Data transmission method and device and data transmission system

Abstract

The embodiment of the invention provides a data transmission method and device and a data transmission system, and relates to the technical field of network security. The method comprises the following steps: the vehicle-mounted terminal equipment takes a true random number as a random salt of a key derivation function, and performs key regeneration on a key distributed by the ground terminal equipment through the key derivation function, so that the vehicle-mounted terminal equipment and the ground terminal equipment synchronously update a regenerated second key as a new preset key, and encrypted communication is performed. And the key is synchronously updated by encrypting the random salt through the vehicle-mounted terminal equipment and then sending the encrypted random salt to the ground terminal equipment. As the length of the random salt is smaller than or equal to the length of the preset keys, and a third key is selected from the remaining preset keys to encrypt the random salt and then is destroyed immediately, and the ciphertext of the random salt is sent to the ground terminal equipment. Therefore, based on the Shannon perfect safety theorem, the ciphertext of the random salt can achieve perfect confidentiality, and the safety of communication between the rail transit and the ground control center is enhanced.

Description

Technical Field

[0001] The present application relates to the field of network security technology, and in particular, to a data transmission method and device, and a data transmission system. Background Art

[0002] With the rapid development of rail transit, the security of vehicle-to-ground transmission is particularly important. Vehicle-to-ground transmission not only carries the transmission of vehicle control instructions, but also involves the exchange of passenger information and operational data. Its security is directly related to the safety of passengers' lives and property and operational efficiency. Therefore, encryption of vehicle-to-ground transmission has become a necessary means to ensure the safe operation of rail transit systems.

[0003] With the development of communication technology and cracking technology, long-term keys may face the risk of being cracked. Therefore, regular replacement of keys can effectively reduce the possibility of keys being monitored or cracked by analysis for a long time, and enhance the security and reliability of communication systems. Although quantum key distribution technology has absolute security characteristics such as "cannot be eavesdropped, cannot be copied, and cannot be deciphered", its requirement for the fixed positions of the communicating parties limits its application in mobile scenarios. Therefore, due to its particularity and dynamic nature, mobile vehicles cannot directly use quantum key distribution technology for key distribution.

[0004] In the prior art, wireless key distribution is a feasible solution. In a wireless environment, key distribution is usually carried out through a secure network channel to ensure the confidentiality and integrity of the key during transmission. After the key is distributed to the device or application that needs to be filled, the key filling stage begins. Traditional cloud key filling mainly relies on classical encryption algorithms to ensure the security of the key during transmission and storage. However, the emergence of quantum computers poses a serious threat to these classical encryption algorithms. Quantum computers can use their powerful parallel computing capabilities and quantum algorithms to crack existing asymmetric encryption algorithms in polynomial time. In addition, quantum computers can attack symmetric encryption algorithms with square root complexity through the Grover algorithm, which actually reduces the encryption strength by half, which means that a 128-bit symmetric encryption algorithm has only 64-bit security strength in front of a quantum computer. Therefore, with the rapid development of quantum computing technology, traditional cloud key filling faces potential security risks and may not be able to resist quantum computing attacks. Summary of the invention

[0005] In order to solve one of the above-mentioned technical defects, a data transmission method and device, and a data transmission system are provided in the embodiments of the present application.

[0006] According to a first aspect of an embodiment of the present application, a data transmission method is provided, which is applied to a vehicle-mounted terminal device, and the method includes:

[0007] Use pre-set keys to encrypt communications with ground terminal equipment;

[0008] When the usage of the preset keys reaches a set ratio, a target number of first keys are obtained from the ground terminal device;

[0009] Using a true random number as a random salt of a key derivation function, and regenerating the first key through the key derivation function to generate a second key; wherein the length of the random salt is less than or equal to the length of the preset key;

[0010] The preset key is updated by the second key, and a third key is selected from the unused preset key to encrypt the random salt to generate a ciphertext, the third key is deleted, and the ciphertext is sent to the ground terminal device.

[0011] In an optional embodiment of the present application, the step of using the pre-set key to perform encrypted communication with the ground terminal device further includes:

[0012] At set intervals, new unused keys are selected from the preset keys to perform encrypted communication with the ground terminal device, and the old used keys are deleted.

[0013] In an optional embodiment of the present application, when the usage of the preset keys reaches a set ratio, the step of acquiring a target number of first keys from the ground terminal device further includes:

[0014] Sending a key distribution request to a ground terminal device; wherein the key distribution request includes a target number of requested keys;

[0015] After receiving the preparation completion status signal sent by the ground terminal device, sending a request to receive a new key to the ground terminal device;

[0016] Receive a target number of first keys sent by a ground terminal device.

