk cache to avoid time delays and consistency problems in vibration generation.

[0058] Step 4: The millimeter wave radar continuously detects along the optimal beam direction determined in step 1 to obtain a signal containing the vibration state of the disk;

[0059] Step 5: Extract the vibration signal through the time-frequency spectrum and the signal containing the vibration state of the disk and the distance bin where the disk is located. Specifically, it includes the following steps:

[0060] 1) By SNR v′(t) The first two steps and the distance bin where the disk is located, extract the vibration signal v′(t) from the received millimeter wave signal;

[0061] 2) Set the time window w based on the packet header duration t , and slide along the vibration signal v′(t) with a fixed step size. In each slide, the time domain signal is converted into a time-frequency spectrum through wavelet transform, and the frequency window w is set f ;

[0062] 3) Cumulative w f The internal frequency energy value is obtained, and the correlation ρ between the vibration signal and the packet header pattern "101" is calculated by matched filtering;

[0063] 4) Repeat step 3) for each slide, and the correlation ρ forms an m×n matrix P, where m is the number of slide steps and n is the number of frequency windows. If P ij Exceeding the threshold value header , then the i-th step is taken as the starting point of the packet header, the j-th frequency window is taken as the frequency range of the disk seek vibration, a vibration signal of a fixed length is taken after the starting point of the packet header, and it is filtered according to the frequency range of the seek vibration.

[0064] Step 6: According to the multi-antenna phase coherent integration algorithm, the vibration signal is enhanced to obtain a high-quality vibration signal. In step 1, the beamforming technology guided by the vibration signal is aimed at reducing the noise N S(t) To improve SNR v′(t) , but the noise also contains another component N other Therefore, the present invention proposes a multi-antenna phase coherent integration algorithm, which uses the coherence of the vibration signals restored by different receiving antennas to achieve N other Due to the layout of the receiving antennas, the millimeter wave signal reflected by the disk and received by the second receiving antenna propagates an additional distance dsinθ than the signal received by the first receiving antenna. 0 , where d is the distance between the two receiving antennas, θ 0 is the beam direction. Therefore, the disk vibration signal recovered by the jth receiving antenna can be expressed as

[0065]

[0066] in, and represents the phase difference between the vibration signal restored by the jth receiving antenna and the first receiving antenna due to sampling delay. They can be calculated by the following formula:

[0067]

[0068] It is worth noting that the vibration frequency of the disk (including f 0 and f 1 ) is about 100Hz, and the speed of light c = 3×108 m / s. Therefore, and is approximately 0. It can be found that the initial phases of the vibration signals recovered by different receiving antennas are roughly synchronized, that is, they are coherent. In order to suppress the noise N other Inspired by the idea of ​​coherent integration, the present invention proposes a multi-antenna phase coherent integration algorithm, that is, by accumulating the phase-synchronized vibration signals restored by multiple receiving antennas to enhance the signal. In this case, the coherent vibration signal power will be amplified by N 2times, while the random and irregular noise power will only be amplified by N times. Therefore, after coherent integration, SNR v′(t) It can be calculated as:

[0069]

[0070] Step 7. According to the data packet design method, since the lengths of the packet header and the payload are fixed, the high-quality vibration signal can be divided into two parts, one part is the vibration signal of the packet header, and the other part is the vibration signal of the packet payload.

[0071] Step 8: Calculate the decoding threshold value through the vibration signal of the data packet header. Since the present invention adopts the switch monitoring modulation method, the signal amplitude can be directly used as the decoding threshold value. Specifically, according to the vibration amplitude A of the bit '1' bit1 and the vibration amplitude A of bit '0' bit0 Set the decoding threshold A = (A bit1 +A bit0 ) / 2.

[0072] Step 9: Decode the vibration signal of the data packet payload according to the decoding algorithm and the decoding threshold to obtain sensitive information. Specifically, if most of the vibration amplitudes within a bit duration T1 are higher than the decoding threshold, the bit is decoded as '1'; otherwise, it is decoded as '0'.

