A global WiFi intercom system and an encryption control method thereof

Abstract

The application discloses a kind of global WiFi intercom systems, comprising: fixed LAN AP and several local communication terminals, the local communication terminal is selected from smart bracelet, smart watch, head-mounted intercom equipment, handheld interphone, inspection pad, wall-mounted dispatching large screen, internal network WiFi passage is only as binary message pure transmission channel, all intercom services, equipment identification management and national secret operation program solidification run in local communication terminal inside.System uses three layers of domestic commercial cryptographic collaborative architecture, including SM4-GCM media encryption layer, SM3 binding equipment identification hash check layer and SM9 cross-domain identity verification layer.The application is equipped with fuse hardware trusted root and SM3 message hash double evidence traceability mechanism, solves the existing equipment identification easy to leak, internal and external network data crosstalk, network cannot intercom, commercial cryptographic non-compliance and other industry pain points, applicable to hospital, construction site, chain stores, industrial park and other scenes.

Description

Technical Field

[0001] This invention relates to the field of wireless communication technology, and in particular to a global WiFi intercom system and its encryption control method. Background Technology

[0002] With the rapid development of IoT technology and the widespread adoption of smart terminal devices, WiFi audio and video intercom technology is playing an increasingly important role in areas such as chain store operation and management, cross-regional construction scheduling, multi-hospital medical service coordination, large-scale warehousing and logistics management, and intelligent operation and maintenance of industrial parks. In complex application scenarios such as hospitals, construction sites, chain stores, and industrial parks, intercom systems not only need to meet the demands for high-efficiency audio and video communication but also face severe information security challenges. Especially in scenarios involving confidential intranet communication and cross-domain interconnection, ensuring the uniqueness, integrity, and traceability of device identities while guaranteeing real-time and reliable communication has become a core technical problem that the industry urgently needs to solve.

[0003] A comprehensive review and analysis of existing WiFi intercom technologies revealed a fundamental technical flaw: the lack of a complete security control link centered around device identification. Specifically, existing WiFi audio / video intercom devices deploy core functionalities such as audio / video encoding / decoding, device identification encryption, and group scheduling on routers, repeater bases, or cloud servers, while terminal devices only handle audio / video capture and playback. This inverted design of computing power and security architecture means that once the external network connection is lost or the repeater is removed, the terminal immediately loses its device identification capability and cannot perform basic intercom communication. More seriously, existing technologies generally confuse the concepts of the repeater base itself and the built-in mobile WiFi transmission path, incorrectly equating the two. Link switching relies solely on software logic, lacking hardware-level electrical isolation protection mechanisms. This makes it extremely easy for confidential device identification on the internal network to be leaked through external network channels, posing a serious security risk.

[0004] Further analysis revealed that existing WiFi audio and video intercom devices merely use device identification as a simple hardware serial number, failing to construct a fully autonomous closed-loop security system centered on encrypted device identification, covering identification generation, encrypted storage, group derivation, message binding, cross-domain encrypted addressing, irreversible destruction, and judicial notarized traceability. Conventional industry solutions employ a fragmented approach with single encryption methods, either storing device identification in plaintext or simple encryption on gateways or cloud servers, posing risks of identification theft and device forgery; or only encrypting audio and video streams separately, failing to integrate device identification into a three-layer commercial cryptographic collaborative system of SM4 media encryption, SM3 integrity hashing, and SM9 cross-domain signature verification. Furthermore, they lack crucial supporting security architectures such as fuse hardware root of trust binding to device identification and electrical isolation of the base hardware to prevent internal network identification leakage. Since none of the above technical solutions have fundamentally solved the problem of secure management of device identity, the existing technology has long been unable to simultaneously meet the needs of secure intercom in offline intranet environments, the needs of reliable calls without plaintext identity in cross-city scenarios across the country, and the needs of tracing identity evidence at the judicial level. This inherent technical contradiction has long been unresolved in the field and has become the main technical bottleneck restricting the development of WiFi intercom technology toward high security and high reliability. Summary of the Invention

[0005] This invention addresses the technical shortcomings of existing WiFi intercom technologies, such as the inversion of computing power and security architecture, confusion between device identification and wireless transmission path concepts, and incomplete and non-compliant commercial cryptographic systems. It provides a global WiFi end-side autonomous audio and video intercom system with local encrypted device identification as the security core and three layers of domestic commercial cryptography working together.

[0006] To achieve the objectives of this invention, a global WiFi intercom system is provided, comprising: a fixed local area network (AP) and several local communication terminals. The fixed LAN AP establishes a two-layer closed local area network and provides an intranet WiFi wireless transmission channel. The fixed LAN AP is a broadband router, and the intranet WiFi wireless transmission channel can transmit binary data. The local communication terminals are selected from smart bracelets, smartwatches, head-mounted intercom devices, handheld walkie-talkies, inspection tablets, and wall-mounted dispatch screens.

[0007] In this invention, the internal WiFi wireless transmission channel serves only as a pure binary message transmission channel and does not carry any business operations such as audio / video acquisition, encoding / decoding, global device identifier allocation, device identifier encrypted storage, number segment addressing, SM4 / SM3 national cryptographic encryption / decryption, group scheduling, key management, or password audit log storage. All intercom services, device identifier segment management, and a complete set of domestically produced commercial cryptographic security programs are permanently and autonomously run within the local communication terminal. The local communication terminal has a built-in audio / video acquisition and playback module and an SE secure storage unit. The device identifier supports three equivalent input methods: local manual input, QR code scanning, and RF import. Changing the terminal shell, strap, screen, or size does not change the core technology solution for local number segment encryption.

[0008] Each local communication terminal independently integrates a WiFi communication module, a main control chip, a national cryptographic security computing unit, a hardware-isolated SE storage unit, a human-machine interaction module, and an audio / video acquisition and playback module. The SE chip communicates with the main control chip via an SPI hardware isolation interface and has a built-in independent commercial cryptographic audit log storage partition. The WiFi communication module has a built-in one-time hardware fuse storage area, with a globally unique hardware trusted root identification code programmed at the factory. This identification code cannot be read, cleared, or rewritten by software programs or external hardware debugging methods. At the moment the terminal is powered on, the WiFi communication module directly reads this hardware trusted root identification code as the terminal's unique physical identity identifier. It does not participate in any business operations throughout the process and only serves as a hardware anchor point for message binding and traceability.

