Post-quantum Internet of Things static key management method and system based on PUF (Physical Unclonable Function)

Abstract

The invention provides a PUF (Physical Unclonable Function)-based post-quantum Internet of Things static key management method and system. Generation and storage of a secret key in the method comprise the following steps: firstly, inputting a challenge signal determined based on Internet of Things equipment into a physical unclonable function (PUF) to generate a PUF response; then, the PUF response is input into a key derivation function (KDF), and a key encryption key (KEK) is obtained; then, generating a PQC public key and a PQC private key by using a post quantum cryptography PQC algorithm; then, the PQC private key is encrypted by using a KEK and a symmetric encryption algorithm, and the encrypted PQC private key is stored in a secure storage area; wherein the KEK and the unencrypted PQC private key are cleared from the memory. By adopting the lightweight algorithm, efficient and low-cost key management can be realized on resource-limited Internet of Things equipment, meanwhile, the PUF characteristic is utilized to avoid storage of KEK, the quantum attack resistance of the key is enhanced in combination with the quantum cryptographic algorithm, and the security improvement of key management is realized.

Description

Technical Field

[0001] The present invention relates to the field of information security, specifically to the field of post-quantum cryptography and Internet of Things security, and in particular to a PUF-based post-quantum Internet of Things static key management method and system. Background Art

[0002] Key management is one of the core technologies of information security, which is mainly used to generate, store, distribute and update encryption keys to ensure the confidentiality, integrity and authenticity of data. However, key management faces special challenges in Internet of Things (IoT) devices. Due to the limited resources, low computing power, high power consumption requirements of IoT devices, as well as the diverse and distributed application scenarios of devices, traditional key management solutions are difficult to deal with effectively.

[0003] Specifically, key management technology in IoT devices faces the following challenges:

[0004] 1) Resource limitations: IoT devices usually have low processing power and limited storage space, making it difficult to host complex encryption algorithms and key management systems.

[0005] 2) Security storage issue: Traditional key management relies on storing keys in a secure area of ​​the device. However, this method is vulnerable to physical attacks and has a high risk of key leakage.

[0006] 3) Quantum computing threat: With the development of quantum computing technology, traditional encryption algorithms face the risk of being cracked.

[0007] 4) Lack of dynamic update mechanism: Many IoT devices have been deployed for a long time and lack an effective dynamic key update mechanism, which may lead to security risks for keys used for a long time.

[0008] Therefore, the present invention proposes a key management solution, which is particularly suitable for IoT devices and aims to solve the technical problems in one or more of the above challenges. Summary of the invention

[0009] In order to solve the above problems, the present invention proposes a key management method applied to an IoT device, the method comprising the following steps:

[0010] A challenge signal determined based on the IoT device is input into a physical unclonable function PUF to generate a PUF response.

[0011] The PUF response is input into a key derivation function KDF to obtain a key encryption key KEK.

[0012] The PQC public key and PQC private key are generated using the post-quantum cryptography PQC algorithm.

[0013] The PQC private key is encrypted using the KEK as a key according to a symmetric encryption algorithm, and the encrypted PQC private key is stored in a secure storage area; the KEK and the unencrypted PQC private key are cleared from the memory.

[0014] In some embodiments, the PUF function is: a software-based PUF function, or a hardware-based PUF function, or a hybrid PUF function combining software and hardware.

[0015] In some embodiments, inputting the PUF response into a key derivation function KDF specifically includes: inputting the PUF response and a random salt value into the KDF function.

[0016] In some embodiments, after storing the encrypted PQC private key in the secure storage area, the method further comprises:

[0017] The challenge signal determined again based on the IoT device is input into the PUF function to regenerate the PUF response.

[0018] The PUF response is input into the KDF function to reconstruct the KEK.

[0019] The encrypted PQC private key read from the secure storage area is decrypted using the KEK and a symmetric decryption algorithm corresponding to the symmetric encryption algorithm.

[0020] After the decrypted PQC private key is used up, it is cleared from the memory.

[0021] In some embodiments, the determination of the challenge signal includes:

[0022] Fixed features of the operating system of the IoT device are collected, and an initial challenge is generated based on the fixed features.

[0023] Applying a cryptographic hash function to the initial challenge generates a final challenge as the challenge signal.

[0024] In some embodiments, after reconstructing the KEK and before decrypting the encrypted PQC private key read from the secure storage area, the method further comprises:

[0025] Check whether the reconstruction is successful; if the reconstruction fails, execute the error recovery process.