[0073] The present invention also discloses a millimeter wave-based mechanical disk covert channel implementation device, comprising:

[0074] Beam Steering Module: It is used to determine the best beam direction for capturing the vibration state of the disk through the millimeter-wave radar by using the beamforming technology guided by the vibration signal, and record the distance bin where the disk is located;

[0075] Information encapsulation module: used to encapsulate sensitive information into data packets according to the data packet design method;

[0076] Information encoding and transmission module: used to encode data packets into the vibration of the disk according to the information encoding method;

[0077] Signal acquisition module: used to continuously detect the optimal beam direction through the millimeter wave radar to obtain a signal containing the vibration status of the disk;

[0078] Vibration signal extraction module: used to extract vibration signals through the time-frequency spectrum and the signals including the vibration state of the disk and the distance bin where the disk is located;

[0079] Vibration signal enhancement module: used to enhance the vibration signal according to the multi-antenna phase coherent integration algorithm to obtain a high-quality vibration signal;

[0080] Information extraction module: used for separating the high-quality vibration signal into the vibration signal of the data packet header and the vibration signal of the data packet payload according to the data packet design method;

[0081] Threshold calculation module: used to calculate the decoding threshold through the vibration signal of the data packet header;

[0082] Information decoding module: used to decode the vibration signal of the data packet payload according to the decoding algorithm and decoding threshold to obtain sensitive information.

[0083] The above description is not a limitation of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several changes, modifications, additions or substitutions can be made without departing from the essential scope of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for realizing a mechanical disk covert channel based on millimeter waves, characterized in that: S1. Determine the optimal beam direction for capturing the disk vibration state through the millimeter wave radar through the beamforming technology guided by the vibration signal, and record the distance bin where the disk is located; S2. Encapsulate sensitive information into data packets according to the data packet design method; S3. Encode the data packet into the vibration of the disk according to the information encoding method; S4. obtaining a signal including the vibration state of the disk by continuously detecting the optimal beam direction through the millimeter wave radar; S5. Extract the vibration signal by using the time-frequency spectrum and obtaining a signal including the vibration state of the disk and the distance bin where the disk is located; S6. According to the multi-antenna phase coherent integration algorithm, the vibration signal is enhanced to obtain a high-quality vibration signal; S7. According to the data packet design method, the high-quality vibration signal is divided into a vibration signal of the data packet header and a vibration signal of the data packet payload; S8. Calculate the decoding threshold by the vibration signal of the data packet header; S9. Decode the vibration signal of the data packet payload according to the decoding algorithm and the decoding threshold to obtain sensitive information.

2. The method for realizing a mechanical disk covert channel based on millimeter waves according to claim 1, characterized in that: In S1, the beamforming technology guided by the vibration signal is specifically as follows: the transmitting antenna scans the space through the beamforming technology, that is, sends beams in all directions and calculates the θ in each direction i The corresponding SNR v′(t) , in all directions, SNR v′(t) The highest direction will be considered the best perceived beam direction, and the SNR in that direction will be recorded. v′(t) Highest distance bin.

3. The method for realizing a mechanical disk covert channel based on millimeter waves according to claim 2, characterized in that: The calculation SNR v′(t) There are three steps involved: 1) Perform fast Fourier transform on the received millimeter wave signal and extract each range bin R j The phase signal 2) According to φ(t)=4πf c R(t) / c, from the phase signal Extracting vibration signals 3) According to the inherent idling vibration frequency f0 of the perceived target, the vibration signal A bandpass filter BPF with a cutoff frequency of f0 is applied, and the signal-to-noise ratio of the detected vibration signal is calculated by the following formula:

4. The method for realizing a mechanical disk covert channel based on millimeter waves according to claim 1, characterized in that: In the above-mentioned S2, the data packet design method is specifically as follows: the data packet consists of two parts: a header and a payload. The header mode is fixed, which is a "101" sequence. The payload length is fixed, and its content is sensitive information presented in the form of a binary sequence.

