Secure Boot Component Look-Up Table for Failure Handling
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Solution Overview
Problem
Existing secure boot systems, such as those defined by the Trusted Computing Group's Mobile Trusted Module, are inflexible and fail completely if one component fails during the boot process, lacking support for optional components and detailed failure reporting, which can lead to legal compliance issues and hinder emergency functionality in mobile devices.
Innovation Solution
A system and method that allows multiple execution sequences for secure boot, records the success or failure of each individual component, and uses multiple RIM Certificates to support optional components, ensuring continued operation and easier fault diagnosis by maintaining a table of component states and alternative execution paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single control path through the boot process is used to ensure security and trust, then verification reliability is improved, but system adaptability deteriorates because all components cannot be used if one component fails
Solution Approach 1:
The boot process is segmented into multiple independent control paths, each corresponding to different component failure scenarios. Instead of a single linear sequence, the system divides the boot process into alternative paths that can be selected based on which components are available, allowing the system to maintain security verification while adapting to various failure conditions.
Solution Approach 2:
The control path selection is made dynamic based on the actual boot status of components. The system determines at runtime which path to follow based on which components have successfully booted, rather than following a fixed predetermined sequence. This allows the system to adapt its verification process to the actual system state.
2Device complexity
If optional components are implemented with explicit switches to support flexibility, then device complexity is reduced, but error handling capability deteriorates when component program file corruption or hardware initialization failure occurs
Solution Approach 1:
The system performs preliminary verification of component integrity and initialization status before attempting to boot optional components. By checking for corruption and initialization failures in advance, the system can prevent errors from propagating and can select appropriate alternative paths before the failure occurs, rather than reacting after the error manifests.
Solution Approach 2:
The system implements feedback mechanisms that monitor the boot status of each component and use this information to determine the next appropriate action. When a component fails to boot or is corrupted, the feedback from this failure status triggers the selection of an alternative control path, allowing the system to adapt to the error condition while maintaining relatively simple device architecture.
3Reliability
If certificate revocation or corruption of non-critical components causes complete boot failure, then security verification is improved, but legal compliance deteriorates due to inability to make emergency calls
Solution Approach 1:
The system segments the boot process into critical and non-critical components, with different verification requirements for each segment. Certificate verification and security checks are applied selectively based on the component's criticality level, allowing non-critical components to be skipped or use alternative verification methods when their certificates are revoked or corrupted, while still maintaining security for critical components.
Solution Approach 2:
Different verification strictness is applied to different parts of the system based on their criticality. Critical components that affect security and legal compliance (such as emergency calling functionality) maintain strict verification, while non-critical components allow for more flexible handling when verification fails, enabling the system to maintain security where needed while preserving essential functionality.
4Device complexity
If a single RIM Certificate is used for each role to simplify verification, then device complexity is reduced, but measurement precision deteriorates in detecting where boot process failures occur
Solution Approach 1:
The verification system is segmented into multiple RIM Certificates, each responsible for verifying specific components or stages of the boot process. Instead of using a single certificate for all verification, the system divides verification tasks across multiple certificates, each with a specific scope. This segmentation enables precise identification of which component or stage caused a failure by determining which certificate's verification failed.
Data Source
AI summary
A method to allow a device to boot in a secure fashion, even though some of the components within the secure device's firmware may not be present, not correctly authorized, or not correctly operating.