[0009] The main control chip serves as the terminal's local computing core, independently performing all of the following functions: audio and video encoding / decoding; global device identifier allocation and SM4 encrypted storage; encrypted identifier-MAC address mapping maintenance; underlying MAC unicast hardware filtering; GM / T0002 SM4-GCM layered media encryption; GM / T 0004 SM3 bound device identifier hash verification; point-to-point or group intercom scheduling based on encrypted identifiers; GM / T 0005 standard national cryptographic key derivation and full lifecycle management. The main control chip performs all of the above functions without requiring a relay base or cloud server to provide computing power. Upon terminal deregistration or loss reporting, the device identifier and key stored in the SE are erased through multiple rounds of overwriting, achieving irreversible data destruction.

[0010] The national cryptographic security computing unit integrates the GM / T 0002 SM4-GCM block cipher algorithm and the GM / T 0004 SM3 hash algorithm, and performs local layered encryption processing: audio data is uniformly divided into 128-byte fixed segments; video data strictly distinguishes between I keyframes and P prediction frames for independent segmentation; the initialization vector IV is generated by the terminal WiFi hardware true random number generator and transmitted synchronously with the message, disabling ECB encryption mode; transmission adopts any one of the directional unicast protocols such as UDP, TCP, and QUIC; each data packet embeds a time stamp, two 16-bit CRC-CCITT check codes, and an SM3 integrity hash value bound to the local encryption device identifier; abnormal messages are directly discarded when the hardware verification result does not match.

[0011] The hardware-isolated SE storage unit includes an independent security encryption chip and a hardware read-write lock, providing dual equivalent isolation. The terminal's external debugging interface features a one-time fuse structure; after the fuse blows, the device identifier and key plaintext cannot be exported. After power failure, the device identifier and key are stored in the SE chip in SM4 encrypted form. The terminal locally manages the offline buffer duration in a tiered manner; after offline timeout, the intercom function is permanently disabled. Upon terminal logout or loss reporting, all encrypted device identifiers, audio / video caches, and session keys are automatically and irreversibly erased.

[0012] The local communication terminal is configured with a globally unique device identifier, ranging from one to sixty-four characters in length, composed of any combination of numbers and uppercase and lowercase letters. This device identifier is stored in the SE chip and encrypted using the terminal's local SM4 algorithm. The terminal's intranet WiFi channel broadcasts an encrypted device identifier and MAC address mapping message; when calling a target identifier, the corresponding MAC address is matched locally to establish a directional unicast connection. The multi-group encrypted number segment subkey derivation program is an optional local extension module for the terminal; omitting this module allows the point-to-point intercom function based on the encrypted device identifier to operate independently and completely. In the pure intranet working mode, no portable dual-path WiFi relay base or cloud-based SM9 global number segment resolution server is required, and Bluetooth, LoRa, and cellular wireless architectures are not used.

[0013] As a preferred technical solution of the present invention, the system is configured with two independently operable working modes: a pure intranet local mode and a cross-city hybrid group mode. In the pure intranet local mode, the system only includes fixed LAN APs and local communication terminals, eliminating the need for relay bases and cloud servers, and enabling complete encrypted device identification and intercom functionality in an offline environment. In the cross-city hybrid group mode, the system adds a portable dual-path WiFi relay base and a cloud-based SM9 full-domain number segment resolution server as transmission auxiliary components and trusted addressing auxiliary components, enabling bidirectional communication between fixed intranet WiFi terminals and field mobile WiFi terminals.

[0014] The portable dual-path WiFi relay base is an independent hardware unit, only responsible for Layer 2 forwarding of encrypted messages and switching between dual transmission channels. It does not integrate any national cryptographic algorithms such as SM4, SM3, or SM9, and has no audio / video encoding / decoding module, device identification processing module, or intercom dispatch program module. The base integrates the base's internal WiFi path, mobile WiFi path, repeater chip, and dual-path hardware electrical isolation circuit, but has no other wireless transceiver hardware. The base only completely transmits the encrypted device identification and audio / video ciphertext output by the terminal, without parsing or tampering with the internal number segments and key ciphertext data of the message.

[0015] The base supports manually disabling the mobile WiFi channel and switching to an internal network-only transmission mode. The base incorporates dual-link automatic switching logic, prioritizing the internal WiFi channel by default; it automatically switches between the two internal wireless transmission channels based on a preset WiFi signal strength threshold and a preset duration of no external network messages; when the signal strength of the internal WiFi channel falls below the threshold, it automatically switches to the mobile WiFi channel; and when there are no external network interaction messages for a preset duration, it automatically switches back to the internal WiFi channel.

[0016] The cloud-based SM9 global number segment resolution server, equipped with a commercial encryption machine, only provides cross-city terminal trusted addressing services and does not perform any business operations such as SM4 media encryption, audio / video encoding / decoding, or device identifier decryption. The cloud uses the GM / T0044 SM9 identifier cryptographic algorithm to encrypt and store the mapping relationship between the encrypted device identifier, public IP address, fuse root of trust, offline duration, and lost / stolen status. All mapping data is hardware-encrypted and stored by the encryption machine. The field terminal reports the encrypted device identifier and fuse root of trust to the cloud via the built-in mobile WiFi channel in its base station or by directly connecting to public mobile WiFi. The SM9 interaction messages only carry the ciphertext identifier, fuse hash, and timestamp, without any plaintext information. After completing SM9 signature verification, the cloud only returns the target terminal's public IP address, without decrypting the plaintext terminal device identifier throughout the entire process.

[0017] Both terminals independently execute the complete SM4 layered encryption and SM3 device identifier hash verification intercom process locally. A single SM4 global root key is shared across the entire region. Cross-regional group-specific encryption sub-keys are derived locally by the terminals. The cloud only synchronizes key update commands and does not participate in key and device identifier derivation calculations. Level 3 key update commands are synchronously pushed to all local communication terminals and relay bases. The bases only forward commands and do not parse the key and device identifier ciphertext.