[0026] In some embodiments, after storing the encrypted PQC private key in the secure storage area, the method further comprises:

[0027] In response to the satisfaction of the preset condition, the updating and encryption operation of the PQC private key is triggered.

[0028] In some more specific embodiments, the preset condition is: the difference between the current time and the generation time of the PQC private key is greater than a time threshold; or, the number of occurrences of security events related to the PQC private key is greater than a counting threshold; or, the error measure of a predetermined performance indicator of the PQC private key generation system is greater than an error threshold.

[0029] On the other hand, the present invention also provides a key management system to implement the above key management method. The system is based on the operation of the Internet of Things device and includes the following parts:

[0030] The PUF module inputs the challenge signal determined based on the IoT device into the PUF function to generate a PUF response. The module uses the physical unclonable function inside the chip to generate a random and unique PUF response.

[0031] The key derivation module is used to input the PUF response into a key derivation function KDF to obtain a key encryption key KEK.

[0032] The PQC key generation module is used to generate a PQC public key and a PQC private key according to the PQC algorithm.

[0033] The PQC key encryption module is used to encrypt the PQC private key according to the KEK and the symmetric encryption algorithm, and store the encrypted PQC private key in a secure storage area, and clear the KEK and the unencrypted PQC private key from the memory.

[0034] The PQC key decryption module is used to reconstruct the KEK according to the original PUF response and the key reconstruction function corresponding to the KDF function, and use the KEK and the symmetric decryption algorithm to decrypt the PQC private key, and clear the PQC private key from the memory after the PQC private key is used.

[0035] In some embodiments, the system may further include a dynamic key update module 506 for triggering the update and encryption operation of the PQC private key when a preset condition is met.

[0036] In some more specific embodiments, the preset condition is: the difference between the current time and the generation time of the PQC private key is greater than a time threshold; or, the number of occurrences of security events related to the PQC private key is greater than a counting threshold; or, the error measure of a predetermined performance indicator of the PQC private key generation system is greater than an error threshold.

[0037] In some embodiments, the key management system 500 further includes a challenge signal determination module, which is used to:

[0038] Fixed features of the operating system of the IoT device are collected, and an initial challenge is generated based on the fixed features.

[0039] Applying a cryptographic hash function to the initial challenge generates a final challenge as the challenge signal.

[0040] In some embodiments, the key derivation module is specifically used to: input the PUF response and the random salt value into a key derivation function KDF to obtain a key encryption key KEK.

[0041] In some embodiments, after reconstructing the KEK, the PQC key decryption module is also responsible for checking whether the reconstruction is successful; if the reconstruction fails, an error recovery process is executed.

[0042] The key management method and system provided by the present invention can realize efficient and low-cost key management on resource-constrained IoT devices. At the same time, the PUF characteristics are utilized to avoid the storage of KEK, and the key's ability to resist quantum attacks is enhanced by combining the post-quantum cryptographic algorithm, thereby improving the security of key management. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0044] Figure 1 A diagram showing the architecture of the key management method provided by the present invention;

[0045] Figure 2 Flowchart for the generation and encrypted storage of private keys;

[0046] Figure 3 This is a flowchart of the decryption and use phases of the private key;

[0047] Figure 4 This is the flowchart of the key update phase;

[0048] Figure 5 This is a schematic diagram of the key management system provided by the present invention. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described below in conjunction with the accompanying drawings.

[0050] The present invention provides a static key management solution based on the combination of Physically Unclonable Function (PUF) and Post-Quantum Cryptography (PQC), which is particularly suitable for Internet of Things devices.

[0051] It should be understood that PUF is a hardware security primitive based on the microscopic differences of physical devices, which can generate an unpredictable and unclonable unique device identifier, similar to a chip fingerprint.

[0052] PQC is a cryptographic algorithm designed to resist quantum computer attacks, such as lattice-based cryptography, code-based cryptography, multivariate cryptography, etc.

[0053] A static key is a key that remains unchanged for a long time and is used continuously for a certain period of time. After the key is generated, it may be used for encryption and decryption operations for a long time until it is explicitly replaced.

[0054] The core idea of ​​the above key management scheme is to use the characteristics of PUF to generate a key encryption key (KeyEncryption Key, referred to as KEK), and use the KEK to encrypt the quantum-resistant PQC private key to achieve secure storage and dynamic update of the private key. The following describes in detail the specific implementation of the key management scheme provided by the present invention in conjunction with the accompanying drawings.

