Targeting Protocol Head for Secure TrEE Key Delivery
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Solution Overview
Problem
The existing key management systems (KMS) face security limitations when delivering secrets or keys to Trusted Execution Environments (TrEEs), as they often require secure channels that can be compromised by untrusted requestors, making it difficult to ensure the confidentiality and integrity of the data.
Innovation Solution
Implementing a targeting protocol head (TPH) as an intermediary between the requestor and the KMS, which encrypts and authenticates data using attestation statements from the TrEE, allowing secure delivery of protected data to nested TrEEs without direct access by the requestor, thus eliminating the need for a secure channel between the requestor and the KMS.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a secure channel is established between the requestor and the KMS, then the confidentiality and integrity of the secret delivery is improved, but the complexity of the system increases and the secure channel can still be compromised by untrusted requestors
Solution Approach 1:
The patent introduces a targeting protocol head (TPH) as an intermediary component between the requestor and the KMS. The TPH receives requests from potentially untrusted requestors, extracts attestation statements, and forwards them to the KMS. It then receives the encrypted secret and forwards it to the TrEE. This intermediary architecture eliminates the need for a direct secure channel between the requestor and KMS, reducing system complexity while maintaining security through the TPH's mediation and the TrEE's attestation-based verification.
2Ease of operation
If direct access to the KMS is provided to the requestor, then the ease of operation is improved, but the security against unauthorized access deteriorates
Solution Approach 1:
The patent segments the secret retrieval process into distinct functional components: the requestor initiates the request, the TPH processes and validates the request using attestation statements, the KMS securely stores and retrieves secrets, and the TrEE receives and uses the secrets. This segmentation allows each component to perform its specific function with appropriate security measures, enabling easy operation for authorized users while preventing unauthorized access through the TPH's validation and the TrEE's isolated environment.
Solution Approach 2:
The TPH acts as a mediator that simplifies the operation for requestors by handling the complex attestation and encryption processes automatically. Requestors only need to provide their public key and secret ID, while the TPH manages the secure communication with the KMS and the TrEE. This mediation maintains ease of operation while implementing robust security checks to prevent unauthorized access.
3Reliability
If the TrEE is isolated from the requestor, then the security against attacks is improved, but the ease of operation deteriorates
Solution Approach 1:
The TPH serves as an intermediary that bridges the isolated TrEE and the external requestor. It receives requests from requestors, processes attestation statements to verify the TrEE's identity, retrieves secrets from the KMS, and delivers them to the appropriate TrEE. This mediation maintains the TrEE's isolation for security while simplifying the data delivery process through automated attestation verification and encrypted secret transmission.
Solution Approach 2:
The system performs preliminary attestation verification by the TPH before secret delivery. The TPH validates the TrEE's attestation statement in advance, ensuring the TrEE's identity and integrity before allowing secret retrieval. This preliminary action establishes trust beforehand, enabling easy and secure operation without compromising the TrEE's isolation, as the verification is performed externally by the TPH rather than requiring the TrEE to expose its internal state.
Data Source
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Figure 1B
Figure 1C
AI summary
Methods, systems, and devices are described herein for delivering protected data to a nested trusted execution environment (TrEE), including a trustlet running on top of secure kernel, associated with a potentially untrusted requestor. In one aspect, a targeting protocol head, or other intermediary between a requestor and a key management system or other store of protected data, may receive a request for protected data from a potentially untrusted requestor, and an attestation statement of the secure kernel. The targeting protocol head may encrypt a transfer encryption key with a second encryption key derived from the attestation statement. The targeting protocol head may retrieve the protected data, and encrypt the protected data with the transfer encryption key and an authentication tag, which binds the requestor with the trustlet ID. The targeting protocol head may provide the encrypted transfer encryption key, the encrypted protected data, and encrypted authentication tag to the requestor.