Method, System, Device and Terminal for Generating Group Secret Key of Backscatter Device System

Abstract

The present invention belongs to the technical field of backscatter communication key generation, and discloses a method, system, device and terminal for generating group keys of a backscatter device system. The backscatter device measures the downlink channel information from the received signal, and the full-duplex signal source measures the reflected cascaded channel information from the reflected signal; the signal source calculates the uplink channel information from the reflected cascaded channel information and generates a symmetric shared key; obtains all the shared channel information of the group, and calculates the difference sequence between the uplink channel information and the uplink channel information of the reference device; based on the difference sequence, performs shared channel extraction and key construction, and at the same time constructs the group keys between all small groups. The method for generating group keys of backscatter devices based on shared channels in the present invention generates secure shared keys by extracting the reciprocity and randomness of the wireless channel, solves the problem of high computational cost of traditional cryptography, realizes a lightweight key protocol, supports multiple schemes, has high security, scalability and high efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of backscatter communication key generation, and particularly relates to a method, system, device and terminal for generating group keys of a backscatter device system. Background Art

[0002] At present, with the continuous development of wireless communication technology and microelectronics technology, a large number of electronic devices have been applied to various fields of human life to achieve interconnection between people and things, and between things and things, such as smart home, smart city, digital countryside, etc. In order to adapt to various applications of the Internet of Things, the size of Internet of Things devices is getting smaller and smaller, and the device batteries and the energy they possess are also becoming more and more limited. However, existing communication technologies use active radio frequency units to transmit wireless signals for information transmission, which requires a large amount of energy consumption and does not meet the requirements of low-power communication in the Internet of Things. Backscatter communication technology is a wireless technology that supports ultra-low-power or even zero-power communication. Compared with traditional wireless devices that actively generate radio frequency signals, backscatter devices use the existing radio frequency signals in the environment as carrier signals, and by changing the antenna impedance, scatter the carrier signals with different amplitudes, phases or frequencies back to the receiver to achieve ultra-low-power or even zero-power data transmission. As a typical application of backscatter, radio frequency identification technology has been widely applied in various Internet of Things scenarios. The signal source transmitter continuously broadcasts wireless signals to the backscatter device. When the device collects energy from the incident signal, it will backscatter the incident signal and perform data back transmission. Compared with wireless devices with traditional active radio frequency architectures, backscatter communication does not need to generate radio frequency signals autonomously, which will greatly reduce the energy consumption and promote the wider deployment of backscatter devices.

[0003] However, the backscattered signal has the characteristics of broadcasting and openness. When a backscatter device performs signal backscattering, all users within its coverage area can receive the signal. This will result in the exposure of the carried information and make it vulnerable to various potential signal attacks, including passive eavesdropping, traffic monitoring and analysis, signal interference, spoofing, forgery, replay attacks, etc. Without providing appropriate security measures, when the device uses backscattered signals for confidential data transmission, it will face serious security risks such as information theft and privacy leakage. Currently, cryptographic security mechanisms are mainly used to ensure the security of backscatter communication and its system. For example, radio frequency identification systems pre-allocate keys for tags using a pre-set cryptographic protocol, and then use exclusive OR operations and hash functions to protect key privacy and communication content through this key. In addition, for backscatter devices with relatively strong computing capabilities, the Diffie-Hellman protocol can be used to generate shared keys for both communication parties or lightweight encryption and decryption algorithms can be used to achieve secure communication. In theory, the more complex the cryptographic algorithm based on computational problems, the higher its security, but it requires more computational, storage, and energy resources, which brings a great energy and computational burden to the resource-limited backscatter communication system. In addition, traditional key exchange protocols require computationally expensive exponential operations, such as complex key distribution, update, and management processes, and are vulnerable to malicious attacks during key distribution and update processes, resulting in key leakage, making the entire system face more serious threats. Therefore, it is difficult to use existing cryptographic security technologies to protect the information transmission between backscatter devices and receivers or between devices.

[0004] Compared with traditional cryptographic key sharing protocols, physical layer key generation technology aims to utilize the randomness and reciprocity of the wireless channel to provide a lightweight and information-theoretically secure key sharing solution for resource-constrained networks and users. This technology can be applied to backscatter communication systems to generate secure shared keys. In traditional physical layer key generation schemes, legitimate communication parties send channel sounding signals, measure the characteristics of the shared wireless channel, use it as a shared random source, and extract session keys. At the same time, since eavesdroppers cannot get infinitely close to legitimate users, when the distance from legitimate users exceeds 1 - 2 physical wavelengths, legitimate users and eavesdropping users will estimate two almost independent channel fades, thus ensuring that it is difficult for eavesdroppers to steal the shared channel information between legitimate users. Since physical layer key generation technology can achieve independent shared key negotiation on demand and does not require a specific server or third-party device for key distribution and management, it is suitable for application in highly flexible environmental backscatter communication systems.

[0005] However, in a backscatter communication system, the reflecting device cannot actively generate channel sounding signals, making it difficult to directly adopt existing physical layer key generation schemes. Moreover, when backscatter communication occurs between reflecting devices, the devices simultaneously receive the downlink signals from the RF source and the reflected signals from other reflecting devices. Both the downlink signals and the transmitted signals will experience different channel fades, which makes the superimposed signals received by both reflecting devices independent of each other and unable to be used as shared channel information.

[0006] Through the above analysis, the problems and defects of the existing technology are as follows:

[0007] (1) Existing backscatter signals have the characteristics of broadcasting and openness, making them vulnerable to signal eavesdropping and illegal reception. The backscatter communication system faces severe security risks such as information theft and privacy leakage. Moreover, the existing backscatter communication system has limited energy and computing resources. Since the key sharing method based on cryptography consumes a large amount of computing and power resources, it is not very suitable for the backscatter communication system to generate shared keys.

[0008] (2) Existing physical layer key generation technologies are all designed for active traditional wireless communication systems, which require both communication parties to actively send sounding signals to estimate channel characteristics and generate shared keys for both parties. However, in a backscatter communication system, the reflecting device cannot actively generate channel sounding signals to estimate channel characteristics. Therefore, the existing physical layer key generation scheme cannot be directly applied to the backscatter communication system to generate shared keys for backscatter communication devices. Summary of the Invention

[0009] Aiming at the problems existing in the existing technology, the present invention provides a method, system, device and terminal for generating group keys for a backscatter device system, and particularly relates to a method, system, medium, device and terminal for generating group keys for a backscatter device system with a star structure.