[0017] In an optional embodiment of the present application, the steps of updating the preset key by the second key, selecting a third key from the unused preset key to encrypt the random salt to generate a ciphertext, deleting the third key, and sending the ciphertext to the ground terminal device also include:

[0018] Selecting a third key from the remaining unused preset keys;

[0019] A bitwise XOR operation is performed on the third key and the random salt to generate a ciphertext of the random salt.

[0020] According to a second aspect of an embodiment of the present application, a data transmission method is provided, which is applied to a ground terminal device, and the method includes:

[0021] Use pre-set keys to encrypt communications with vehicle-mounted terminal devices;

[0022] Receiving a key distribution request sent by a vehicle-mounted terminal device, and sending a target number of first keys to the vehicle-mounted terminal device; wherein the key distribution request includes the target number of requested keys;

[0023] Receiving the ciphertext sent by the vehicle terminal device, decrypting the ciphertext using the third key to obtain a random salt, and deleting the third key; wherein the length of the random salt is less than or equal to the length of the preset key;

[0024] The first key is regenerated using a random salt to obtain a second key, and the preset key is updated using the second key.

[0025] In an optional embodiment of the present application, receiving the ciphertext sent by the vehicle-mounted terminal device, decrypting the ciphertext using the third key to obtain the random salt, and deleting the third key further includes:

[0026] A bit-by-bit XOR operation is performed on the ciphertext and the third key to obtain a random salt.

[0027] In an optional embodiment of the present application, the step of using the pre-set key to perform encrypted communication with the vehicle-mounted terminal device further includes:

[0028] At set intervals, new unused keys are selected from the preset keys to perform encrypted communication with the vehicle terminal device, and the old used keys are deleted.

[0029] In an optional embodiment of the present application, the step of receiving a key distribution request sent by the vehicle-mounted terminal device and sending a target number of first keys to the vehicle-mounted terminal device further includes:

[0030] Send the key distribution preparation status to the vehicle terminal device;

[0031] A new key receiving request sent by the vehicle-mounted terminal device is received, and a target number of first keys are sent to the vehicle-mounted terminal device.

[0032] According to a third aspect of an embodiment of the present application, there is provided a data transmission device, comprising a processor and a memory storing program instructions, wherein the processor is configured to execute a data transmission method as described in any one of the first and second aspects of the embodiment of the present application when running the program instructions.

[0033] According to a third aspect of an embodiment of the present application, a data transmission system is provided, including:

[0034] On-board terminal equipment, including main control processing module, train bus module, data encryption module, and wireless communication module;

[0035] A ground terminal device is communicatively connected with the vehicle-mounted terminal device; and

[0036] For example, the data transmission device according to the third aspect of the embodiment of the present application is installed in a vehicle-mounted terminal device and / or a ground terminal device.

[0037] A data transmission method provided in an embodiment of the present application is used for railway vehicle-to-ground transmission key distribution, which has the following beneficial effects:

[0038] The on-board terminal device uses a true random number as the random salt of the key derivation function, and regenerates the key distributed by the ground terminal device through the key derivation function, so that the on-board terminal device and the ground terminal device synchronously update the regenerated second key as the new preset key, thereby performing encrypted communication. Synchronous key update requires the on-board terminal device to encrypt the random salt and send it to the ground terminal device. Since the length of the random salt is less than or equal to the length of the preset key, and the third key is selected from the remaining preset keys to encrypt the random salt and immediately destroy the third key, and send the ciphertext of the random salt to the ground terminal device. Therefore, based on Shannon's perfect security theorem, the ciphertext of the random salt can achieve theoretically perfect confidentiality, enhance the security and reliability of communication between rail transit and the ground control center, and enable the vehicle-to-ground transmission system to resist attacks by quantum computers. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0040] Figure 1 is a schematic diagram of a data transmission system provided in an embodiment of the present application;

[0041] Figure 2 is a schematic diagram of a data transmission method provided in an embodiment of the present application;

[0042] Figure 3 is a schematic diagram of another data transmission method provided in an embodiment of the present application;

[0043] Figure 4 It is a schematic diagram of a data transmission device provided in an embodiment of the present application.

[0044] Reference numerals:

[0045] 100: On-board terminal equipment: 101: Main control processing module; 102: Train bus module; 103: Data encryption module: 104: Wireless communication module: 200: Ground terminal equipment;

[0046] 800: data transmission device; 801: processor; 802: memory; 803: communication interface; 804: bus; 900: data transmission system. DETAILED DESCRIPTION

[0047] In order to make the technical solutions and advantages in the embodiments of the present application more clearly understood, the exemplary embodiments of the present application are further described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than an exhaustive list of all the embodiments. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0048] With the rapid development of rail transit, the security of vehicle-to-ground transmission is particularly important. Vehicle-to-ground transmission not only carries the transmission of vehicle control instructions, but also involves the exchange of passenger information and operational data. Its security is directly related to the safety of passengers' lives and property and operational efficiency. Therefore, encryption of vehicle-to-ground transmission has become a necessary means to ensure the safe operation of rail transit systems.

