Backscatter device two-end key group generation method, system, device and terminal

Abstract

The application discloses a kind of backscattering equipment double-end key group generation method, system, equipment and terminal, equipment provided by the application can obtain downlink channel information and related reflection cascade channel information;Triangle channel information is constructed, and group key is generated;Signal source calculates the position of BD stage;Group decision and broadcast stage;Time-sharing backscattering stage;Backscattering equipment broadcast stage;Key construction stage.The backscattering equipment double-end key group and the decentralized group key generation method based on triangle channel provided by the application realize lightweight key agreement, support multiple schemes, high security, scalability, high efficiency.The application realizes lightweight key agreement, supports multiple schemes, scalability;Security shared key is generated by extracting reciprocity and randomness of wireless channel.Using physical layer key generation technology solves the problem of high computing cost of traditional cryptography.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of backscatter communication key generation, and particularly relates to a backscatter device double-end key group generation method, system, device and terminal. BACKGROUND

[0002] As a new type of wireless communication technology, backscatter communication has the characteristics of strong energy collection ability and low energy consumption, and can ensure the continuous and stable operation of the Internet of Things system in a low energy consumption environment, and has attracted widespread attention. Backscatter devices (BDs) communicate at ultra-low power by backscattering radio frequency signals from a radio frequency source while collecting energy to power their circuits, without relying on battery energy. The emergence of BDs effectively solves the bottleneck of the serious dependence of traditional Internet of Things devices on battery energy and the problem of the need for regular maintenance and replacement of batteries. Therefore, backscatter communication promotes the large-scale deployment of BDs in any location, for example, through body implantation to support various applications such as environmental monitoring, healthcare, smart home, etc.

[0003] Compared with traditional high-power wireless devices, BDs do not have a radio frequency module and can only rely on the received radio frequency signals to achieve information transmission between each other through backscattering and modulation. However, due to the openness and broadcast nature of wireless communication, as well as the dependence of backscatter on the source, the backscatter system is extremely vulnerable to attacks such as eavesdropping, identity spoofing, and wireless fraud. These attacks pose a greater threat to the backscatter system, such as data interception, privacy leakage, etc. Therefore, there is an urgent need for a practical backscatter communication security mechanism.

[0004] Key generation can guarantee the security of private communication between BDs. Information encrypted by the key ensures the confidentiality and security of BD communication in the backscatter system. There are two main methods at present, one is to use a lightweight cryptography-based method, and the other is to use physical layer security technology. For backscatter devices with strong computing power, the Diffie-Hellman (DH) protocol can be used to generate shared keys between devices, and lightweight encryption and decryption methods can also be used to achieve secure communication between devices. From a theoretical point of view, encryption algorithms based on high computational overhead and difficulty have higher security, but they also have higher requirements for computing, storage and energy, which will cause a huge energy consumption and computing burden on BDs. Therefore, the existing key generation technology using lightweight cryptography is difficult to protect information between receivers or BDs in backscatter systems that are generally applicable to those with low computing and communication capabilities.

[0005] Unlike traditional public-key encryption-based lightweight cryptography, physical layer key generation is a method that fully exploits the random and reciprocity characteristics of the wireless channel, and can provide a lightweight, information-theoretically secure key sharing method for users in limited resource environments. The traditional physical layer two-end key generation method is that the BD transmits a probe signal for measuring the characteristics of the common channel, and the channel information measurement value is used as a shared random source, so as to obtain a common session key. Compared with the lightweight cryptography method based on channel estimation, the method of obtaining the key greatly reduces the computational overhead of generating a shared key by using cryptography. Therefore, the physical layer key generation technology can guarantee the secure communication between the backscatter devices with low computing and communication capabilities.

[0006] However, in backscatter communication, the BD cannot actively generate a channel probe signal, which makes it difficult to directly apply the existing physical layer key generation method. Existing schemes usually require devices to send probe signals to other devices to measure the relevant channel characteristics of the nodes, such as the signal strength of the receiving end, the channel state information between nodes, etc., so as to generate a key. Because the BD has no radio frequency (RF) module, it cannot generate a channel probe signal, nor does it have an independent RSS measurement module, so the BD lacks the ability to measure CSI or RSS. Therefore, the existing scheme cannot be applied to the communication of the BD under the condition of backscatter.

[0007] With the continuous expansion of the Internet of Things, efficient group key generation technology for large-scale device clusters has become a problem to be solved. In many cases, in order to realize the exchange of secret information between multiple BDs, a shared group key needs to be established. For example, in a human body sensor network, a group of implantable devices need to exchange human health information with each other, and need to use a secure group key to ensure the confidentiality of the information. In the crowdsourcing mode, the collected data will be distributed to some legal enterprises in a confidential manner. However, some group key generation schemes rely on the signal source to actively distribute key information to backscatter devices to achieve the effect of group key generation. However, the security of this centralized group key generation scheme is relatively low, because an attacker can break the group key by analyzing the key information sent by the signal source to the device; or in a group where an untrusted signal source exists, the group key ultimately used by the device is controlled by the untrusted signal source. At present, various existing decentralized group key generation technologies cannot be used in backscatter communication systems due to hardware conditions and limitations of computing and communication resources.

[0008] Through the above analysis, the problems and defects of the prior art are:

[0009] (1) The BD communication in the wireless communication scenario has the characteristics of broadcast and openness, which makes the backscatter system face serious security risks such as information loss and privacy leakage. In addition, due to the hardware conditions and limited computing and communication resources of BD, traditional public key encryption methods are difficult to universally apply to protect the private communication of BD.

[0010] (2) The existing physical layer key generation technology needs both parties to actively send probe signals to estimate CSI or requires the device to estimate RSS to obtain shared random information and then generate a session key. However, in the backscatter communication system, the reflecting device cannot actively generate channel probe signals or has corresponding modules to estimate RSS. Therefore, the existing physical layer key generation scheme cannot be applied to the backscatter system.