[0010] The present invention is implemented as follows. A method for generating group keys for a backscatter device system includes: the backscatter device measures the downlink channel information from the received signal, and the full-duplex signal source measures the reflected cascade channel information from the reflected signal; the signal source calculates the uplink channel information from the reflected cascade channel information and generates a symmetric shared key between the signal source and the reflecting device; obtains all the shared channel information, and calculates the difference sequence between the uplink channel information and the uplink channel information of the reference device; based on the difference sequence, performs shared channel extraction and shared group key construction. In addition, a large number of backscatter devices are divided into multiple small groups to sequentially generate small group keys and construct the overall group key based on these.

[0011] Further, the method for generating group keys for a backscatter device system includes the following steps:

[0012] Step 1, obtaining downlink channel information: The signal source AP sends a signal, and all backscatter devices BD are in the listening mode. The BD measures the downlink channel information from the received signal;

[0013] Step 2, obtaining the reflected cascade channel information: The signal source sends a signal, the BD is in the backscatter mode, and the full-duplex signal source AP receives the reflected signal of the BD and measures the reflected cascade channel information from the reflected signal;

[0014] Step 3, constructing the uplink channel information: The reflected cascade channel includes the downlink channel information and the uplink channel information. The AP calculates the uplink channel from the reflected cascade channel information. The AP and the BD use the uplink channel information and the downlink channel information as shared random information respectively to generate the symmetric shared key between the two parties;

[0015] Step 4, obtaining the shared channel information of the entire group: The signal source sends signals to all BDs at different times. The BDs work in the listening mode and the backscatter mode successively to generate the shared information between the signal source and all BDs;

[0016] Step 5, calculating the difference: The signal source AP calculates the difference between the uplink channel information corresponding to other devices and the uplink channel information of the reference device to form a difference sequence, and broadcasts it to all BDs;

[0017] Step 6, shared channel extraction and key construction: Based on its own downlink channel information and the received difference sequence, the BD recursively obtains all round-trip channel information, which is used as the shared random information within the group and generates the shared group key between the AP and all BDs;

[0018] Step 7, according to the actual number of BDs, divide the BDs into several small groups according to the geographical location, generate the group key within the small group, and the AP encrypts the group keys of other small groups with the group key of the corresponding small group and distributes them to other small groups, thereby constructing the group key between all small groups.

[0019] Furthermore, in Step 1, before generating the key between the AP and the BD, the device is in the listening mode to obtain the downlink channel information, specifically including: BDA1 works in the listening mode and directly receives the radio frequency signal s(t) from the signal source; the radio frequency signal of the signal source passes through the downlink channel h1 and is received by A1 respectively; in the ideal noiseless case, the received signal is expressed as c1(t) = h1s(t), where is the downlink channel from the AP to A1; at this time, A1 obtains the signal containing the downlink channel information.

[0020] In Step 2, before generating the key between the AP and the BD, the AP has full-duplex communication capabilities, simultaneously transmitting radio frequency signals and receiving reflected signals to obtain uplink channel information, which specifically includes: The signal source AP continuously transmits radio frequency signal s(t), and BDA1 operates in backscatter mode, reflecting the signal to the AP; while continuously transmitting the radio frequency signal, the AP simultaneously receives the reflected information αh′1h1s(t) from the BD, where h′1 is the uplink channel from A1 to the AP and α is the reflection coefficient; within the coherence time, due to the reciprocity of the channel, h′1 = h1, and the AP obtains a signal containing the reflected cascaded channel information h′1h1.

[0021] In Step 3, before generating the key between the AP and the BD, the AP and the BD respectively construct shared random information and then generate a shared key, which specifically includes: After the BD and the AP respectively obtain the downlink channel information and the reflected cascaded channel information, BDA1 directly squares the downlink channel information c1(t) and multiplies it by the reflection coefficient α to obtain the information αh1h1s 2 (t), which contains the downlink channel information; at the same time, the AP multiplies the received reflected information αh′1h1s(t) by the source signal s(t) to obtain the information αh′1h1s 2 (t), which contains the uplink channel information. Due to the reciprocity of the channel, the uplink channel is equal to the downlink channel information, h1 = h′1, and the information obtained by all the BD and the AP is equal, αh1h1s 2 (t) = αh′1h1s 2 (t), so the information obtained by both parties is used as the shared random information to generate the symmetric key K1 between the two parties.

[0022] In Step 4, before generating the group key of the BD, the signal source sends signals to all BDs in a time-sharing manner, and the BDs work in the listening mode and the backscatter mode successively to generate the shared random information between the signal source and all BDs, which specifically includes:

[0023] (1) The signal source sends signals to each BD: The signal source sends the radio frequency signal s(t) to A i The radio frequency signal s(t) is transmitted, and the signal passes through the downlink channel h i and is received by A i in the listening mode, and A i then obtains a signal containing the downlink channel information h i ;

[0024] (2) Within the coherence time, A i switches from the listening mode to the backscatter mode; A i backscatters the incident signal to the AP, and the signal received by the AP is αh′ i h i s(t), where αh′i h i For the reflected cascaded channel information, BDA i and the signal source will use αh i h i s 2 (t) = αh′ i h i s 2 (t) as the shared random information.

[0025] Furthermore, in step five, the AP calculates the differences and broadcasts the difference sequence to all BDs, so that all BDs can obtain all the shared channel information. Specifically, the signal source selects a backscatter device as a reference, denoted as BDA1, and calculates the reflected cascaded channel information of all BDs (αh′ i h i s 2 (t)) and the reflected cascaded channel information αh′1h1s 2 (t) of the reference A1 to obtain the difference sequence {δ2,..., δ N}, where δ i = αh′ i h i s 2 (t) - αh′1h1s 2 (t), and broadcasts this difference sequence.

[0026] In step six, before generating the group key of the BDs, each BD recursively recovers all the reflected cascaded channel information. Specifically, each BD squares the received downlink information and multiplies it by the reflection coefficient to construct the information αh i h i s 2 (t); all BDs calculate all the information values (αh′1h1s N ) using the received difference sequence {δ2,..., δ 2 (t),..., αh′ N h N s 2 (t)); (αh′1h1s 2 (t),..., αh′ N h N s 2 (t)) is used as the shared random information between the AP and all BDs to generate the shared group key GK.