[0018] This invention provides an encryption control method for a global WiFi intercom system. All device identification management and SM4 / SM3 national cryptographic operations are performed locally on the local communication terminal. The intranet WiFi path, the base intranet WiFi path, and the mobile WiFi path only serve as message transmission channels and do not participate in any service, national cryptographic, or number segment processing operations. The method includes the following steps:

[0019] The device identifier and national cryptographic key are synchronized locally in a trusted manner. Upon power-up, the terminal reads the fuse hardware root of trust, supporting three equivalent input methods: local manual input, QR code scanning, and RF import, and generates an SM4 encrypted global device identifier. A mapping table between the encrypted identifier and MAC address is maintained locally. The terminal implements tiered management of offline cache duration, prioritizing 72 hours for wall-mounted terminals and 48 hours for field terminals. Upon terminal deregistration or loss reporting, the SE storage performs multiple rounds of irreversible overwriting to erase the local encrypted device identifier and temporary session key. All WiFi packets sent by the terminal are written with the SM3 hash value bound to the device identifier as an evidence identification identifier. The SE chip synchronizes encrypted storage password audit logs via the SPI hardware isolation interface. In full-domain mode, the terminal only uploads the encrypted device identifier and fuse root of trust to the cloud to complete SM9 identity registration, without uploading plaintext.

[0020] The terminal-side SM4-GCM layered encryption transmission steps are as follows: The terminal locally performs 128-byte audio segmentation and independent segmentation of video I-frames and P-frames, and then calls the SM4-GCM algorithm for layered encryption. An SM3 integrity hash checksum binding the device identifier is attached to the message, and the encrypted message is transmitted and received via the corresponding WiFi path. A directional unicast message is established based on the MAC address, and the terminal performs the retransmission operation locally when the message is retransmitted after a preset duration. The initialization vector IV is generated by the terminal's WiFi hardware true random number generator and transmitted synchronously with the message, disabling ECB encryption mode. Each data packet embeds a timestamp and two 16-bit CRC-CCITT checksums. Abnormal messages are discarded directly when the hardware checksum does not match.

[0021] Local group encryption identifier isolation steps. The terminal derives independent encryption subkeys for each group based on the global SM4 root key, following the GM / T 0005 KDF standard. The terminal performs three levels of national cryptographic key lifecycle management: single-terminal key reset, group key update, and global batch key push. Terminals marked as lost or offline timed out have all encrypted identifier transmission and reception messages directly intercepted and discarded at the WiFi hardware level, physically prohibiting access to the internal WiFi network.

[0022] The dual-path switching procedure for the base is only performed in global mode, where the base has no number segment or national cryptographic operations. The relay base uses a hardware electrical isolation circuit to isolate the base's internal WiFi path from the mobile WiFi path, forwarding only complete encrypted messages. Terminals are pre-marked with group types: for purely internal local groups, the hardware electrical isolation circuit permanently physically isolates external network messages; for globally mixed groups, the software distributes messages to both paths separately, without any change in the hardware isolation structure, enabling cross-network intercom communication between the two types of terminals. The base automatically switches the internal wireless path based on a preset WiFi signal threshold and external network idle time. This step is skipped in purely internal mode.

[0023] The cloud-based SM9 number segment verification process is only performed in global mode, and the cloud does not decrypt the device identifier. The field terminal initiates an SM9 identity verification and identifier IP query request to the cloud; the exchange message contains no plaintext device information. After completing the SM9 verification, the cloud only returns the target terminal's public IP address. The cloud adds a global hybrid group identifier registry to uniformly store encrypted device identifiers for both internal fixed WiFi terminals and field mobile WiFi terminals. Upon receiving hybrid group intercom messages, it distributes encrypted messages in batches according to the registry, sending them to both internal WiFi terminals and mobile WiFi terminals respectively, without decrypting the device identifier or audio / video content throughout the process. The cloud automatically reclaims idle encrypted identifiers that have been offline for a preset period, preferably ninety days. This step is skipped in pure internal network mode.

[0024] The encryption control method includes a cross-regional group key synchronization step, which is only executed in global mode. The cloud only issues group number segment key update instructions, which are received locally by the terminal and the key replacement and group communication isolation configuration are completed in the local SE chip. This step is skipped in pure intranet mode.

[0025] The encryption control method includes a global national cryptographic key synchronization step. The key update ciphertext instruction is transmitted to the terminal via WiFi, where the terminal's SE chip decrypts and replaces the global root key and group number subkey. The relay base and cloud server only forward the instruction and do not parse the key and device identifier ciphertext.

[0026] The encryption control method includes a dual-credible evidence collection step. The two types of physical evidence—the terminal fuse hardware root of trust and the SM3 hash of the device identifier bound to the message—can be independently extracted for infringement notarization and tracing. The encrypted audit log within the SE serves as supplementary evidence of infringement, recording the entire lifecycle operations of key derivation, cancellation and destruction, and loss reporting and interception. The hardware fuse root evidence is a globally credible hardware root written once at the factory of the WiFi module, which cannot be erased or rewritten, serving as physical notarization evidence of the device's uniqueness. The message hash evidence is the SM3 hash value of the device identifier bound to any communication message, serving as on-chain notarization evidence of data flow and identity association. These two types of physical evidence can be extracted separately for infringement notarization and tracing, forming a closed loop of hardware, data, and log-based judicial evidence collection.

[0027] The omni-channel WiFi intercom system of this invention creates hybrid groups based on existing hardware architecture, supporting mutual calling and two-way group intercom between fixed WiFi terminals on the intranet and mobile WiFi terminals in the field. In pure intranet mode, it can achieve complete encrypted device identification intercom function without the need for a relay base and cloud server; in omni-channel cross-city mode, it achieves secure interoperability between intranet and internet terminals through the electrical isolation of the relay base hardware and the cloud SM9 signature verification.

[0028] Furthermore, the global WiFi intercom system of this invention adopts a three-layer domestically produced commercial cryptographic collaborative core security system. The media encryption layer uses the GM / T 0002 SM4-GCM encryption algorithm, disables ECB mode, segments audio into 128-byte segments, and segments video into independent I-frames and P-frames. The initialization vector is generated by a WiFi hardware true random number generator. The integrity verification layer uses the GM / T 0004 SM3 hash algorithm, binding each message to the current terminal's encryption device identifier, serving both anti-tampering and evidence collection purposes. The cross-domain identity layer uses the GM / T 0044 SM9 identifier cryptographic algorithm, with a cloud-based commercial encryption machine storing encrypted number segment mappings, ensuring no decryption of plaintext devices throughout the process; key derivation follows the GM / T 0005 KDF standard.