[0011] (3) Due to the hardware, resource limitations and other problems analyzed above, the existing double-end key generation scheme and decentralized group key generation scheme cannot be applied to the backscatter system. Therefore, the key generation technology that can protect the double-end communication and decentralized group device communication in the backscatter system needs to be improved. SUMMARY

[0012] In order to solve the above problems existing in the prior art, the present application provides a backscatter device double-end key group generation method, system, device and terminal. The technical problems to be solved by the present application are realized by the following technical solutions:

[0013] A backscatter device double-end key group generation method, characterized in that the backscatter device double-end key group generation method comprises the following steps:

[0014] Step one, obtaining downlink channel information: the signal source sends a signal, and two backscatter devices (BDs) are in a listening mode;

[0015] Step two, obtaining relevant reflection cascade channel information: the signal source sends a signal, one of the devices is in a backscatter mode, the other device is in a listening mode, and the two BDs exchange working modes within a coherence time;

[0016] Step three, constructing triangular channel information: using the three channels formed by the double-end BDs and the signal source in the environment backscatter system, multiplying the obtained downlink channel and reflection cascade channel information, and further constructing triangular channel information as shared random information of the two BDs to generate a shared key;

[0017] Step four: the signal source calculates the position of BD: in this stage, each BD works in the backscattering mode in turn, ensuring that only one BD backscatters at each moment. The signal source calculates the position of each BD according to the received signal strength (RSS) and the angle of arrival (AoA) of the backscattering signal;

[0018] Step five: grouping decision and broadcasting stage: the signal source calculates the optimal grouping result by using a distance-based hierarchical grouping algorithm based on the positions of the BDs, and broadcasts the grouping result;

[0019] Step six: time-sharing backscattering stage: each BD works in the backscattering mode in turn, and the other BDs remain in the listening mode, so that all BDs can obtain the shared backscattering channel information;

[0020] Step seven: BD broadcasting stage: each BD broadcasts the combination of all constructed triangular channel measurements to all other BDs in each time slot, and appends a weight vector to the broadcast signal;

[0021] Step eight: key construction stage: each BD obtains the shared triangular channel information set by calculating the triangular channel measurement values that are not estimated in step six.

[0022] In an embodiment of the present application, in step one, before generating the key between the two devices, the process of being in the receiving and listening mode at the same time to obtain the downlink channel information includes:

[0023] BDA1 and BDA2 both work in the listening mode and directly receive the radio frequency signal s(t) from the signal source; the radio frequency signal of the signal source passes through the downlink channels h1 and h2 and is received by A1 and A2, respectively; in the ideal noiseless case, the received signals are represented as c1(t) = h1s(t) and c2(t) = h2s(t); at this time, the BD obtains the signal containing the downlink channel information;

[0024] In step two, before generating the key between the two devices, the process of being in the backscattering mode and the listening mode respectively to obtain the information of the concatenated channel includes:

[0025] (1) the signal source continuously transmits the radio frequency signal s(t), and BDA1 works in the backscattering mode to reflect the signal to BDA2; in the listening mode, the backscattering signal received by BDA2 is αh 1，2 h1s(t); at the same time, since the signal source continuously transmits the radio frequency signal, BDA2 receives not only the backscattering signal transmitted by BDA1 but also the signal h2s(t) transmitted by the signal source; the two signals are superimposed, and the superimposed signal received by BDA2 is αh 1，2h1s(t) + h2s(t);

[0026] (2) Same as (1), when BDA l works in the listening mode, and BDA2 works in the backscattering mode, BDA1 will receive the superimposed signal αh 2，1 h2s(t) + h1s(t);

[0027] In the process of (1) and (2), BDA l and BDA2 receive the information about the reflection cascade channel h 1，2 h1 or h 2，1 h2 respectively;

[0028] In the third step, the triangular channel information is constructed as shared random information before the key between the two devices is generated, and the process of generating the shared key comprises:

[0029] After the downlink channel information and the reflection cascade channel information are obtained, BDA1 and BDA2 multiply the downlink channel information with the reflection cascade channel information to construct the triangular channel information; the triangular channel information constructed by BDA1 is represented as h1h 1，2 h2, and the information constructed by BDA2 is represented as h1h 2，1 h2; since the channel has reciprocity, h 2，1 = h 1，2 , the triangular channel information constructed by BDA1 and BDA2 is the same, and the two BDs use the triangular channel as shared random information.

[0030] In an embodiment of the present application, in the fourth step, the position calculation stage of the signal source to the BD: in this stage, each BD works in the backscattering mode in turn to ensure that only one BD performs backscattering at each moment. The signal source calculates the position of each BD according to the received signal strength (RSS) and the angle of arrival (AoA) of the backscattering signal.

[0031] In the fifth step, the grouping decision and broadcasting stage: the signal source calculates the optimal grouping result by using the distance-based hierarchical grouping algorithm based on the position of the BD, and broadcasts the grouping result.

[0032] In the sixth step, before the group key of the BD is generated, each BD needs to work in the backscattering mode in turn, and the process comprises:

[0033] In the backscattering stage, the signal source continuously broadcasts radio frequency signals, and in each time slot, each BD works in the backscattering mode in turn, while the others remain in the listening mode; after all the BDs have completed the backscattering process, each device obtains a set Q containing N-1 triangular channel information.

[0034] In the step seven, before generating the group key of the BDs, the process that each BD works in the broadcast mode in time includes:

[0035] In the broadcast phase, each BD broadcasts the combination of all constructed triangular channel measurements to all other BDs in time, so that each BD supplements the set Q;

[0036] In the step eight, before generating the group key of the BDs, the process that each BD obtains the shared triangular channel information set by calculation includes:

[0037] In the construction phase, each BD will obtain the triangular channel measurement value that is not estimated in the step six by calculation, supplement the set Q to obtain the set Q' of N triangular channel information shared by all BDs.

[0038] In the second aspect, the embodiment of the present application provides a backscattering device two-end key group generation system, the backscattering device two-end key group generation system includes:

[0039] The downlink channel information acquisition module is used for a signal source to send a signal, and both devices are in a listening mode;

[0040] The reflection cascade channel information acquisition module is used for the signal source to send a signal, wherein one device is in a backscattering mode and the other device is in a listening mode; within a coherence time, the two devices exchange working modes;

[0041] The triangular channel information construction module is used for multiplying the obtained downlink channel and reflection cascade channel information to construct triangular channel information, and taking the triangular channel information as shared random information of the two devices to generate a shared key;

[0042] The time-sharing backscattering module is used for each backscattering device to work in the backscattering mode in turn, and the others remain in the listening mode, so that all backscattering devices can obtain shared backscattering cascade channel information;

[0043] The backscattering device broadcast module is used for each backscattering device to broadcast the combination of all constructed triangular channel measurements to all other backscattering devices in each time slot, and to attach a weight vector in the broadcast signal;

[0044] The key construction module is used for each backscattering device to obtain the shared triangular channel information set by calculating the triangular channel measurement value that is not estimated in the time-sharing backscattering module.

