Safe starting method and system for control chip of low-voltage power distribution system

Abstract

The invention provides a safe starting method and system for a control chip of a low-voltage power distribution system, and the method comprises the steps: generating a root key based on a random number generator and a PUF technology when the control chip is started; constructing a first trust chain taking the root key as a trust root according to the root key; based on the first trust chain, activating a security bootstrap program of the control chip, and updating the first trust chain based on the security bootstrap program to obtain a corresponding second trust chain; based on the second trust chain, using the security bootstrap program to perform starting and security verification on an operating system of the control chip, and updating the second trust chain based on the operating system to obtain a third trust chain; and based on the third trust chain, starting and security verification are carried out on each application program in the control chip by using the security bootstrap program, so that the security starting of the control chip is completed, and the starting security of the control chip is improved.

Description

Technical Field

[0001] The present application relates to the field of chip safety technology, and in particular to a safe startup method and system for a control chip of a low-voltage power distribution system. Background Art

[0002] The low-voltage distribution system refers to the distribution system that transmits electric energy from the power system to various loads. It is mainly composed of distribution substations (reducing the transmission voltage of the power grid to distribution voltage), high-voltage distribution lines (voltage above 1 kV), distribution transformers, low-voltage distribution lines (voltage below 1 kV) and corresponding control and protection equipment. As an important part of the smart grid, the low-voltage distribution system is directly related to the stability and safety of power supply, and its intelligent upgrade is particularly urgent. The control chip used in the low-voltage distribution system is usually a low-voltage distribution lightweight control chip. The low-voltage distribution lightweight control chip is a chip that integrates multiple functions into one. It can realize intelligent control, monitoring and protection of power equipment in the low-voltage distribution system. This control chip usually has a small size and power consumption, and can meet the requirements of the low-voltage distribution system for control accuracy and reliability.

[0003] In terms of secure startup of control chips, compared with most of the current chip secure startup based on TEE technology, these are control chips that are not specifically used for low-voltage power distribution systems. Some of the hardware and software and the calculation process are relatively complex, which is not practical for the above chips. Therefore, more optimization should be done in terms of chip area, cost, computing power, speed, and compatibility. How to start more safely based on low-voltage power distribution chips has become the primary issue for the intelligentization of low-voltage power distribution systems. Summary of the invention

[0004] In response to the above technical problems, the present application provides a safe startup method and system for a control chip of a low-voltage power distribution system to improve the safety of startup of the control chip.

[0005] In a first aspect, an embodiment of the present application provides a safe startup method for a control chip of a low-voltage power distribution system, comprising:

[0006] When the control chip starts, a root key is generated based on the random number generator and PUF technology;

[0007] According to the root key, construct a first trust chain with the root key as a trust root;

[0008] Based on the first trust chain, activating the secure boot program of the control chip, and updating the first trust chain based on the secure boot program to obtain a corresponding second trust chain;

[0009] Based on the second trust chain, use the secure boot program to start and securely verify the operating system of the control chip, and update the second trust chain based on the operating system to obtain a third trust chain;

[0010] Based on the third trust chain, the secure boot program is used to start and securely verify each application in the control chip, thereby completing the secure startup of the control chip.

[0011] The embodiment of the present application provides a secure boot method for a control chip of a low-voltage power distribution system. The method adopts a hierarchical trust chain startup by building a trust chain, so that the security measures of each layer cooperate with each other. Each layer updates the trust chain after completing its own security verification, and then passes the security status to the next layer, forming a coherent security protection system to improve the security and reliability of the chip. In the process of building the trust chain, the root key, as the starting evidence of the trust chain, participates in the construction of this starting trust foundation, provides a hardware-level identity for subsequent verification, is the source of the trust chain of the entire secure boot process, and determines the overall security of the trust chain. Therefore, the embodiment of the present application combines a random number generator and PUF technology to generate a root key, which ensures the security and non-replicability of the root key and further improves the security of the control chip during startup.

[0012] In a possible implementation, the generating of the root key based on the random number generator and the PUF technology includes:

[0013] Generate a first random number sequence of a preset length using the PUF technology;

[0014] Generate a second random number sequence with the same length as the first random number sequence using the random number generator;

[0015] Based on a preset fusion algorithm, the first random number sequence and the second random number sequence are fused to obtain the root key.

[0016] Furthermore, the fusing the first random number sequence with the second random number sequence based on a preset fusion algorithm to obtain the root key includes:

[0017] Performing an XOR operation on the first random number sequence and the second random number sequence to obtain an initial fusion sequence, wherein the length of the initial fusion sequence is twice the preset length;

[0018] Performing several hash iterations on the initial fusion sequence using a KDF algorithm to obtain the root key;

[0019] The root key is stored in an encrypted non-volatile memory of the control chip.

[0020] The embodiment of the present application provides a method for generating a root key, which cleverly combines PUF technology with a random number generator. Since the output of PUF is chip-specific, unique and non-replicable, PUF is bound to hardware security parameters in a trusted execution environment: the unique identifier generated by PUF is bound and stored with some key hardware security parameters. In this way, once the PUF is tampered with or forged, the hardware security parameters bound to it will also become invalid, thereby ensuring the security at the hardware level. During the chip manufacturing process, the unique identifier generated by the PUF is associated and stored with the initial key expansion parameters of the hardware encryption engine. When the chip is started, the trust chain management module in the TEE will simultaneously verify the consistency of the PUF identifier and the parameters of the hardware encryption engine to ensure that the hardware encryption engine runs under the correct security parameters from the beginning. Therefore, the embodiment of the present application combines the random number sequence generated by the PUF with the sequence generated by the random number generator to improve the confidentiality of the root key. For example, if the PUF outputs a 256-bit binary sequence, 128 bits of it can be selected as the seed of the HRNG (random number generator). This ensures that the initial states of HRNG on different chips are different, thus laying the foundation for generating different random number sequences. Furthermore, in the process of merging random number sequences, the embodiment of the present application does not simply merge, but uses an XOR operation to generate an initial fusion sequence, and then uses the KDF algorithm to perform several hash iterations on the initial fusion sequence to obtain a root key. This setting makes it difficult for an attacker to forge the same root key, thereby improving the security of the control chip startup process.