[0029] Compared with the prior art, the present invention provides a global WiFi intercom system, which has the following advantages:

[0030] This invention completely solves the technical defect of the inverted computing power and security architecture in existing technologies by locally embedding all device identification encryption, audio and video intercom, and three-layer domestic commercial cryptographic operation programs on the local communication terminal. In this invention, the intranet WiFi path and mobile WiFi path only serve as the medium for transmitting binary encrypted messages, completing data transmission and reception, and do not carry any business operations. The base and cloud server do not store any plaintext device identification or national cryptographic operation capabilities. After disconnecting the external network connection or removing the relay base, the terminal in pure intranet mode can still fully execute the encrypted device identification intercom function. Physical anti-sniffing of the local area network is achieved through the terminal WiFi underlying hardware MAC address unicast transmission mechanism. Packets with mismatched MAC addresses are directly discarded by the terminal WiFi hardware, intercepting illegal packets at the physical layer and eliminating the risk of device identification and audio / video content leakage caused by broadcast packet capture. The dual-path hardware electrical isolation circuit of the relay base is an irreplaceable and essential feature. Relying solely on software logic to isolate the two built-in wireless paths of the base cannot achieve the same physical isolation effect, completely blocking the leakage path of classified data from the field intranet. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the method flow of the present invention;

[0032] Figure 2 This is a schematic diagram of the entire process of the encryption control method according to an embodiment of the present invention. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] Please see Figures 1-2 This invention provides a global WiFi intercom system, comprising: a fixed LAN access point (AP), several local communication terminals, a portable dual-path WiFi relay base, and a cloud-based SM9 global number segment resolution server. The system offers two independently operable modes: a pure intranet local mode and a global cross-city hybrid group mode. In the pure intranet local mode, the system only includes the fixed LAN AP and local communication terminals, eliminating the need for the portable dual-path WiFi relay base and the cloud-based SM9 global number segment resolution server, thus enabling fully encrypted device identification intercom functionality within a pure intranet environment. In the global cross-city hybrid group mode, the system adds a portable dual-path WiFi relay base and a cloud-based SM9 global number segment resolution server as transmission and reliable addressing auxiliary components, enabling bidirectional communication between fixed intranet WiFi terminals and field mobile WiFi terminals.

[0035] In one embodiment of the present invention, the local communication terminal is selected from at least one of a smart bracelet, smartwatch, head-mounted intercom device, handheld walkie-talkie, inspection tablet, and wall-mounted dispatch screen. The local communication terminal is equipped with an audio / video acquisition and playback module and an SE secure storage unit. The device identifier supports three equivalent input methods: local manual input, QR code scanning, and RF import. Changing the terminal shell, strap, screen, or size does not alter the core technology solution for local number segment encryption. Each local communication terminal independently integrates a WiFi communication module, a main control chip, a national cryptographic security computing unit, a hardware-isolated SE storage unit, a human-computer interaction module, and an audio / video acquisition and playback module.

[0036] The WiFi communication module of the local communication terminal has a built-in one-time hardware fuse storage area, which stores a globally unique hardware root of trust identifier code at the factory. This hardware root of trust identifier code is written once through a physical fuse process, and once the fuse blows, it forms an irreversible physical state. Software programs and external hardware debugging methods cannot read, clear, or rewrite this identifier code. Upon power-up of the terminal, the WiFi communication module directly reads this hardware root of trust identifier code as the terminal's unique physical identity. It does not participate in any business operations throughout the process, serving only as a hardware anchor point for message binding and traceability.

[0037] The SE chip in the local communication terminal communicates with the main control chip via an SPI hardware isolation interface. The SPI hardware isolation interface provides physical-level electrical isolation, ensuring that data transmission between the SE chip and the main control chip is not interfered with or stolen by external malicious programs. The SE chip has a built-in independent commercial cryptographic audit log storage partition, which uses independent storage sectors and is physically isolated from the regular data storage area. The SE chip also includes an independent security encryption chip and a hardware read-write lock as a dual equivalent isolation carrier, used to store the encrypted device identifier, global root key, and group number segment key. The terminal's external debugging interface is equipped with a one-time fuse structure; after the fuse blows, the device identifier and key plaintext cannot be exported. After power failure, the device identifier and key are retained in the SE chip in SM4 encrypted form.

[0038] The main control chip is the local computing core of the terminal, independently completing all the following functions without the need for a relay base or cloud server to provide computing power: Audio and video encoding / decoding functions are executed by the audio and video encoding / decoding engine built into the main control chip, supporting PCM encoding, G.711 or AAC format conversion of audio signals, and H.264 or H.265 format encoding and decoding of video signals; the global device identifier allocation function is generated by the main control chip during terminal initialization or received from the input interface and then encrypted and stored using SM4; the encrypted identifier and MAC address mapping maintenance function is maintained by the main control chip in memory using a dynamically updated mapping table that records the correspondence between the encrypted device identifier and the corresponding MAC address of each terminal; the underlying MAC unicast hardware filtering function is executed by the MAC address filtering engine built into the WiFi communication module, allowing only packets matching the target MAC address; the GM / T 0002 SM4-GCM layered media encryption function is executed by the national cryptographic security computing unit; GM / T 0004 The SM3 binding device identifier hash verification function is executed by the national cryptographic security computing unit; the point-to-point or group intercom scheduling function based on encrypted identifiers is executed by the intercom scheduling module built into the main control chip; the GM / T 0005 standard national cryptographic key derivation and full lifecycle management function are executed collaboratively by the main control chip and the SE chip. When the terminal is deregistered or reported lost, the main control chip performs multiple rounds of overwrite erasure of the device identifier and key stored in the SE chip, achieving irreversible data destruction.

[0039] The national cryptographic security computing unit integrates the GM / T 0002 SM4-GCM block cipher algorithm and the GM / T 0004 SM3 hash algorithm, performing layered encryption locally. The specific processing flow is as follows: Audio data is uniformly divided into 128-byte fixed segments, each segment is independently encrypted using SM4-GCM, generating corresponding ciphertext segments and authentication tags; Video data strictly distinguishes between I-frames and P-frames for independent segmentation. I-frames serve as key reference frames, using independent encryption keys and initialization vector parameters, while P-frames are encoded based on the prediction residual of the previous frame and also undergo SM4-GCM encryption. The initialization vector IV is generated by a true random number generator built into the terminal's WiFi communication module, following the GM / T 0008 commercial cryptographic random number detection standard, ensuring that each encryption uses a globally unique initialization vector and is transmitted synchronously with the message. This invention prohibits the use of ECB encryption mode. The transmission uses any one of the directional unicast protocols: UDP, TCP, or QUIC. Each data packet embeds a timestamp, two 16-bit CRC-CCITT checksums, and an SM3 integrity hash value bound to the local encryption device identifier. The receiver's WiFi communication module hardware layer performs an initial check on the packet's MAC address, and the main control chip performs a second check on the SM3 hash value. If the hardware check results do not match, the abnormal packet is discarded.