[0027] In step six, before generating the group keys of all BDs, all BDs are divided into several small groups according to their geographical locations, and the group keys are generated for each small group, and then the overall shared group key is generated through an encrypted sharing method. Specifically,

[0028] (1) Divide all BDs into several small groups (G1, ..., G K ) according to their geographical locations and distances, and for each small group G k , generate a small group key GK k respectively according to the above steps;

[0029] (2) The AP encrypts the other small group key sequences by using a certain small group key, and then sends the small group G k ; The small group decrypts S by using the key GK k it owns to obtain all small group keys (GK1, ..., GK K ), and so on, all small groups obtain all small group keys (GK1, ..., GK K ), thereby obtaining the overall shared group key.

[0030] Another object of the present invention is to provide a backscatter device system group key generation system applying the backscatter device system group key generation method described above. The backscatter device system group key generation system includes:

[0031] A downlink channel information acquisition module, which is used for the signal source to send a signal and the reflection device to be in the listening mode;

[0032] A reflection cascade channel information acquisition module, which is used for the signal source to send a signal, and one of the reflection devices to be in the backscatter mode, and the AP receives the reflected signal based on the full-duplex capability;

[0033] An uplink channel information acquisition module, which is used for extracting the shared channel information from the reflected signal;

[0034] A group shared channel information acquisition module, which is used for the signal source to send signals to all BDs in a time-sharing manner, and the BDs work in the listening mode and the backscatter mode successively to generate the shared information between the signal source and all BDs;

[0035] A difference calculation module, which is used for the signal source to calculate the difference between the received reflection cascade channel information and the reflection cascade channel information of the reference device after specifying the reference device, and obtain the difference sequence;

[0036] A difference sequence broadcast module, which is used for the AP to broadcast the constructed difference sequence to each backscatter device;

[0037] A shared channel extraction and key construction module, which is used for each backscatter device to recursively obtain all shared channel information based on the received difference sequence and the downlink channel information constructed by itself, as the in-group shared random information, so as to extract the shared group key.

[0038] Another object of the present invention is to provide a computer device, which includes a memory and a processor. The memory stores a computer program. When the computer program is executed by the processor, the processor executes the steps of the reverse scattering device system group key generation method.

[0039] Another object of the present invention is to provide a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, the processor executes the steps of the reverse scattering device system group key generation method.

[0040] Another object of the present invention is to provide a reverse scattering device that executes the steps of the reverse scattering device system group key generation method.

[0041] Another object of the present invention is to provide a signal source that executes the steps of the reverse scattering device system group key generation method.

[0042] Another object of the present invention is to provide an information data processing terminal for implementing the reverse scattering device system group key generation system.

[0043] Combined with the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solutions to be protected by the present invention are as follows:

[0044] First, in view of the technical problems existing in the above-mentioned prior art and the difficulty of solving the problems, closely combined with the technical solutions to be protected by the present invention and the results and data in the R & D process, etc., analyze in detail and profoundly how the technical solutions of the present invention solve the technical problems and the creative technical effects brought after solving the problems. The specific description is as follows:

[0045] The reverse scattering device group key generation method based on a shared channel provided by the present invention realizes a lightweight key protocol, supports multiple schemes, has high security, scalability, and high efficiency.

[0046] (1) Lightweight key protocol. By utilizing the physical layer characteristics of the wireless channel, the present invention provides a lightweight key protocol framework in the reverse scattering communication system, rather than a complex encryption algorithm that induces a large amount of computational overhead. For example, compared with the Diffie-Hellman (ECDH) scheme based on elliptic curves, the energy consumed by the ECDH protocol is about 100 times that of the physical layer key generation scheme, and the complexity brought is about 1000 times. Therefore, the present invention can realize lightweight key generation between different parties in the reverse scattering communication system.

[0047] (2) Support multiple solutions. The present invention supports the generation of symmetric keys between the signal source and the backscatter device, and also supports the generation of shared group keys between the AP and multiple BDs in the backscatter communication system.

[0048] (3) High security. The present invention extracts the reciprocity and randomness of the wireless channel to generate shared keys, which has been proven to be secure in information theory. Since all relevant channels are independent of each other, attackers cannot intercept any information about the shared group key.

[0049] (4) Scalability. The present invention can be easily extended to a backscatter communication system with any number of backscatter devices. The method is to divide a single group of backscatter devices into several subgroups according to their geographical locations or distances from each other, so as to generate the shared group keys of each subgroup, thereby reducing the complexity of the entire group key generation and supporting high scalability. In addition, the present invention can also be extended to multiple signal sources by allowing these signal sources to cooperate with each other to achieve the generation of group keys between different groups of backscatter devices within the coverage ranges of different signal sources.

[0050] (5) High efficiency. By overcoming the disadvantages of cryptographic solutions, such as high computational cost and limitations on resource-constrained backscatter devices, the present invention can achieve high-efficiency group key generation in the backscatter communication system.

[0051] Second, considering the technical solution as a whole or from the perspective of the product, the technical effects and advantages of the technical solution to be protected by the present invention are specifically described as follows:

[0052] The method for generating group keys for backscatter devices based on a shared channel provided by the present invention extracts the reciprocity and randomness of the wireless channel to generate secure shared keys for the reflection device and the signal source, as well as between the reflection devices, solves the problem of high computational cost of traditional cryptography, solves the problem that cannot be utilized by existing physical layer key generation schemes, realizes a lightweight key negotiation protocol in the backscatter communication system, supports multiple solutions, and has high security, scalability, and efficiency.

[0053] Third, as the creative auxiliary evidence of the claims of the present invention, it is also reflected in the following important aspects:

[0054] (1) The expected benefits and commercial value after the transformation of the technical solution of the present invention are:

[0055] The technology of the present invention can be used for key generation in the backscatter communication system, solves the cost problem of cryptographic calculations for low-power devices, can greatly reduce the total energy consumption of the devices, extend the service life of the devices, and in addition, can increase the security of the backscatter communication system, is easy to deploy, and has high commercial value.

[0056] (2) The technical solution of the present invention fills the technical gaps in the domestic and international industries: The existing domestic and international technologies have not proposed a key generation scheme between efficient backscatter devices. Currently, lightweight cryptography principles are mainly adopted, but they have the characteristic of high energy consumption and are not suitable for resource-constrained micro backscatter devices. At the same time, traditional physical layer key generation schemes require devices to be able to send detection signals, which are completely unsuitable for backscatter systems that can only reflect signals.

[0057] According to the two characteristics of resource constraints of backscatter devices and the inability to actively send detection signals, the present invention designs a group key generation scheme for backscatter devices based on a shared channel, which can solve the limitations of resource constraints of backscatter devices and the inability to actively send detection signals, and provide a secure and reliable shared group key for backscatter devices.