[0021] In a possible implementation, activating the secure boot program of the control chip based on the first trust chain, and updating the first trust chain based on the secure boot program to obtain the corresponding second trust chain includes:

[0022] According to the root key in the first trust chain, the national secret SM3 algorithm is used to statically measure the operating environment of the control chip;

[0023] When the static measurement is passed, performing hash encryption calculation on each preset reference value in the control chip according to the root key to obtain corresponding encrypted reference values, and adding each encrypted reference value to the first trust chain;

[0024] Based on the first trust chain, verify the integrity of the secure boot program;

[0025] When the integrity verification passes, the secure boot program is activated, and the secure boot program is added to the first trust chain, and the second trust chain is updated.

[0026] Further, the performing integrity verification on the secure boot program based on the first trust chain includes:

[0027] Using the root key to perform hash encryption calculation on each code segment of the secure boot to obtain a corresponding hash value of each code segment;

[0028] Compare and verify the hash value of each code segment with the corresponding encrypted reference values ​​in the first trust chain;

[0029] The integrity of the secure boot program is determined based on the result of the comparison and verification.

[0030] In the embodiment of the present application, the secure boot program is activated by static measurement and integrity verification. Static measurement technology usually involves pre-configuration, startup detection, verification and decision-making stages in the chip security startup process. Under static measurement, the secure boot process will record the results of all verification steps, but will not dynamically monitor or intervene in the system. These measurement results can be used for subsequent security audits or troubleshooting. The secure boot boot program plays a vital role in the secure startup of the chip. Therefore, after completing the static measurement, the secure boot boot program itself must be verified for integrity to ensure the integrity and security of the secure boot boot program. At the same time, the verification process is carried out under a trust system built based on the root key generated by the chip hardware security, realizing the transfer from hardware trust to boot program trust, and completing the construction of the trust chain while verifying. Even if the subsequent startup is interrupted due to security issues, the risk position can be quickly located through the trust chain to ensure the security and startup efficiency of the control chip startup process.

[0031] In a possible implementation, the starting and security verification of the operating system of the control chip using the secure boot program based on the second trust chain includes:

[0032] Use the secure boot program to load the operating system into the memory and start it;

[0033] When the operating system is started, the root key is used to perform hash encryption calculation on the data at the preset location of the operating system to obtain corresponding encrypted hash values;

[0034] Comparing and verifying each of the encrypted hash values ​​with a number of corresponding encrypted reference values ​​in the second trust chain;

[0035] Determining whether the security verification of the operating system has passed according to the comparison verification results of each of the encrypted reference values;

[0036] When the security verification passes, the operating system is added to the second trust chain, and the third trust chain is updated.

[0037] Further, based on the third trust chain, using the secure boot program to start and securely verify each application in the control chip includes:

[0038] Using the secure boot program, sequentially loading each application into the memory based on a preset order;

[0039] When any first application is loaded into the memory, digital signature verification and integrity verification are performed on the first application based on the third trust chain, wherein the verification public key used in the digital signature verification is obtained by encrypting the program public key of the first application using the root key, and the program public key is a public key provided by the publisher of the first application;

[0040] If the digital signature verification or integrity verification of the first application fails, the first application is refused to be started.

[0041] In the embodiment of the present application, the secure boot program starts the operating system and each application program based on the preset trust chain. Among them, the security verification of the operating system is mainly based on the root key to perform encrypted hash calculation on the key data of the operating system itself (such as the important part of the operating system kernel, key configuration information), generate each encrypted hash value and compare and verify with the preset several encrypted reference values ​​to ensure the security of the operating system. When the operating system runs stably, the application program starts to be loaded. Since the publishers of different applications are not the same, it is necessary not only to verify the integrity of the application program, but also to verify the digital signature to ensure that the currently started application program is a legitimate application program published by the publisher rather than a program forged by the attacker, thereby improving the security of the control chip startup process. At the same time, in the digital signature verification process, the embodiment of the present application uses the root key to encrypt and save the program public key provided by the publisher to ensure the security and authenticity of the public key. In this way, when verifying the legitimacy and integrity of the application program, the whole process is carried out in a secure environment protected by the root key, ensuring that the application program comes from a legitimate source and has not been tampered with during transmission and storage, and completing the transfer of the trust chain to the application layer.

[0042] In a possible implementation, after the root key is generated based on the random number generator and the PUF technology, the root key is divided into a plurality of root key fragments, and each of the root key fragments is stored in a different security area of ​​the chip.

[0043] In the embodiment of the present application, the security of the control chip is further enhanced in the storage link of the root key, and the root key is divided into multiple fragments, which are stored in different security areas of the chip and protected by special encryption algorithms and access control mechanisms. In this way, even if an attacker breaks through a certain storage area, he cannot obtain the complete root key, which greatly improves the security of the root key and further improves the security of the control chip startup.

[0044] In a possible implementation, when the control chip is started, the voltage data of the input power supply is continuously monitored, and the real-time voltage of the input power supply is controlled within a preset voltage range by means of voltage boost, voltage reduction or voltage stabilization control;

[0045] When the voltage data exceeds a preset threshold, an alarm is triggered and the startup process of the control chip is stopped.

[0046] In the embodiment of the present application, the safety of the control chip startup is improved through the design at the hardware level. Specifically, when the control chip is started, the change of the main power supply voltage is monitored in real time. When the main power supply voltage fluctuates under low voltage, the output voltage is adjusted quickly, and the power supply voltage is stabilized within the range required for the chip to start safely by means of boost, buck or voltage stabilization control. At the same time, the input power supply is monitored and the voltage threshold is set. Once it exceeds the range, an alarm is issued in time or protective measures are taken, such as using a voltage monitoring device to monitor the input voltage in real time. When the voltage is abnormal, an alarm is triggered and the chip startup process is stopped to avoid damage to the chip when it is started under unstable voltage.