[0040] The local communication terminal is configured with a globally unique device identifier, ranging from one to sixty-four characters in length, composed of any combination of numbers and uppercase and lowercase letters. The device identifier is stored in the SE chip and encrypted using the terminal's local SM4 algorithm. The terminal's internal WiFi network broadcasts an encrypted device identifier and MAC address mapping message, used for device discovery and address resolution within the local area network. When calling a target identifier, the local main control chip looks up the corresponding MAC address in the encrypted identifier-MAC address mapping table, and then establishes a directed unicast connection for subsequent communication.

[0041] In pure intranet operating mode, the system requires no portable dual-path WiFi repeater base or cloud-based SM9 full-domain number segment resolution server, and does not use Bluetooth, LoRa, or cellular wireless architecture. The standardized operating procedure in this mode includes the following five steps:

[0042] The first step is the trusted synchronization of the device identifier. After the terminal is powered on, the WiFi communication module reads the globally unique hardware trusted root identification code from the hardware fuse storage area, which serves as the physical identity anchor for the terminal. The terminal supports three methods to obtain the plaintext device identifier: local manual input, QR code scanning, or RFID import. If using local manual input, the user manually inputs the device identifier characters on the terminal display screen through the human-machine interface module. If using QR code scanning, the human-machine interface module uses the camera to capture the QR code image and decodes it to extract the device identifier. If using RFID import, the human-machine interface module reads the device identifier pre-installed on the work card or tag through the NFC or RFID RFID module. After obtaining the plaintext device identifier, the main control chip calls the national cryptographic security computing unit to perform SM4 encryption, generating encrypted device identifier ciphertext, and storing the mapping relationship between the encrypted device identifier and the MAC address in the encrypted storage partition of the SE chip. A local maintenance table of encrypted identifier and MAC address mapping is used for subsequent communication addressing. All WiFi packets sent by the terminal embed an SM3 hash value bound to the terminal device identifier at the end of the packet as an evidence identification identifier. This hash value is calculated and generated by the national cryptographic security computing unit and transmitted along with the encrypted packet. The SE chip synchronously and encryptedly stores the password audit log through the SPI hardware isolation interface, recording operation timestamps and operation types such as device identifier entry time, encryption operation time, and key derivation time.

[0043] The second step is the end-side layered encryption transmission process. After the terminal locally completes the 128-byte audio fragmentation and the independent fragmentation of video I-frames and P-frames, it calls the national cryptographic security computing unit to execute the SM4-GCM algorithm for layered encryption. During the encryption process, the initialization vector is generated by the hardware true random number generator of the WiFi communication module, and each fragment uses an independent initialization vector. The message is appended with an SM3 integrity hash checksum of the bound device identifier, and the encrypted message is sent and received via the internal WiFi path. The encrypted message establishes a directed unicast transmission based on the target MAC address, and each data packet embeds a time stamp and two 16-bit CRC-CCITT checksums. If the sending end does not receive an acknowledgment signal from the receiving end for the corresponding message within a preset time period, a retransmission mechanism is triggered, and the terminal locally performs the re-encryption and retransmission of the message.

[0044] The third step involves local key and number segment management. During system initialization, the main control chip generates an SM4 global root key within the SE chip, which remains consistent across all terminals. The main control chip derives independent encrypted number segment subkeys based on the global root key, following the GM / T 0005 key derivation function standard and employing the specified derivation algorithm and parameters. Terminals locally support three levels of national cryptographic key management: single-terminal key reset, group key update, and batch key push across the entire network. Terminals marked as lost or offline timed out have their WiFi communication module hardware directly intercept and discard all encrypted transmitted and received messages, physically prohibiting access to the internal WiFi network. Audit logs are synchronously encrypted and stored in a separate partition of the SE chip.

[0045] The fourth step is the MAC address hardware anti-sniffing procedure. The MAC address filtering engine of the terminal's WiFi communication module is configured in unicast reception mode. Packets with non-matching MAC addresses are directly discarded at the physical layer without needing to be reported to the main control chip for processing. This mechanism eliminates the risk of device identification and audio / video content leakage caused by broadcast packet capture.

[0046] The fifth step is the local decryption and playback process. After receiving the encrypted message, the receiving WiFi communication module first performs hardware verification on the target MAC address. If the verification passes, the encrypted message is handed over to the main control chip for processing. The main control chip extracts the SM3 hash value bound in the message and compares it with the device identifier hash value calculated locally at the receiving end. If the hash values ​​match, the national cryptographic security computing unit is invoked to perform SM4-GCM decryption. After decryption, audio and video decoding is performed and output. If the hash values ​​do not match, the message source is determined to be abnormal, and the message is discarded and recorded in the audit log.

[0047] In one embodiment of the present invention, the portable dual-path WiFi relay base is an independent hardware unit, solely responsible for Layer 2 forwarding of encrypted messages and switching between dual transmission channels. The base does not integrate any SM4, SM3, or SM9 national cryptographic algorithms, nor does it have audio / video encoding / decoding modules, device identification processing modules, or intercom dispatching program modules. The base integrates the base's internal WiFi path, mobile WiFi path, relay chip, and dual-path hardware electrical isolation circuitry, without any other wireless transceiver hardware. The base only completely transmits the encrypted device identifier and audio / video ciphertext output by the terminal, without parsing or tampering with the internal number segments and key ciphertext data of the messages.

[0048] In one embodiment of the present invention, a dual-path hardware electrical isolation circuit is an indispensable and essential feature. This circuit uses physical electrical isolation devices to permanently isolate the base's internal WiFi path from the mobile WiFi path. The electrical isolation devices are selected from digital isolation chips or optocoupler isolation devices that meet industrial-grade isolation standards, with an isolation withstand voltage of not less than one kilovolt. There is no software-level communication channel between the two wireless paths built into the base; physical signal isolation is achieved solely through the dual-path hardware electrical isolation circuit. The base supports manually disabling the mobile WiFi path and switching to an internal network-only transmission mode.

