Local Certificate Deprecation for Secure Boot
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Solution Overview
Problem
Connected devices, particularly IoT and legacy devices, lack computing resources and network connectivity, making it difficult to implement modern certificate revocation techniques, and there is a need for secure management of security credentials without relying on external networks.
Innovation Solution
A local certificate management system that uses multiple certificates stored in secure memory, allowing for secure boot operations by iteratively validating firmware with active certificates, enabling deprecation of compromised certificates without external communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If modern certificate revocation techniques are implemented, then security credential management is improved, but device complexity and resource requirements increase
Solution Approach 1:
The patent segments the certificate management function by storing multiple certificates in a certificate store and maintaining a separate deprecated certificate list. This allows the device to manage security credentials through simple list operations rather than complex revocation checking, resolving the contradiction between security management capability and device complexity.
Solution Approach 2:
The patent uses a simplified copy-based approach where instead of implementing full certificate revocation checking, the system maintains a list of deprecated certificate identifiers. The validation process simply checks whether the current certificate identifier appears in the deprecated list, which is a much lighter computational operation that fits resource-constrained devices.
2Reliability
If modern certificate revocation techniques are implemented, then security credential management is improved, but network connectivity requirements increase
Solution Approach 1:
The patent implements self-service certificate management by storing deprecated certificate identifiers locally in the device memory. The system can independently validate whether a certificate is deprecated by checking the local list without needing to communicate with external certificate authorities or networks, making the device adaptable to isolated network environments.
Solution Approach 2:
The patent performs preliminary action by pre-storing deprecated certificate identifiers in the device memory before they are actually needed for validation. This allows the device to immediately recognize and reject deprecated certificates without requiring real-time network communication, enabling secure operation in offline environments.
3Reliability
If multiple certificates are stored in secure memory, then firmware validation security is improved, but memory requirements increase
Solution Approach 1:
The patent extracts only the essential information needed for certificate validation by storing only certificate identifiers rather than full certificate data. This minimizes the memory footprint while maintaining the ability to perform secure firmware validation, as the system only needs to compare identifiers against the deprecated list rather than store complete certificate structures.
Data Source
AI summary
Embodiments described herein provide techniques for securely validating firmware on a device using certificates and providing a mechanism for deprecating select certificates when a traditional certificate authority is unavailable or otherwise cannot be used. When a first firmware package is installed on the device, a first certificate in a first secure memory location is associated with an active status. Responsive to validation and installation of a second firmware package on the device, a second certificate in a second secure memory location on the device is associated with an active status. During a boot-up operation on the device, embodiments determine to use the second certificate to validate the second firmware package by starting at a predefined secure memory location and scanning backwards until a status of active is identified. The second firmware package on the device is then validated using the second certificate.