[0049] Keys need to be updated frequently. With the development of communication technology and cracking technology, keys that have been used for a long time may face the risk of being cracked. Once the keys are leaked, the security of the entire communication system will be seriously threatened. Therefore, regular key replacement can effectively reduce the possibility of keys being cracked by long-term monitoring or analysis, and enhance the security and reliability of the communication system.

[0050] However, due to the particularity and dynamic nature of mobile vehicles, it is not possible to directly use quantum key distribution (QKD) technology for key distribution. Although QKD has absolute security features such as "cannot be eavesdropped, cannot be copied, and cannot be deciphered", its requirement for the fixed positions of both communicating parties limits its application in mobile scenarios. Therefore, how to achieve efficient and secure key distribution in a mobile vehicle environment has become an urgent problem to be solved.

[0051] As a feasible solution, the security and importance of wireless key distribution are self-evident. In the process of wireless key distribution between rail vehicles and ground transmission, network security issues are particularly prominent. First, the wireless channel itself is open, which makes the key extremely vulnerable to external interference and malicious interception during transmission, increasing the risk of key leakage. Secondly, wireless key distribution needs to ensure the integrity and authenticity of the transmission process to prevent attackers from tampering with or forging key information. In addition, with the continuous development of technology, new security threats emerge in an endless stream. How to update the key distribution protocol and encryption algorithm in a timely manner to deal with potential security vulnerabilities and attack methods is also a major challenge facing wireless key distribution. Therefore, when designing and implementing a wireless key distribution system, these factors must be comprehensively considered and a variety of security measures must be taken to ensure the network security of vehicle-to-ground transmission.

[0052] In wireless environments, key distribution is usually carried out through a secure network channel to ensure the confidentiality and integrity of the key during transmission. Commonly used transmission security protocols include Transport Layer Security (TLS) and Internet Protocol Security (IPsec), which can encrypt transmission data and provide authentication to prevent man-in-the-middle attacks. In addition to using an encrypted transmission channel, key distribution also requires strict authentication and authorization management.

[0053] After the key is distributed to the device or application that needs to be injected, the key injection phase begins. The core task of this phase is to securely load the key into the secure storage area of ​​the device or the secure storage module of the application. For hardware devices, such as IoT devices or smart cards, key injection can be completed through remote commands or secure update mechanisms. These devices usually have built-in security modules for storing and processing keys, such as Trusted Platform Module (TPM) chips or dedicated security processors. The key management platform sends key injection commands through an encrypted channel and performs key storage operations on the device side. The entire process requires multi-factor authentication and digital signature verification to ensure the legitimacy of the injection operation and the integrity of the key.

[0054] Traditional cloud key filling mainly relies on classical encryption algorithms to ensure the security of keys during transmission and storage. However, the emergence of quantum computers poses a serious threat to these classical encryption algorithms. Quantum computers can use their powerful parallel computing capabilities and quantum algorithms to crack existing asymmetric encryption algorithms in polynomial time. These keys that originally took billions of years to crack on classical computers only take minutes or even less time in front of quantum computers. In addition, quantum computers can attack symmetric encryption algorithms with square root complexity through the Grover algorithm, which actually halves the encryption strength. This means that a 128-bit symmetric encryption algorithm has only 64-bit security strength in front of a quantum computer. Therefore, with the rapid development of quantum computing technology, traditional cloud key filling faces potential security risks and may not be able to resist quantum computing attacks. New quantum-resistant cryptographic algorithms need to be developed to meet this challenge.

[0055] The embodiment of the present application proposes a cloud key distribution method based on Shannon's perfect security theory, which solves the problem that mobile terminals cannot use proprietary optical fiber networks for key distribution, solves the inconvenience of charging keys through mobile media (manual charging with USB flash drives), and avoids the security issues of eavesdropping, tampering and forgery in wireless open networks. It realizes convenient and fast key distribution of rail vehicle ground transmission systems.