[0045] In a third aspect, an embodiment of the present application provides a computer device, comprising a memory and a processor, the memory storing a computer program, and the computer program, when executed by the processor, causing the processor to perform the steps of the reverse scattering device double-end key group generation method.

[0046] In a fourth aspect, an embodiment of the present application provides a computer readable storage medium, storing a computer program, and the computer program, when executed by a processor, causing the processor to perform the steps of the reverse scattering device double-end key group generation method.

[0047] In a fifth aspect, an embodiment of the present application provides a reverse scattering device, applying the steps of the reverse scattering device double-end key group generation method.

[0048] In a sixth aspect, an embodiment of the present application provides a signal source, applying the steps of the reverse scattering device double-end key group generation method.

[0049] In a seventh aspect, an embodiment of the present application provides an information data processing terminal, applying the steps of the reverse scattering device double-end key group generation method.

[0050] Advantages of the present application:

[0051] In combination with the above technical solutions and the technical problems solved, the technical solutions of the present application have the following advantages and positive effects:

[0052] First, in view of the technical problems existing in the prior art and the difficulty in solving the problems, the present application closely combines the technical solutions to be protected and the results and data obtained during the research and development process, and analyzes in detail and depth how the technical solutions solve the technical problems and bring some creative technical effects after solving the problems. The specific description is as follows:

[0053] The reverse scattering device double-end key and decentralized group key generation method based on a triangular channel provided by the present application realizes support for multiple schemes, high security, low computing overhead, and high scalability.

[0054] (1) Support multiple schemes. The present application supports the generation of symmetric keys between any two pairs of reverse scattering devices in a reverse scattering communication system, and also supports the generation of decentralized group keys among multiple reverse scattering devices.

[0055] (2)High security. The present application generates a shared key using the mutual randomness of wireless channels, and the generated key is information-theoretically secure. Since the channels are mutually independent, an attacker cannot intercept the group key. Through security analysis and simulation verification, it is found that the security of the scheme under eavesdropping attacks and some mainstream active attacks is also higher than that of traditional schemes.

[0056] (3) Low computational overhead. The present application proposes an efficient and low-computational-overhead two-end key generation and secure decentralized group key generation method based on physical layer key generation, which overcomes the defects of existing cryptographic algorithms such as large computational overhead and limitation by backscatter devices.

[0057] (4) High scalability. The present application can be easily extended to a backscatter communication system with any number of backscatter devices with a multi-layer, multi-group scheme. The method is to divide a single backscatter device group into several subgroups according to their distances from each other, the computing power of the devices, or the communication tasks, etc. Therefore, the present application reduces the complexity of group key generation and supports high scalability. In addition, the present application can also enable the signal sources to cooperate with each other to generate group keys between different group backscatter devices within the coverage of different signal sources, thereby extending to multiple signal sources.

[0058] Secondly, from the perspective of the product or as a whole, the technical effects and advantages of the technical solution to be protected by the present application are described as follows:

[0059] The present application provides a backscatter device two-end key and decentralized group key generation method based on triangular channels, which realizes a lightweight key protocol, supports multiple schemes, has high security, scalability, and high efficiency.

[0060] The present application realizes a lightweight key protocol, supports multiple schemes, and has scalability. It generates a secure shared key by extracting the reciprocity and randomness of wireless channels. Using physical layer key generation technology, the problem of high computational cost in traditional cryptography is solved.

[0061] Thirdly, as the auxiliary evidence for the creativity of the claims of the present application, it is also embodied in the following important aspects:

[0062] (1) The technical solution of the present application fills the technical gap in the industry at home and abroad:

[0063] The existing domestic and foreign technologies do not propose an efficient key generation scheme between backscatter devices. They usually adopt a lightweight cryptography principle or a traditional physical layer key generation principle to generate a key. The former has the characteristics of high energy consumption, and the latter requires that the device can send a probe signal to generate a key. Since the backscatter device is a resource-limited micro device, the above two methods are not suitable for the key generation of the backscatter device. Therefore, the physical layer key generation method based on the triangular channel adopted by the present application can greatly reduce the resource overhead of the key generation of the backscatter device, prolong the terminal life, improve the security of the backscatter communication, facilitate deployment, and has important commercial value.

[0064] The present application proposes a backscatter device group key generation method based on a triangular channel in view of the characteristics of the resource-limited backscatter device and the lack of a radio frequency signal transmitting module. The scheme proposed in the present project can meet the two constraints of the resource-limited backscatter device and the inability to actively send a probe signal, and provide a secure two-end key and a decentralized group key for the backscatter device.

[0065] (2) The technical scheme proposed in the present project solves a technical problem that has been urgently needed to be solved but has not been successfully solved for a long time: due to the limited computing power of the backscatter communication system, it is difficult to guarantee the generation of a shared key through a complex cryptographic algorithm, and there are also security risks such as illegal eavesdropping. The present application can provide a two-end and multi-end shared key generation scheme for the backscatter system, which can guarantee the security of two-party or multi-party communication, thereby solving the security problem existing in the backscatter communication system. BRIEF DESCRIPTION OF DRAWINGS

[0066] Figure 1 A backscatter device two-end key and decentralized group key generation method flow chart provided by the embodiment of the present application;

[0067] Figure 2 A backscatter device two-end key generation method schematic diagram provided by the embodiment of the present application;

[0068] Figure 3 A backscatter device decentralized group key generation method schematic diagram provided by the embodiment of the present application;

[0069] Figure 4 A backscatter device decentralized group key generation method schematic diagram under a plurality of independent backscatter device grouping instances provided by the embodiment of the present application;

[0070] Figure 5 A backscatter device decentralized group key generation method schematic diagram under a plurality of repeated backscatter device grouping instances provided by the embodiment of the present application;

[0071] Figure 6 The key consistency and security of the reverse scattering device provided by the embodiment of the present application to generate a double-end key by using a triangular channel method are compared with the consistency and security of a conventional scheme. DETAILED DESCRIPTION

[0072] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0073] I. Explanation of the embodiments. In order for those skilled in the art to fully understand how the present application is specifically implemented, this part is an explanation of the embodiments of the technical solutions of the claims.

[0074] In view of the problems in the prior art, the present application provides a reverse scattering device double-end key group generation method, system, device and terminal, which will be described in detail below with reference to the drawings.