[0058] (3) The technical solution of the present invention solves the technical problems that people have been eager to solve but have never succeeded in: Due to the limitations of insufficient computing power in the backscatter communication system, it is difficult to apply complex cryptographic algorithms to ensure the generation of shared keys, and there are always security risks such as illegal eavesdropping. The present invention can provide a shared key generation scheme for backscatter devices, ensure the security of communication between both parties, and solve the security problems of low-power backscatter communication systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required to be used in the embodiments of the present invention. Obviously, the following described drawings are only some embodiments of the present invention, and those of ordinary skill in the art can obtain other drawings based on these drawings without creative efforts.

[0060] Figure 1 It is a flowchart of the method for generating a group key of a backscatter device system provided by an embodiment of the present invention;

[0061] Figure 2 It is a schematic diagram of the method for generating a key between a backscatter device and a signal source device provided by an embodiment of the present invention;

[0062] Figure 3 It is a system diagram of the method for generating a group key of a backscatter device group facing a star structure provided by an embodiment of the present invention;

[0063] Figure 4 It is a schematic diagram of the method for generating a hierarchical group key of a backscatter device group facing a star structure provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0064] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0065] In view of the problems existing in the prior art, the present invention provides a method, system, device and terminal for generating group keys of a backscatter device system. The present invention will be described in detail below with reference to the accompanying drawings.

[0066] I. Explanation of embodiments. In order to enable those skilled in the art to fully understand how the present invention is specifically implemented, this part is an explanatory embodiment that expands on the technical solutions of the claims.

[0067] As Figure 1 shown, the method for generating group keys of the backscatter device system provided by the embodiment of the present invention includes the following steps:

[0068] S101, obtaining downlink channel information: The signal source AP sends a signal, and all backscatter devices BD are in the listening mode. BD measures the downlink channel information from the received signal.

[0069] S102, obtaining reflected cascade channel information: The signal source sends a signal, BD is in the backscatter mode, and the full-duplex signal source AP receives the reflected signal of BD and measures the reflected cascade channel information from the reflected signal.

[0070] S103, constructing uplink channel information: The reflected cascade channel includes downlink channel information and uplink channel information. AP calculates the uplink channel from the reflected cascade channel information. AP and BD respectively use the uplink channel information and the downlink channel information as shared random information to generate a symmetric shared key between the two parties.

[0071] S104, obtaining all group shared channel information: The signal source sends signals to all BD in a time-sharing manner, and BD works in the listening mode and the backscatter mode successively to generate shared information between the signal source and all BD.

[0072] S105, calculating the difference: The signal source AP calculates the difference between the uplink channel information corresponding to other devices and the uplink channel information of the reference device to form a difference sequence, and broadcasts it to all BD.

[0073] S106, shared channel extraction and key construction: Based on its own downlink channel information and the received difference sequence, BD recursively obtains all loop channel information as group-internal shared random information and generates a shared group key between AP and all BD.

[0074] S107. According to the actual quantity of BDs, divide the BDs into several small groups according to geographical locations, generate the group keys within the small groups, and the AP encrypts the group keys of other small groups with the group key of the corresponding small group and distributes them to other small groups, thereby constructing the group keys among all small groups.

[0075] As a preferred embodiment, as Figure 2 shown, the method for generating the group key of the backscatter device system provided by the embodiment of the present invention specifically includes the following steps:

[0076] Step 1. Obtain the downlink channel information: The signal source (AP) sends a signal, and all backscatter devices (BDs) are in the listening mode. The BDs measure the downlink channel information from the received signal.

[0077] Step 2. Obtain the reflected cascade channel information: The signal source sends a signal, and the BDs are in the backscatter mode. The full-duplex signal source AP receives the reflected signals of the BDs, and the AP measures the reflected cascade channel information from the reflected signals.

[0078] Step 3. Construct the uplink channel information: The reflected cascade channel includes the downlink channel information and the uplink channel information, and within the coherence time, the uplink channel is approximately the same as the downlink channel. Therefore, the AP can calculate the uplink channel from the reflected cascade channel information. Like the BDs, both can obtain the shared channel information (the uplink channel or the downlink channel, which are equal) between the two parties. This shared channel information is used as the shared random information between the AP and the BDs to generate the symmetric shared key between the two parties.

[0079] Step 4. Obtain the shared channel information of all groups: The signal source sends signals to all BDs in a time-sharing manner, and the BDs work in the listening mode and the backscatter mode successively to generate the shared information between the signal source and all BDs.

[0080] Step 5. Calculate the difference: After specifying the reference reflection device, the signal source AP calculates the difference between the uplink channel information corresponding to other devices and the uplink channel information of the reference device to form a difference sequence, and broadcasts it to all BDs.

[0081] Step 6. Shared channel extraction and key construction module: Based on its own downlink channel information and the received difference sequence, the BD recursively obtains all round-trip channel information, which is used as the shared random information within the group and generates the shared group key between the AP and all BDs.

[0082] Step 7. According to the actual quantity of BDs, the BDs can be divided into several small groups according to geographical locations. The group keys within the small groups are generated according to the above steps within the small groups. The AP encrypts the group keys of other small groups with the group key of the corresponding small group and distributes them to other small groups to construct the group keys among all small groups.

[0083] In step 1 provided by the embodiment of the present invention, before generating the key between the AP and the BD, the device is in the listening mode to obtain the downlink channel information, and the process includes:

[0084] The backscatter device BDA1 operates in the listening mode and directly receives the radio frequency signal s(t) from the signal source; the radio frequency signal of the signal source is received by A1 through the downlink channel h1 respectively; in the case of ideal noise-free, the received signal is expressed as c1(t) = h1s(t), where h1 is the downlink channel from the AP to A1; at this time, A1 obtains the signal containing the downlink channel information.

[0085] In step 2 provided by the embodiment of the present invention, before generating the key between the AP and the BD, the AP has full-duplex communication capabilities and can simultaneously transmit radio frequency signals and receive reflected signals to obtain the uplink channel information, and the process includes:

[0086] The signal source AP continuously transmits the radio frequency signal s(t), and BDA1 operates in the backscatter mode to reflect the signal to the AP; while continuously transmitting the radio frequency signal, the AP simultaneously receives the reflected information αh′1h1s(t) from the BD, where h′1 is the uplink channel from A1 to the AP and α is the reflection coefficient. During the coherence time, due to the reciprocity of the channel, h′1 = h1. At this time, the AP obtains the signal containing the reflected cascade channel information h′1h1.