[0056] The present application proposes a data transmission system 900 for implementing the distribution of railway vehicle-to-ground transmission keys. Figure 1 For a schematic diagram of a data transmission system provided in an embodiment of the present application, see Figure 1 :

[0057] The vehicle-mounted terminal device 100, the ground terminal device 200 connected to the vehicle-mounted terminal device 100 for communication, and the processor installed in the vehicle-mounted terminal device 100 and the ground terminal device 200. The vehicle-mounted terminal device 100 includes a main control processing module 101, a train bus module 102, a data encryption module 103 and a wireless communication module 104; wherein the data encryption module 103 includes an encryption algorithm unit, a quantum true random number generator, a quantum true random number generator, a secure storage unit, a main control unit, a read-only memory module, an electrically erasable programmable read-only memory module, a data receiving module and a data sending module. The encryption algorithm unit is used to implement symmetric encryption algorithms (such as AES, DES) and asymmetric encryption algorithms (such as RSA, ECC), etc., to encrypt and decrypt data. The quantum true random number generator is used to generate true random numbers. The quantum true random number generator is used to generate random salts through true random numbers. The secure storage unit is used to securely store the second key, identity authentication information, and encryption certificates. Reading the data in the secure storage unit requires verifying the identity of the visitor through digital certificates, digital signatures, etc., to ensure that only legitimate users or devices can access the data in the storage unit. The main control unit is used to manage the parameters of the encryption algorithm unit and execute the key derivation function. The read-only memory module is used to store fixed data or programs. These contents are written when the device is manufactured and are generally not allowed to be changed during the use of the device. It is used to store the program of the main control unit. The electrically erasable programmable read-only memory module is used to store non-secure user configuration data. The processor is electrically connected to the above-mentioned electrical components and is used to control the above-mentioned electrical components to perform actions.

[0058] Figures 2 to 3 It is a schematic diagram of the data transmission method provided in the embodiment of the present application. Any of the following methods can be executed in the data transmission system, or in a server or terminal device that is connected to the data transmission system. In the embodiment of the present application, the vehicle-mounted terminal device and the ground terminal device of the data transmission system are used as the execution subjects to illustrate the scheme.

[0059] Based on the structure of the above data transmission system, such as Figure 2 As shown, an embodiment of the present application provides a data transmission method for implementing rail vehicle-to-ground transmission key distribution, including:

[0060] S21: The vehicle-mounted terminal device uses the preset key to perform encrypted communication with the ground terminal device.

[0061] S22: When the usage of the preset keys reaches a set ratio, the vehicle-mounted terminal device obtains a target number of first keys from the ground terminal device.

[0062] S23: The vehicle-mounted terminal device uses a true random number as a random salt of a key derivation function, and regenerates the first key through the key derivation function to generate a second key; wherein the length of the random salt is less than or equal to the length of the preset key.

[0063] S24: The vehicle-mounted terminal device updates the preset key through the second key, selects a third key from the unused preset key to encrypt the random salt to generate a ciphertext, deletes the third key, and sends the ciphertext to the ground terminal device.

[0064] In the embodiment of the present application, the same key can be pre-filled into the vehicle-mounted terminal device and the ground terminal device in a secure manner as the initial preset key. The size of the preset key can be any size, such as 10Mbit or 16Mbit. Assuming that the SM4 symmetric encryption algorithm uses a 128-bit (16-byte) key, the preset key has 78125 keys.

[0065] In an embodiment of the present application, the vehicle-mounted terminal device establishes a communication connection with the ground terminal device through a wireless communication module. The wireless communication technology used by the wireless communication module includes Wi-Fi, LTE, 5G, etc., thereby supporting reliable data transmission in a high-speed mobile environment.

[0066] In an embodiment of the present application, the on-board terminal device uses a preset key to perform encrypted communication with the ground terminal device, including: the on-board terminal device collects the train's operating data, such as speed, position, acceleration, equipment status, energy consumption, etc., and encrypts the operating data using a preset key corresponding to the time period of the current time, and finally transmits the encrypted operating data to the ground terminal device through a wireless communication module. After receiving the encrypted operating data, the ground terminal device decrypts the encrypted operating data using the same preset key as the on-board terminal device to obtain the initial operating data, and uses big data analysis and intelligent algorithms to process the initial operating data to obtain the health status of the train. In this way, by evaluating the health status of the train, potential equipment failures or abnormal conditions can be discovered in a timely manner, thereby helping the operation and maintenance team to formulate maintenance plans and strategies in advance and reduce the probability of failure shutdowns and emergencies.

[0067] In the embodiment of the present application, the set ratio can be any ratio, such as 70%, 80% or 90%.

[0068] In an embodiment of the present application, after the vehicle-mounted terminal device has completely received all the first keys, it can generate a 128-bit true random number as a random salt for a key derivation function (such as PBKDF2, scrypt, bcrypt) through an onboard quantum random number generator, and regenerate the key by performing multiple iterations and adding random salts on the first key just received through the selected key derivation function, thereby generating a second key to replace the first key just received, so as to replace the preset key that has been used. At the same time, the vehicle-mounted terminal device and the ground terminal device simultaneously replace the new 128-bit key (generated regularly from the 1024-bit preset key). Specifically, the vehicle-mounted terminal device selects a third key from the preset key to perform bit-by-bit XOR operation on the 128-bit random salt to generate the ciphertext of the random salt, and sends the ciphertext of the random salt to the ground terminal device. The ground terminal device uses the same third key to perform XOR operation on the ciphertext of the random salt to obtain the same random salt, and then uses the random salt to perform the same key regeneration process on the first key just sent, so as to obtain the same second key as the vehicle-mounted terminal device, and replace the used preset key with the second key, and completely delete the 128-bit third key that has just been used once, so as to achieve one-time one-key. In this way, in the entire process of transmitting the random salt, the one-time one-key encryption method of the key with equal bits (128 bits) is adopted, so as to achieve the purpose of high-security encryption, and the updated first key is derived and replaced, so as to achieve high-reliability and high-security distribution of keys in a wireless environment.

