Trusted Execution Environment Key Refresh Mechanism
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Refreshing key material in a trusted execution environment (TEE) is challenging as it may affect applications and interactions between a mobile device and other parties, requiring a seamless transition from old to new key material without disrupting cryptographic operations.
Innovation Solution
A method to refresh key material in a TEE by receiving new key material, setting a new key identifier, and providing it directly or indirectly with cryptographic outputs, using key diversification techniques to manage the transition, ensuring compatibility with both hardware and software environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If key material is refreshed in a TEE, then security against subversion is improved, but applications and interactions relying on cryptographic operations are disrupted
Solution Approach 1:
The system performs preliminary actions by establishing a new key pair and generating the new public key before the old key material expires or is compromised. This allows the TEE to have the new key material ready and waiting, so that when the refresh occurs, applications can transition smoothly without interruption or disruption to their cryptographic operations.
Solution Approach 2:
The patent introduces an intermediary mechanism through the use of key identifiers and the structured key material refresh process. The system uses a key identifier to track which key material is currently in use, and the refresh process itself acts as an intermediary transition mechanism that allows applications to continue operating with the old key while the new key is being prepared and validated, ensuring no disruption to application continuity.
2Device complexity
If a single master key is used in a TEE, then device complexity is reduced, but the key remains vulnerable over the operating lifetime of the TEE
Solution Approach 1:
The patent implements dynamic key material management by enabling the TEE to refresh its key material during operation rather than relying on a static single master key. The system dynamically generates new key pairs, updates key identifiers, and manages transitions between different key materials based on operational needs, security policies, or time-based criteria, making the key management system adaptive and resilient over the TEE's operating lifetime.
Solution Approach 2:
The system changes the parameter of key material freshness by implementing a key refresh mechanism that periodically or event-driven updates the cryptographic keys. Instead of using a single master key throughout the TEE's lifetime, the system changes the key material parameters (generating new keys, updating identifiers) to maintain security effectiveness while managing the complexity through structured processes.
3Reliability
If key material is changed in a TEE, then security is improved, but transitions to new key material become complex and error-prone
Solution Approach 1:
The patent segments the key material into distinct components including key identifiers, public keys, and private keys, and further segments the refresh process into discrete steps. This segmentation allows the system to manage key transitions systematically, tracking which key material is active through identifiers, and processing refreshes in controlled stages that reduce errors and complexity in the transition process.
Solution Approach 2:
The system implements feedback mechanisms through key identifiers that track the current key material state and through the structured refresh process that provides feedback on the status of key transitions. This feedback enables the TEE and external parties to verify which key material is currently in use, monitor the refresh process, and ensure successful transitions, reducing complexity and errors in key material changes.
Data Source
AI summary
A method of refreshing key material is described for use in a trusted execution environment logically protected from a regular execution environment. The trusted execution environment further comprises a key identifier. New key material is received at the trusted execution environment to replace existing key material. The key identifier is set to a new value to indicate that new key material is present. The new value of the key identifier is provided directly or indirectly to other parties in association with cryptographic outputs provided by the trusted execution environment using the refreshed key material. This approach is described in connection with an application executing securely on a mobile device.