Hybrid TEE Device Cache Purging Controller Memory Isolation
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Solution Overview
Problem
Existing trusted execution environments (TEEs) are vulnerable to malicious code execution due to inadequate memory isolation, cache manipulation, and information leakage issues, such as the 'Rowhammer' vulnerability.
Innovation Solution
A Hybrid TEE device is implemented using hardware elements like a Cache Purging Controller (CPC), Memory Isolation Gateway (MIG), and Memory Clean Up (MCU) in conjunction with TEE-enabled System software to enhance security and prevent malicious code execution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional TEE memory isolation is used, then code execution security is improved, but memory isolation adequacy deteriorates due to cache leakage and resource sharing
Solution Approach 1:
The patent segments the memory architecture into separate secure and non-secure memory spaces with dedicated isolation gateways. The secure memory region is physically separated from non-secure memory, and access between them is controlled through isolation gateways that enforce strict access control policies, preventing cache leakage and resource sharing vulnerabilities.
Solution Approach 2:
The patent introduces isolation gateways as intermediary components between secure and non-secure memory regions. These gateways act as mediators that control and monitor all memory access transitions, ensuring that only authorized access is permitted while blocking unauthorized access attempts, thereby resolving the memory isolation adequacy issue.
2Adaptability or versatility
If functional module switching from secure world to normal world is implemented, then application flexibility is improved, but switching vulnerability increases
Solution Approach 1:
The patent implements preliminary security checks and validation procedures before allowing switching from the secure world to the normal world. The system performs verification of access rights, validates memory addresses, and ensures security policies are met prior to enabling the functional module switching, thereby reducing switching vulnerabilities while maintaining application flexibility.
3Productivity
If resource sharing between secure world and normal world is allowed, then system efficiency is improved, but cache leakage risk increases
Solution Approach 1:
The patent segments the cache memory into separate secure and non-secure cache regions, physically isolating them to prevent cache leakage. Each cache region is independently managed with its own access control mechanisms, allowing system efficiency through resource sharing while eliminating the cache leakage risk through strict segmentation.
Solution Approach 2:
The patent introduces cache isolation gateways as intermediary components that control access between secure and non-secure cache regions. These gateways monitor and regulate cache access operations, preventing unauthorized data exposure while maintaining efficient resource sharing capabilities through controlled intermediation.
4Reliability
If memory access control is strengthened, then security against malicious code is improved, but device complexity increases
Solution Approach 1:
The patent merges multiple security functions into integrated isolation gateway components that handle memory access control, cache management, and security policy enforcement in a unified architecture. This consolidation reduces the overall device complexity by combining what would otherwise be separate complex subsystems into coordinated single-point-of-control components.
Data Source
AI summary
A Hybrid TEE device allows a Trusted Execution Environment (TEE) by incorporating hardware comprising a Cache Purging Controller, a Memory Isolation Gateway, and a Memory Clean Up into a System on a Chip device, a general purpose computing device, or a special purpose or proprietary computing or electronic device. The addition of the hardware enables a method of protecting the Trusted Execution Environment and thus reducing vulnerability to malicious software or other program code.