Trusted Execution Environment Access Control via Dynamic Security Domains
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Solution Overview
Problem
Current mobile computing devices face challenges in securely accessing trusted applications due to the risk of malicious applications tricking payment processes and the complexity of access control mechanisms, which can lead to security vulnerabilities and poor user experience.
Innovation Solution
A processor-based system that configures a rich execution environment and a trusted execution environment with a security domain and access control list, where client applications are authorized based on public keys to securely access trusted applications, ensuring improved security and access control without compromising user experience.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a trusted user interface is included within the TEE to prevent fraudulent use of trusted applications, then security is improved, but device complexity increases and user experience deteriorates due to distinct interface requirements
Solution Approach 1:
The patent introduces a Trusted Service Manager (TSM) as an intermediary component that operates at the boundary between REE and TEE. The TSM receives authentication requests from REE applications, validates them against trusted criteria, and controls access to TEE services without requiring a separate trusted user interface. This mediator approach maintains security while avoiding the complexity and user experience issues of implementing a full trusted UI within TEE.
2Ease of operation
If access control mechanisms are implemented in the REE to control TEE access, then access control is improved, but device complexity increases and security reliability decreases due to susceptibility to tampering
Solution Approach 1:
The patent extracts the access control functionality from the REE and relocates it to the TEE level through the Trusted Service Manager. The TSM is installed within the TEE and maintains a trusted access control list that REE applications must present credentials for. This extraction ensures that access control decisions are made by trusted code in the TEE rather than by potentially compromised REE software, thereby improving security reliability while maintaining ease of access control.
3Device complexity
If predefined CA lists are used for access control, then access control is simplified, but adaptability decreases because new CAs cannot be added after installation
Solution Approach 1:
The patent implements a dynamic access control mechanism where the Trusted Service Manager maintains an accessible access control list that can be dynamically updated. The TSM receives authentication requests from REE applications in real-time, validates them against the current access control list, and can add new CAs as needed. This dynamic approach provides both simplicity in operation and adaptability to add new client applications without requiring system reinstallation or complex configuration changes.
Data Source
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AI summary
A processor configured to provide a REE and a TEE where memory in the TEE is protected from access or modification by applications executing within the REE. The processor installs within the REE, a client application, and verifies a signature that was generated with a service provider private key. The processor determines that the client application requires services from a TA, contacts an outside entity, and receives a service provider public key along with data for installing the TA. The key and data are securely transferred the TEE. The processor configures a security domain within the TEE, installs the TA within the security domain, and associates the TA with the security domain, where the security domain is also associated with the service provider public key. The processor configures an access control list within the security domain, where access to the TA is controlled by the access control list.