[0075] As shown in Figure 1 The reverse scattering device double-end key group generation method provided by the embodiment of the present application includes the following steps:

[0076] Step one, obtaining downlink channel information: the signal source sends a signal, and two reverse scattering devices (BDs) are in a listening mode;

[0077] Step two, obtaining relevant reflection cascade channel information: the signal source sends a signal, one of the devices is in a reverse scattering mode, the other device is in a listening mode, and within a coherence time, the two BDs exchange working modes;

[0078] Step three, constructing triangular channel information: using the three channels formed by the double-end BDs and the signal source in the environment reverse scattering system, the obtained downlink channel and reflection cascade channel information are multiplied to further construct triangular channel information as shared random information of the two BDs, so as to generate a shared key;

[0079] Step four, signal source position calculation stage of BD: in this stage, each BD works in a reverse scattering mode in turn, so that only one BD performs reverse scattering at each moment. The signal source calculates the position of each BD according to the received signal strength (RSS) and angle of arrival (AoA) of the reverse scattering signal;

[0080] Step five: grouping decision and broadcast phase: the signal source through the position of the BD, using distance-based hierarchical grouping algorithm to calculate the optimal grouping results. And broadcast the grouping results;

[0081] Step six, time-sharing backscattering phase: each BD takes turns in the backscattering mode, and other BDs remain in the listening mode, to ensure that all BDs can obtain the shared backscattering channel information;

[0082] Step seven, BD broadcast phase: each BD broadcasts all the combinations of the constructed triangular channel measurements to all other BDs in each time slot, and adds a weight vector in the broadcast signal;

[0083] Step eight, key construction phase: each BD obtains the shared triangular channel information set by calculating the triangular channel measurement values that are not estimated in step six.

[0084] The backscattering device two-end key group generation system provided by the embodiment of the application comprises:

[0085] A downlink channel information acquisition module is configured to send a signal by a signal source, and both devices are in a listening mode;

[0086] A reflection cascade channel information acquisition module is configured to send a signal by the signal source, wherein one device is in a backscattering mode, and the other device is in a listening mode; within a coherence time, the two devices exchange the working modes;

[0087] A triangular channel information construction module is configured to multiply the acquired downlink channel and reflection cascade channel information to construct triangular channel information, and use the triangular channel information as shared random information of the two devices to generate a shared key;

[0088] A time-sharing backscattering module is configured to make each backscattering device take turns in the backscattering mode, and the others remain in the listening mode, to ensure that all backscattering devices can obtain the shared backscattering channel information;

[0089] A backscattering device broadcast module is configured to make each backscattering device broadcast all the combinations of the constructed triangular channel measurements to all other backscattering devices in each time slot, and add a weight vector in the broadcast signal;

[0090] A key construction module is configured to make each backscattering device obtain a shared triangular channel information set by calculating the triangular channel measurement values that are not estimated in the time-sharing backscattering module.

[0091] As shown in Figure 2 the key generation method between two devices of the backscattering device based on a triangular channel provided by the embodiment of the application comprises the following steps:

[0092] (1) BDA1 and A2 both work in the listening mode, directly receiving the radio frequency signal s(t) from the signal source. The radio frequency signal of the signal source passes through the downlink channel hi, h2, and is received by A1 and A2, respectively. The signals received by A1 and A2 are:

[0093] c1(t) = hi s(t) + n1(t), (1)

[0094] c2(t) = h2s(t) + n2(t). (2)

[0095] where hi and h2 are the downlink channels, and n1, n2 are additive white Gaussian noise (AWGN). In this process, the BD can receive information about the downlink channel.

[0096] (2) The signal source continuously broadcasts the radio frequency signal, and BDA1 works in the backscatter mode to reflect the signal to A2. In the listening mode, the superimposed signal received by A2 includes the signal reflected from A1 and the signal directly sent from the signal source, which is given by the following formula:

[0097]

[0098] where a is the backscatter coefficient, b(t) is the backscatter signal, h 1，2 is the inner channel. The present application refers to h 1，2 hi as the reflection cascade channel.

[0099] (3) In the coherence time, the working modes of the two devices are exchanged. A2 works in the backscatter mode, and A1 works in the listening mode. The superimposed signal received by A1 is:

[0100]

[0101] In (2), (3), the BD can receive information about the reflection cascade channel.

[0102] (4) For simplicity, it is assumed that there is no environmental noise, and the signals s(t) and b(t) are known to all parties in the system. BDA1 and A2 can estimate their respective channels in each step, then:

[0103] C1 = hi, (5)

[0104] C2 = h2, (6)

[0105] Y1 = a h 2，1 h2 + hi, (7)

[0106] Y2 = a h 1，2 hi + h2. (8)

[0107] With the estimated channel information, A1 and A2 can construct the end-to-end channel information between them by calculating the following formula:

[0108] V1 = (Y1 - C1) C1 = ah 2，1 h2h1, (9)

[0109] V2 = (Y2 - C2) C2 = ah 1，2 h1h2. (10)

[0110] Since the channel has reciprocity, h 2，1 = h 1，2 is true, and all channels, h1, h2, h 1，2 , h 2，1 remain unchanged, then the channel information constructed between A1 and A2 is theoretically equal to each other, that is, V1 = V2, therefore, the two BDs can use the two triangular channels as shared random information, and a series of triangular channel information measurement results and as shared random information.

[0111] (5) After channel measurement and randomness extraction, the BDs can quantize, information reconcile, and privacy amplify the shared random information and in three steps to obtain the final key.

[0112] In step one, the process of being in receiving and listening mode at the same time to obtain the downlink channel information before generating the key between the two devices includes:

[0113] BDA1 and BDA2 work in listening mode and directly receive the radio frequency signal s(t) from the signal source; the radio frequency signal of the signal source is received by A1 and A2 through the downlink channels h1 and h2, respectively; in the ideal noiseless case, the received signals are represented as c1(t) = h1s(t) and c2(t) = h2s(t), respectively; at this time, the BD obtains the signal containing the downlink channel information;

[0114] In step two, the process of being in backscattering mode and listening mode respectively to obtain the information of the concatenated channel before generating the key between the two devices includes:

[0115] (1) The signal source continuously emits the radio frequency signal s(t), BDA1 works in backscattering mode and reflects the signal to BDA2; in the listening mode, the backscattering signal received by BDA2 is ah 1，2h1s(t) ; meanwhile, since the signal source continuously sends RF signals, BDA2 receives not only the backscatter signal sent by BDA1 but also the signal h2s(t) sent by the signal source; the two signals are superimposed, and then BDA2 receives the superimposed signal αh 1，2 h1s(t) + h2s(t) ;