[0087] In step 3 provided by the embodiment of the present invention, before generating the key between the AP and the BD, the AP and the BD respectively construct shared random information, and then generate a shared key, and the process includes:

[0088] After the BD and the AP respectively obtain the downlink channel information and the reflected cascade channel information, BDA1 directly squares the downlink channel information c1(t) and multiplies it by the reflection coefficient α to obtain the information αh1h1s 2 (t), which contains the downlink channel information h1. At the same time, the AP multiplies the received reflected information αh′1h1s(t) by the source signal s(t) to obtain the information αh′1h1s 2 (t), which contains the uplink channel information h′1. Since the channel has reciprocity, the uplink channel is equal to the downlink channel information, h1 = h′1, and the information obtained by all the BD and the AP is equal, that is, αh1h1s 2 (t) = ααh′1h1s 2 (t), so the information obtained by both parties can be used as the shared random information to generate the symmetric key K1 between the two parties.

[0089] In step 4 provided by the embodiment of the present invention, if there are N backscatter devices A in the system i ,..., A N, before generating the group key of the BD, the signal source sends signals to all BDs in a time-sharing manner, and the BDs work in the listening mode and the backscattering mode successively to generate the shared random information between the signal source and all BDs. The process includes:

[0090] (1) The signal source sends signals to each BD: The signal source sends the radio frequency signal s(t) to the backscattering device A i through the downlink channel h i , and it is received by A in the listening mode i . Then A i obtains the signal containing the downlink channel information h i .

[0091] (2) Within the coherence time, A i switches from the listening mode to the backscattering mode; A i backscatters the incident signal to the AP, and the signal received by the AP is αh′ i h i s(t), where αh′ i h i is the reflected cascade channel information, and the BDA i and the signal source take αh i h i s 2 (t) = αh′ i h i s 2 as the shared random information.

[0092] In step 5 provided by the embodiment of the present invention, the AP calculates the difference and broadcasts the difference sequence to all BDs, so that all BDs can obtain all the shared channel information. The process includes:

[0093] The signal source selects a backscattering device as a reference, denoted as BDA1, and calculates the difference between the reflected cascade channel information of all BDs (αh′ i h i s 2 (t)) and the reflected cascade channel information αh′1h1s 2 (t) of the reference A1, to obtain the difference sequence {δ2,..., δ N}, δ i = αh′ i h i s 2 (t) - αh′1h1s 2 (t), and broadcasts this difference sequence.

[0094] In step 6 provided by the embodiment of the present invention, before generating the group key of the BD, each BD recursively recovers all the reflected cascade channel information. The process includes:

[0095] As shown above, each BD squares the received downlink information and multiplies it by the reflection coefficient to construct the information αh i h i s 2 (t); all BDs (including BDA1) respectively use the received difference sequences {δ2,..., δ N} to calculate all information values (αh′1h1s 2 (t),..., αh′ N h N s 2 (t)). For example, A2 has αh′2h2s 2 (t), and can calculate αh′1h1s 2 (t) from δ2, and further recursively calculate all other αh′ i h i s 2 (t), and so on for other backscatter devices. Therefore, (αh′1h1s 2 (t),..., αh′ N h N s 2 (t)) can be used as the shared random information between the AP and all BDs to generate the shared group key GK.

[0096] In step 6 provided by the embodiment of the present invention, before generating the group keys of all BDs, all BDs are divided into several small groups according to geographical locations, and the group keys are generated for each small group, and then the overall shared group key is generated through an encrypted sharing method. The process includes:

[0097] (1) According to geographical locations and their distances, all BDs are divided into several small groups (G1,..., G K ), and within each small group G k , according to the above steps, the small group key GK k is generated respectively.

[0098] (2) The AP encrypts the sequences of other small group keys by using one of the small group keys (for example, G k ), that is, and sends the small group G k . This small group decrypts S by using the key GK k it owns to obtain all the small group keys (GK1,..., GK K ), and so on. All small groups can obtain all the small group keys (GK1,..., GK K ), thus obtaining the overall shared group key.

[0099] The backscatter device system group key generation system provided by the embodiment of the present invention includes:

[0100] Downlink channel information acquisition module, used for the signal source to send a signal and the reflector device to be in a listening mode;

[0101] A reflection cascade channel information acquisition module is used for a signal source to send a signal, one of the reflection devices is in backscatter mode, and the AP receives the reflection signal based on full-duplex capability;

[0102] An uplink channel information acquisition module, used to extract shared channel information from the reflected signal;

[0103] The group shared channel information acquisition module is used for the signal source to send signals to all BDs in time division, and the BDs work in the listening mode and the backscattering mode successively to generate shared information between the signal source and all BDs;

[0104] A difference calculation module, which is used to calculate the difference between the received reflection cascade channel information and the reflection cascade channel information of the reference device after specifying the reference device, and obtain a difference sequence;

[0105] A difference sequence broadcast module is used for the AP to broadcast the constructed difference sequence to each backscatter device;

[0106] The shared channel extraction and key construction module is used for each backscatter device to recursively obtain all shared channel information based on the received difference sequence and the downlink channel information constructed by itself, so as to use it as the shared random information within the group, thereby extracting the shared group key.

[0107] 2. Application Examples: In order to prove the creativity and technical value of the technical solution of the present invention, this section provides application examples of the technical solution of the claims on specific products or related technologies.

[0108] like Figure 2 As shown, the key generation method between the AP and the BD in the star-structured backscatter system provided by the embodiment of the present invention includes the following steps:

[0109] (1) BDA1 works in the listening mode and directly receives the RF signal s(t) from the signal source. The RF signal from the signal source is received by A1 through the downlink channel h1. The signals received by A1 are:

[0110] c1(t)=h1s(t)+n1(t), (1)

[0111] Where h1 is the downlink channel and n1 is the additive white Gaussian noise AWGN. In this process, BD can receive information about the downlink channel.

[0112] (2) The signal source continuously broadcasts radio frequency signals, and BDA1 operates in backscatter mode, reflecting the signals to the AP. In full-duplex mode, the superimposed signals received by the AP, including the signals backscattered from A1 and the signals directly transmitted from the signal source, are given by the following formula:

[0113] y AP (t) = αh′1h1b(t)s(t) + βs(t) + n1(t). (2)

[0114] Where α is the backscatter coefficient, β is the signal self-interference coefficient (which can be measured experimentally), b(t) is the backscatter modulation signal, and h′1 is the uplink channel. In the present invention, h′1h1 is called the reflection cascade channel.

