CN117176528A - Signal steganography and safe transmission method based on additional phase modulation of environmental signal - Google Patents

Abstract

The present invention relates to the field of wireless communication technology, and in particular to a signal steganography and secure transmission method based on additional phase modulation of environmental signals. The steganographic information to be transmitted is mapped into a control code that the steganographic sending end can regulate electromagnetic response hardware on demand. word, the phase of the environmental signal is regulated on demand according to the control code word, so that the phase offset of the environmental signal is superimposed on each transmitting element of the electromagnetic response hardware that can be regulated on demand, and the phase change is used to carry the information to be steganographed in covert communication; The writing receiver estimates the cascade channel status through the public pilot broadcast by the environmental signal source to receive and recover the steganographic information using the channel status. The present invention realizes signal steganography by regulating the phase of environmental signals, and has the advantages of small size, low power consumption, strong communication behavior concealment, etc.; on the basis of signal steganography, location-based secure transmission is realized, and the security of communication content is It is more secure and efficient, and is convenient for practical application in covert communication scenarios.

Description

Signal steganography and secure transmission method based on additional phase modulation of environmental signals

Technical field

The present invention relates to the field of wireless communication technology, and in particular to a signal steganography and secure transmission method based on additional phase modulation of environmental signals.

Background technique

Traditional covert communication systems such as frequency hopping and spread spectrum communication disperse signal energy in time or frequency according to established rules or codebooks to increase the difficulty of signal detection. However, this type of communication system needs to actively transmit signals with unique characteristics, and its situation cannot be hidden and is easily exposed. Information steganography technology based on multimedia information as the carrier uses the redundant characteristics of media information to hide information bits. However, such schemes act on the information layer and require changing the information structure of the carrier through various hiding and extraction algorithms, resulting in high complexity. , the problem of low efficiency. Therefore, how to ensure the concealment of communication behaviors in a more covert and efficient way is still an important issue that needs to be solved in the field of modern information countermeasures.

As a communication technology that does not actively transmit signals, the core principle of backscattering is to filter out the original information in the environmental signal and collect the energy, and then use the collected energy to send the information to be sent. However, as far as environmental signals are concerned, since the signal emitted by backscattering does not contain the information of the environmental signal, the backscattering device is equivalent to an interference source at the same frequency at the same time, resulting in poor concealment performance of its communication behavior. Using the different gains of RIS reflected beams to carry information, information can also be transmitted without actively transmitting signals. However, the switching of different gain beams in this scheme allows regular amplitude response changes to be detected within the receiver within the RIS coverage area, resulting in insufficient concealment of communication behavior and easy detection; secondly, regular amplitude response changes imply that the transmitter is transmitting The security of the transmitted binary information and communication content cannot be guaranteed, which will affect the practical application of the solution in covert communication.

Contents of the invention

To this end, the present invention provides a signal steganography and secure transmission method based on additional phase modulation of environmental signals, which solves the problem of insufficient concealment of existing solutions and the inability to guarantee the security of communication content, and can pass through the environment without transmitting signals. The signal phase is modulated to realize steganography at the signal level to complete the covert transmission of information. It is simple to implement. The transmitter does not need to actively transmit signals. It can enhance the concealment of communication behavior and the security of information transmission, and has certain application value.

According to the design scheme provided by the present invention, on the one hand, a signal steganography method based on additional phase modulation of environmental signals is provided, including the following contents:

Mapping the steganographic information to be transmitted into a control codeword that the steganographic sender can control the electromagnetic response hardware on demand;

The phase of the environmental signal is regulated on demand according to the control code word, so that the phase offset of the environmental signal is superimposed on each transmitting element of the electromagnetic response hardware that can be regulated on demand, and the phase change is used to carry the information to be steganographically transmitted in covert communications.

In this case, for signal steganography and secure transmission scenarios, various types of hardware that can regulate electromagnetic response on demand are used as the system transmitter. Technologies such as directional modulation and eavesdropping azimuth nulling can be used to generate secure beams by regulating the phase of environmental signals. To ensure the safe transmission of steganographic information; superimpose the phase offset on each element of the electromagnetic response hardware, carry information through phase changes, and achieve signal steganography and safe transmission.