[0049] In one embodiment of the present invention, the base has built-in dual-link automatic switching logic, which prioritizes the base's internal WiFi path by default. When the signal strength of the base's internal WiFi path is lower than a preset threshold, the base automatically switches to the mobile WiFi path; when there are no external network interaction packets for a preset duration, the base automatically switches back to the base's internal WiFi path. During the switching process, the base does not parse or modify the packet content in any way, but only performs the physical path switching operation.

[0050] In one embodiment of the present invention, the terminal pre-marks the group type. If the group type is a pure intranet local group, the dual-path hardware electrical isolation circuit maintains a permanent physical isolation state, and external network packets cannot enter the intranet path; if the group type is a global mixed group, the software distributes packets to the two paths respectively, and the hardware isolation structure does not change, realizing cross-network intercom communication between the intranet fixed WiFi terminal and the field mobile WiFi terminal.

[0051] In one embodiment of the present invention, the synchronization process between the terminal fuse root of trust and the encrypted device identifier is as follows: After the terminal is powered on, the main control chip sends a hardware fuse read command to the WiFi communication module. The WiFi communication module reads the globally unique hardware root of trust identifier code burned at the factory from the hardware fuse storage area and outputs the identifier code to the main control chip in the form of a hardware register value. This read operation cannot be disabled or bypassed by software. The user selects the device identifier input method through the human-machine interaction module. If the local manual input method is selected, the device identifier is entered character by character through the display screen interface; if the QR code scanning input method is selected, the QR code image containing the device identifier information is captured by the camera and decoded; if the radio frequency import method is selected, the preset device identifier is read through the NFC or RFID module. After the main control chip obtains the plaintext device identifier, it calls the national cryptographic security operation unit to perform SM4 encryption operation to generate encrypted device identifier ciphertext and stores the ciphertext in the encryption partition of the SE chip. At the same time, the main control chip writes the mapping relationship between the encrypted device identifier and the MAC address of the WiFi communication module into the mapping table partition of the SE chip. Password audit logs are synchronously written to the SE chip's independent audit partition, recording the operation type, timestamp, and result. In global mode, the main control chip only uploads the encrypted device identifier ciphertext and fuse root of trust identification code to the cloud SM9 global number segment resolution server via the base's built-in mobile WiFi to complete identity registration; the upload process does not contain any plaintext information.

[0052] In one embodiment of the present invention, the terminal SM4-GCM layered encryption and SM3 device identifier hash verification process is as follows: After the audio and video acquisition and playback module acquires the original audio signal, it performs fixed segmentation in 128-byte units, with each audio segment accompanied by a segment sequence number and a timestamp. After the audio and video acquisition and playback module acquires the original video signal, the video encoder built into the main control chip identifies the frame type and processes them separately: I keyframes are extracted as complete encoded frames and encrypted separately, and P prediction frames are extracted based on the prediction residual of the previous frame and encrypted. Each segment of data is encrypted by calling the SM4-GCM encryption module in the national cryptographic security operation unit, and the initialization vector is generated by the true random number generator of the WiFi communication module. The national cryptographic security operation unit simultaneously calculates the SM3 hash value corresponding to the segment, which is calculated based on the original segment data and the bound device identifier. The encrypted segment data, initialization vector, SM3 hash value, and timing information are assembled into a complete data packet and sent via unicast based on the target MAC address through the WiFi communication module. The receiving end executes the reverse process: After the WiFi communication module receives the data packet, it first performs hardware verification of the MAC address, then the main control chip extracts the SM3 hash value and compares it with the hash value calculated by the local device identifier. After the comparison is successful, the SM4-GCM decryption module is called to perform decryption, and finally the audio and video are decoded and played.

[0053] In one embodiment of the present invention, the terminal level 3 key and group number segment derivation process is as follows: During the system deployment phase, the main control chip generates a globally shared SM4 global root key in the secure environment of the SE chip. This key is generated by a physical random number generator and written to the key storage partition of the SE chip. After the global root key is generated, the main control chip derives the independent encrypted number segment subkeys for each group based on the global root key and the GM / T 0005 key derivation function. The key derivation process is completed in the secure execution environment inside the SE chip, and the derivation parameters include the group identifier, derivation index, and key usage identifier. When a single terminal key is reset, the main control chip sends a key reset command to the SE chip. The SE chip internally generates a new random number and re-derives a new number segment subkey with the global root key, while retaining the old key for decrypting historical messages. When a group key is updated, the main control chip pushes the new derivation parameters to all terminals in a specific group, and each terminal re-executes the key derivation operation locally. When pushing keys in batches across the entire domain, the cloud-based SM9 global number segment resolution server initiates a global key update command. This command is transmitted to all terminals via WiFi. The terminal's SE chip decrypts and replaces the global root key and all group number segment sub-keys.

[0054] In one embodiment of the present invention, the hardware interception logic for a reported lost terminal is as follows: After receiving a lost terminal notification, the main control chip marks the terminal's device identifier as reported lost and writes it to the blacklist partition of the SE chip. The MAC filtering engine built into the WiFi communication module reads the marking information in the blacklist partition and performs hardware-level discarding operations on all packets whose target MAC addresses belong to the reported lost terminal. Simultaneously, the main control chip performs multiple rounds of overwrite erasure operations on the encrypted device identifier and session key of the terminal in the SE chip, with no less than seven overwrite operations, each using a different random data pattern.

[0055] In one embodiment of the present invention, the cloud-based SM9 global number segment resolution server is used in conjunction with a commercial encryption machine. The server uses the GM / T 0044 SM9 identifier cryptographic algorithm to encrypt and store the mapping relationship between the encrypted device identifier, public IP address, fuse root of trust, offline duration, and lost / stolen status. All mapping data is stored after being hardware-encrypted by the commercial encryption machine. Field terminals report the encrypted device identifier and fuse root of trust to the cloud-based SM9 global number segment resolution server via mobile WiFi or direct connection to public mobile WiFi. SM9 interaction messages only carry the ciphertext identifier, fuse hash, and timestamp, and do not contain any plaintext information. After completing SM9 signature verification, the cloud only returns the target terminal's public IP address, without decrypting the plaintext terminal device identifier throughout the entire process.

[0056] A cloud-based hybrid group identifier registry is added to uniformly store encrypted device identifiers for both internal fixed WiFi terminals and field mobile WiFi terminals. Upon receiving a hybrid group intercom message, the cloud performs batch addressing based on the registry and distributes encrypted messages to both internal WiFi terminals and mobile WiFi terminals. The device identifiers and audio / video content are not decrypted throughout the distribution process. The cloud automatically reclaims idle encrypted identifiers that have been offline for a preset period, with a preferred reclamation cycle of ninety days.