[0069] In practical applications, assuming that 60,000 1024-bit first keys need to be replaced, the PBKDF2 function can be used to regenerate the key based on the first secret key and a 128-bit random salt, and a stronger second key can be generated by applying the hash function multiple times. Specifically, the vehicle terminal device can first prepare input parameters, including the first key P, the random salt S, the number of iterations c, and the expected output key length dkLen, and the length of dkLen can be set to 1024 bits. The PBKDF2 function divides the output second key DK into multiple key blocks T i For each key block T i , calculate U1 = HMAC(P, S||INT_32_BE(i)), U2 = HMAC(P, U1)...U c =HMAC(P,U {c-1} ), then the key block T i =U1⊕U2⊕…⊕U c; Where INT_32_BE(i) is the 32-bit big-endian representation of the integer i, and HMAC() is an algorithm that uses a hash function and a key to generate a message authentication code (MAC). HMAC algorithm: HMAC(P, S) = H((P⊕opad)∥H((P⊕ipad)∥S)), P is the first key, S is a random salt, H is the selected hash function (such as SHA-256), ⊕ is a bitwise XOR operation, ∥ represents a concatenation operation, ipad is the inner key padding (repeated from 0x36 to the hash block size), and opad is the outer key padding (repeated from 0x5C to the hash block size). Combine the key blocks, and add all the key blocks T1, T2, ..., T n Combine into a second key DK, and cut off the required length dkLen. Finally, output the regenerated second key DK.

[0070] Using the data transmission method provided in the embodiment of the present application, the on-board terminal device uses a true random number as the random salt of the key derivation function, and regenerates the key distributed by the ground terminal device through the key derivation function, so that the on-board terminal device and the ground terminal device synchronously update the regenerated second key as a new preset key, thereby performing encrypted communication. Synchronous key update requires the on-board terminal device to encrypt the random salt and send it to the ground terminal device. Since the length of the random salt is less than or equal to the length of the preset key, and the third key is immediately destroyed after the random salt is selected from the remaining preset keys to encrypt the random salt, and the ciphertext of the random salt is sent to the ground terminal device. Therefore, based on Shannon's perfect security theorem, the ciphertext of the random salt can achieve theoretically perfect confidentiality, enhance the security and reliability of communication between rail transit and the ground control center, and enable the vehicle-to-ground transmission system to resist attacks by quantum computers.

[0071] Optionally, the vehicle-mounted terminal device uses a preset key to perform encrypted communication with the ground terminal device, including: the vehicle-mounted terminal device selects an unused new key from the preset key at a set interval to perform encrypted communication with the ground terminal device, and deletes the used old key.

[0072] In the embodiment of the present application, the set duration can be any duration, such as 5 minutes or 6 minutes or other durations. Specifically, the set duration is 5 minutes, that is, the key replacement cycle is 5 minutes. After 5 minutes, the vehicle terminal device and the ground terminal device simultaneously replace the new unused preset key for encrypted communication. The preset key can be used for about 652 hours. Assuming that the work day is 10 hours, the key can be used continuously for about 65 days.

[0073] In this way, the vehicle terminal device selects unused new keys from the preset keys at set intervals to perform encrypted communication with the ground terminal device, and deletes the old keys that have been used. Because attackers need to crack the keys within the key replacement cycle, with the development of communication technology and cracking technology, the keys used for a long time may face the risk of being cracked. By regularly replacing the keys, the risk of the keys being monitored or cracked by analysis for a long time can be effectively reduced, significantly improving the security of communications.

[0074] Optionally, the vehicle-mounted terminal device obtains a target number of first keys from a ground terminal device, including: the vehicle-mounted terminal device sends a key distribution request to the ground terminal device; wherein the key distribution request includes the target number of requested keys; after the vehicle-mounted terminal device receives the preparation completion status signal sent by the ground terminal device, the vehicle-mounted terminal device sends a request to receive new keys to the ground terminal device; the vehicle-mounted terminal device receives the target number of first keys sent by the ground terminal device.