Further, the steganographic information to be transmitted is mapped into a control codeword that the steganographic sending end can control the electromagnetic response hardware on demand, including:

First, the steganographic transmitter obtains the signal incident angle and exit angle based on the location information of the environmental signal source and the steganographic receiver, and aligns the main lobe of the outgoing beam with the steganographic receiver to generate a secure phase shift matrix;

Then, the secure phase shift matrix is used as the initial control codeword to configure the electromagnetic response hardware of the steganographic sender that can be adjusted on demand.

Furthermore, the electromagnetic response hardware in the steganographic transmitter can be adjusted on demand. The hardware uses a reflective reconfigurable smart surface or a transmissive controllable glass antenna to obtain the incident environmental signal based on the location of the environmental signal source and the steganographic receiver. angle and exit angle to generate a safe phase shift matrix.

Further, generate a safe phase shift matrix, including:

First, according to the position of the base station and the steganographic receiver, the signal incident angle and reflection angle at the electromagnetic response hardware can be adjusted as needed, and the reflected beam gain and phase shift matrix of the steganographic receiver's orientation are obtained based on the signal incident angle and reflection angle. relationship between;

Then, a secure phase shift matrix is generated according to preset rules, where the preset rules include but are not limited to maximizing the receiving end gain generation rules, eavesdropping azimuth null generation rules, and directional modulation generation rules.

Furthermore, the environmental signal phase is regulated on demand according to the control codeword, including:

The steganographic sender maps the steganographic information to be transmitted into a phase offset, superimposes the phase offset into each element of the security phase shift matrix and generates a steganographic phase shift matrix, and uses the steganographic phase shift matrix as a control codeword The electromagnetic response hardware can be adjusted as needed by reconfiguration to parasitize the steganographic information on environmental signals to perform the transmission of the steganographic information.

Further, the phase offset is superimposed into each element of the security phase shift matrix and a steganographic phase shift matrix is generated, including:

When each element of the electromagnetic response hardware that can be adjusted on demand is superimposed with the same phase offset, the main lobe direction and amplitude of the beam remain unchanged. The steganographic sender determines based on the mapping relationship between the steganographic information to be transmitted and the phase offset. For the phase shift to be modulated, the phase offset mapping is superimposed on each element of the security phase shift matrix to use the phase offset to carry the steganographic information to be transmitted.

Further, the process of superposing the phase offset to each element of the safe phase shift matrix can be expressed as: Φ=e ^jθ Φ ^* , where θ is the phase shift offset, Φ ^* is the safe phase shift matrix, and Φ is the hidden Write the phase shift matrix.

On the other hand, the present invention also provides a safe signal transmission method, including the following content:

Based on the above signal steganography method, the steganographic information to be transferred is steganographically transmitted;

The steganographic receiver estimates the cascade channel status through the public pilot broadcast by the environmental signal source to receive and recover the steganographic information using the channel status.

Since the phase change of the environmental signal occurs during the propagation process of the environmental signal, the change of the environmental signal caused by the sender can be equivalent to the change of the channel phase response; the receiving end can obtain the phase response through the public pilot channel estimation sent by the environmental signal changes to identify the steganographic information transmitted by the sender. Beam agility with different phase shifts is used to complete information transmission. During the agility process, since the transmitter transmits information by reflecting environmental signals, the impact on the original communication system is only equivalent to a change in a multipath, and the communication behavior The concealment is stronger; the steganographic information is transmitted through the security beam, which can minimize the leakage of information; finally, because the amplitude patterns of different beams are the same, it will not cause regular amplitude response changes, reducing the risk of communication behavior exposure. , to ensure the concealment of communication behavior and the security of information content.