[0116] (2) The same as (1), when BDA l h1s(t) + h2s(t) ; 2，1 h2s(t) + h1s(t) ;

[0117] In the process of (1) and (2), BDA1 and BDA2 respectively receive information about the reflection cascade channel h 1，2 h1 or h 2，1 h2;

[0118] In step three, before generating the key between the two devices, the triangular channel information is constructed as shared random information, and then the process of generating the shared key includes:

[0119] After obtaining the downlink channel information and the reflection cascade channel information, BDA1 and BDA2 multiply the downlink channel information with the reflection cascade channel information to construct the triangular channel information; the triangular channel information constructed by BDA1 is represented as h1h 1，2 h2, and the information constructed by BDA2 is represented as h1h 2，1 h2; since the channel has reciprocity, h 2，1 = h 1，2 , so the triangular channel information constructed by BDA1 and BDA2 is the same, and the two BDs use the triangular channel as shared random information.

[0120] In step four, the position calculation stage of the signal source to the BD: in this stage, each BD works in the backscatter mode in turn, ensuring that only one BD performs backscatter at each moment. The signal source calculates the position of each BD according to the received signal strength (RSS) and the angle of arrival (AoA) of the backscatter signal.

[0121] In step five, the grouping decision and broadcast stage: the signal source calculates the optimal grouping result by using a distance-based hierarchical grouping algorithm based on the positions of the BDs, and broadcasts the grouping result.

[0122] In step six, before generating the group key of the BD, each BD needs to work in the backscatter mode in turn, and the process includes:

[0123] In the backscattering phase, the signal source continuously broadcasts radio frequency signals, and in each time slot, each BD takes turns to work in backscattering mode, while the others remain in listening mode; after all the BDs have completed the backscattering process, each device obtains a set Q containing N-1 triangular channel information;

[0124] In step seven, before generating the group key of the BD, the process in which each BD works in the broadcasting mode in time includes:

[0125] In the broadcasting phase, each BD broadcasts the combination of all the constructed triangular channel measurements to all other BDs in time, so that each BD supplements the set Q;

[0126] In step eight, before generating the group key of the BD, the process in which each BD obtains the shared triangular channel information set by calculation includes:

[0127] In the construction phase, each BD will supplement the set Q by calculating the triangular channel measurements that are not estimated in step six, to obtain a set Q' of N triangular channel information shared by all BDs.

[0128] As shown in Figure 3 ,4,5, the triangular channel-based BD decentralized group key generation method provided by the embodiment of the application includes the following steps:

[0129] (1) In the signal source position calculation phase of the BD: In this phase, each BD takes turns to work in backscattering mode to ensure that only one BD performs backscattering at each moment. Each BD takes turns to work in backscattering mode and backscatters its downlink signal. The signal source uses the RSS and AoA of the backscattered signal to locate the position of each BD.

[0130] In order to realize accurate positioning estimated from RSS and AoA, since the signal source needs to have full-duplex functional requirements, the signal source needs to estimate SIC before receiving the backscattered signal from the BD, to ensure that the influence of SIS on accurate estimation of RSS and AoA can be eliminated when the backscattered signal is received.

[0131] (2) In the grouping decision and broadcasting phase:

[0132] · Grouping decision: We use complete-linkage hierarchical clustering as our grouping algorithm, because it provides a tree diagram of clustering, which can well understand the influence of d τ on the clustering result, so as to further adjust. In addition, we can set a maximum number of devices N τIf the number of BDs in a subgroup is greater than N τ , this subgroup should be further divided until the number of BDs in each subgroup is less than N τ .

[0133] After a group is divided into several subgroups, the signal source selects a center subgroup from the several subgroups. The center subgroup combines the keys of the different subgroups to generate the key of the whole group after obtaining the key information of the different subgroups. Since the center subgroup needs to exchange the key information with all the remaining subgroups, the average distance from the selected center subgroup to the other subgroups should be the smallest among all the candidate center subgroups.

[0134] After the optimal center subgroup is selected, the RFS can select some gateway BDs according to the distance of the different subgroups to the center subgroup.

[0135] Broadcast phase: the signal source modulates the final grouping information into the RF signal and then broadcasts it. The grouping information includes: the BD information in each group, whether the group is a center group, and the information of the gateway BDs in the group. The BDs can demodulate the broadcast RF signal and recover the grouping information. Then the generation of the group key can begin.

[0136] (3) In the probing phase, the signal source broadcasts the RF signal, and all the BDs are in the listening mode. Therefore, each BD A i can measure the information of the downlink channel C i = h i .

[0137] (4) In the backscattering phase, the signal source continuously broadcasts the RF signal, and in each time slot, each BD works in the backscattering mode in turn, while the others remain in the listening mode. Therefore, each BD can measure the superimposed channel (Y i = αh i，j h j + h i ). Then each BD can remove the downlink channel from the superimposed channel and construct a triangular channel measurement V i = (Y j - C i，j )C i = αh i h i h j，i between BDA j and A i . In the backscattering phase, A i will construct triangular channels from the measured signal together with the other N-1 BDs, where the superscript 2 refers to step (2). The present application represents the set of these channels as and Q represents the set of N triangular channel measurements used for group key generation.

[0138] (5) During the broadcast phase, each BD needs to broadcast a combination of all constructed triangular channel measurements to all other BDs in a time-division manner, along with a weight vector. For example, in the j-th frame of the broadcast phase, BDA j Broadcast group Where ω j It is a weight vector. (This invention sets V) j，j =0) is A j Vectors of all triangular channel measurements constructed in step 2.

[0139] (6) During the construction phase, each BD will calculate the triangular channel measurements (i.e., values ​​not estimated in step (2)) that were not estimated in step (2). (This invention sets) ), to obtain all triangular channel measurements V in set Q. i，j (For i, j = 1, ..., N). A i The set of channel measurements that needs to be obtained in step (4) is For example, when N=3, BDA1 estimates V in step (2). 2，1 and V 3，1 and receive from BDA2 in step (3) Received from BDA3 Wherein the present invention sets ω i = [1, 1, 1] (i = 1, 3). Therefore, A1 can calculate V. 3，2 =V 2，3 And in step (4), the measurements (V) of all triangular channels are obtained. i ={V 2，1 V 3，1 V 3，2}), which is further used as a shared key.

