Key derivation and distribution method of two-stage physical ca architecture

Abstract

This invention relates to the field of information security technology, and in particular to a key derivation and distribution method for a two-level physical CA architecture. By employing a physical two-level architecture of an offline root CA and a mobile secondary CA, combined with a mechanism of seed derivation rather than direct transmission of working keys, the risk of the root CA's private key being exposed on the network is eliminated. Simultaneously, the working key pairs of the secondary CA possess flexible characteristics of being reconstructable and replaceable. Furthermore, when the mobile secondary CA becomes inoperable due to loss, damage, or changes in its trusted status, there is no need to revoke the original secondary CA certificate or replace the root CA certificate. Only reactivation of the offline root CA and generation of a new seed are required, allowing the new hardware security chip to derive entirely new working key pairs. This achieves rapid disaster recovery through decoupling of certificate and key logic. It avoids the cumbersome process and business interruption of reapplying for certificates, redistributing public keys, and notifying all dependent parties to update the trust chain.

Description

Technical Field

[0001] This invention relates to the field of information security technology, and in particular to a key derivation and distribution method for a two-level physical CA architecture. Background Technology

[0002] Public Key Infrastructure (PKI) is the core security infrastructure in cyberspace, ensuring secure information transmission and trusted identity authentication. It provides security services such as identity authentication, data encryption, and digital signatures to communicating entities by issuing digital certificates through Certificate Authorities (CAs). In a PKI system, the security of the CA's private key directly determines the security foundation of the entire trust system. To mitigate the security risks of the root CA's private key, current technologies typically employ a layered CA architecture, where the root CA is at the top level and responsible for issuing certificates to secondary subordinate CAs. The routine digital certificate issuance is handled by the secondary CAs.

[0003] However, in the existing two-level CA architecture, the working key pairs of the second-level CA are generated in a fixed manner and cannot be rebuilt without replacing the certificate. Once the device is damaged or the private key is leaked, the certificate must be revoked and reissued by the root CA. The recovery process is lengthy and has a wide impact. Summary of the Invention

[0004] The purpose of this invention is to provide a key derivation and distribution method for a two-level physical CA architecture, which solves the technical problems in the prior art where the working key pairs of the second-level CA are fixed and cannot be rebuilt without changing the certificate, and once the device is damaged or the private key is leaked, the certificate must be revoked and reissued by the root CA, resulting in a long recovery process and a wide impact.

[0005] To achieve the above objectives, the present invention provides a key derivation and distribution method for a two-level physical CA architecture, comprising:

[0006] It provides a two-tier physical architecture of offline root CA and mobile secondary CA. The offline root CA is only used to issue secondary CA certificates for mobile secondary CA. After the issuance is completed, it switches to offline state and is physically archived.

[0007] The offline root CA generates a seed for deriving keys, rather than directly generating or transmitting the working key itself;

[0008] The seeds are securely transmitted to the hardware security chip of the mobile secondary CA via a physical security carrier.

[0009] The hardware security chip of the mobile secondary CA calls the built-in key derivation function, using the seed as the unique root input, to independently derive the working key pair used for daily certificate issuance in the chip's closed computing environment. The working key pair does not leave the hardware security chip throughout the derivation process.

[0010] Mobile secondary CAs only use the private key in the working key pair to perform routine digital certificate issuance operations, and the private key is always stored inside the hardware security chip and cannot be exported.

[0011] When the mobile secondary CA is lost or unavailable, the offline root CA is reactivated. The offline root CA regenerates the seed and distributes it to the new mobile secondary CA hardware security chip via a physical security carrier. The new hardware security chip then derives a new working key pair based on the regenerated seed, thus achieving disaster recovery without the need to reissue the secondary CA certificate or replace the root CA certificate.

[0012] The physical archiving of the offline root CA includes:

[0013] The hardware device of the offline root CA is physically disconnected from all network interfaces and stored in a secure environment with physical access control. It is only temporarily activated when a secondary CA certificate is needed for issuance or disaster recovery. After issuance or recovery is completed, it is restored to the offline archived state and all network interfaces are disconnected again.

[0014] The physical security carrier is a tamper-proof storage medium with two-way authentication. The seed is stored in the physical security carrier in encrypted form. After receiving the physical security carrier, the hardware security chip of the mobile secondary CA first performs two-way authentication with the offline root CA. Only after successful authentication can the seed be decrypted and imported.

[0015] Two-way authentication is performed based on the unique hardware identifier of the hardware security chip and the signature certificate of the offline root CA, ensuring that the seed can only be imported by authorized hardware security chips.