Among them, the steganographic receiver estimates the cascade channel status through the public pilot broadcast by the environmental signal source to use the channel status to receive and recover the steganographic information. It can be designed to include:

First, the steganographic receiver uses the public pilot broadcast by the environmental signal source to continuously monitor the channel, obtain the steganographic transmission channel status, and obtain the cascade channel status with phase modulation through channel estimation;

Then, the phase offset configured by the steganographic transmitter is determined based on the phase difference between the cascade channel state and the steganographic transmission channel state, and the phase offset configured by the steganographic transmitter is recovered based on the mapping relationship between the phase offset and binary data. conveyed steganographic information

On the other hand, combined with the above signal steganography and secure transmission method based on additional phase modulation of environmental signals, the present invention also provides a signal secure transmission system, including: a steganography sending end and a steganography receiving end, wherein,

The steganographic sending end includes a source mapping unit and electromagnetic response hardware that can be adjusted on demand. The source mapping unit is used to map the steganographic information to be transmitted into a control code word that can adjust the electromagnetic response hardware on demand. The electromagnetic response hardware that needs to be controlled is used to adjust the phase of the environmental signal on demand based on the control code word, so as to superimpose the phase offset of the environmental signal on each transmitting element of the electromagnetic response hardware that can be controlled on demand and use the phase change to carry covert communication waiting steganographic information;

The steganographic receiver is used to estimate the cascade channel state through the public pilot broadcast by the environmental signal source, so as to receive and recover the steganographic information by utilizing the channel state changes.

Beneficial effects of the present invention:

Without actively transmitting signals, the present invention can use hardware that can control electromagnetic response on demand as the sending end, and realize signal steganography by regulating the phase of environmental signals. It has small size, low power consumption, and concealment of communication behavior. It has strong advantages; it realizes location-based secure transmission on the basis of signal steganography, and the security of communication content is more guaranteed and more efficient, which facilitates practical application in covert communication scenarios.

Picture description:

Figure 1 is a schematic diagram of the signal steganography process based on additional phase modulation of environmental signals in the embodiment;

Figure 2 is a schematic diagram of the signal steganography transmission model framework in the embodiment;

Figure 3 is a schematic diagram of the steganographic sending and receiving process in the embodiment;

Figure 4 is a schematic diagram of the RIS amplitude pattern in the embodiment;

Figure 5 is a schematic diagram of the RIS phase pattern in the embodiment.

Detailed ways:

In order to make the purpose, technical solutions and advantages of the present invention clearer and clearer, the present invention will be described in further detail below in conjunction with the accompanying drawings and technical solutions.

In view of the situation described in the background art that the existing solutions have insufficient concealment and the security of communication content cannot be guaranteed, in an embodiment of the present invention, a signal steganography method based on additional phase modulation of environmental signals is provided, which includes the following content:

The steganographic information to be transmitted is mapped to a control codeword that the steganographic sending end can control the electromagnetic response hardware on demand; the phase of the environmental signal is regulated on demand according to the control codeword, so that the phase offset of the environmental signal is superimposed on the control codeword that can be controlled according to the need. It is necessary to control each transmitting element of the electromagnetic response hardware and use phase changes to carry the information to be steganographically transmitted in covert communications.

As shown in Figures 1 and 2, the hardware that can control the electromagnetic response on demand is used as the steganography transmitter, and a safe beam is generated by regulating the phase of the environmental signal to ensure the safe transmission of steganographic information; then, the hardware that can control the electromagnetic response on demand is used. The same phase offset is superimposed on each element of the response hardware without changing the properties of the beam's main lobe direction and amplitude. The phase offset is superimposed on each element of the electromagnetic response hardware, and information is carried through phase changes to achieve signal steganography and secure transmission. .

Among them, the steganographic information to be transmitted is mapped into a control codeword that the steganographic sender can control the electromagnetic response hardware on demand, which can be designed to include the following content:

First, the steganographic transmitter obtains the signal incident angle and exit angle based on the location information of the environmental signal source and the steganographic receiver, and aligns the main lobe of the outgoing beam with the steganographic receiver to generate a secure phase shift matrix;

Then, the secure phase shift matrix is used as the initial control codeword to configure the electromagnetic response hardware of the steganographic sender that can be adjusted on demand.

Specifically, the electromagnetic response hardware in the steganographic transmitter can be adjusted on demand. The hardware uses a reflective reconfigurable smart surface or a transmissive controllable glass antenna to obtain the incident environmental signal according to the location of the environmental signal source and the steganographic receiver. angle and exit angle to generate a safe phase shift matrix.

