Embedded Controller Attestation Using TPM Firmware Measurements
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Solution Overview
Problem
Existing attestation techniques, both local and remote, face issues such as lack of secure storage for reference measurements, vulnerability to tampering, and high costs, making electronic devices susceptible to cyber attacks.
Innovation Solution
Implementing on-device attestation using secure embedded controllers and secure storage, such as secondary SPI's non-volatile storage or one-time-programmable fuses, to store and compare reference measurements during the boot process, ensuring secure and local verification without remote components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If remote attestation is used, then security verification can be performed, but cost increases and device complexity increases
Solution Approach 1:
The patent extracts the attestation functionality from remote services and implements it locally within the device using the secure embedded controller and secure storage. This removes the need for remote attestation services, reducing device complexity and cost while maintaining security verification capabilities through local comparison of reference and current measurements.
Solution Approach 2:
The device performs self-attestation by using its own secure embedded controller and secure storage to store reference measurements and compare them with current firmware component measurements. This self-service approach eliminates dependency on external remote attestation services, reducing complexity and cost.
2Reliability
If secure storage for reference measurements is implemented, then attestation security is improved, but device complexity increases
Solution Approach 1:
The secure embedded controller performs multiple functions including storing reference measurements in secure storage, retrieving current measurements from the TPM, comparing the measurements, and controlling remediation actions. This multi-functionality reduces overall device complexity by consolidating attestation-related components into a single integrated controller.
3Ease of manufacture
If local attestation is used, then cost is reduced, but vulnerability to tampering increases
Solution Approach 1:
The patent segments the attestation process into distinct phases: storing reference measurements in secure storage during initialization, retrieving current measurements from the TPM during boot, comparing the measurements locally, and executing remediation actions if tampering is detected. This segmentation allows cost-effective local attestation while maintaining security through proper separation of functions and use of hardware security modules.
Data Source
AI summary
A method includes performing attestation of an electronic device. Performing the attestation includes retrieving preset security measurements stored in secure storage of a secure embedded controller of the electronic device. Performing the attestation also includes retrieving current firmware component measurements from platform configuration registers (PCRs) of a trusted platform module (TPM) of the electronic device. Performing the attestation includes comparing the preset security measurements with the current firmware component measurements. Performing the attestation includes approving or denying the attestation based on the comparison of the preset security measurements with the current firmware component measurements.