Persistent File System in Secure Enclave via Key Derivation
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Solution Overview
Problem
Secure enclaves face challenges in persisting data across different CPUs and enclave versions, as well as ensuring data integrity and confidentiality, especially in cloud computing environments where the CPU may change.
Innovation Solution
A key derivation provider system that includes a key derivation enclave (KDE) generates and manages keys that can be used by application enclaves (AEs) to decrypt data, regardless of the CPU on which the AEs are executing. This system ensures that the same key is provided to affiliated AEs and that the keys are compatible across different platforms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If data is encrypted using CPU-specific keys for persistence, then data confidentiality is improved, but data accessibility across different CPUs deteriorates
Solution Approach 1:
The patent introduces a key derivation provider as an intermediary service that mediates between the encryption requirement and cross-CPU accessibility. This service derives platform-independent encryption keys from platform-specific materials, allowing data to be encrypted with keys that work across different CPUs while maintaining confidentiality. The key derivation provider acts as the mediator that translates CPU-specific security requirements into universal key materials.
Solution Approach 2:
The patent segments the key management functionality into separate components: CPU-specific key material generation, platform-independent key derivation, and data encryption/decryption operations. This segmentation allows each component to operate independently with well-defined interfaces, enabling the system to maintain strong CPU-specific security while achieving cross-platform compatibility through the derived keys.
2Reliability
If enclave versions are updated to fix security vulnerabilities, then security is improved, but data persistence compatibility deteriorates
Solution Approach 1:
The patent implements dynamic key derivation that adapts to different enclave versions and CPU platforms. The key derivation process is designed to be flexible and version-agnostic, allowing the same derived keys to work across multiple enclave versions. This dynamic adaptation enables security updates without breaking data persistence compatibility, as the derivation mechanism automatically adjusts to the running environment while producing compatible keys.
3Strength
If platform-specific key material is used for encryption, then encryption strength is improved, but portability across platforms deteriorates
Solution Approach 1:
The patent transforms platform-specific key material parameters into platform-independent derived key parameters through a mathematical derivation process. The transformation changes the parameter space from CPU-specific identifiers to universal key materials that maintain the cryptographic strength properties while becoming portable across different platforms. This parameter transformation is the core mechanism that resolves the contradiction between strong local encryption and broad portability.
Data Source
AI summary
A secure enclave is hosted by an untrusted host. To securely persist data on the untrusted host, the secure enclave generates or updates a persistent file system, wherein the persistent file system is a collection of logical files. The secure enclave segments the persistent file system into a plurality of sectors. The secure enclave provides a key specification to a key derivation enclave. The secure enclave obtains an encryption key dynamically generated based on the key specification. The secure enclave cryptographically protects each of the plurality of sectors using the key and causes the host to write a plurality of encrypted sectors to a disk as a single physical file.