In the embodiment of this case, a Reconfigurable Intelligent Surface (RIS) is used as the electromagnetic response hardware in the steganography transmitter that can be adjusted on demand. Transmissive adjustable glass antennas can also be used as the steganography transmitter. The electromagnetic response hardware can be adjusted on demand; a safe phase shift matrix is generated by maximizing the reflection gain in the receiver's azimuth, and regular methods such as eavesdropping azimuth nulls and directional modulation can also be used to generate a safe phase shift matrix.

Among them, the safe phase shift matrix is generated by maximizing the reflection gain in the receiving end azimuth, which can be designed to include the following content:

First, according to the position of the base station and the steganographic receiver, the signal incident angle and reflection angle at the electromagnetic response hardware can be adjusted as needed, and the reflected beam gain and phase shift matrix of the steganographic receiver's orientation are obtained based on the signal incident angle and reflection angle. relationship between;

Then, a target optimization problem is established with the goal of maximizing the azimuth reflection gain of the receiving end, and the relationship between the reflected beam gain and the phase shift matrix is set to be the largest when multi-channel signals are superimposed in phase. The optimal safe phase shift is obtained by solving the target optimization problem. matrix. As shown in Figure 2, the base station is a single-antenna base station. The steganographic transmitter includes an RIS reflective surface and its control unit. The RIS is a column-controlled uniform plane array with M array elements. The receiving end is a single-antenna receiver. The channel from the environmental signal source to the steganographic transmitter is The channel from the steganographic receiver to the steganographic sender is/> The signal received at the receiving end can be expressed as

in, is the RIS phase shift matrix,/> θ _m∈ [0,2π], is the base station precoding vector, s is the data symbol sent by the base station, P is the transmit power of the base station,/> is the additive Gaussian white noise received by the user, which is a complex Gaussian random variable with mean 0 and variance σ ² .

In order to achieve signal steganography and secure transmission, the designed RIS phase shift consists of two parts: Φ=e ^jθ Φ ^* . Among them, θ is the phase offset, which carries binary information and realizes the transmission of steganographic information; Φ ^* is the secure phase shift matrix, which can align the main lobe of the reflected beam at the receiving end, reduce the leakage of steganographic information, and realize location-based Secure transmission.

In order to obtain the safe phase shift matrix Φ ^* , the signal incident angle γ and reflection angle at the RIS are obtained according to the base station and receiving end positions. Then the relationship f(Φ) between the reflected beam gain in the receiving end azimuth and the RIS phase shift matrix is obtained, and an optimization problem is established with the goal of maximizing the receiving end azimuth reflection gain:

in, is the environmental signal incident array manifold, is the reflection array manifold, where d is the RIS array element spacing and λ is the wavelength.

From this problem P0 can be expressed as:

P1:

When multiple signals are superimposed in phase, f(Φ) is the largest, and the optimal phase shift matrix is obtained from this.

Among them, the environmental signal phase is regulated on demand according to the control codeword, which can be designed to include the following content:

The steganographic sender maps the steganographic information to be transmitted into a phase offset, superimposes the phase offset into each element of the security phase shift matrix and generates a steganographic phase shift matrix, and uses the steganographic phase shift matrix as a control codeword The electromagnetic response hardware can be adjusted as needed by reconfiguration to parasitize the steganographic information on environmental signals to perform the transmission of the steganographic information.

Specifically, when each element of the electromagnetic response hardware that can be adjusted on demand is superimposed with the same phase offset, the main lobe direction and amplitude of the beam remain unchanged. The mapping relationship determines the phase shift to be modulated, and the phase offset mapping is superimposed on each element of the security phase shift matrix to use the phase offset to carry the steganographic information to be transmitted.

Further, the embodiment of the present invention also provides a signal safe transmission method, including the following content:

Based on the above signal steganography method, the steganographic information to be transferred is steganographically transmitted;

The steganographic receiver estimates the cascade channel status through the public pilot broadcast by the environmental signal source to receive and recover the steganographic information using the channel status.