[0016] The key derivation function built into the hardware security chip is a key derivation function based on the national cryptographic SM series algorithm. Before calling the key derivation function, the hardware security chip first executes a chip self-test program to verify the physical integrity of the chip and the code integrity of the key derivation function. Only after the self-test is passed can the derivation operation be executed.

[0017] During the derivation operation, the seed and intermediate operation data in the derivation process are stored in the secure storage area of ​​the hardware security chip. The secure storage area has physical anti-read protection to ensure that the seed and intermediate operation data never leave the physical boundary of the hardware security chip.

[0018] Among them, when the hardware security chip derives working key pairs, it also uses the current timestamp and the count value of the derivation counter as auxiliary input parameters of the key derivation function to participate in the derivation operation, so that the working key pairs obtained by each derivation are unique.

[0019] The derivation counter automatically increments after each successful derivation, and its count value is synchronously stored in the secure storage area of ​​the hardware security chip and the audit database of the offline root CA. This is used to verify the legitimacy of the derivation operation and prevent replay attacks during disaster recovery.

[0020] The key derivation and distribution method of the two-level physical CA architecture also includes a full storage step for the key derivation and distribution process:

[0021] Record root CA operation logs on the offline root CA side. The root CA operation logs should include at least the root CA activation time, activation reason, operator identity information, seed generation time, and seed hash digest.

[0022] On the mobile secondary CA side, record the secondary CA operation log. The secondary CA operation log should include at least the seed import time, the time of each key derivation operation, the count value of the derivation counter, the derivation record of the working key pair, and the record of each certificate issuance.

[0023] The root CA operation log and the secondary CA operation log are linked together by a hash chain, and tampering with any log can be detected by breaking the hash chain;

[0024] Upload the root CA operation log and the secondary CA operation log to the audit server for unified storage.

[0025] The key derivation and distribution method of the two-tier physical CA architecture also includes a data mining optimization step based on storage logs:

[0026] The audit server performs data mining on the stored root CA operation logs and secondary CA operation logs to extract key derivation frequency, certificate issuance frequency, derivation success rate, and operation distribution in different time periods as correlation data.

[0027] Based on the correlation data, the relationship between the key derivation efficiency and certificate issuance load of the mobile secondary CA is analyzed, and suggestions for optimizing the derivation parameters are generated.

[0028] The derivation parameter optimization suggestions include suggestions for adjusting the iteration rounds of the key derivation function, suggestions for adjusting the validity period of the working key pair, and suggestions for adjusting the derivation triggering strategy;

[0029] The derivation parameter optimization suggestions are fed back to the configuration management module of the mobile secondary CA, and the configuration management module dynamically adjusts the subsequent key derivation parameters based on the derivation parameter optimization suggestions.

[0030] This invention discloses a key derivation and distribution method based on a two-tier physical CA architecture. Through a physical two-tier architecture of an offline root CA and a mobile secondary CA, combined with a mechanism of seed derivation rather than direct transmission of working keys, it eliminates the risk of the root CA's private key being exposed on the network. Simultaneously, it enables the secondary CA's working key pairs to possess flexible characteristics of being reconstructable and replaceable. Specifically, the offline root CA is only briefly online when issuing secondary CA certificates, and is then physically sealed, greatly compressing the attack surface of the root key. After the seed is injected into the hardware security chip via a physical security carrier, the key derivation function runs independently in the chip's closed environment. The working key pair never leaves the chip, and the private key cannot be exported, ensuring that even in high-risk environments, the key materials will not be stolen or tampered with externally during routine issuance operations. Furthermore, when the mobile secondary CA becomes inoperable due to loss, damage, or changes in its trusted status, there is no need to invalidate the original secondary CA certificate or replace the root CA certificate. Simply reactivating the offline root CA and generating a new seed allows the new hardware security chip to derive entirely new working key pairs, achieving rapid disaster recovery through decoupling of certificate and key logic. It avoids the cumbersome process and business interruption of reapplying for certificates, redistributing public keys, and notifying all dependent parties to update the trust chain, reducing recovery time from hours or even days to minutes. At the same time, it reduces the risk of chain revocation caused by private key leakage, and significantly improves the availability, resilience and operation and maintenance efficiency of public key infrastructure in mobile scenarios. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0032] Figure 1 This is a flowchart of the key derivation and distribution method of the two-level physical CA architecture of the present invention. Detailed Implementation

[0033] The embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, but should not be construed as limiting the present invention.