[0140] Therefore, all BDs can individually utilize all their triangular channel measurements V. i ={V i，j For i, j = l, ..., N, the same shared random information is used to further generate the group key.

[0141] The above-described decentralized group key generation method based on triangular channels can be extended to two instances: group key generation for multiple independent BD packets and group key generation for multiple overlapping BD packets.

[0142] Decentralized group key generation method for multiple independent backscattering devices, such asFigure 4 As shown, the two-end key and the decentralized group key generation method based on the triangular channel of the backscatter device provided by the embodiment of the present application comprises the following steps in the group key generation of a plurality of independent backscatter device groups:

[0143] In the group key generation of a plurality of independent backscatter device groups, the present application proposes a hierarchical grouping scheme to solve the problem of reduced channel reciprocity when the group size becomes large. First, through steps S104 and S105, all backscatter devices in a large group can be divided into several independent small groups according to their geographical positions or distances between each other. Each sub-group will use the efficient detection scheme proposed in the group key generation between single-group backscatter devices to generate keys, which can be achieved by executing from step S106 to step S108. Each sub-group will select a backscatter device as a gateway, which is referred to as a gateway backscatter device (the gateway backscatter device can be used in turn for each key generation session, or selected according to energy availability or computing power). Then, the gateway backscatter devices will generate symmetric keys between each other using the two-device key generation scheme. Then, each sub-group can share its group key with other sub-groups through the secure channel established by the pairwise key between the gateway backscatter devices, thereby contributing to the final group key.

[0144] Figure 4 An example of a communication network composed of six backscatter devices is shown. The group is divided into two small sub-groups. Backscatter devices A3 and A4 are selected as gateway backscatter devices. For each sub-group, all backscatter devices will first construct the triangular channel information between each two backscatter devices. Then, each backscatter device will broadcast the combination of all constructed triangular channel information with a weight vector to other backscatter devices in the same sub-group. Therefore, all backscatter devices in the same sub-group will generate a group key with all shared triangular channels. Next, A3 and A4 will generate a pair of keys according to steps S101 to S103, and generate a secure channel between them. Finally, the two sub-groups can exchange their own sub-group keys through the secure A3-A4 channel, generating a common group key among all backscatter devices.

[0145] The decentralized group key generation method of a plurality of overlapping backscatter device groups is as shown in Figure 5 As shown, the two-end key and the decentralized group key generation method based on the triangular channel of the backscatter device provided by the embodiment of the present application comprises the following steps in the group key generation of a plurality of overlapping backscatter device groups:

[0146] Similar to the decentralized group key generation method grouped with multiple independent backscatter devices, the present application can first select a gateway backscatter device contained in at least two subgroups, as shown in Figure 5 The same is that all backscatter devices in the same subgroup will generate a group key. Therefore, the gateway backscatter device, i.e. backscatter device A4, will obtain multiple subgroup keys participating in the key generation of each subgroup. Next, the gateway can encrypt the keys of other subgroups with the selected subgroup keys and broadcast the encrypted information to other backscatter devices in the selected subgroup. Each backscatter device in the selected subgroup will finally obtain a set of subgroup keys consisting of one subgroup, and then generate the final group key by combining all subgroup keys. Therefore, all backscatter devices in the system can generate a shared group key with several subgroups and overlapping gateway backscatter devices.

[0147] II. Application Examples. In order to prove the creativity and technical value of the technical solutions of the present application, this part is an application example of the technical solutions of the claims on specific products or related technologies.

[0148] The embodiments of the present application use MATLAB to establish a program in WINDOWS, in which the operations of obtaining downlink channel information, obtaining related reflection cascade channel information, constructing triangular channel information, time-sharing backscattering, broadcasting, shared channel extraction and shared key construction, i.e. the processes mentioned in the present application, are implemented, simulated and analyzed.

[0149] In the preferred embodiments of the present application, the backscatter device needs to obtain the information of the downlink channel before constructing the triangular channel information. The specific process is as follows:

[0150] BDA1 and A2 work in listening mode and directly receive the radio frequency signal s(t) from the signal source. The radio frequency signal of the signal source passes through the downlink channels h1 and h2 and is received by A1 and A2, respectively. The received signals can be represented as c1(t) = h1s(t) + n1(t) and c2(t) = h2s(t) + n2(t), respectively. At this time, the BD can obtain the signal containing the downlink channel information. The communication channel model adopts an exponential Rayleigh fading wireless channel model, which is expressed as where θ is a circularly symmetric complex Gaussian variable, d is the distance between the transmitter and the receiver, and λ is the path loss exponent; the noise n(t) adopts additive white Gaussian noise (AWGN) which is subject to Gaussian distribution. In the simulation, the present application sets θ = 5, λ = 3, the distances of the signal source from BDA1 and A2 are d1 = 8 and d2 = 7, respectively, and the distance between the two BDs is d3 = 3.

[0151] The radio frequency signal s(t) is generated by a signal source after modulating a randomly generated binary digital signal with orthogonal frequency division multiplexing (ofdm_module function). The radio frequency signal s(t) passes through a Rayleigh fading channel (ofdm_trans function) and is received by the receiver of the BD. When the signal is received, additive environmental Gaussian noise is also received. The size of the noise is defined by the signal-to-noise ratio SNR. The present application keeps the average power of the radio frequency signal constant at 1, changes the size of the SNR, and limits the power of the noise. Generally, the present application sets SNR = 30. In the case of known noise and wireless signals, the noise can be removed first, and then the channel information can be recovered through the process of inverse convolution (invert_conv function). Thus, the downlink channel information can be obtained by the present application.

[0152] In the preferred embodiment of the present application, the BD needs to obtain the relevant reflection cascade channel information before constructing the triangular channel information. The specific process is as follows:

[0153] The signal source continuously transmits the radio frequency signal s(t), and the BD A1 works in the backscatter mode to reflect the signal to A2. At this time, A2 receives the backscattered signal in the listening mode as αh 1，2 h1s(t). At the same time, since the signal source continuously transmits the radio frequency signal, A2 receives not only the backscattered signal sent by A1, but also the signal h2s(t) sent by the signal source. At this time, the two signals are superimposed, and A2 receives the superimposed signal αh 1，2 h1s(t) + h2s(t). When A1 works in the listening mode and A2 works in the backscatter mode, A1 receives the superimposed signal αh 2，1 h2s(t) + h1s(t).