Among them, the steganographic receiver estimates the cascade channel status through the public pilot broadcast by the environmental signal source, so as to receive and recover the steganographic information using the channel status. It can be designed to include the following content:

First, the steganographic receiver uses the public pilot broadcast by the environmental signal source to continuously monitor the channel, obtain the steganographic transmission channel status, and obtain the cascade channel status with phase modulation through channel estimation;

Then, the phase offset configured by the steganographic transmitter is determined based on the phase difference between the cascade channel state and the steganographic transmission channel state, and the phase offset configured by the steganographic transmitter is recovered based on the mapping relationship between the phase offset and binary data. conveyed steganographic information.

As shown in Figure 3, the steganographic transmitter obtains the incident angle γ and reflection angle of the steganographic receiver based on the location information of the environmental signal source and the steganographic receiver. According to the principle of maximizing the azimuth reflection gain of the receiving end, a safe phase shift matrix Φ ^* is generated to align the main lobe of the reflected beam with the receiving end; the RIS is configured based on the obtained safe phase shift matrix Φ ^* as the initial control code word; the receiving end is steganographically The status information of the steganographic transmission channel can be obtained based on the public pilot sent by the environmental signal/> The binary data to be transmitted is mapped to a phase offset θ, and the phase offset θ is superimposed on each element of the security phase shift matrix Φ ^* to generate a steganographic phase shift matrix Φ=e ^jθ Φ ^* , and then the steganographic phase shift matrix The phase shift matrix is used as a control codeword to configure the RIS, which is parasitic on the environmental signal to complete the transmission of steganographic data; the steganographic receiving end performs channel estimation based on the public pilot acquisition sent by the environmental signal to obtain the cascade channel state information with phase modulation/ > Based on h _arb and/> The phase response difference between the two determines the phase offset θ configured at the steganographic sending end. According to the mapping relationship between the phase offset and binary data, the sent binary data is determined to complete the reception of the steganographic signal.

RIS has the property that the phase shift of all array elements is the same and does not change the amplitude pattern. As shown in Figures 4 and 5, the amplitude patterns of Φ and Φ×e ^{j π/2} are the same but the phase patterns are different. This is a good way to achieve steganographic information. The possibility of secure transmission is provided. The steganographic sender determines the phase shift offset θ through the mapping relationship between the binary information to be transmitted and the phase shift, and superimposes the phase offset mapping on the secure phase shift matrix to generate the steganographic phase shift matrix Φ=e ^jθ Φ ^* , and then use the steganographic phase shift matrix as a control codeword to configure RIS, which is parasitic on the environmental signal to complete the transmission of steganographic data.

The public pilot monitoring channel sent by the receiving end through the environmental signal source. When the steganographic sending end does not perform steganographic communication, the RIS array phase shift matrix is configured as a safe phase shift matrix Φ ^* . At this time, the receiving end obtains through pilot estimation The cascade channel status information is When the steganographic transmitter performs steganographic communication, the RIS array phase shift matrix is configured as the steganographic phase shift matrix Φ. At this time, the cascade channel state information obtained by the receiving end through pilot estimation, the estimation process can be expressed as:

According to h _arb and The phase offset θ of the RIS front configuration is obtained from the phase response difference between the two, and then based on the mapping relationship between the phase offset and the binary information, the binary information sent by the steganographic sender is determined, and the reception of the steganographic information is completed.

Further, combined with the above signal steganography and secure transmission method based on additional phase modulation of environmental signals, embodiments of the present invention also provide a signal secure transmission system, including: a steganography sending end and a steganography receiving end, wherein,

The steganographic sending end includes a source mapping unit and electromagnetic response hardware that can be adjusted on demand. The source mapping unit is used to map the steganographic information to be transmitted into a control code word that can adjust the electromagnetic response hardware on demand. The electromagnetic response hardware that needs to be controlled is used to adjust the phase of the environmental signal on demand based on the control code word, so as to superimpose the phase offset of the environmental signal on each transmitting element of the electromagnetic response hardware that can be controlled on demand and use the phase change to carry covert communication waiting steganographic information;

The steganographic receiver is used to estimate the cascade channel status through the public pilot broadcast by the environmental signal source, so as to receive and recover the steganographic information using the channel status.