[0115] (3) For simplicity, assume there is no environmental noise, and the signals s(t) and b(t) are known to all parties of the system. BDA1 and the AP can estimate the channel information respectively, then:

[0116] C1 = h1, (3)

[0117] Y AP = αh′1h1 + β. (4)

[0118] Based on the estimated channel information, A1 and the AP can construct the end-to-end channel information between them by calculating the following formula:

[0119] V1 = C1 = h1, (5)

[0120]

[0121] Due to the reciprocity of the channel, h′1 = h1 holds, and all channels, h1, h′1, remain unchanged within the coherence time. Then the channel information constructed between A1 and the AP is theoretically equal to each other, that is, V1 = V2, that is Therefore, A1 and the AP can use this channel as shared random information, with a series of channel information measurement results and as shared random information.

[0122] (4) After channel measurement and randomness extraction, the BD can perform three steps of quantization, information reconciliation, and privacy amplification on the shared random information and to obtain the final key.

[0123] When multiple BDs need to construct a group shared key, in addition to generating a shared key with the BD, the signal source can also provide all channel shared information for the BD through the channel difference sequence to generate a shared group key.

[0124] At this time, the key generation step can be executed from S104 to S106. As Figure 3 shown, the method for generating group keys of the backscatter system for star structures provided by the embodiments of the present invention includes the following steps:

[0125] (1) The signal source needs to send signals to each BD. Since the process of sending signals to different BDs is the same, the present invention takes BDA i as an example. The signal source sends the radio frequency signal s(t) to A i . At the same time, A i can estimate the information of the downlink channel from the received signal. The signal received by A i is:

[0126] c i (t) = h i s(t) + n i (t). (7)

[0127] (2) Within the coherence time, A i backscatters the incident signal to the signal source, and the signal source continuously emits radio frequency signals. The signal received by the signal source is:

[0128]

[0129] For simplicity, it is assumed that there is no environmental noise, and the signals s(t) and b(t) are known to all parties of the system. BDA i and AP can estimate the channel information respectively, then there is:

[0130] C i = h i . (9)

[0131]

[0132] Because the present invention assumes that the entire process is completed within a time less than the channel coherence time, the channel reciprocity will hold (i.e., h i = h' i ), that is, all channels will remain unchanged. Therefore, AP can construct a channel information that is equal to C i , that is

[0133] (3) The signal source selects a BD as a reference (the present invention represents it as BDA1), and calculates the difference between the uplink channel information of all other BDs and the uplink channel information of the reference A1.

[0134]

[0135] Then, the signal source broadcasts the difference sequence {δ2,..., δ i} to all BDs.

[0136] (4) BDA1 uses the downlink channel value h1 and the difference sequence {δ2,..., δ i} to calculate the other shared channel values {h2,..., h i}, thus obtaining all the shared channel information {h1,..., h i}; other BDs use their own downlink channel value h i to first calculate h1, and then successively calculate all the shared channel information {h1,..., h i}.

[0137] Therefore, both the signal source and all BDs can use the obtained all-channel information {h1,..., h i} (i = 1,..., N) as the same shared random signal, and after going through three steps of quantization, information reconciliation, and privacy amplification, a group key can be generated.

[0138] The above group key generation method can be extended to other instances with a larger number of BDs. The BDs are divided into multiple small groups, and each small group respectively generates its own group key according to the above process. Its system and grouping form are as Figure 4 shown, including the following steps:

[0139] First, all the backscatter devices in a large group are divided into several independent small subgroups according to their geographical locations or the distances between them. Each subgroup will use the group key generation method for a single group of backscatter devices to generate a group key, and only need to execute from step S104 to step S106 to achieve it.

[0140] Subsequently, the AP encrypts the remaining keys using the key pairs of each small group, that is and sends the small group G k . This small group decrypts S using the key GK k it owns to obtain all the small group keys (GK1,..., GK K ), and so on. All small groups can obtain all the small group keys (GK1,..., GK K ), thereby obtaining the overall shared group key.

[0141] Figure 4Shows an example of a communication network consisting of 8 backscatter devices. The group is divided into two subgroups. For each subgroup, for example, group 1 (A1, A2, A3) and the AP execute from S104 to step S106 all the time to generate the shared group key GK1 of this small group. And so on, group 2 (A4, A5, A6) generates the shared group key GK2, and group 3 (A7, A8) generates the shared group key GK3. The AP calculates and sends it to (A1, A2, A3). (A1, A2, A3) can calculate and obtain (GK2, GK3), so as to obtain all the keys (GK1, GK2, GK3). And so on, (A4, A5, A6, A7, A8) will also obtain (GK1, GK2, GK3)

[0142] In order to reduce the computational overhead when BD estimates the channel, the embodiment of the present invention designs s(t) as a dedicated signal so that the signal power distribution of the period is stable, thereby improving the method for measuring the channel. BD does not need to perform channel measurement, specifically as follows:

[0143] (1) BDA1 works in the listening mode and directly receives the radio frequency signal s(t) from the signal source. The radio frequency signal of the signal source passes through the downlink channel h1 and is received by A1. The signals received by A1 are respectively:

[0144] c1(t) = h1s(t) + n1(t), (12)

[0145] where h1 is the downlink channel and n1 is the additive white Gaussian noise AWGN. In this process, BD can receive information about the downlink channel.

[0146] (2) The signal source continuously broadcasts the radio frequency signal, and BDA1 works in the backscatter mode and reflects the signal to the AP. In the full-duplex mode, the superimposed signal received by the AP, including the signal backscattered from A1 and the signal directly sent from the signal source, is given by the following formula:

[0147] y AP (t) = αh′1h1b(t)s(t) + βs(t) + n1(t). (13)

[0148] where α is the backscattering coefficient, β is the signal self-interference coefficient (which can be measured through experiments), b(t) is the backscattering modulation signal, and h′1 is the uplink channel. The present invention calls h′1h1 the reflection cascade channel.