[0075] In the embodiment of the present application, when the used preset keys reach 80% of the pre-filled preset keys, the vehicle terminal device sends a key distribution request and the target number of requested keys to the ground terminal device, and the ground terminal device feeds back the key distribution preparation status to the vehicle terminal device. After the vehicle terminal device receives the ready signal sent by the ground terminal device, it sends a new key acceptance request to the ground terminal device, and the ground terminal device sends the target number of first keys to the vehicle terminal device. The vehicle terminal device detects the verification code of each first key in the process of accepting the first key to ensure the accuracy of the accepted first key. Specifically, when the ground terminal device generates the first key, it will generate a verification code corresponding to the first key according to the content of the first key and other possible security parameters (such as timestamp, serial number, etc.) through the algorithm for generating the verification code, and then send each first key and its corresponding verification code to the vehicle terminal device. After receiving the first key and the verification code, the vehicle terminal device will use the same verification code generation algorithm as the ground terminal device to independently calculate the verification code of the received first key, and then compare the independently calculated verification code with the received verification code. If the two are consistent, it means that the first key has not been tampered with during the transmission process and can be considered accurate; if they are inconsistent, it means that the first key may have been tampered with during the transmission process, and the on-board terminal device will reject the first key, record the security event, trigger an alarm to notify the system administrator and / or request the ground terminal device to resend the first key.

[0076] In this way, the vehicle-mounted terminal device sends a key distribution request including the target number of requested keys to the ground terminal device. By making the vehicle-mounted terminal device clearly request the number of keys, it can ensure that the ground terminal device accurately understands the needs of the vehicle-mounted terminal device, thereby preparing the correct number of keys to avoid excessive or insufficient keys. There is no need to frequently request keys, which reduces the number of communications and makes the key distribution process more efficient. Therefore, after the preset key usage reaches the set ratio, a new key can be quickly obtained to maintain the continuity and security of communication. In addition, after the vehicle-mounted terminal device receives the preparation completion status signal sent by the ground terminal device, it sends a request to receive a new key to the ground terminal device. Since the transmission of the key is carried out under the condition of confirming security, by confirming the preparation completion status before key distribution, it can be ensured that the ground terminal device has prepared the key when the key is distributed, reducing the risk of the key being intercepted during the transmission process.

[0077] Optionally, the vehicle-mounted terminal device selects a third key from unused preset keys to encrypt a random salt to generate a ciphertext, including: the vehicle-mounted terminal device selects a third key from the remaining unused preset keys; the vehicle-mounted terminal device performs a bit-by-bit XOR operation on the third key and the random salt to generate a ciphertext of the random salt.

[0078] In practical applications, in order to use Shannon's perfect security theorem, the vehicle terminal device and the ground terminal device can simultaneously select a 128-bit key K from the remaining preset keys. The length of the key K is the same as the 128-bit random salt S to be transmitted, and the key K is only used once. The vehicle terminal uses the key K and the random salt S to perform a bitwise XOR operation to encrypt the message, C = S ⊕ K, where C is the ciphertext of the random salt, and ⊕ represents a bitwise XOR operation. Since the key K is a preset random key, the generated ciphertext C of the random salt is also random and secure. The vehicle terminal device sends the generated ciphertext C to the ground terminal device through the wireless communication module. Since the key K is a preset key and has randomness, and the random salt S is also generated by a true random number, and the key K and the random salt S have the same length, the probability of the ciphertext appearing is equal for any possible plaintext, so any attacker who intercepts the ciphertext C cannot obtain any information about the random salt S from it. Correspondingly, after receiving the ciphertext C, the ground terminal device can use the same key K to decrypt the message and recover the original 128-bit random salt S. The ciphertext C received by the ground terminal device uses the same key K for bitwise XOR operation, S = C ⊕ K. Due to the nature of the XOR operation (A ⊕ A = 0 and A ⊕ 0 = A), the onboard random salt S can be accurately recovered. After successful decryption, in accordance with Shannon's perfect security requirements, the onboard terminal device and the ground terminal device must destroy the used key K to ensure that it is not used again.

[0079] In this way, the vehicle terminal device selects the third key from the remaining unused preset keys, and encrypts the random salt by selecting the third key from the unused preset keys, so as to ensure the randomness of the third key to meet the randomness condition of Shannon's perfect security theorem. In addition, the length of the random salt is less than or equal to the length of the third key, which meets the data length condition of Shannon's perfect security theorem. The third key is only used once, which meets the one-time condition of Shannon's perfect security theorem. Therefore, in the embodiment of the present application, the encrypted transmission of the random salt meets the three conditions of Shannon's perfect security theorem that the key is random, the length is equal to or greater than the length of the message, and it is destroyed immediately after each use (not reused), and the data transmission of the random salt can achieve theoretically perfect confidentiality. Since the random salt is a key component in the key derivation process, its confidentiality is crucial to the security of the entire system. Therefore, the random salt is subjected to bit-by-bit XOR operation using the third key for encryption processing, and the ciphertext of the random salt is generated, which can ensure the safety of the random salt during transmission and prevent potential eavesdropping or tampering.