[0034] Please refer to Figure 1 , Figure 1 This is a flowchart of the key derivation and distribution method for a two-level physical CA architecture according to the present invention. An embodiment of the present invention provides a key derivation and distribution method for a two-level physical CA architecture, including:

[0035] S1. Provides a two-level physical architecture of offline root CA and mobile secondary CA. The offline root CA is only used to issue secondary CA certificates of mobile secondary CA. After the issuance is completed, it is switched to offline state and physically sealed.

[0036] In this specific implementation, the physical archiving of the offline root CA includes:

[0037] The hardware device of the offline root CA is physically disconnected from all network interfaces and stored in a secure environment with physical access control. It is only temporarily activated when a secondary CA certificate is needed for issuance or disaster recovery. After issuance or recovery is completed, it is restored to the offline archived state and all network interfaces are disconnected again.

[0038] S2. The offline root CA generates a seed for deriving keys, rather than directly generating or transmitting the working key itself.

[0039] S3. Securely transmit the seed to the hardware security chip of the mobile secondary CA through a physical security carrier;

[0040] In this specific embodiment, the physical security carrier is a tamper-proof storage medium with two-way authentication. The seed is stored in the physical security carrier in encrypted form. After receiving the physical security carrier, the hardware security chip of the mobile secondary CA first performs two-way authentication with the offline root CA. Only after successful authentication can the seed be decrypted and imported.

[0041] Two-way authentication is performed based on the unique hardware identifier of the hardware security chip and the signature certificate of the offline root CA, ensuring that the seed can only be imported by authorized hardware security chips.

[0042] S4. The hardware security chip of the mobile secondary CA calls the built-in key derivation function, using the seed as the unique root input, to independently derive the working key pair used for daily certificate issuance in the chip's closed computing environment. The working key pair does not leave the hardware security chip throughout the derivation process.

[0043] In this specific implementation, the key derivation function built into the hardware security chip is a key derivation function based on the national cryptographic SM series algorithm. Before calling the key derivation function, the hardware security chip first executes a chip self-test program to verify the physical integrity of the chip and the code integrity of the key derivation function. Only after the self-test passes can the derivation operation be executed.

[0044] During the derivation operation, the seed and intermediate operation data in the derivation process are stored in the secure storage area of ​​the hardware security chip. The secure storage area has physical anti-read protection to ensure that the seed and intermediate operation data never leave the physical boundary of the hardware security chip.

[0045] When deriving working key pairs, the hardware security chip also uses the current timestamp and the count value of the derivation counter as auxiliary input parameters of the key derivation function to participate in the derivation operation, so that the working key pairs obtained by each derivation are unique.

[0046] The derivation counter automatically increments after each successful derivation, and its count value is synchronously stored in the secure storage area of ​​the hardware security chip and the audit database of the offline root CA. This is used to verify the legitimacy of the derivation operation and prevent replay attacks during disaster recovery.

[0047] S5, the mobile secondary CA only uses the private key in the working key pair to perform daily digital certificate issuance operations, and the private key is always stored inside the hardware security chip and cannot be exported;

[0048] S6. When the mobile secondary CA is lost or unavailable, the offline root CA is reactivated. The offline root CA regenerates the seed and distributes it to the new mobile secondary CA hardware security chip via the physical security carrier. The new hardware security chip derives a new working key pair based on the regenerated seed, thus achieving disaster recovery without having to reissue the secondary CA certificate or replace the root CA certificate.

[0049] For this specific implementation, the key derivation and distribution method of the two-level physical CA architecture also includes a full-process storage step for the key derivation and distribution:

[0050] Record root CA operation logs on the offline root CA side. The root CA operation logs should include at least the root CA activation time, activation reason, operator identity information, seed generation time, and seed hash digest.

[0051] On the mobile secondary CA side, record the secondary CA operation log. The secondary CA operation log should include at least the seed import time, the time of each key derivation operation, the count value of the derivation counter, the derivation record of the working key pair, and the record of each certificate issuance.

[0052] The root CA operation log and the secondary CA operation log are linked together by a hash chain, and tampering with any log can be detected by breaking the hash chain;

[0053] Upload the root CA operation log and the secondary CA operation log to the audit server for unified storage.

[0054] The key derivation and distribution method of the two-tier physical CA architecture also includes a data mining optimization step based on storage logs:

[0055] The audit server performs data mining on the stored root CA operation logs and secondary CA operation logs to extract key derivation frequency, certificate issuance frequency, derivation success rate, and operation distribution in different time periods as correlation data.

[0056] Based on the correlation data, the relationship between the key derivation efficiency and certificate issuance load of the mobile secondary CA is analyzed, and suggestions for optimizing the derivation parameters are generated.