[0047] In a second aspect, accordingly, an embodiment of the present application provides a secure boot system for a control chip of a low-voltage power distribution system, including a root key generation module, a trust chain construction module, a boot program activation module, an operating system startup module, and an application startup module;

[0048] The root key generation module is used to generate a root key based on a random number generator and PUF technology when the control chip is started;

[0049] The trust chain construction module is used to construct a first trust chain with the root key as the trust root according to the root key;

[0050] The boot program activation module is used to activate the secure boot program of the control chip based on the first trust chain, and update the first trust chain based on the secure boot program to obtain a corresponding second trust chain;

[0051] The operating system startup module is used to start and securely verify the operating system of the control chip based on the second trust chain using the secure boot program, and update the second trust chain based on the operating system to obtain a third trust chain;

[0052] The application startup module is used to start and securely verify each application in the control chip based on the third trust chain using the secure boot program, thereby completing the secure startup of the control chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 : A flow chart of a safe startup method for a control chip of a low-voltage power distribution system provided in an embodiment of the present application.

[0054] Figure 2 : A schematic diagram of the trust chain structure of a secure startup method for a control chip of a low-voltage power distribution system provided in an embodiment of the present application.

[0055] Figure 3 : A schematic diagram of a digital signature process for a secure startup method of a control chip for a low-voltage power distribution system provided in an embodiment of the present application.

[0056] Figure 4 : A schematic diagram of the digital signature verification process for a secure startup method of a control chip for a low-voltage power distribution system provided in an embodiment of the present application.

[0057] Figure 5 : A schematic diagram of the voltage management process during chip startup of a safe startup method for a control chip of a low-voltage power distribution system provided in an embodiment of the present application.

[0058] Figure 6 : A schematic diagram of the voltage management process when the chip is continuously running in a safe startup method for a control chip of a low-voltage power distribution system provided in an embodiment of the present application.

[0059] Figure 7 : A structural schematic diagram of a safe startup system for a control chip of a low-voltage power distribution system provided in an embodiment of the present application. DETAILED DESCRIPTION

[0060] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0061] It should be noted that the step numbers in the text are only for the convenience of explanation of the specific embodiments and do not serve to limit the order in which the steps are executed. In the description of this application, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features.

[0062] Throughout the specification, the low-voltage distribution system described in this specification is a distribution system with a voltage of 1kV and below, a current usually not exceeding 1000A, and a rated frequency of 50Hz. The main function of the system is to transmit electrical energy from the power system to various loads. In practical applications, the low-voltage distribution system may include components such as distribution substations, high-voltage distribution lines, distribution transformers, low-voltage distribution lines, and corresponding control and protection equipment. These devices and components work together to ensure that electrical energy can be transmitted to various loads stably and reliably. The control chip described in this specification integrates a PUF circuit, which can generate a unique identifier and key based on the physical characteristics of the chip. PUF technology is non-clonable, and even if an attacker obtains the physical structure of the chip, it is difficult to copy the same key. This ensures that the data of the control chip is difficult to be obtained externally, and even if it is obtained, the correct key cannot be found to access the data.

[0063] Embodiment 1:

[0064] like Figure 1 As shown, embodiment 1 provides a safe startup method for a control chip of a low-voltage power distribution system, including steps S1-S5:

[0065] Step S1: When the control chip starts, a root key is generated based on a random number generator and PUF technology;

[0066] Step S2: constructing a first trust chain with the root key as a trust root according to the root key;

[0067] Step S3: based on the first trust chain, activating the secure boot program of the control chip, and updating the first trust chain based on the secure boot program to obtain a corresponding second trust chain;

[0068] Step S4: Based on the second trust chain, use the secure boot program to start and securely verify the operating system of the control chip, and update the second trust chain based on the operating system to obtain a third trust chain;

[0069] Step S5: Based on the third trust chain, use the secure boot program to start and securely verify each application in the control chip, thereby completing the secure startup of the control chip.

[0070] The embodiment of the present application provides a secure boot method for a control chip of a low-voltage power distribution system. The method adopts a hierarchical trust chain startup by building a trust chain, so that the security measures of each layer cooperate with each other. Each layer updates the trust chain after completing its own security verification, and then passes the security status to the next layer, forming a coherent security protection system to improve the security and reliability of the chip. In the process of building the trust chain, the root key, as the starting evidence of the trust chain, participates in the construction of this starting trust foundation, provides a hardware-level identity for subsequent verification, is the source of the trust chain of the entire secure boot process, and determines the overall security of the trust chain. Therefore, the embodiment of the present application combines a random number generator and PUF technology to generate a root key, which ensures the security and non-replicability of the root key and further improves the security of the control chip during startup.

[0071] In a preferred embodiment, Figure 2 As shown, the control chip in the embodiment of the present application is started by a layered trust chain, and the security measures of each layer cooperate with each other. After completing its own security verification, each layer generates a security token. When proceeding to the next layer, it first verifies the validity of the security token, and then passes the security status to the next layer, forming a coherent security protection system to improve the security and reliability of the chip. If the security verification of a certain layer fails, the chip should take corresponding exception handling measures. At the same time, in order to prevent the spread of security issues, the chip has a rollback mechanism that can restore the system to the previous security state.

[0072] In a possible implementation, in step S1, generating a root key based on a random number generator and PUF technology includes:

[0073] Generate a first random number sequence of a preset length using the PUF technology;

[0074] Generate a second random number sequence with the same length as the first random number sequence using the random number generator;

[0075] Based on a preset fusion algorithm, the first random number sequence and the second random number sequence are fused to obtain the root key.

[0076] Furthermore, the fusing the first random number sequence with the second random number sequence based on a preset fusion algorithm to obtain the root key includes:

[0077] Performing an XOR operation on the first random number sequence and the second random number sequence to obtain an initial fusion sequence, wherein the length of the initial fusion sequence is twice the preset length;

[0078] Performing several hash iterations on the initial fusion sequence using a KDF algorithm to obtain the root key;

[0079] The root key is stored in an encrypted non-volatile memory of the control chip.