[0057] A single SM4 global root key is used across the entire domain, while independent encryption sub-keys for cross-regional groups are derived locally by each terminal. The cloud only synchronizes key update commands and does not participate in the derivation calculations of keys and device identifiers. Level 3 key update commands are synchronously pushed to all local communication terminals and relay bases. The bases only forward the commands and do not parse the key and device identifier ciphertext.

[0058] This invention also includes a terminal-side number segment encryption control method applicable to pure intranet systems or cross-city systems. All device identification management and SM4 / SM3 national cryptographic operations are performed locally on the local communication terminal. The intranet WiFi path and the base-built mobile WiFi path serve only as message transmission channels and do not participate in any business, national cryptographic, or number segment processing operations. The method includes the following steps:

[0059] S1. Device identifier and national cryptographic key are locally synchronized with trusted credentials. Upon power-up, the terminal reads the fuse hardware root of trust, supporting three equivalent input methods: local manual input, QR code scanning, or RF import, and generates an SM4 encrypted global device identifier. A local mapping table of encrypted identifiers and MAC addresses is maintained. The terminal implements tiered management of offline cache duration, prioritizing 72 hours for wall-mounted terminals and 48 hours for field terminals. Upon terminal deregistration or loss reporting, multiple rounds of irreversible overwrite operations are performed on the SE chip storage, clearing all encrypted device identifiers and temporary session keys. All WiFi packets sent by the terminal are written with the SM3 hash value bound to the device identifier as an evidence identification identifier. The SE chip synchronously and encryptedly stores password audit logs via the SPI hardware isolation interface. In full-domain mode, the terminal only uploads the encrypted device identifier and fuse root of trust to the cloud to complete SM9 identity registration.

[0060] S2. End-side SM4-GCM layered encrypted transmission. After the terminal locally completes the 128-byte audio fragmentation and independent fragmentation of video I-frames and P-frames, it calls the SM4-GCM algorithm for layered encryption. An SM3 integrity hash checksum bound to the device identifier is appended to the message. The encrypted message is transmitted and received via the corresponding WiFi path. Directed unicast messages are established based on the MAC address, and retransmission is performed locally on the terminal when a retransmission is triggered after a preset duration. The initialization vector is generated by the terminal's WiFi hardware true random number generator and transmitted synchronously with the message, disabling ECB encryption mode. Each data packet embeds a timestamp and two 16-bit CRC-CCITT checksums.

[0061] S3. Local Group Encryption Identifier Isolation. The terminal derives independent encryption subkeys for each group based on the global SM4 root key, following the GM / T 0005 key derivation function standard. The terminal performs three levels of national cryptographic key lifecycle management: single-terminal key reset, group key update, and global batch key push. Terminals marked as lost or offline timed out have all encrypted identifier transmission and reception messages directly intercepted and discarded at the WiFi hardware level, physically prohibiting access to the internal WiFi network.

[0062] S4. Dual-path switching on the base station only occurs in full-domain mode. The base station does not include any number segment management or national cryptographic calculation functions. The relay base station relies on a dual-path hardware electrical isolation circuit to isolate the base station's internal WiFi path from the mobile WiFi path, forwarding only complete encrypted messages. The terminal pre-marks the group type: if it is a pure internal network local group, the hardware electrical isolation circuit maintains a permanent physical isolation state, and external network messages cannot enter the internal network path; if it is a full-domain mixed group, the software distributes messages to both paths separately, and the hardware isolation structure does not change, enabling cross-network intercom communication between the two types of terminals. The base station automatically switches the internal wireless path based on the preset WiFi signal threshold and the external network idle time. This step is skipped in pure internal network mode.

[0063] S5 and cloud-based SM9 number segment verification are performed only in global mode, and the cloud does not decrypt device identifiers. The field terminal initiates an SM9 identity verification and identifier IP query request to the cloud-based SM9 global number segment resolution server; the exchange message does not contain any plaintext device information. After completing the SM9 verification, the cloud only returns the target terminal's public IP address. The cloud adds a global hybrid group identifier registry to uniformly store encrypted device identifiers for both intranet fixed WiFi terminals and field mobile WiFi terminals. Upon receiving hybrid group intercom messages, the cloud performs batch distribution based on the registry, distributing encrypted messages to both intranet WiFi terminals and mobile WiFi terminals, without decrypting device identifiers or audio / video content throughout the process. The cloud automatically reclaims idle encrypted identifiers that have been offline for a preset duration, with a preferred reclamation period of ninety days. This step is skipped in pure intranet mode.

[0064] S6, Cross-regional group key synchronization, is only performed in global mode. The cloud-based SM9 global number segment resolution server only issues group number segment sub-key update commands. After receiving the commands locally on the terminal, the key replacement and group communication isolation configuration are completed within the SE chip. This step is skipped in pure intranet mode.

[0065] S7 features full-domain national cryptographic key synchronization. Key update ciphertext commands are transmitted to the terminal via WiFi. The terminal's SE chip decrypts and replaces the global root key and group number subkey. The relay base and cloud server only forward commands and do not parse the key and device identifier ciphertext.

[0066] S8. Dual Trusted Evidence Collection: Two types of physical evidence—the terminal fuse hardware root of trust and the SM3 hash of the device identifier bound to the message—can be independently extracted for infringement notarization and tracing. The hardware fuse root evidence is a global hardware root of trust written once at the factory for the WiFi communication module; it cannot be erased or rewritten and serves as physical notarization evidence of the device's uniqueness. The message hash evidence is the SM3 hash value of the device identifier bound to any communication message, serving as on-chain notarization evidence of data flow and identity association. The encrypted audit log within the SE chip serves as supplementary evidence of infringement, recording the entire lifecycle operations of key derivation, cancellation, destruction, and interception. These three types of physical evidence together form a closed loop of triple judicial evidence collection: hardware, data, and logs.