[0055] According to a first aspect, the present invention provides a key management method, which is applied to an Internet of Things device. The method architecture diagram is as follows: Figure 1 As shown. This method is mainly divided into three stages: private key generation and encrypted storage, private key decryption and use, and key update. When this method is run for the first time, the private key is first generated and encrypted for storage, and then decrypted and used. During the use of the private key, the key update is triggered according to the set policy. After the key update is triggered, the private key generation and encrypted storage are executed again. The specific implementation steps of each stage are introduced below.

[0056] When this method is run for the first time, it first enters the private key generation and encryption storage stage. In this stage, the characteristics of PUF are used to generate KEK for the first time, and the KEK is used to encrypt the PQC private key, and the PQC private key is securely stored. The flowchart of this stage is as follows Figure 2 As shown, the specific steps include:

[0057] S11. Generate PUF response: Input the challenge signal determined based on the IoT device into the PUF function to generate a PUF response.

[0058] Exemplarily, the above-mentioned IoT devices may include wearable devices (such as smart watches), smart homes (such as smart door locks), and the like.

[0059] The determination of the above challenge signal can be obtained by executing the following steps S111-S114:

[0060] S111. Collect fixed features: First, collect various fixed features of the operating system of the IoT device, which may include hardware features (such as CPU ID), software features (such as operating system version), and environmental features (such as geographic location).

[0061] S112, generating an initial challenge: using the collected fixed features to generate an initial challenge (eg, a memory address or a set of random numbers).

[0062] S113. Apply cryptographic hash function: Apply a cryptographic hash function to the initial challenge to increase the security and unpredictability of the challenge.

[0063] S114. Generate final challenge: The hash result becomes the final challenge, which serves as the above challenge signal.

[0064] Regarding the above-mentioned PUF function, its implementation can be based on software, hardware, or both. That is to say, the indicator extraction source of the output of the PUF function (i.e., the PUF response) can be a hardware-level indicator, for example, measuring the delay difference of the signal transmission along the path in the system chip to generate a PUF response, or using the chip's built-in hardware PUF module to generate a PUF response; it can also be a software-level indicator, for example, measuring the memory access delay, code execution time and other information of the IoT device, and generating a PUF response through the differences in these runtime performances, or it can be a combination of software and hardware levels to generate a more secure and reliable PUF response.

[0065] Based on the above, the determined challenge signal can be input into the PUF function to obtain the corresponding output PUF response.

[0066] S12, deriving a key: inputting the PUF response into a key derivation function (KDF) to obtain a key encryption key KEK.

[0067] It should be understood that a key derivation function is a cryptographic algorithm that can derive a key from input information. When the input information is the same, the derived key is also the same. The derived key can be used in an encryption algorithm or system to meet specific security requirements. Exemplarily, the KDF function can be HKDF or TLS PRF.

[0068] In this step, the input of the KDF function includes the PUF response obtained in S11. In one embodiment, a random salt value may also be added to the input to improve key security. In this case, the random salt value needs to be securely stored for use in regenerating the KEK in the subsequent key decryption stage.

[0069] In this step, the output of the KDF function is the key encryption key KEK.

[0070] S13. Generate key pair: Generate PQC public key and PQC private key using post-quantum cryptography PQC algorithm.

[0071] Exemplarily, the PQC algorithm may specifically use the Kyber algorithm.

[0072] S14, encrypt and store private key: use the KEK as a key, encrypt the PQC private key according to a symmetric encryption algorithm, and store the encrypted PQC private key in a secure storage area; the KEK and the unencrypted PQC private key are cleared from the memory.

[0073] Exemplarily, the symmetric encryption algorithm may be AES-256.

[0074] Exemplarily, the secure storage area may be a trusted execution environment TEE or a secure storage chip.

[0075] The above introduces the implementation steps of the private key generation and encryption storage stage. After this stage, the private key decryption and use stage begins. This stage uses the characteristics of PUF to reconstruct the PUF response based on the same IoT device, and then reconstructs the KEK, which is used to decrypt the PQC private key. The flowchart of this stage is as follows Figure 3 As shown, the specific steps include:

[0076] S21. Trigger decryption: When the PQC private key is required to perform an operation, the PQC private key decryption process is triggered.

[0077] S22. Reconstruct KEK: same as S11-S12.