5. The method for realizing a mechanical disk covert channel based on millimeter waves according to claim 1, characterized in that: In the S3, the information encoding method is on-off keying modulation. Specifically, the duration T1 of the seek vibration caused by the movement of the read / write head represents bit '1', and the duration T0 of the idling vibration caused by the read / write head not moving and only the disk rotating represents bit '0'. The source address and destination address of the seek are two fixed files in the disk. When the bit '1' is transmitted, the read / write head moves repeatedly between the source address and the destination address. When the bit '0' is transmitted, the read / write head remains stationary.

6. The method for realizing a mechanical disk covert channel based on millimeter waves according to claim 1, characterized in that: In the above S5, the vibration signal is extracted by obtaining a signal including the vibration state of the disk and the distance bin where the disk is located through the time-frequency spectrum diagram, specifically including: 1) By SNR v′(t) The first two steps and the distance bin where the disk is located, extract the vibration signal from the received millimeter wave signal; 2) Set the time window w based on the packet header duration t , and slide along the vibration signal with a fixed step size. In each slide, the time domain signal is converted into a time-frequency spectrum through wavelet transform, and the frequency window w is set f ; 3) Cumulative w f The internal frequency energy value is obtained, and the correlation ρ between the vibration signal and the packet header pattern "101" is calculated by matched filtering; 4) Repeat step 3) for each slide, and the correlation ρ forms an m×n matrix P, where m is the number of slide steps and n is the number of frequency windows. If P ij Exceeding the threshold value header , then the i-th step is taken as the starting point of the packet header, the j-th frequency window is taken as the frequency range of the disk seek vibration, a vibration signal of a fixed length is taken after the starting point of the packet header, and it is filtered according to the frequency range of the seek vibration.

7. The method for realizing a mechanical disk covert channel based on millimeter waves according to claim 1, characterized in that: In the above-mentioned S6, the multi-antenna phase coherent integration algorithm is specifically as follows: accumulating the vibration signals extracted from the millimeter wave signals captured by multiple receiving antennas.

8. The method for realizing a mechanical disk covert channel based on millimeter waves according to claim 1, characterized in that: In the above S8, the process of calculating the decoding threshold value by the vibration signal of the packet header is specifically as follows: according to the vibration amplitude A of the bit '1' bit1 and the vibration amplitude A of bit '0' bit0 Set the decoding threshold A = (A bit1 +A bit0 ) / 2.

9. The method for realizing a mechanical disk covert channel based on millimeter waves according to claim 1, characterized in that: In the above S9, the decoding algorithm is specifically as follows: if most of the vibration amplitudes within a bit duration T1 are higher than the decoding threshold, the bit is decoded as '1'; otherwise, it is decoded as '0'.

10. A millimeter wave based mechanical disk covert channel implementation device, characterized in that: include: Beam Steering Module: It is used to determine the best beam direction for capturing the vibration state of the disk through the millimeter-wave radar by using the beamforming technology guided by the vibration signal, and record the distance bin where the disk is located; Information encapsulation module: used to encapsulate sensitive information into data packets according to the data packet design method; Information encoding and transmission module: used to encode data packets into the vibration of the disk according to the information encoding method; Signal acquisition module: used to continuously detect the optimal beam direction through the millimeter wave radar to obtain a signal containing the vibration status of the disk; Vibration signal extraction module: used to extract vibration signals through the time-frequency spectrum and the signals including the vibration state of the disk and the distance bin where the disk is located; Vibration signal enhancement module: used to enhance the vibration signal according to the multi-antenna phase coherent integration algorithm to obtain a high-quality vibration signal; Information extraction module: used for separating the high-quality vibration signal into the vibration signal of the data packet header and the vibration signal of the data packet payload according to the data packet design method; Threshold calculation module: used to calculate the decoding threshold through the vibration signal of the data packet header; Information decoding module: used to decode the vibration signal of the data packet payload according to the decoding algorithm and decoding threshold to obtain sensitive information.

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