[0080] The embodiment of the present application provides a method for generating a root key, which cleverly combines PUF technology with a random number generator. Since the output of PUF is chip-specific, unique and non-replicable, PUF is bound to hardware security parameters in a trusted execution environment: the unique identifier generated by PUF is bound and stored with some key hardware security parameters. In this way, once the PUF is tampered with or forged, the hardware security parameters bound to it will also become invalid, thereby ensuring the security at the hardware level. During the chip manufacturing process, the unique identifier generated by the PUF is associated and stored with the initial key expansion parameters of the hardware encryption engine. When the chip is started, the trust chain management module in the TEE will simultaneously verify the consistency of the PUF identifier and the parameters of the hardware encryption engine to ensure that the hardware encryption engine runs under the correct security parameters from the beginning. Therefore, the embodiment of the present application combines the random number sequence generated by the PUF with the sequence generated by the random number generator to improve the confidentiality of the root key. For example, if the PUF outputs a 256-bit binary sequence, 128 bits of it can be selected as the seed of the HRNG (random number generator). This ensures that the initial states of HRNG on different chips are different, thus laying the foundation for generating different random number sequences. Furthermore, in the process of merging random number sequences, the embodiment of the present application does not simply merge, but uses an XOR operation to generate an initial fusion sequence, and then uses the KDF algorithm to perform several hash iterations on the initial fusion sequence to obtain a root key. This setting makes it difficult for an attacker to forge the same root key, thereby improving the security of the control chip startup process.

[0081] In a preferred embodiment, the specific process of step S1 is as follows: after the control chip is powered on, a self-check at the hardware level is first performed to check whether key hardware modules such as the processor core, memory, and communication interface are working properly and whether there are any faults or damage. If a problem is found in the self-check, the chip can stop starting or enter a fault handling mode, such as flashing a specific indicator light or outputting an error code to prompt the fault information. The hardware encryption acceleration unit performs self-check and initialization to ensure that it can work properly. At the same time, the hardware isolation mechanism is tested to ensure that the isolation between the TEE area and the non-trusted area is intact. Then, the trust chain management module in the TEE first activates the PUF, reads the unique identifier generated by the PUF, and stores it in the secure area of ​​the TEE. At the same time, the random number generator starts working, and the random number is also stored in the secure area of ​​the TEE as a seed for subsequent key generation and encryption operations. Subsequently, according to the PUF identifier and the random number generated by the HRNG, the key management module is called to use a specific algorithm to generate the initial trust chain root key. The unique identification information generated by the PUF based on the physical characteristics of the chip and the initial random number generated by the HRNG are stored as the starting evidence of the trust chain in a secure area accessible to the TEE. The root key participates in building this initial trust foundation, provides hardware-level identity for subsequent verification, and is the source of the trust chain of the entire secure boot process. After the power-on hardware self-test is completed, the hardware initialization operation is performed first, such as the setting of the reset circuit, the configuration of the clock, and other basic hardware initialization. After these operations are completed, the key verification phase begins. Load the encrypted key from the secure storage area. Use the national secret SM3 algorithm in TEE to decrypt the encrypted key. After decryption, the decrypted hash value is compared and verified with the pre-stored hash value to ensure the correctness and legitimacy of the key. Only verified keys can be used for subsequent chip operation and security operations. Among them, the specific process of PUF and HRNG jointly generating the root key is as follows:

[0082] A portion of the binary sequence generated by the PUF is used as the initialization seed for the HRNG. Since the output of the PUF is chip-specific, this approach makes the startup of the HRNG chip-unique. For example, if the PUF outputs a 256-bit binary sequence, 128 bits of it can be selected as the seed for the HRNG. This ensures that the initial state of the HRNG on different chips is different, laying the foundation for generating different random number sequences. After the seed is injected, the HRNG starts working and goes through a certain number of internal state transitions, a process called the warm-up phase. During the warm-up phase, the physical random source inside the HRNG (such as thermal noise, avalanche noise, etc.) begins to perturb the initial seed, causing the HRNG to gradually enter a stable random number generation state. The purpose of this phase is to eliminate any potential regularity that may be brought about by the seed and ensure that the generated random numbers are highly random. Finally, the sequences generated by the PUF and HRNG are spliced ​​or fused through a specific algorithm, and the PUF and HRNG can be XORed to obtain an intermediate result. This intermediate result is then further processed by the key derivation function (KDF) to increase the entropy value and security of the key. Finally, a unique hardware root key is output, which is recorded as Hardware_Root_Key. The generated root key and other keys are hashed by the national secret SM3 algorithm, and the hash values ​​are stored in a secure storage area. In a specific chip design, the PUF module generates a 128-bit binary sequence PUF = [10110011...11010100] based on the difference in transistor threshold voltage. The HRNG module generates a random number sequence HRNG = [01101100...01101011] of the same length. The key generation logic module first performs an XOR operation on PUF and HRNG to obtain an intermediate result = [11011111...10111111]. Then, the intermediate result is processed using KDF. Assuming that KDF is an algorithm based on a hash function, after multiple hash iterations, a 256-bit hardware root key Hardware_Root_Key = [10101101...01011010] is output. Finally, the control logic module stores the Hardware_Root_Key in the chip's encrypted non-volatile memory. Only during a specific secure boot process, after strict authentication and authorization, can this hardware root key be accessed for secure boot and encryption operations of the chip.

[0083] In a possible implementation, in step S3, activating the secure boot program of the control chip based on the first trust chain, and updating the first trust chain based on the secure boot program to obtain the corresponding second trust chain includes:

[0084] According to the root key in the first trust chain, the national secret SM3 algorithm is used to statically measure the operating environment of the control chip;

[0085] When the static measurement is passed, performing hash encryption calculation on each preset reference value in the control chip according to the root key to obtain corresponding encrypted reference values, and adding each encrypted reference value to the first trust chain;

[0086] Based on the first trust chain, verify the integrity of the secure boot program;

[0087] When the integrity verification passes, the secure boot program is activated, and the secure boot program is added to the first trust chain, and the second trust chain is updated.

[0088] Further, the performing integrity verification on the secure boot program based on the first trust chain includes:

[0089] Using the root key to perform hash encryption calculation on each code segment of the secure boot to obtain a corresponding hash value of each code segment;

[0090] Compare and verify the hash value of each code segment with the corresponding encrypted reference values ​​in the first trust chain;

[0091] The integrity of the secure boot program is determined based on the result of the comparison and verification.

[0092] In the embodiment of the present application, the secure boot program is activated by static measurement and integrity verification. Static measurement technology usually involves pre-configuration, startup detection, verification and decision-making stages in the chip security startup process. Under static measurement, the secure boot process will record the results of all verification steps, but will not dynamically monitor or intervene in the system. These measurement results can be used for subsequent security audits or troubleshooting. The secure boot boot program plays a vital role in the secure startup of the chip. Therefore, after completing the static measurement, the secure boot boot program itself must be verified for integrity to ensure the integrity and security of the secure boot boot program. At the same time, the verification process is carried out under a trust system built based on the root key generated by the chip hardware security, realizing the transfer from hardware trust to boot program trust, and completing the construction of the trust chain while verifying. Even if the subsequent startup is interrupted due to security issues, the risk position can be quickly located through the trust chain to ensure the security and startup efficiency of the control chip startup process.