[0067] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A global WiFi intercom system, characterized in that, include: A fixed local area network (AP) and several local communication terminals, wherein the fixed local area network (AP) establishes a two-layer closed local area network and provides an intranet WiFi wireless transmission channel; The local communication terminal independently integrates a WiFi communication module, a main control chip, a national cryptographic security computing unit, a hardware-isolated SE storage unit, a human-computer interaction module, and an audio / video acquisition and playback module. The main control chip is the core of the terminal's local computing, independently completing audio / video encoding and decoding, global device identifier allocation and SM4 encrypted storage, encrypted identifier-MAC address mapping maintenance, underlying MAC unicast hardware filtering, SM4-GCM layered media encryption, SM3 bound device identifier hash verification, point-to-point or group intercom scheduling based on encrypted identifiers, and GM / T0005 standard national cryptographic key derivation and full lifecycle management. The main control chip does not require a relay base or cloud server to provide computing power support when performing all the above functions.

2. The omni-channel WiFi intercom system according to claim 1, characterized in that: The local communication terminal includes at least one of the following: smart bracelet, smartwatch, head-mounted intercom device, handheld walkie-talkie, inspection tablet, and wall-mounted dispatch screen; the local communication terminal is equipped with an audio and video acquisition and playback module and an SE secure storage unit, and the device identifier supports three equivalent input methods: local manual input, QR code scanning input, and radio frequency import.

3. The omni-channel WiFi intercom system according to claim 1, characterized in that: The WiFi communication module has a built-in one-time hardware fuse storage area, which is programmed with a globally unique hardware root of trust identification code at the factory. The hardware root of trust identification code is written once through a physical fuse process, and the physical state is irreversible after the fuse blows. The identification code cannot be read, cleared, or rewritten by software programs or external hardware debugging methods. At the moment the terminal is powered on, the WiFi communication module directly reads the hardware root of trust identification code as the terminal's unique physical identity.

4. The omni-channel WiFi intercom system according to claim 1, characterized in that: The system is configured with two independent operating modes: a pure intranet local mode and a cross-city hybrid group mode. In the pure intranet local mode, the system only includes a fixed LAN AP and a local communication terminal, without the need to deploy a relay base or a cloud server. In the cross-city hybrid group mode, the system adds a portable dual-path WiFi relay base and a cloud-based SM9 full-domain number segment resolution server to the pure intranet local mode.

5. A global WiFi intercom system according to claim 4, characterized in that: The portable dual-path WiFi relay base is an independent hardware unit that only performs Layer 2 forwarding of encrypted messages and switching between dual transmission channels. The portable dual-path WiFi relay base has a built-in base intranet WiFi path, a mobile WiFi path, a relay chip, and a dual-path hardware electrical isolation circuit. The portable dual-path WiFi relay base only fully transmits the encrypted device identifier and audio / video ciphertext output by the terminal, without parsing or tampering with the internal number segments and key ciphertext data of the message.

6. A global WiFi intercom system according to claim 5, characterized in that: The dual-path hardware electrical isolation circuit uses physical electrical isolation devices to achieve a permanent physical separation between the base's internal WiFi path and the mobile WiFi path; the portable dual-path WiFi relay base supports manually turning off the mobile WiFi path and switching to an internal network-only transmission mode; the portable dual-path WiFi relay base has built-in dual-link automatic switching logic, which enables the base's internal WiFi path by default, automatically switches to the mobile WiFi path when the signal strength of the base's internal WiFi path is lower than a preset threshold, and automatically switches back to the base's internal WiFi path when there are no external network interaction messages for a preset duration.

7. An encryption control method applied to a global WiFi intercom system as described in any one of claims 1-6, characterized in that, Includes the following steps: S1. Local trusted synchronization of device identifier and national cryptographic key: When the terminal is powered on, it reads the trusted root of the hardware fuse, supports three equivalent input methods: local manual input, QR code scanning input or radio frequency import, and generates an SM4 encrypted global device identifier. It also maintains a local mapping table of encrypted identifier and MAC address. S2, End-side SM4-GCM layered encryption transmission: After the terminal completes audio segmentation and video I-frame and P-frame independent segmentation locally, it calls the SM4-GCM algorithm for layered encryption, and attaches an SM3 integrity hash check to the message with the device identifier attached; S3. Local group encryption identifier isolation: The terminal derives independent encryption number segment subkeys for each group based on the global SM4 root key. The terminal performs three-level national cryptographic key lifecycle management, including single terminal key reset, group key update, and full-domain batch key push.

8. The encryption control method for a global WiFi intercom system according to claim 7, characterized in that: In step S2, audio data is uniformly segmented into fixed 128-byte segments, and video data is strictly segmented independently, distinguishing between I keyframes and P predicted frames; the initialization vector is generated by the terminal's WiFi hardware true random number generator and transmitted synchronously with the message, and ECB encryption mode is disabled; each data packet embeds a time stamp and two 16-bit CRC-CCITT checksums; a directional unicast message is established based on the MAC address, and the terminal performs the retransmission operation locally when a retransmission is triggered after a preset duration; if the hardware verification result does not match, the abnormal message is directly discarded.

9. The encryption control method for a global WiFi intercom system according to claim 7, characterized in that: In step S3, the key derivation process follows the GM / T0005 key derivation function standard; for terminals that have been marked as lost or have timed out offline, their WiFi hardware layer directly intercepts and discards all encrypted identifier transmission and reception messages, physically prohibiting access to the base station's internal WiFi path; when a terminal is deregistered or reported lost, multiple rounds of overwrite irreversible clearing operations are performed on the SE chip storage to clear all encrypted device identifiers and temporary session keys on the local machine.

10. The encryption control method for a global WiFi intercom system according to claim 7, characterized in that: When the system is running in a global, cross-city hybrid group mode, the method further includes: S4. Dual-path switching of the base station: The relay base relies on the dual-path hardware electrical isolation circuit to isolate the base station's internal network WiFi path and the mobile WiFi path, and only forwards complete encrypted messages; the terminal pre-marks the group type. If it is a pure internal network local group, the hardware electrical isolation circuit maintains a permanent physical isolation state. If it is a global mixed group, the software distributes messages to the two paths respectively. S5, Cloud-based SM9 Number Segment Verification: Field terminals initiate SM9 identity verification and identifier IP query requests to the cloud-based SM9 global number segment resolution server. After completing the SM9 verification, the cloud only returns the public IP address of the target terminal, without decrypting the plaintext identifier of the terminal device throughout the process. The cloud adds a global mixed group identifier registry to uniformly store the encrypted device identifiers of fixed WiFi terminals on the intranet and mobile WiFi terminals in the field. After receiving mixed group intercom messages, encrypted messages are distributed in batches according to the registry.

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