[0057] The derivation parameter optimization suggestions include suggestions for adjusting the iteration rounds of the key derivation function, suggestions for adjusting the validity period of the working key pair, and suggestions for adjusting the derivation triggering strategy;

[0058] The derivation parameter optimization suggestions are fed back to the configuration management module of the mobile secondary CA, and the configuration management module dynamically adjusts the subsequent key derivation parameters based on the derivation parameter optimization suggestions.

[0059] Furthermore, a real-time monitoring module is deployed in the hardware security chip of the mobile secondary CA. During the key derivation and distribution process, the real-time monitoring module continuously monitors the following detection items: the physical environment parameters of the hardware security chip, the running status of the chip self-test program, the legality of the input parameters of the key derivation function, the continuity of the derivation counter, the consistency of the derivation results of the working key pair, and the connection status of the physical security carrier.

[0060] When the real-time monitoring module detects an anomaly in any detection item, it immediately triggers an anomaly rollback operation.

[0061] Abnormal rollback operations include: terminating the current key derivation operation, clearing all intermediate data generated in this derivation from the secure storage area of ​​the hardware security chip, reverting the derivation counter to the value before the start of this derivation, and reporting the abnormal event to the audit server.

[0062] The abnormal rollback operation also includes: when the physical environment parameters of the hardware security chip are detected to exceed the preset security threshold, the hardware security chip automatically triggers a physical layer data clearing operation, permanently erasing the seeds and all derived data stored in the secure storage area, and sending an emergency alarm signal to the management end of the offline root CA to request the redistribution of seeds.

[0063] Disaster recovery specifically includes:

[0064] After confirming that the mobile secondary CA is lost or unavailable, the management terminal of the offline root CA retrieves the last known derivation counter value of the mobile secondary CA from the audit server.

[0065] The offline root CA is temporarily activated. Based on the last known derivation counter value, a new seed is generated and the derivation start count value of the new seed is recorded.

[0066] The new seed and derived start count value are securely transmitted to the hardware security chip of the new mobile secondary CA through a new physical security carrier.

[0067] After the new mobile secondary CA's hardware security chip is introduced with a new seed, it continues to perform key derivation operations from the derivation start count value, so that the newly derived working key pair remains logically continuous with the working key pair before it was lost, thus achieving secure and seamless disaster recovery.

[0068] This invention discloses a key derivation and distribution method based on a two-tier physical CA architecture. Through a physical two-tier architecture of an offline root CA and a mobile secondary CA, combined with a mechanism of seed derivation rather than direct transmission of working keys, it eliminates the risk of the root CA's private key being exposed on the network. Simultaneously, it enables the secondary CA's working key pairs to possess flexible characteristics of being reconstructable and replaceable. Specifically, the offline root CA is only briefly online when issuing secondary CA certificates, and is then physically sealed, greatly compressing the attack surface of the root key. After the seed is injected into the hardware security chip via a physical security carrier, the key derivation function runs independently in the chip's closed environment. The working key pair never leaves the chip, and the private key cannot be exported, ensuring that even in high-risk environments, the key materials will not be stolen or tampered with externally during routine issuance operations. Furthermore, when the mobile secondary CA becomes inoperable due to loss, damage, or changes in its trusted status, there is no need to invalidate the original secondary CA certificate or replace the root CA certificate. Simply reactivating the offline root CA and generating a new seed allows the new hardware security chip to derive entirely new working key pairs, achieving rapid disaster recovery through decoupling of certificate and key logic. It avoids the cumbersome process and business interruption of reapplying for certificates, redistributing public keys, and notifying all dependent parties to update the trust chain, reducing recovery time from hours or even days to minutes. At the same time, it reduces the risk of chain revocation caused by private key leakage, and significantly improves the availability, resilience and operation and maintenance efficiency of public key infrastructure in mobile scenarios.

[0069] The above-disclosed embodiments are merely one or more preferred embodiments of this application and should not be construed as limiting the scope of this application. Those skilled in the art can understand that all or part of the processes for implementing the above embodiments and equivalent changes made in accordance with the claims of this application still fall within the scope of this application.