[0093] In a preferred embodiment, before the boot program is securely started, we use static measurement and the national secret SM3 algorithm to measure its image when the operating environment is initially installed or restarted. Static measurement technology usually involves pre-configuration, startup detection, verification and decision-making stages in the chip security startup process. Under static measurement, the secure startup process will record the results of all verification steps, but will not dynamically monitor or intervene in the system. These measurement results can be used for subsequent security audits or troubleshooting. The results of static measurement are stored in the secure area of ​​​​the TEE for easy call during subsequent comparison. The pre-configuration is to set a series of security reference values ​​for the chip. These reference values ​​​​may include the hash value of the firmware, the expected values ​​​​of key configuration parameters, etc. First, the root key is used to encrypt the key data of the operating system to ensure the confidentiality of these data during the storage process, and then the SM3 hash calculation is performed. The final result is a hash value based on the root key, which not only contains the integrity information of the key data of the operating system, but also carries the security and chip association provided by the root key. In this way, the bootloader code is statically measured. The results of static measurement are stored in the secure area of ​​​​the TEE for easy call during subsequent comparison.

[0094] When the static measurement is passed, the secure boot boot program will first verify its own integrity. The root key indirectly participates in the verification process of the Bootloader code integrity. During the execution of the Bootloader, the trust chain management module in the TEE reads the Bootloader code segment in real time through the hardware interface and calculates its hash value. At the same time, the trusted hash value of the pre-stored version of the Bootloader is read from the secure area for comparison. If the hash value matches, the Bootloader continues to execute; if the hash value does not match, the trust chain management module immediately triggers a security interrupt, stops the execution of the Bootloader, and records the security event log, preparing for subsequent troubleshooting and repair work. Ensure that the verification process is carried out under the trust system built based on the root key generated by the chip hardware security, thereby ensuring the security of the Bootloader and realizing the transfer of trust from hardware trust to boot program trust. In the TEE environment, starting from the root of trust, the security and integrity of the entire trust chain are ensured. The trusted root of TEE is the cornerstone of the TEE security architecture. It is a component that can provide an initial trust point to ensure the security and reliability of the entire TEE environment. From the moment the chip is powered on, the root of trust starts and establishes a secure foundation to prevent malware or attackers from interfering or tampering with the system at the early stage of startup. In the secure boot program, after the first-level image is successfully started, it will be responsible for loading and starting the next-level image, usually the operating system kernel image. It will provide the necessary hardware and software environment for the loading of the next-level image, such as initializing the memory management unit, so that the next-level image can be correctly loaded into the appropriate location in the memory. At the same time, it may pass some startup parameters to the next-level image to ensure the smooth progress of the subsequent startup process. Since the operating system may require multiple levels of startup images when starting, as long as any of the images does not execute the secureboot process, all subsequent images are actually untrusted. Therefore, in the startup process, each level of the image is verified for legitimacy by its previous image, thus forming a whole chain of trust. If the signature verification fails, the startup process is blocked to ensure that unauthorized software will not be executed. A whole chain of trust is formed through level-by-level verification and level-by-level measurement.

[0095] In a possible implementation, in step S4, based on the second trust chain, using the secure boot program to start and securely verify the operating system of the control chip includes:

[0096] Using the secure boot program to load the operating system into the memory for startup;

[0097] When the operating system is started, the root key is used to perform hash encryption calculation on the data at the preset location of the operating system to obtain corresponding encrypted hash values;

[0098] Comparing and verifying each of the encrypted hash values ​​with a number of corresponding encrypted reference values ​​in the second trust chain;

[0099] Determining whether the security verification of the operating system has passed according to the comparison verification results of each of the encrypted reference values;

[0100] When the security verification passes, the operating system is added to the second trust chain, and the third trust chain is updated.

[0101] Further, based on the third trust chain, using the secure boot program to start and securely verify each application in the control chip includes:

[0102] Using the secure boot program, sequentially loading each application into the memory based on a preset order;

[0103] When any first application is loaded into the memory, digital signature verification and integrity verification are performed on the first application based on the third trust chain, wherein the verification public key used in the digital signature verification is obtained by encrypting the program public key of the first application using the root key, and the program public key is a public key provided by the publisher of the first application;

[0104] If the digital signature verification or integrity verification of the first application fails, the first application is refused to be started.

[0105] In the embodiment of the present application, the secure boot program starts the operating system and each application program based on the preset trust chain. Among them, the security verification of the operating system is mainly based on the root key to perform encrypted hash calculation on the key data of the operating system itself (such as the important part of the operating system kernel, key configuration information), generate each encrypted hash value and compare and verify with the preset several encrypted reference values ​​to ensure the security of the operating system. When the operating system runs stably, the application program starts to be loaded. Since the publishers of different applications are not the same, it is necessary not only to verify the integrity of the application program, but also to verify the digital signature to ensure that the currently started application program is a legitimate application program published by the publisher rather than a program forged by the attacker, thereby improving the security of the control chip startup process. At the same time, in the digital signature verification process, the embodiment of the present application uses the root key to encrypt and save the program public key provided by the publisher to ensure the security and authenticity of the public key. In this way, when verifying the legitimacy and integrity of the application program, the whole process is carried out in a secure environment protected by the root key, ensuring that the application program comes from a legitimate source and has not been tampered with during transmission and storage, and completing the transfer of the trust chain to the application layer.

[0106] In a preferred embodiment, the startup and verification process of the operating system and application is as follows: the bootloader loads the operating system into the memory and starts the operating system. After the operating system is started, the trust chain management module in the TEE requires the operating system to perform self-authentication. The operating system uses the root key to perform encrypted hash calculations on its own key data (such as important parts of the operating system kernel and key configuration information) through the hardware encryption engine to generate a hash value. The trust chain management module obtains the pre-stored trusted hash value of the operating system from the secure area of ​​the TEE, and compares the calculated hash value with the trusted hash value. If the hash values ​​match, the operating system continues to run; if the hash values ​​do not match, the trust chain management module triggers a security exception, stops the operating system from running, and starts a secure recovery process, such as trying to start from a backup operating system or enter safe mode for fault diagnosis.