[0149] (3) For simplicity, assume that there is no environmental noise, and the signals s(t) and b(t) are known to all parties in the system. The information that BDA1 and the AP can obtain respectively is:

[0150] C1 = h1s(t), (14)

[0151] Y AP = αh′1h1b(t)s(t) + βs(t). (15)

[0152] Based on the above information, A1 and AP can obtain the channel information by constructing the following formula:

[0153]

[0154] V2 = (Y AP - βs(t))·s(t) = αh′1h1b(t)s 2 (t). (17)

[0155] Due to the reciprocity of the channel, h′1 = h1 holds, and all channels, h1, h′1, remain unchanged within the coherence time and have a longer period than s(t), so b(t) can be regarded as 1. Therefore, the information constructed between A1 and AP is theoretically equal to each other, that is, V1 = V2, that is, αh1h1s 2 (t) = αh′1h1s 2 (t). Therefore, A1 and AP can use this information as shared random information, using a series of channel information measurement results and as the shared random information.

[0156] (4) After channel measurement and randomness extraction, BD can perform three steps of quantization, information reconciliation, and privacy amplification on the shared random information and to obtain the final key.

[0157] In the group key production processes S104 to S106, the method remains the same, only the construction method and content of the shared information need to be replaced.

[0158] III. Evidence of the relevant effects of the embodiments. The embodiments of the present invention have achieved some positive effects during the R & D or use process, and indeed have great advantages compared with the prior art. The following content is described in combination with the data, charts, etc. of the test process.

[0159] At present, for the communication security between backscatter devices, it mainly relies on lightweight cryptographic mechanisms. By using pre-shared master keys or establishing session keys between both parties through the Diffie-Hellman key exchange protocol, the communication content is encrypted and decrypted to ensure the transmission security between backscatter devices. Among them, for the master key method, the scale of backscatter device deployment is large, the system structure is dynamically distributed, and it is difficult to deploy a trusted third party for the distribution and update of master keys. Moreover, in specific scenarios, the master key distribution and update process is vulnerable to eavesdropping. Once leaked, all communication content may be leaked, and forward secrecy cannot be provided. In addition, for the Diffie-Hellman key exchange protocol, updating for backscatter devices will bring complex computational and communication interaction overheads, consuming the limited energy and computational resources of the backscatter devices themselves.

[0160] Compared with the above two types of key sharing schemes based on cryptographic mechanisms, the present invention will utilize the randomness and reciprocity of the shared physical layer channel to provide a lightweight key sharing scheme with information-theoretic security (one-time pad) for resource-constrained backscatter communication systems and devices. According to the physical layer security model, an eavesdropper cannot approach a legitimate user wirelessly. When the distance from the backscatter device or AP exceeds 1-2 signal wavelengths, the legitimate user and the eavesdropping user will experience almost independent channel fading. Therefore, the eavesdropper cannot obtain the shared channel information and its shared key between legitimate users. In addition, the present invention can achieve independent key establishment on demand, without the need for a specific server or third-party device, and is more suitable for dynamically distributed backscatter communication systems. In addition, according to the actual experimental comparison of the MCS-51 single-chip microcomputer, the energy consumed by the physical layer key generation scheme is about 1 / 100 of that of the elliptic curve Diffie-Hellman (ECDH) scheme, and its computational complexity is 1 / 1000 of the latter.

[0161] In addition, compared with the existing active physical layer key generation schemes, the present invention does not need to actively transmit detection signals to estimate the shared channel information, and can further reduce the energy consumption of terminal devices, especially backscatter devices, and is more suitable for low-power backscatter communication systems relying on wireless energy.

[0162] It should be noted that the embodiments of the present invention can be implemented by hardware, software, or a combination of software and hardware. The hardware part can be implemented using dedicated logic; the software part can be stored in a memory and executed by an appropriate instruction execution system, such as a microprocessor or dedicated designed hardware. Those of ordinary skill in the art can understand that the above devices and methods can be implemented using computer-executable instructions and / or included in processor control code, for example, such code is provided on a carrier medium such as a disk, CD, or DVD-ROM, a programmable memory such as a read-only memory (firmware), or a data carrier such as an optical or electronic signal carrier. The devices and their modules of the present invention can be implemented by hardware circuits of programmable hardware devices such as very large scale integrated circuits or gate arrays, semiconductors such as logic chips, transistors, etc., or field programmable gate arrays, programmable logic devices, etc., can also be implemented by software executed by various types of processors, or can be implemented by a combination of the above hardware circuits and software such as firmware.

[0163] As described above, the above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention should be covered by the protection scope of the present invention.

Claims

1. A method for generating a group key of a backscatter device system, characterized in that, The method for generating the group key of the backscatter device system includes: the backscatter device measures the downlink channel information from the received signal, and the full-duplex signal source measures the reflected cascade channel information from the reflected signal; the signal source calculates and obtains the uplink channel information from the reflected cascade channel information and generates a symmetric shared key; obtains all the shared channel information of the group, and calculates the difference sequence between the uplink channel information and the uplink channel information of the reference device; based on the difference sequence, performs shared channel extraction and key construction, and simultaneously constructs the group key between all small groups. The method specifically includes the following steps: Step 1, obtain the downlink channel information: The signal source AP sends a signal, and all backscatter devices BD are in the listening mode. The BD measures the downlink channel information from the received signal. Step 2, obtain the reflected cascade channel information: The signal source sends a signal, the BD is in the backscatter mode, the full-duplex signal source AP receives the reflected signal of the BD, and measures the reflected cascade channel information from the reflected signal. Step 3, construct the uplink channel information: The reflected cascade channel includes the downlink channel information and the uplink channel information. The AP calculates and obtains the uplink channel information from the reflected cascade channel information. The AP and the BD respectively use the uplink channel information and the downlink channel information as the shared random information to generate the symmetric shared key between the two parties. Step 4, obtain all the shared channel information of the group: The signal source sends signals to all BDs at different times, and the BDs work in the listening mode and the backscatter mode successively to generate the shared information between the signal source and all BDs. Step 5, calculate the difference: The signal source AP calculates the difference between the uplink channel information corresponding to other devices and the uplink channel information of the reference device to form a difference sequence, and broadcasts it to all BDs. Step 6, shared channel extraction and key construction: Based on its own downlink channel information and the received difference sequence, the BD recursively obtains all the loop channel information, which is used as the intra-group shared random information and generates the shared group key between the AP and all BDs. Step 7, according to the actual number of BDs, divide the BDs into several small groups according to the geographical location, generate the group key within the small group, and the AP encrypts the group keys of other small groups with the group key of the corresponding small group and distributes them to other small groups, thereby constructing the group key between all small groups.