Claims

1. A key derivation and distribution method for a two-level physical CA architecture, characterized in that, include: It provides a two-tier physical architecture of offline root CA and mobile secondary CA. The offline root CA is only used to issue secondary CA certificates for mobile secondary CA. After the issuance is completed, it switches to offline state and is physically archived. The offline root CA generates a seed for deriving keys, rather than directly generating or transmitting the working key itself; The seeds are securely transmitted to the hardware security chip of the mobile secondary CA via a physical security carrier. The hardware security chip of the mobile secondary CA calls the built-in key derivation function, using the seed as the unique root input, to independently derive the working key pair used for daily certificate issuance in the chip's closed computing environment. The working key pair does not leave the hardware security chip throughout the derivation process. Mobile secondary CAs only use the private key in the working key pair to perform routine digital certificate issuance operations, and the private key is always stored inside the hardware security chip and cannot be exported. When the mobile secondary CA is lost or unavailable, the offline root CA is reactivated. The offline root CA regenerates the seed and distributes it to the new mobile secondary CA hardware security chip via a physical security carrier. The new hardware security chip then derives a new working key pair based on the regenerated seed, thus achieving disaster recovery without the need to reissue the secondary CA certificate or replace the root CA certificate.

2. The key derivation and distribution method of the two-level physical CA architecture as described in claim 1, characterized in that, The physical archive of the offline root CA includes: The hardware device of the offline root CA is physically disconnected from all network interfaces and stored in a secure environment with physical access control. It is only temporarily activated when a secondary CA certificate is needed for issuance or disaster recovery. After issuance or recovery is completed, it is restored to the offline archived state and all network interfaces are disconnected again.

3. The key derivation and distribution method of the two-level physical CA architecture as described in claim 2, characterized in that, The physical security carrier is a tamper-proof storage medium with two-way authentication. The seed is stored in the physical security carrier in encrypted form. After receiving the physical security carrier, the hardware security chip of the mobile secondary CA first performs two-way authentication with the offline root CA. Only after successful authentication can the seed be decrypted and imported. Two-way authentication is performed based on the unique hardware identifier of the hardware security chip and the signature certificate of the offline root CA, ensuring that the seed can only be imported by authorized hardware security chips.

4. The key derivation and distribution method of the two-level physical CA architecture as described in claim 3, characterized in that, The key derivation function built into the hardware security chip is a key derivation function based on the national cryptographic SM series algorithm. Before calling the key derivation function, the hardware security chip first executes a chip self-test program to verify the physical integrity of the chip and the code integrity of the key derivation function. Only after the self-test passes can the derivation operation be executed. During the derivation operation, the seed and intermediate operation data in the derivation process are stored in the secure storage area of ​​the hardware security chip. The secure storage area has physical anti-read protection to ensure that the seed and intermediate operation data never leave the physical boundary of the hardware security chip.

5. The key derivation and distribution method of the two-level physical CA architecture as described in claim 4, characterized in that, When deriving working key pairs, the hardware security chip also uses the current timestamp and the count value of the derivation counter as auxiliary input parameters of the key derivation function to participate in the derivation operation, so that the working key pairs obtained by each derivation are unique. The derivation counter automatically increments after each successful derivation, and its count value is synchronously stored in the secure storage area of ​​the hardware security chip and the audit database of the offline root CA. This is used to verify the legitimacy of the derivation operation and prevent replay attacks during disaster recovery.

6. The key derivation and distribution method of the two-level physical CA architecture as described in claim 5, characterized in that, The key derivation and distribution method of the two-tier physical CA architecture also includes a full storage step in the key derivation and distribution process: Record root CA operation logs on the offline root CA side. The root CA operation logs should include at least the root CA activation time, activation reason, operator identity information, seed generation time, and seed hash digest. On the mobile secondary CA side, record the secondary CA operation log. The secondary CA operation log should include at least the seed import time, the time of each key derivation operation, the count value of the derivation counter, the derivation record of the working key pair, and the record of each certificate issuance. The root CA operation log and the secondary CA operation log are linked together by a hash chain, and tampering with any log can be detected by breaking the hash chain; Upload the root CA operation log and the secondary CA operation log to the audit server for unified storage.

7. The key derivation and distribution method of the two-level physical CA architecture as described in claim 6, characterized in that, The key derivation and distribution method of the two-tier physical CA architecture also includes data mining optimization steps based on storage logs: The audit server performs data mining on the stored root CA operation logs and secondary CA operation logs to extract key derivation frequency, certificate issuance frequency, derivation success rate, and operation distribution in different time periods as correlation data. Based on the correlation data, the relationship between the key derivation efficiency and certificate issuance load of the mobile secondary CA is analyzed, and suggestions for optimizing the derivation parameters are generated. The derivation parameter optimization suggestions include suggestions for adjusting the iteration rounds of the key derivation function, suggestions for adjusting the validity period of the working key pair, and suggestions for adjusting the derivation triggering strategy; The derivation parameter optimization suggestions are fed back to the configuration management module of the mobile secondary CA, and the configuration management module dynamically adjusts the subsequent key derivation parameters based on the derivation parameter optimization suggestions.

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