[0107] When the operating system runs stably, the application starts to load. Before the application is loaded, the trust chain management module in the TEE requires the application to perform digital signature verification and integrity verification. The digital signature verification is: after obtaining the digital signature information of the application, the trust chain management module performs signature verification with the public key of the application developer obtained in advance. The root key can be used to encrypt and store these public keys to ensure the security and authenticity of the public keys. In this way, when verifying the legitimacy and integrity of the application, the entire process is carried out in a secure environment protected by the root key, ensuring that the application comes from a legitimate source and has not been tampered with during transmission and storage, completing the transfer of the trust chain to the application layer. The application uses the hardware encryption engine to sign itself using a partial key shared with the operating system, and the trust chain management module uses the public key of the application developer pre-stored in the TEE to verify the signature. The integrity verification is: encrypting the hash calculation of the application code and comparing it with the trusted hash value pre-stored in the TEE. If the signature verification passes and the hash value matches, the application is loaded and run; if the signature verification fails or the hash value does not match, the application is refused to load, and the security event is recorded and the administrator is notified for processing.

[0108] Among them, in the digital signature verification process, the SM2 asymmetric algorithm is used to sign the hash value of the image with the private key and attach it to the image file. In this way, when the system starts, you only need to verify the image with its public key to determine the source of the image. The principle is as follows: (1) Since only the owner of the private key can obtain the private key, other people cannot obtain the private key and thus cannot forge the signature. (2) When the public key is verified, since only the data signed by the corresponding private key can be verified, other forged data will fail the verification. That is, only the image signed by the owner of the corresponding private key can pass the verification, thereby ensuring the identity of the image publisher.

[0109] like Figure 3 As shown, it is a schematic diagram of a signature process involved in an embodiment of the present application. The sender calculates a first hash value based on the original information. The sender uses a private key (i.e., the first key information) to sign the first summary value to obtain a first signature value. The sender sends the original information and the first signature value to the receiver. Figure 4 As shown, it is a schematic diagram of a signature verification process involved in an embodiment of the present application. After the receiver receives the information sent by the sender, it splits the original information and the message signature value A (i.e., the first signature value). The receiver uses the public key (i.e., the second key information) to calculate the original information to obtain the first verification value. The receiver performs a hash operation on the original information to obtain the second verification value, and compares the first verification value with the second verification value. If they are the same, it means that the signature verification is successful, otherwise it means that the verification fails.

[0110] After the startup and verification of the application is completed, the chip enters the low-voltage power distribution function operation state, and the trust system built by the root key is still in effect. The trust chain management module continuously monitors the chip operation status and external environment. When facing possible security threats and trust chain interruptions, the root key can be used as a key basis for restoring the security state and re-verification. During the re-verification process, the root key is required to ensure the security and accuracy of the verification link to maintain the chip in a high-trust operation state.

[0111] In a possible implementation, after the root key is generated based on the random number generator and the PUF technology, the root key is divided into a plurality of root key fragments, and each of the root key fragments is stored in a different security area of ​​the chip.

[0112] In the embodiment of the present application, the security of the control chip is further enhanced in the storage link of the root key, and the root key is divided into multiple fragments, which are stored in different security areas of the chip and protected by special encryption algorithms and access control mechanisms. In this way, even if an attacker breaks through a certain storage area, he cannot obtain the complete root key, which greatly improves the security of the root key and further improves the security of the control chip startup.

[0113] In addition, ordinary keys can be stored in a dedicated TEE hardware security module. These hardware devices usually have physical protection mechanisms that can resist physical attacks, such as probe attacks, side channel attacks, etc., to prevent the keys from being illegally read or tampered with. And when the keys are stored in a memory that is not a hardware security module (such as ordinary flash memory or EEPROM), the keys are encrypted. The stored keys are encrypted using a strong encryption algorithm and a unique encryption key, making it difficult for attackers to obtain the original keys even if the data in the memory is stolen.

[0114] In a possible implementation, when the control chip is started, the voltage data of the input power supply is continuously monitored, and the real-time voltage of the input power supply is controlled within a preset voltage range by means of voltage boost, voltage reduction or voltage stabilization control;

[0115] When the voltage data exceeds a preset threshold, an alarm is triggered and the startup process of the control chip is stopped.

[0116] In a preferred embodiment, Figure 5 As shown, the control chip is equipped with a power management unit (PMU), which can automatically adjust the output voltage to cope with grid voltage fluctuations. As the startup process progresses, the PMU will gradually switch to the main power supply and monitor the changes in the main power supply voltage in real time. When the main power supply voltage fluctuates under low voltage, the PMU will quickly adjust the output voltage and stabilize the power supply voltage within the range required for the chip to start safely by means of boost, buck or voltage regulation control. Figure 6 As shown, during the operation of the control chip, the input power is monitored and the voltage threshold is set. Once it exceeds the range, an alarm is issued in time or protective measures are taken, such as using a voltage monitoring device to monitor the input voltage in real time. When the voltage is abnormal, an alarm is triggered and the chip startup process is stopped to avoid damage to the chip when it is started under unstable voltage. In addition, a backup power supply can be provided for the control chip, and an uninterruptible power supply (UPS) can be installed. When the main power fails or is interrupted, the UPS can immediately and seamlessly switch to power the chip to ensure continuous operation of the chip. A backup battery pack is equipped as an emergency power supply to provide temporary power support for the chip when the main power fails. In terms of data security, the chip can be further physically protected, and a tamper-proof detection mechanism can be added by using a physical packaging design. Special packaging materials and structures are used to make physical attacks on the chip difficult. Sensors can also be integrated to detect whether there is a physical attack, such as cover opening detection, temperature anomaly detection, etc. Once an attack is detected, a security response mechanism is immediately triggered. The above settings provide guarantees for the safe startup and stable operation of the control chip at the hardware level.