[0078] Based on the same IoT device and PUF function, a PUF response that is consistent and unique with that in S11 can be generated. Then, this PUF response is input into the same KDF function as in S12 to reconstruct the KEK.

[0079] If a random salt value is added to the input of the KDF function in S12, the random salt value needs to be read here and added to the input of the KDF function.

[0080] After reconstructing the KEK, you can perform a reconstruction success judgment to check whether the KEK is reconstructed successfully.

[0081] If the reconstruction fails, execute the error recovery process, which may include retrying, using alternative methods, or notifying the administrator.

[0082] S23, decrypting private key: reading the encrypted PQC private key from the secure storage area, and decrypting the PQC private key using the reconstructed KEK and the symmetric decryption algorithm corresponding to the symmetric encryption algorithm in S13.

[0083] S24, use private key: use the decrypted PQC private key to sign, decapsulate, etc. After the operation is completed, immediately clear the decrypted PQC private key from the memory to reduce the risk of exposure.

[0084] The above introduces the implementation steps of the decryption and use phase of the private key. In addition, for the reconstruction of the KEK in the above step S22. In order to prevent the inability to reconstruct the KEK due to tampering with certain fixed features, the following solution can be adopted:

[0085] 1. Multiple feature verification: Instead of relying on a single feature, multiple features are combined to verify the identity of the user or operating system of the IoT device. For example, instead of relying on a single feature that is easily tampered with, such as the hardware's MAC address or hard disk serial number, a more complex verification method is formed by combining multiple biometric features (such as fingerprints, facial recognition), device features (such as device ID, operating system information), and usage behaviors (such as user login habits, network connection mode, etc.). Even if individual features are tampered with or changed, other unaffected features can provide reliable verification information, thereby enhancing system security.

[0086] 2. Fault tolerance mechanism: Introduce a certain fault tolerance range in the feature collection and verification process to allow small changes. Fixed features may change slightly due to hardware damage, updates, or changes in system operation, such as temperature changes causing hardware performance fluctuations or feature fine-tuning due to firmware updates. The fault tolerance mechanism allows changes within a certain deviation range and will not be immediately regarded as feature tampering or invalidation, thereby reducing the problem of KEK being unable to be reconstructed due to natural changes.

[0087] 3. Dynamic update: Regularly update fixed features to adapt to normal changes in the system. The baseline of a feature is the standard value used by the system to verify the feature. The system can regularly update the baseline values ​​of these fixed features to adapt to normal changes caused by natural aging, software updates, hardware upgrades, etc. For example, after each device hardware upgrade or system operating environment adjustment, the baseline can be updated in a safe way to match the actual state of the current system. This can reduce errors caused by normal changes in the system and make the system more sensitive and flexible to changes in its environment.

[0088] 4. Backup mechanism: Store multiple versions of fixed features and auxiliary information to cope with feature changes. When using fixed features for verification, the backup mechanism can prevent verification failures due to feature mutations by storing multiple versions of fixed features and auxiliary information. For example, old versions of feature information can be backed up on multiple storage media or in the cloud. When features are irreversibly tampered with, the system status can be restored through the backed-up data. This mechanism can be used as an emergency measure for the system to ensure that in the event of damage or loss of features, KEK reconstruction can still be achieved by restoring old versions of features.

[0089] 5. Anomaly detection: Implement a monitoring system to promptly detect and report abnormal changes in features. In order to prevent the risks brought by feature tampering, the system should have anomaly detection capabilities. By continuously monitoring system feature data, it is possible to issue an alarm in a timely manner when abnormal changes occur in features. Anomaly detection can be combined with machine learning technology to establish a normal operating feature pattern based on historical feature data and automatically identify unreasonable changes. For some sensitive features, an alarm mechanism can be set up. Once an abnormal change is detected, the system can automatically lock, restrict functions, or initiate a repair process.

[0090] 6. Security recovery process: Design a reliable error recovery mechanism to safely reset or restore the system when features are tampered with. The security recovery process is a post-event remediation mechanism, that is, when fixed features are detected to be tampered with, the system can start a reliable error recovery plan to ensure that it can be reset or repaired without affecting normal operations. The security environment that KEK relies on can be re-established through security processes such as re-authentication, secondary verification, and backup keys. This process must strictly follow security specifications to prevent further security risks during the recovery process.

[0091] The above is a backup plan to prevent the KEK from being unable to be reconstructed. The key update phase is introduced below.