[0154] A1 works in the backscatter mode to reflect the signal to A2. When A1 receives the downlink signal, it also receives additive Gaussian noise, and the signal and noise are backscattered together through the antenna (ofdm_back function). In the simulation, the present application multiplies the downlink signal h1s(t) by the backscatter coefficient α to represent the signal attenuation after backscattering. The present application takes α = 0.3 + 0.4i. After backscattering, the signal is received by the receiver of A2 through the Rayleigh fading channel h 1，2 between the two BDs. At the same time, the receiver also receives additive Gaussian environmental noise. In the case of known noise and wireless signals and the downlink channel information of the previous step, the noise can be removed first, and then the noise in the backscatter can be removed through a multi-step inverse convolution process, and the channel information of the cascade channel can be further recovered.

[0155] In the preferred embodiment of the present application, the triangular channel information can be constructed after the above two steps. The specific process is as follows:

[0156] After obtaining the downlink channel information and the reflection cascade channel information, the BDA1, A2 can multiply the downlink channel information and the reflection cascade channel information to construct the triangular channel information. The triangular channel information constructed by A1 can be expressed as h1h 1，2 h2, and the information constructed by A2 can be expressed as h1h 2，1 h2. Since the channel has reciprocity, h 2，1 = h 1，2 , so the triangular channel information constructed by A1 and A2 is the same. Therefore, the two BDs can use the triangular channel as shared random information.

[0157] The cascade channel information and the downlink channel information are convolved and quantized to obtain the same key bits. By repeating the above steps, two highly correlated key sequences (generate_key_bit function) can be obtained.

[0158] In the preferred embodiment of the present application, in the decentralized group key generation scheme, each BD needs to be in the time-sharing backscatter phase first. The specific process is as follows:

[0159] In the backscatter phase, the signal source continuously broadcasts radio frequency signals, and in each time slot, each BD takes turns to work in the backscatter mode, while the others remain in the listening mode; after all the BDs have completed the backscatter process, each device obtains a set Q containing N-1 triangular channel information.

[0160] In the preferred embodiment of the present application, before generating the group key, each BD needs to be in the broadcast phase without a central signal source first. The specific process is as follows:

[0161] In the broadcast phase, each BD broadcasts the combination of all constructed triangular channel measurements to all other BDs in time-sharing. This enables each BD to supplement the set Q of the previous step.

[0162] In the preferred embodiment of the present application, before generating the group key, key construction needs to be performed without a central signal source. The specific process is as follows:

[0163] In the construction phase, each BD will calculate the rest of the triangular channel measurements that were not estimated in the fourth step to supplement the set Q (the calculate_rest_channel function). Further, the set Q' of N triangular channel information shared by all BDs can be obtained. Then, all the triangular channel information in the set Q' is convolved or point-multiplied and quantized to obtain the same key bits. By repeating the above steps, a plurality of key sequences with high correlation can be obtained (the generate_key_bit function).

[0164] It should be noted that the embodiments of the present application can be realized by hardware, software, or a combination of software and hardware. The hardware part can be realized by using special logic; the software part can be stored in a memory and executed by a suitable instruction execution system, such as a microprocessor or a specially designed hardware. Those skilled in the art can understand that the above-mentioned devices and methods can be realized by using computer executable instructions and / or included in processor control code, such as provided on a carrier medium, such as a magnetic 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 of the present application and their modules can be realized by hardware circuits, such as very large scale integrated circuits or gate arrays, semiconductors, such as logic chips, transistors, or programmable hardware devices, such as field programmable gate arrays, programmable logic devices, etc. They can also be realized by software executed by various types of processors, or by a combination of the above-mentioned hardware circuits and software, such as firmware.

[0165] III. Evidence of the effects related to the embodiments. The embodiments of the present application have achieved some positive effects during research and development or use, and indeed have great advantages compared with the prior art. The following content is described in combination with data, graphs, etc. during the test process.

[0166] As Figure 6 shown, after implementing the present application, the present application and the conventional device key generation scheme are compared under eavesdropping attacks.

[0167] Due to the eavesdropping attack, the communication environment and the eavesdropping position will determine the eavesdropped information obtained by the eavesdropper. The change of the eavesdropping position will cause the change of the correlation coefficient between the attack channel and the inward channel of the attacker. Therefore, the present application discusses the influence on the mutual information of the key and the secure key rate when the signal-to-noise ratio and the correlation coefficient of the attack channel and the inward channel change at the same time. In the case of fixed environmental signal transmission power, the present application can further improve the signal-to-noise ratio by reducing the environmental noise power.

[0168] As Figure 6As shown, both the mutual information and the secure key rate increase with the increase of the signal-to-noise ratio due to the reduction of the influence of noise, but the mutual information of the key in the traditional scheme exceeds that in the triangular channel scheme. This is because in the triangular channel scheme, when one BD is in the listening mode and generates a key by using the received signal, additive Gaussian noise will be received at the same time, and the other BD will also backscatter the additive Gaussian noise it receives. This results in multiple noises received by the BD. Moreover, since the BD cannot actively send a probe signal to estimate the channel information, the signal generated by the key needs to use the signal sent by the signal source, which will undergo more channel attenuation, thereby resulting in a lower performance of the generated key than the traditional scheme. When observing the secure key rate of the two schemes, it is obvious that the secure key rate of the triangular channel scheme is always higher than that of the traditional scheme, even when the correlation between the attack channel and the inward channel of the attacker becomes stronger. This shows that even though the mutual information of the key is higher in the traditional model, the information leakage is more serious. Therefore, compared with the traditional scheme, the present application is worse than the traditional scheme in key generation efficiency (mutual information of the key), but far superior to the traditional scheme in security (secure key rate).

[0169] The triangular channel-based BD group key generation scheme is also the same as the result of the two-device key generation scheme described above, and the key generation efficiency is lower than that of the traditional scheme, but the security is far superior to that of the traditional scheme.

[0170] It should be noted that in the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements indicated must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0171] In addition, the terms "first" and "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first" and "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise specifically limited.

[0172] The various embodiments in the specification are described in a related manner, and the same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on the difference from other embodiments. In particular, for the system embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and the relevant parts can be referred to the part of the method embodiments.