[0117] In terms of software, a real-time trust evaluation system can also be established to monitor the operating status of key components inside the chip (such as the working status of the hardware encryption engine, abnormal memory access), the security of external network communications (such as whether there is a malicious data packet intrusion), and the system's performance indicators (such as changes in the response time of processing tasks) and other multi-dimensional information. The trust chain management module performs trust evaluation based on these real-time monitoring data. Once the trust level of a certain link is found to have decreased (such as signs of abnormal operation of the hardware encryption engine), the re-verification process is immediately triggered. During the re-verification process, the root key provides support for this system, and re-verification is performed using the root key to ensure the accuracy and security of the re-verification process. Re-verification not only verifies the link with problems separately, but also traces back along the trust chain and re-verifies the previous links to ensure the reliability of the entire trust chain.

[0118] In addition, by recording key events and operations during the chip's secure startup and operation, detailed logs are generated. These logs can be used for post-analysis and troubleshooting, and can also serve as a basis for security audits. Use a secure log storage mechanism to prevent logs from being tampered with or deleted. For example, store logs in encrypted storage devices or send them to a secure log server over the network for centralized storage. Analyze logs regularly to find potential security issues and abnormal behaviors. Log analysis tools or machine learning algorithms can be used to automatically detect abnormal patterns and improve the efficiency and accuracy of security monitoring.

[0119] Embodiment 2:

[0120] like Figure 7 As shown, embodiment 2 provides a secure boot system for a control chip of a low-voltage power distribution system, including a root key generation module 10, a trust chain construction module 20, a boot program activation module 30, an operating system startup module 40, and an application startup module 50;

[0121] The root key generation module 10 is used to generate a root key based on a random number generator and PUF technology when the control chip is started;

[0122] The trust chain construction module 20 is used to construct a first trust chain with the root key as the trust root according to the root key;

[0123] The boot program activation module 30 is used to activate the secure boot program of the control chip based on the first trust chain, and update the first trust chain based on the secure boot program to obtain a corresponding second trust chain;

[0124] The operating system startup module 40 is used to start and securely verify the operating system of the control chip based on the second trust chain using the secure boot program, and update the second trust chain based on the operating system to obtain a third trust chain;

[0125] The application startup module 50 is used to start and securely verify each application in the control chip based on the third trust chain using the secure boot program, thereby completing the secure startup of the control chip.

[0126] In a possible implementation, the root key generation module 10 generates a root key based on a random number generator and PUF technology, including:

[0127] Generate a first random number sequence of a preset length using the PUF technology;

[0128] Generate a second random number sequence with the same length as the first random number sequence using the random number generator;

[0129] Based on a preset fusion algorithm, the first random number sequence and the second random number sequence are fused to obtain the root key.

[0130] Furthermore, the fusing the first random number sequence with the second random number sequence based on a preset fusion algorithm to obtain the root key includes:

[0131] Performing an XOR operation on the first random number sequence and the second random number sequence to obtain an initial fusion sequence, wherein the length of the initial fusion sequence is twice the preset length;

[0132] Performing several hash iterations on the initial fusion sequence using a KDF algorithm to obtain the root key;

[0133] The root key is stored in an encrypted non-volatile memory of the control chip.

[0134] In a possible implementation, the boot program activation module 30 activates the secure boot program of the control chip based on the first trust chain, and updates the first trust chain based on the secure boot program to obtain a corresponding second trust chain, including:

[0135] According to the root key in the first trust chain, the national secret SM3 algorithm is used to statically measure the operating environment of the control chip;

[0136] When the static measurement is passed, performing hash encryption calculation on each preset reference value in the control chip according to the root key to obtain corresponding encrypted reference values, and adding each encrypted reference value to the first trust chain;

[0137] Based on the first trust chain, verify the integrity of the secure boot program;

[0138] When the integrity verification passes, the secure boot program is activated, and the secure boot program is added to the first trust chain, and the second trust chain is updated.

[0139] Further, the performing integrity verification on the secure boot program based on the first trust chain includes:

[0140] Using the root key to perform hash encryption calculation on each code segment of the secure boot to obtain a corresponding hash value of each code segment;

[0141] Compare and verify the hash value of each code segment with the corresponding encrypted reference values ​​in the first trust chain;

[0142] The integrity of the secure boot program is determined based on the result of the comparison and verification.

[0143] In a possible implementation, the operating system startup module 40 uses the secure boot program to start and securely verify the operating system of the control chip based on the second trust chain, including:

[0144] Using the secure boot program to load the operating system into the memory for startup;

[0145] When the operating system is started, the root key is used to perform hash encryption calculation on the data at the preset location of the operating system to obtain corresponding encrypted hash values;

[0146] Comparing and verifying each of the encrypted hash values ​​with a number of corresponding encrypted reference values ​​in the second trust chain;

[0147] Determining whether the security verification of the operating system has passed according to the comparison verification results of each of the encrypted reference values;

[0148] When the security verification passes, the operating system is added to the second trust chain, and the third trust chain is updated.

[0149] In a possible implementation, the application startup module 50 uses the secure boot program to start and securely verify each application in the control chip based on the third trust chain, including:

[0150] Using the secure boot program, sequentially loading each application into the memory based on a preset order;

[0151] When any first application is loaded into the memory, digital signature verification and integrity verification are performed on the first application based on the third trust chain, wherein the verification public key used in the digital signature verification is obtained by encrypting the program public key of the first application using the root key, and the program public key is a public key provided by the publisher of the first application;

[0152] If the digital signature verification or integrity verification of the first application fails, the first application is refused to be started.

[0153] In a possible implementation, after the root key is generated based on the random number generator and the PUF technology, the root key is divided into a plurality of root key fragments, and each of the root key fragments is stored in a different security area of ​​the chip.

[0154] In a possible implementation, when the control chip is started, the voltage data of the input power supply is continuously monitored, and the real-time voltage of the input power supply is controlled within a preset voltage range by means of voltage boost, voltage reduction or voltage stabilization control;

[0155] When the voltage data exceeds a preset threshold, an alarm is triggered and the startup process of the control chip is stopped.