The source mapping unit maps the steganographic information to be transmitted into a control code word that can control the electromagnetic response hardware on demand; the hardware that can control the electromagnetic response on demand can independently realize on-demand control of the phase of the incident environmental signal according to the control code word. , and emitted through reflection, transmission, etc. Based on this function, the steganographic transmitter realizes the phase modulation of the steganographic information by changing the phase of the environmental signal, and completes the sending of the steganographic signal. For the steganographic receiver, since the change in the phase of the environmental signal occurs during the signal propagation process, the change in the phase of the environmental signal by the steganographic sender can be equivalent to the change in the cascade channel from the environmental signal source to the steganographic receiver. The steganographic receiver continuously monitors the channel through the public pilot broadcast by the environmental signal source, obtains phase information from channel changes, and then recovers the steganographic information. Beam agility with different phase shifts is used to complete information transmission. During the agility process, since the transmitter transmits information by reflecting environmental signals, the impact on the original communication system is only equivalent to a change in a multipath, and the communication behavior The concealment is stronger; the steganographic information is transmitted through the secure beam, which can minimize the leakage of information; finally, since the amplitude patterns of different beams are the same, RIS agility will not cause regular amplitude response changes, thereby reducing communication Risk of content interception.

Unless otherwise specifically stated, the relative order of components and steps, numerical expressions, and numerical values set forth in these examples do not limit the scope of the invention.

Each embodiment in this specification is described in a progressive manner. Each embodiment focuses on its differences from other embodiments. The same and similar parts between the various embodiments can be referred to each other. As for the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple. For relevant details, please refer to the description in the method section.

The units and method steps of each example described in conjunction with the embodiments disclosed herein can be implemented with electronic hardware, computer software, or a combination of both. In order to clearly illustrate the interchangeability of hardware and software, in the above description The composition and steps of each example have been generally described in terms of function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Persons of ordinary skill in the art may use different methods to implement the described functions for each specific application, but such implementations are not considered to be beyond the scope of the present invention.

Those of ordinary skill in the art can understand that all or part of the steps in the above method can be completed by instructing relevant hardware through a program. The program can be stored in a computer-readable storage medium, such as a read-only memory, a magnetic disk or an optical disk. Optionally, all or part of the steps of the above embodiments can also be implemented using one or more integrated circuits. Correspondingly, each module/unit in the above embodiments can be implemented in the form of hardware, or can also be implemented in the form of software function modules. Form realization. The invention is not limited to any particular form of combination of hardware and software.

Finally, it should be noted that the above-mentioned embodiments are only specific implementations of the present invention and are used to illustrate the technical solutions of the present invention rather than to limit them. The protection scope of the present invention is not limited thereto. Although refer to the foregoing The embodiments illustrate the present invention in detail. Those of ordinary skill in the art should understand that any person familiar with the technical field can still modify the technical solutions recorded in the foregoing embodiments within the technical scope disclosed by the present invention. It may be easy to think of changes, or equivalent substitutions of some of the technical features; and these modifications, changes or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and they should all be included in the present invention. within the scope of protection. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (10)

1. A method for steganography based on additional phase modulation of an ambient signal, comprising:

mapping the hidden information to be transferred into a control codeword of which the hidden sending end can regulate and control electromagnetic response hardware according to the requirement;

the environmental signal phase is regulated and controlled according to the control code word, so that the environmental signal phase offset is superposed on each emission element of the electromagnetic response hardware which can be regulated and controlled according to the requirement, and the hidden communication information to be hidden is carried by utilizing the phase change.

2. The method for signal steganography based on additional phase modulation of environmental signals according to claim 1, wherein mapping steganography information to be transferred into control code words of electromagnetic response hardware which can be regulated and controlled as required by a steganography transmitting end comprises:

firstly, a steganography sending end obtains a signal incident angle and an emergent angle according to position information of an environment signal source and a steganography receiving end, and aims an emergent beam main lobe at the steganography receiving end to generate a safety phase shift matrix;

then, the safety phase shift matrix is used as an initial control code word to configure the electromagnetic response hardware of the steganography sending end which can be regulated and controlled according to the requirement.