[0173] The above merely describes the preferred embodiments of the present application, but not for limiting the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for generating a two-ended key group for a backscattering device, characterized in that, The backscattering device dual-end key group generation method includes the following steps: Step 1, Obtain downlink channel information: The signal source transmits a signal, and both backscatter devices (BDs) are in listening mode; Step 2: Obtain relevant reflection cascade channel information: The signal source sends a signal, one device is in backscatter mode, and the other device is in listening mode. During the coherence time, the two BDs switch working modes. Step 3, construct triangular channel information: using the three channels formed by the two-ended BD and the signal source in the environmental backscattering system, the downlink channel and reflection concatenation channel information are multiplied to further construct triangular channel information as shared random information of the two BDs to generate a shared key; Step 4: Position calculation stage of the signal source for the BD: In this stage, each BD works in backscatter mode in turn to ensure that only one BD performs backscatter at any given time. The signal source calculates the position of each BD based on the arrival signal strength (RSS) and arrival signal angle AoA of the backscattered signal. Step 5: Grouping Decision and Broadcasting Phase: Based on the location of the signal source via BD, a distance-based hierarchical grouping algorithm is used to calculate the optimal grouping result, and the grouping result is broadcast. Step 6, Time-division backscattering stage: Each BD takes turns working in backscattering mode, while other BDs remain in listening mode to ensure that all BDs can obtain the shared back cascaded channel information; Step 7, BD Broadcast Phase: Each BD broadcasts a combination of all constructed triangular channel measurements to all other BDs in each time slot and appends a weight vector to the broadcast signal; Step 8, Key Construction Phase: Each BD will obtain a shared set of triangular channel information by calculating the triangular channel measurements that were not estimated in Step 6.

2. The method for generating a dual-end key group for a backscattering device according to claim 1, characterized in that, In step one, the process of simultaneously being in receive / listen mode to obtain downlink channel information before generating the key between the two devices includes: BD and BD All operate in listening mode, directly receiving radio frequency signals from the signal source. The radio frequency signal from the signal source passes through the downlink channel. They were respectively BD and BD The received signals, under ideal noise-free conditions, are respectively represented as follows: , At this point, BD acquires the signal containing downlink channel information. In step two, the process of being in backscatter mode and listening mode respectively before generating the key between the two devices to obtain information about the cascaded channel includes: (1) The signal source continuously transmits radio frequency signals BD Operating in backscatter mode, it reflects the signal to the BD. In listening mode, BD The received backscattered signal is Meanwhile, because the signal source continuously transmits radio frequency signals, BD In addition to receiving BD In addition to the backscattered signal it sent, it also received a signal sent by the signal source. The two signals are superimposed, then BD Received superimposed signals ; (2) is the same as (1), when BD It works in listening mode, while BD When operating in backscatter mode, BD Superimposed signals will be received ; In processes (1) and (2), BD and BD Received information about the reflection concatenation channel or Information; In step three, the process of constructing triangular channel information as shared random information before generating the key between the two devices, and then generating the shared key, includes: After acquiring downlink channel information and reflection concatenation channel information, BD and BD The downlink channel information is multiplied by the reflection concatenated channel information to construct triangular channel information; BD The constructed triangular channel information is represented as follows , while BD The constructed information is represented as Because the channel is reciprocal, Established, therefore BD and BD The constructed triangular channel information is identical, and the two BDs utilize the triangular channel as shared random information.

3. The method for generating a dual-end key group for a backscattering device according to claim 1, characterized in that, In step four, the signal source calculates the position of the BD: In this stage, each BD works in backscatter mode in turn, ensuring that only one BD performs backscatter at any given time. The signal source calculates the position of each BD based on the arrival signal strength (RSS) and arrival signal angle AoA of the backscattered signal. In step five, the grouping decision and broadcasting stage: the signal source calculates the optimal grouping result using a distance-based hierarchical grouping algorithm based on the location of BD, and broadcasts the grouping result; In step six, the process of each BD operating in backscatter mode in a time-division manner before generating the group key of the BD includes: During the backscatter phase, the signal source continuously broadcasts radio frequency signals. In each time slot, each BD (Digital Broadcasting Unit) operates in backscatter mode in turn, while the others remain in listening mode. After all BDs have completed the backscatter process, each device obtains a signal containing... N-1 A collection of triangular channel information ; In step seven, the process of each BD operating in broadcast mode in a time-sharing manner before generating the group key for the BD includes: During the broadcast phase, each BD broadcasts a combination of all constructed triangular channel measurements to all other BDs in a time-division manner, so that each BD will set... To supplement; In step eight, the process of calculating the shared triangular channel information set for each BD before generating the group key of the BD includes: During the construction phase, each BD will calculate the triangular channel measurements that were not estimated in step six, for the set. By supplementing this information, we obtain a set of N triangular channel information shared with all BDs. .

4. A backscattering device two-end key group generation system applying the backscattering device two-end key group generation method as described in any one of claims 1 to 3, characterized in that, The backscattering device dual-end key group generation system includes: The downlink channel information acquisition module is used for the signal source to transmit signals, and both devices are in listening mode; A reflection cascade channel information acquisition module is used for the signal source to transmit signals, where one device is in backscatter mode and the other device is in listening mode; the two devices exchange operating modes within a certain time period. The triangular channel information construction module is used to construct triangular channel information by multiplying the acquired downlink channel and reflection concatenated channel information, and to use the triangular channel information as shared random information between the two devices to generate a shared key; The time-division backscatter module is used so that each backscatter device can work in backscatter mode in turn, while the others remain in listening mode, to ensure that all backscatter devices can obtain the shared backscatter channel information. The backscatter device broadcast module is used by each backscatter device to broadcast a combination of all constructed triangular channel measurements to all other backscatter devices in each time slot, and appends a weight vector to the broadcast signal; The key construction module is used by each backscattering device to obtain a shared set of triangular channel information by calculating triangular channel measurements that were not estimated in the time-division backscattering module.

5. A computer device, characterized in that, The computer device includes a memory and a processor. The memory stores a computer program, which, when executed by the processor, causes the processor to perform the steps of the backscattering device dual-end key group generation method as described in any one of claims 1 to 3.

6. A computer-readable storage medium, characterized in that, The device contains a computer program that, when executed by a processor, causes the processor to perform the steps of the backscattering device dual-end key group generation method as described in any one of claims 1 to 3.

7. A backscattering device, characterized in that, The backscattering device applies the steps of the backscattering device dual-end key group generation method as described in any one of claims 1 to 3.

8. A signal source, characterized in that, The signal source applies the steps of the backscattering device dual-end key group generation method as described in 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 backscattering device dual-end key group generation system as described in claim 4.

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