Security Coprocessor Signing for Trusted REE Evaluation
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Solution Overview
Problem
The reliability of security evaluation methods for electronic devices is poor, particularly in rich execution environments, leading to potential tampering and insecurity in accessing application services.
Innovation Solution
A security coprocessor determines a target security evaluation result, decrypts a ciphertext using a root key to obtain a private key, signs the result with the private key, and sends a signature to an application server, ensuring the security evaluation result is bound to the device and resistant to attacks like hardware side channels and fault injection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If security evaluation is performed in a rich execution environment, then service access can be provided, but the reliability of the security evaluation result is poor and susceptible to tampering
Solution Approach 1:
The system divides the execution environment into two separate parts: a rich execution environment (REE) for service operations and a trusted execution environment (TEE) for security evaluation. This segmentation allows service access to continue in the REE while security evaluation is performed in the isolated TEE, ensuring reliability without sacrificing adaptability.
Solution Approach 2:
A security coprocessor is introduced as an intermediary component that bridges the REE and TEE. It collects security status information from the REE, performs evaluation in the TEE, and returns results to the REE. This intermediary ensures that the security evaluation process is protected from tampering while still enabling service access.
2Device complexity
If security evaluation results are not bound to the device, then processing is simpler, but tampering and insecurity occur
Solution Approach 1:
The security evaluation result is bound to the device's private key in advance through digital signature. The TEE signs the evaluation result with the device's private key before returning it to the REE, creating a tamper-evident binding. This preliminary action ensures that any subsequent tampering can be detected without adding complex verification processes.
Solution Approach 2:
The system transforms the security evaluation result from a plain data value into a cryptographically signed parameter. By changing the parameter format from unsigned to digitally signed, the system provides tamper protection while maintaining relatively simple processing through standard cryptographic operations.
3Speed
If the private key is stored in plaintext, then access is faster, but security is compromised
Solution Approach 1:
The private key is stored in an encrypted state within the TEE, with different access paths for different operations. The TEE maintains local security properties by keeping the key encrypted at rest while providing fast access during authorized operations through hardware-accelerated decryption, thus achieving both speed and security.
Solution Approach 2:
The key storage system uses a composite structure combining encrypted storage with hardware-based decryption capabilities in the TEE. This composite approach integrates both security (encrypted storage) and performance (hardware acceleration) into a unified key management solution.
Data Source
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AI summary
This application provides a security evaluation method, a service processing method, a security information transmission method, and a related device, and relates to the field of communication technologies. The method includes: determining a target security evaluation result based on first security information in a case that a security evaluation request sent by an application server is received, where the first security information includes security status information of an REE of an electronic device or a security evaluation result of the REE; decrypting a first ciphertext by using a root key of the electronic device, to obtain a private key of the electronic device, where the first ciphertext is a ciphertext obtained by a security coprocessor by encrypting the private key of the electronic device by using the root key of the electronic device; signing the target security evaluation result by using the private key of the electronic device, to obtain a signature of the target security evaluation result; and sending second security information to the application server, where the second security information includes the target security evaluation result and the signature of the target security evaluation result.