3. The method of claim 1 or 2, wherein the steganographic transmitting end can regulate electromagnetic response hardware as required, and the hardware adopts a reflective reconfigurable intelligent surface or adopts a transmission type controllable glass antenna to obtain an incident angle and an emergent angle of an environmental signal according to the positions of the environmental signal source and the steganographic receiving end so as to generate a safe phase shift matrix.

4. The method of signal steganography based on additional phase modulation of an ambient signal according to claim 2, wherein generating a secure phase shift matrix comprises:

firstly, acquiring a signal incident angle and a reflection angle which can be used for regulating and controlling electromagnetic response hardware according to needs according to a base station and a position of a steganography receiving end, and acquiring a relation between a reflection beam gain and a phase shift matrix of the steganography receiving end azimuth according to the signal incident angle and the reflection angle;

then, a safe phase shift matrix is generated according to preset rules, wherein the preset rules comprise, but are not limited to, a maximum receiving end gain generation rule, a eavesdropping azimuth null generation rule and a direction modulation generation rule. .

5. The method for signal steganography based on additional phase modulation of an ambient signal according to claim 1, wherein the on-demand regulation of the ambient signal phase according to the control codeword comprises:

the hidden information to be transferred is mapped into phase offset by the hidden sending end, the phase offset is superimposed into each element of the security phase shift matrix, the hidden phase shift matrix is generated, the hidden phase shift matrix is used as a control code word to reconfigure electromagnetic response hardware which can be regulated and controlled according to the need, so that the hidden information is parasitic on an environment signal to send the hidden information.

6. The method of steganography based on additional phase modulation of an ambient signal according to claim 5 wherein superimposing phase offsets into elements of a secure phase shift matrix and generating a steganographic phase shift matrix comprises:

setting the beam main lobe direction and the amplitude unchanged when elements of the electromagnetic response hardware can be regulated and controlled as required to overlap the same phase offset, determining the phase shift to be modulated by the steganography sending end according to the mapping relation between steganography information to be transmitted and the phase offset, and overlapping the phase offset map in the elements of the safe phase shift matrix so as to bear the steganography information to be transmitted by using the phase offset.

7. A method of steganography and secure transmission based on additional phase modulation of ambient signals according to claim 5 or 6, characterized in that the process of superimposing the phase offset onto the elements of the secure phase shift matrix is expressed as: phi=e ^jθ Φ ^* Wherein θ is the phase shift offset, Φ ^* For the safe phase shift matrix, Φ is the steganographic phase shift matrix.

8. The signal safety transmission method is characterized by comprising the following steps:

steganographically transferring steganographic information to be transferred based on the method of claim 1;

the steganography receiving end estimates the cascade channel state through the public pilot frequency broadcasted by the environment signal source so as to receive and recover steganography information by utilizing the channel state.

9. The signal security transmission method according to claim 8, wherein the steganographic receiving end estimates a concatenated channel state through a public pilot frequency broadcasted by an environmental signal source to receive and recover steganographic information using the channel state, comprising:

firstly, a steganography receiving end continuously monitors a channel by utilizing a public pilot frequency broadcast by an environment signal source, acquires a steganography transmission channel state, and acquires a cascade channel state with phase modulation through channel estimation;

and then, determining the phase offset configured by the steganography sending end according to the corresponding phase difference between the cascade channel state and the steganography transmission channel state, and recovering the steganography information transmitted by the steganography sending end according to the mapping relation between the phase offset and binary data.

10. A system for secure transmission of signals, comprising: a steganography sending end and a steganography receiving end, wherein,

the hidden write transmitting end comprises an information source mapping unit and electromagnetic response hardware capable of being regulated and controlled according to needs, wherein the information source mapping unit is used for mapping hidden write information to be transmitted into a control code word of the electromagnetic response hardware capable of being regulated and controlled according to needs, and the electromagnetic response hardware capable of being regulated and controlled according to needs is used for regulating and controlling the phase of an environment signal according to the control code word so as to superimpose the phase offset of the environment signal on each transmitting element of the electromagnetic response hardware capable of being regulated and controlled according to needs and bear hidden communication information to be hidden written by utilizing phase change;

and the steganography receiving end is used for estimating the cascade channel state through the public pilot frequency broadcasted by the environment signal source so as to receive and recover steganography information by utilizing the channel state change.