[0092] In order to reduce the risk of key leakage and improve the long-term security of the system, the key needs to be updated during operation. The process of the key update phase is as follows: Figure 4 As shown, the specific steps of this stage include:

[0093] S31, update trigger: trigger key update according to preset policies or detected security events.

[0094] This step can be performed according to the dynamic key update trigger algorithm, the algorithm formula is as follows:

[0095]

[0096] Formula explanation:

[0097] 1. Update trigger: This is a binary output, 1 means trigger update, 0 means do not trigger update.

[0098] 2. Trigger conditions: The formula contains three trigger conditions. As long as one of them is met, the update will be triggered:

[0099] Time condition (tt last >T t ), where t is the current time, t last is the time of last update, T t is a time threshold. This ensures that the system is updated after a certain time interval, even if other conditions are not met.

[0100] Counting condition (n>N t ), where n is some count (such as the number of times the PQC private key is read), N t This is a counting threshold that allows the system to trigger an update after a certain event occurs enough times.

[0101] Error condition (e>E t ), where e is a measure of some error or deviation (such as the error of some fixed feature), E t is the error threshold. This enables the system to update when the performance or accuracy drops to a certain threshold, avoiding the impact of changes in fixed features on the reconstruction of KEK.

[0102] The key update trigger algorithm provides a flexible key update strategy that takes into account both security and efficiency, avoiding overly frequent updates while ensuring timely updates when necessary. The key update trigger algorithm is also flexible and can adjust various parameters according to specific application scenarios to meet different needs.

[0103] S32, private key update: re-execute all steps of the private key generation and encryption storage phase, and replace the old private key in the secure storage area with the new encrypted private key.

[0104] The above is a specific implementation of the key management method provided by the present invention. Compared with the prior art, the method has the following beneficial effects:

[0105] 1. Using PUF to generate KEK eliminates the need to securely store KEK, fundamentally solving the KEK storage security issue.

[0106] 2. The PQC algorithm is used to generate keys, which enhances the key's ability to resist quantum attacks.

[0107] 3. The use of lightweight algorithms and storage solutions reduces the consumption of device resources and makes it easier to deploy in resource-constrained IoT devices.

[0108] 4. Adopt a dynamic key update mechanism to update keys regularly or on demand to reduce the risk of key leakage and improve the long-term security of the system.

[0109] According to a second aspect, the present invention further provides a key management system, wherein the system is operated based on an Internet of Things device. Figure 5 The key management system 500 is a schematic diagram of the system, which includes the following parts:

[0110] The PUF module 501 inputs the challenge signal determined based on the IoT device into the PUF function to generate a PUF response. This module generates a random and unique PUF response using a physical unclonable function inside the chip.

[0111] A key derivation module 502, configured to input the PUF response into a key derivation function KDF to obtain a key encryption key KEK;

[0112] A PQC key generation module 503, used to generate a PQC public key and a PQC private key according to a PQC algorithm;

[0113] A PQC key encryption module 504 is used to encrypt the PQC private key according to the KEK and the symmetric encryption algorithm, and store the encrypted PQC private key in a secure storage area, and clear the KEK and the unencrypted PQC private key from the memory;

[0114] The PQC key decryption module 505 is used to reconstruct the KEK according to the original PUF response and the key reconstruction function corresponding to the KDF function, and use the KEK and the symmetric decryption algorithm to decrypt the PQC private key, and clear the PQC private key from the memory after the PQC private key is used.

[0115] In some embodiments, the system may further include a dynamic key update module 506 for triggering the update and encryption operation of the PQC private key when a preset condition is met.

[0116] In some more specific embodiments, the preset condition is: the difference between the current time and the generation time of the PQC private key is greater than a time threshold; or, the number of occurrences of security events related to the PQC private key is greater than a counting threshold; or, the error measure of a predetermined performance indicator of the PQC private key generation system is greater than an error threshold.

[0117] In some embodiments, the key management system 500 further includes a challenge signal determination module 507, which is used to:

[0118] Fixed features of the operating system of the IoT device are collected, and an initial challenge is generated based on the fixed features.

[0119] Applying a cryptographic hash function to the initial challenge generates a final challenge as the challenge signal.

[0120] In some embodiments, the PUF function is: a software-based PUF function, or a hardware-based PUF function, or a hybrid PUF function combining software and hardware.