[0080] Based on the structure of the above data transmission system, such as Figure 3 As shown, an embodiment of the present application provides a data transmission method, including:

[0081] S31: The ground terminal device uses the preset key to perform encrypted communication with the vehicle terminal device.

[0082] S32: The ground terminal device receives the key distribution request sent by the vehicle-mounted terminal device, and sends a target number of first keys to the vehicle-mounted terminal device; wherein the key distribution request includes the target number of requested keys.

[0083] S33: The ground terminal device receives the ciphertext sent by the vehicle terminal device, decrypts the ciphertext using the third key to obtain a random salt, and deletes the third key; wherein the length of the random salt is less than or equal to the length of the preset key.

[0084] S34: The ground terminal device regenerates the first key using a random salt to obtain a second key, and updates the preset key using the second key.

[0085] Using the data transmission method provided in the embodiment of the present application, since the preset keys used by the ground terminal device and the vehicle-mounted terminal device are the same, the ground terminal device can decrypt the received ciphertext through the same third key as the vehicle-mounted terminal device, thereby obtaining a random salt. Then, the first key is regenerated using the same random salt as the vehicle-mounted terminal device to obtain the same second key as the vehicle-mounted terminal device, and the regenerated second key is synchronously updated with the vehicle-mounted terminal device as a new preset key, thereby performing encrypted communication. Since the process of transmitting random salts by the vehicle-mounted terminal device complies with Shannon's perfect security theorem, the ciphertext of the random salt can achieve theoretically perfect confidentiality, enhancing the security and reliability of communication between rail transit and the ground control center, and enabling the vehicle-to-ground transmission system to resist attacks by quantum computers.

[0086] Optionally, the ground terminal device decrypts the ciphertext using a third key to obtain a random salt, including: the ground terminal device performs a bit-by-bit XOR operation on the ciphertext and the third key to obtain the random salt.

[0087] In this way, the ground terminal device uses the third key in the preset key that is the same as the vehicle terminal device and the ciphertext received from the vehicle terminal device to perform a bit-by-bit XOR operation to restore the random salt generated by the vehicle terminal device for regenerating the first key.

[0088] Optionally, the ground terminal device uses a preset key to perform encrypted communication with the vehicle terminal device, including: the ground terminal device selects an unused new key from the preset key at a set interval to perform encrypted communication with the vehicle terminal device, and deletes the used old key.

[0089] In this way, after a specific time interval, the ground terminal device selects an unused new key from the preset key set to perform encrypted communication with the vehicle terminal device, and deletes the old key after the communication is completed. By replacing the key after a set time interval, the risk of the key being monitored or analyzed for a long time is reduced, thereby effectively countering attacks that require long-term data collection to crack the key. In addition, since the old key is deleted after use, this reduces the chance of the key being illegally accessed during storage or transmission.

[0090] Optionally, the ground terminal device sends a target number of first keys to the vehicle-mounted terminal device, including: the ground terminal device sends a key issuance preparation status to the vehicle-mounted terminal device; the ground terminal device receives a new key receiving request sent by the vehicle-mounted terminal device, and sends the target number of first keys to the vehicle-mounted terminal device.

[0091] In this way, by sending the key distribution preparation status, the ground terminal device can ensure that before actually sending the key, the vehicle terminal device is ready to receive the new key, preventing the key from being sent when it is not ready, thereby reducing the risk of the key being intercepted during transmission.

[0092] Further, such as Figure 4 As shown, an embodiment of the present application provides a data transmission device 800, including a processor (processor) 801 and a memory (memory) 802. Optionally, the device may also include a communication interface (Communication Interface) 803 and a bus 804. Among them, the processor 801, the communication interface 803, and the memory 802 can communicate with each other through the bus 804. The communication interface 803 can be used for information transmission. The processor 801 can call the logic instructions in the memory 802 to execute the data transmission method of the above embodiment.

[0093] In addition, the logic instructions in the memory 802 described above may be implemented in the form of software functional units and when sold or used as independent products, may be stored in a computer-readable storage medium.

[0094] The memory 802 is a computer-readable storage medium that can be used to store software programs and computer executable programs, such as program instructions / modules corresponding to the method in the embodiment of the present application. The processor 801 executes the functional application and data processing by running the program instructions / modules stored in the memory 802, that is, implementing the data transmission method in the above embodiment.

[0095] The memory 802 may include a program storage area and a data storage area, wherein the program storage area may store an operating system and an application required for at least one function; the data storage area may store data created according to the use of the terminal device, etc. In addition, the memory 802 may include a high-speed random access memory and may also include a non-volatile memory.