2. The method for generating a group key of a backscatter device system according to claim 1, wherein, In Step 1, before generating the key between the AP and the BD, the device is in the listening mode to obtain the downlink channel information, which specifically includes: The signal source selects a backscatter device as a reference, denoted as BDA1. BDA1 works in the listening mode and directly receives the radio frequency signal s(t) from the signal source; the radio frequency signal of the signal source passes through the downlink channel h1 and is received by BDA1 respectively; in the ideal noiseless case, the received signal is expressed as c1(t) = h1s(t), where h1 is the downlink channel from the AP to BDA1; at this time, BDA1 obtains the signal containing the downlink channel information. In step 2, before generating the key between the AP and the BD, the AP has full-duplex communication capability and simultaneously transmits a radio frequency signal and receives the reflected signal to obtain the uplink channel information, which specifically includes: The signal source AP continuously transmits the radio frequency signal s(t), and BDA1 operates in the backscattering mode to reflect the signal to the AP; while continuously transmitting the radio frequency signal, the AP simultaneously receives the reflected information αh′1h1s(t) from the BD, where h′1 is the uplink channel from BDA1 to the AP and α is the reflection coefficient; within the coherence time, due to the reciprocity of the channel, h′1 = h1, and the AP obtains the signal containing the reflected cascaded channel information h′1h1. In step 3, before generating the key between AP and BD, AP and BD respectively construct shared random information and then generate a shared key, which specifically includes: after BD and AP respectively obtain the downlink channel information and the reflected cascaded channel information, BDA1 directly squares the downlink channel information c1(t) and multiplies it by the reflection coefficient α to obtain the information αh1h1s 2 (t), which contains the downlink channel information; at the same time, AP multiplies the received reflected information αh′1h1s(t) by the source signal s(t) to obtain the information αh′1h1s 2 (t), which contains the uplink channel information; due to the reciprocity of the channel, the uplink channel information is equal to the downlink channel information, h1 = h′1, so the information obtained by BD and AP is equal, αh1h1s 2 (t) = αh′1h1s 2 (t), so the information obtained by both parties is used as the shared random information to generate the symmetric key K1 between the two parties; In step 4, before generating the group key of the BD, the signal source sends signals to all BDs in a time-sharing manner, and the BDs work in the listening mode and the backscattering mode successively to generate the shared random information between the signal source and all BDs, which specifically includes: (1) The signal source sends signals to each BD: The signal source sends the radio frequency signal s(t) to BD A i through the downlink channel h i , and the signal is received by A i in the listening mode. Then BD A i obtains the signal containing the downlink channel information h i . (2) Within the coherence time, BDA i Switches from the listening mode to the backscatter mode; BDA i Backscatters the incident signal to the AP, and the signal received by the AP is αh′ i h i s(t), where αh′ i h i Is the reflected cascaded channel information, BDA i And the signal source then takes αh i h i s 2 (t) = αh′ i h i s 2 (t) as the shared random information.

3. The method for generating a group key of a backscatter device system according to claim 2, wherein In step five, the AP calculates the differences and broadcasts the difference sequence to all BDs, enabling all BDs to obtain all the shared channel information, which specifically includes: The signal source selects a backscatter device as a reference, denoted as BDA1, and calculates the reflected cascaded channel information (αh′ i h i s 2 (t)) of all BDs and the reflected cascaded channel information αh′1h1s 2 (t) of the reference A1, obtains the difference sequence {δ2,...,δ N}, where δ i = αh′ i h i s 2 (t) - αh′1h1s 2 (t), and broadcasts this difference sequence; In step six, before generating the group key of BD, each BD recursively recovers all reflected cascade channel information, specifically including: each BD squares the received downlink information and multiplies it by the reflection coefficient to construct the information αh i h i s 2 (t); all BDs respectively use the received difference sequences {δ2,...,δ N} to calculate all information values (αh′1h1s 2 (t),...,αh′ N h N s 2 (t)); (αh′1h1s 2 (t),...,αh′ N h N s 2 (t)) is used as the shared random information between the AP and all BDs to generate the shared group key GK; In step 6, before generating the group keys of all BDs, all BDs are divided into several small groups according to their geographical locations, the group keys are generated for each small group, and then the overall shared group key is generated through an encrypted sharing method, which specifically includes: (1) Divide all BDs into several small groups (G1, …, G K ) according to their geographical locations and distances. For each small group G k , generate a small group key GK k respectively according to the above steps; (2) The AP encrypts other subgroup key sequences by using a certain subgroup key, then S = GK k ⊕ (GK1,…, GK k-1 , GK k+1 ,…, GK K ), and sends the subgroup G k ; The subgroup decrypts S by using its own key GK k to obtain all subgroup keys (GK1,…, GK K ), and so on. All subgroups obtain all subgroup keys (GK1,…, GK K ), thereby obtaining the overall shared group key.

4. A backscatter device system group key generation system applying the backscatter device system group key generation method according to any one of claims 1 to 3, characterized in that, The backscattering device system group key generation system includes: The downlink channel information acquisition module is used for the signal source to send signals while the reflection device is in the listening mode. The reflected cascaded channel information acquisition module is used for the signal source to send signals, where one of the reflection devices is in the backscattering mode, and the AP receives the reflected signal based on its full-duplex capability. The uplink channel information extraction module is used to extract the shared channel information from the reflected signal. The group shared channel information acquisition module is used for the signal source to send signals to all BDs in a time-sharing manner, and the BDs work in the listening mode and the backscattering mode successively to generate the shared information between the signal source and all BDs. The difference calculation module is used to calculate the difference between the received reflected cascaded channel information and the reflected cascaded channel information of the reference device after specifying the reference device, so as to obtain the difference sequence. The difference sequence broadcasting module is used for the AP to broadcast the constructed difference sequence to each backscattering device. The shared channel extraction and key construction module is used for each backscattering device to recursively calculate all the shared channel information based on the received difference sequence and the downlink channel information constructed by itself as the in-group shared random information, so as to extract the shared group key.

5. A computer device, characterized in that, The computer device includes a memory and a processor. When the computer program stored in the memory is executed by the processor, the processor executes the steps of the backscattering device system group key generation method according to any one of claims 1 to 3.

6. A computer-readable storage medium stores a computer program. When the computer program is executed by the processor, the processor executes the steps of the backscattering device system group key generation method according to any one of claims 1 to 3.

7. A backscattering device, characterized in that, The backscattering device executes the steps of the backscattering device system group key generation method according to any one of claims 1 to 3.

8. A signal source, characterized in that, The signal source executes the steps of the backscattering device system group key generation method according to any one of claims 1 to 3.

9. An information data processing terminal, characterized in that, The information data processing terminal is used to implement the backscatter device system group key generation system as described in claim 4.

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