[0121] In some embodiments, the key derivation module 502 is specifically used to: input the PUF response and the random salt value into a key derivation function KDF to obtain a key encryption key KEK.

[0122] In some embodiments, after reconstructing the KEK, the PQC key decryption module is also responsible for checking whether the reconstruction is successful; if the reconstruction fails, an error recovery process is executed.

[0123] It should be noted that the above system can execute the key management method provided in the first aspect. In addition, the functions of each module can also refer to the above introduction to the method, which will not be repeated here.

[0124] In the description of the embodiments of the present application, words such as "exemplary", "for example" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary", "for example" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary", "for example" or "for example" is intended to present related concepts in a concrete way.

[0125] In the description of the embodiments of the present application, the term "and / or" is merely a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, B exists alone, and A and B exist at the same time. In addition, unless otherwise specified, the term "plurality" means two or more.

[0126] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. The terms "include", "comprises", "has" and their variations all mean "including but not limited to", unless otherwise specifically emphasized.

[0127] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made on the basis of the technical solution of the present invention should be included in the scope of protection of the present invention.

Claims

1. A key management method, characterized in that: The method is applied to an IoT device and comprises the following steps: Inputting a challenge signal determined based on the IoT device into a physical unclonable function PUF to generate a PUF response; Input the PUF response into a key derivation function KDF to obtain a key encryption key KEK; Generate PQC public key and PQC private key using post-quantum cryptography PQC algorithm; The PQC private key is encrypted using the KEK as a key according to a symmetric encryption algorithm, and the encrypted PQC private key is stored in a secure storage area; the KEK and the unencrypted PQC private key are cleared from the memory.

2. The method according to claim 1, characterized in that The PUF function is: a software-based PUF function, a hardware-based PUF function, or a hybrid PUF function combining software and hardware.

3. The method according to claim 1, characterized in that Inputting the PUF response into a key derivation function KDF specifically includes: The PUF response and the random salt value are input together into the KDF function.

4. The method according to claim 1, characterized in that After storing the encrypted PQC private key in the secure storage area, the method further includes: Inputting the challenge signal determined again based on the IoT device into the PUF function to regenerate the PUF response; Input the PUF response into the KDF function to reconstruct the KEK; Decrypting the encrypted PQC private key read from the secure storage area using the KEK and a symmetric decryption algorithm corresponding to the symmetric encryption algorithm; After the decrypted PQC private key is used up, it is cleared from the memory.

5. The method according to claim 1 or 4, characterized in that: The determination of the challenge signal includes: Collecting fixed features of the operating system of the IoT device, and generating an initial challenge based on the fixed features; Applying a cryptographic hash function to the initial challenge generates a final challenge as the challenge signal.

6. The method according to claim 4, characterized in that After reconstructing the KEK and before decrypting the encrypted PQC private key read from the secure storage area, the method further includes: Check whether the reconstruction is successful; if the reconstruction fails, execute the error recovery process.

7. The method according to claim 1, wherein: After storing the encrypted PQC private key in the secure storage area, the method further includes: in response to the satisfaction of a preset condition, triggering an update and encryption operation of the PQC private key.

8. The method according to claim 7, wherein: The preset condition is: the difference between the current time and the generation time of the PQC private key is greater than the time threshold; or, the number of occurrences of security events related to the PQC private key is greater than the counting threshold; or, the error metric of a predetermined performance indicator of the generation system of the PQC private key is greater than the error threshold.

9. A key management system, characterized in that: The system is based on IoT devices and includes the following parts: A PUF module, which inputs a challenge signal determined based on the IoT device into a physical unclonable function PUF to generate a PUF response; A key derivation module, used for inputting the PUF response into a key derivation function KDF to obtain a key encryption key KEK; A PQC key generation module, used to generate a PQC public key and a PQC private key according to a PQC algorithm; A PQC key encryption module, used to encrypt the PQC private key according to the KEK and the symmetric encryption algorithm, and store the encrypted PQC private key in a secure storage area, and clear the KEK and the unencrypted PQC private key from the memory; The PQC key decryption module is used to reconstruct the KEK according to the PUF response and the KDF function, and use the KEK and the symmetric decryption algorithm to decrypt the PQC private key, and clear the PQC private key from the memory after the PQC private key is used.

10. The key management system according to claim 9, characterized in that: The system also includes a key update module, which is used to trigger the update and encryption operation of the PQC private key when a preset condition is met.

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