[0096] The embodiment of the present application provides a data transmission system 900, including: a data transmission system body, and the above-mentioned data transmission device 800. The data transmission device 800 is installed in the data transmission system body. The installation relationship described here is not limited to placement inside the data transmission system, but also includes installation connections with other components of the data transmission system, including but not limited to physical connections, electrical connections, or signal transmission connections. It can be understood by those skilled in the art that the data transmission device 800 can be adapted to a feasible data transmission system body, thereby realizing other feasible embodiments.

[0097] An embodiment of the present application provides a computer-readable storage medium storing computer-executable instructions, wherein the computer-executable instructions are configured to execute the above-mentioned data transmission method.

[0098] The technical solution of the embodiment of the present application can be embodied in the form of a software product, which is stored in a storage medium and includes one or more instructions for a computer device (which may be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in the embodiment of the present application. The aforementioned storage medium may be a non-transient storage medium, including: a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, and other media that can store program codes.

[0099] Although the preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0100] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A data transmission method, characterized in that: Applied to vehicle-mounted terminal equipment; the method includes: Use pre-set keys to encrypt communications with ground terminal equipment; When the usage of the preset keys reaches a set ratio, a target number of first keys are obtained from the ground terminal device; Using a true random number as a random salt of a key derivation function, and regenerating the first key through the key derivation function to generate a second key; wherein the length of the random salt is less than or equal to the length of the preset key; The preset key is updated by the second key, and a third key is selected from the unused preset key to encrypt the random salt to generate a ciphertext, the third key is deleted, and the ciphertext is sent to the ground terminal device.

2. The method according to claim 1, characterized in that: The step of using the pre-set key to perform encrypted communication with the ground terminal device also includes: At set intervals, new unused keys are selected from the preset keys to perform encrypted communication with the ground terminal device, and the old used keys are deleted.

3. The method according to claim 1, characterized in that When the usage of the preset keys reaches a set ratio, the step of acquiring a target number of first keys from the ground terminal device also includes: Sending a key distribution request to a ground terminal device; wherein the key distribution request includes a target number of requested keys; After receiving the preparation completion status signal sent by the ground terminal device, sending a request to receive a new key to the ground terminal device; Receive a target number of first keys sent by a ground terminal device.

4. The method according to any one of claims 1 to 3, characterized in that The steps of updating the preset key by the second key, selecting a third key from the unused preset key to encrypt the random salt to generate a ciphertext, deleting the third key, and sending the ciphertext to the ground terminal device also include: Selecting a third key from the remaining unused preset keys; A bitwise XOR operation is performed on the third key and the random salt to generate a ciphertext of the random salt.

5. A data transmission method, characterized in that: Applied to ground terminal equipment; the method includes: Use pre-set keys to encrypt communications with vehicle-mounted terminal devices; Receiving a key distribution request sent by a vehicle-mounted terminal device, and sending a target number of first keys to the vehicle-mounted terminal device; wherein the key distribution request includes the target number of requested keys; Receiving the ciphertext sent by the vehicle-mounted terminal device, decrypting the ciphertext using the third key to obtain a random salt, and deleting the third key; wherein the length of the random salt is less than or equal to the length of the preset key; The first key is regenerated using a random salt to obtain a second key, and the preset key is updated using the second key.

6. The method according to claim 5, characterized in that The step of receiving the ciphertext sent by the vehicle-mounted terminal device, decrypting the ciphertext using the third key to obtain the random salt, and deleting the third key also includes: A bit-by-bit XOR operation is performed on the ciphertext and the third key to obtain a random salt.

7. The method according to claim 5, characterized in that The step of using the pre-set key to perform encrypted communication with the vehicle-mounted terminal device also includes: At set intervals, new unused keys are selected from the preset keys to perform encrypted communication with the vehicle terminal device, and the old used keys are deleted.

8. The method according to any one of claims 5 to 7, characterized in that The step of receiving a key distribution request sent by the vehicle-mounted terminal device and sending a target number of first keys to the vehicle-mounted terminal device also includes: Send the key distribution preparation status to the vehicle terminal device; A new key receiving request sent by the vehicle-mounted terminal device is received, and a target number of first keys are sent to the vehicle-mounted terminal device.

9. A data transmission device, comprising a processor and a memory storing program instructions, characterized in that: The processor is configured to execute the data transmission method according to any one of claims 1 to 8 when running the program instructions.

10. A data transmission system, characterized in that: include: On-board terminal equipment, including main control processing module, train bus module, data encryption module, and wireless communication module; A ground terminal device is communicatively connected with the vehicle-mounted terminal device; and The data transmission device as described in claim 9 is installed in a vehicle-mounted terminal device and / or a ground terminal device.

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