[0156] The embodiment of the present application provides a secure boot system for a control chip of a low-voltage power distribution system. The system adopts a hierarchical trust chain startup by building a trust chain, so that the security measures of each layer cooperate with each other. Each layer updates the trust chain after completing its own security verification, and then passes the security status to the next layer, forming a coherent security protection system to improve the security and reliability of the chip. In the process of building the trust chain, the root key, as the starting evidence of the trust chain, participates in the construction of this starting trust foundation, provides a hardware-level identity for subsequent verification, is the source of the trust chain of the entire secure boot process, and determines the overall security of the trust chain. Therefore, the embodiment of the present application combines a random number generator and PUF technology to generate a root key, which ensures the security and non-replicability of the root key and further improves the security of the control chip during startup.

[0157] The more detailed working principle and step flow of this embodiment can refer to, but are not limited to, the relevant records of Embodiment 1.

[0158] The specific embodiments described above further describe the purpose, technical solutions and beneficial effects of the present application in detail. It should be understood that the above description is only a specific embodiment of the present application and is not intended to limit the scope of protection of the present application. It is particularly pointed out that for those skilled in the art, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A safe startup method for a control chip of a low-voltage power distribution system, characterized in that: include: When the control chip starts, a root key is generated based on the random number generator and PUF technology; According to the root key, construct a first trust chain with the root key as a trust root; Based on the first trust chain, activating the secure boot program of the control chip, and updating the first trust chain based on the secure boot program to obtain a corresponding second trust chain; Based on the second trust chain, use the secure boot program to start and securely verify the operating system of the control chip, and update the second trust chain based on the operating system to obtain a third trust chain; Based on the third trust chain, the secure boot program is used to start and securely verify each application in the control chip, thereby completing the secure startup of the control chip.

2. A safe startup method for a control chip of a low voltage power distribution system as claimed in claim 1, characterized in that: The generating of the root key based on the random number generator and the PUF technology includes: Generate a first random number sequence of a preset length using the PUF technology; Generate a second random number sequence with the same length as the first random number sequence using the random number generator; Based on a preset fusion algorithm, the first random number sequence and the second random number sequence are fused to obtain the root key.

3. A safe startup method for a control chip of a low voltage power distribution system as claimed in claim 2, characterized in that: The fusing the first random number sequence with the second random number sequence based on a preset fusion algorithm to obtain the root key includes: Performing an XOR operation on the first random number sequence and the second random number sequence to obtain an initial fusion sequence, wherein the length of the initial fusion sequence is twice the preset length; Performing several hash iterations on the initial fusion sequence using a KDF algorithm to obtain the root key; The root key is stored in an encrypted non-volatile memory of the control chip.

4. A safe startup method for a control chip of a low voltage power distribution system as claimed in claim 1, characterized in that: The activating the secure boot program of the control chip based on the first trust chain, and updating the first trust chain based on the secure boot program to obtain a corresponding second trust chain includes: According to the root key in the first trust chain, the national secret SM3 algorithm is used to statically measure the operating environment of the control chip; When the static measurement is passed, performing hash encryption calculation on each preset reference value in the control chip according to the root key to obtain corresponding encrypted reference values, and adding each encrypted reference value to the first trust chain; Based on the first trust chain, verify the integrity of the secure boot program; When the integrity verification passes, the secure boot program is activated, and the secure boot program is added to the first trust chain, and the second trust chain is updated.

5. A safe startup method for a control chip of a low voltage power distribution system as claimed in claim 4, characterized in that: The performing integrity verification on the secure boot program based on the first trust chain includes: Using the root key to perform hash encryption calculation on each code segment of the secure boot to obtain a corresponding hash value of each code segment; Compare and verify the hash value of each code segment with the corresponding encrypted reference values ​​in the first trust chain; The integrity of the secure boot program is determined based on the result of the comparison and verification.

6. A safe startup method for a control chip of a low voltage power distribution system as claimed in claim 1, characterized in that: The method of starting and securely verifying the operating system of the control chip using the secure boot program based on the second trust chain includes: Use the secure boot program to load the operating system into the memory and start it; When the operating system is started, the root key is used to perform hash encryption calculation on the data at the preset location of the operating system to obtain corresponding encrypted hash values; Comparing and verifying each of the encrypted hash values ​​with a number of corresponding encrypted reference values ​​in the second trust chain; Determining whether the security verification of the operating system has passed according to the comparison verification results of each of the encrypted reference values; When the security verification passes, the operating system is added to the second trust chain, and the third trust chain is updated.

7. A safe startup method for a control chip of a low voltage power distribution system as claimed in claim 1, characterized in that: The method of starting and securely verifying each application in the control chip using the secure boot program based on the third trust chain includes: Using the secure boot program, sequentially loading each application into the memory based on a preset order; When any first application is loaded into the memory, digital signature verification and integrity verification are performed on the first application based on the third trust chain, wherein the verification public key used in the digital signature verification is obtained by encrypting the program public key of the first application using the root key, and the program public key is a public key provided by the publisher of the first application; If the digital signature verification or integrity verification of the first application fails, the first application is refused to be started.

8. A safe startup method for a control chip of a low voltage power distribution system according to any one of claims 1 to 7, characterized in that: After the root key is generated based on the random number generator and the PUF technology, the root key is divided into a plurality of root key fragments, and each of the root key fragments is stored in a different security area of ​​the chip.

9. A safe startup method for a control chip of a low voltage power distribution system according to any one of claims 1 to 7, characterized in that: When the control chip is started, the voltage data of the input power supply is continuously monitored, and the real-time voltage of the input power supply is controlled within a preset voltage range by means of voltage boost, voltage reduction or voltage stabilization control; When the voltage data exceeds a preset threshold, an alarm is triggered and the startup process of the control chip is stopped.

10. A safe startup system for a control chip of a low-voltage power distribution system, characterized in that: It includes a root key generation module, a trust chain building module, a boot program activation module, an operating system startup module, and an application startup module; The root key generation module is used to generate a root key based on a random number generator and PUF technology when the control chip is started; The trust chain construction module is used to construct a first trust chain with the root key as the trust root according to the root key; The boot program activation module is used to activate the secure boot program of the control chip based on the first trust chain, and update the first trust chain based on the secure boot program to obtain a corresponding second trust chain; The operating system startup module is used to start and securely verify the operating system of the control chip based on the second trust chain using the secure boot program, and update the second trust chain based on the operating system to obtain a third trust chain; The application startup module is used to start and securely verify each application in the control chip based on the third trust chain using the secure boot program, thereby completing the secure startup of the control chip.

Images