Out-of-band Microcontroller Secure Boot Key Management
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Solution Overview
Problem
Existing secure boot protocols, such as those defined by the UEFI standard, are vulnerable to attacks due to the inability to revoke public keys or certificates at boot time, allowing counterfeit loaders to be introduced into the platform, as the security relies on the platform's ability to securely store public keys which can be compromised.
Innovation Solution
A system and method utilizing an out-of-band microcontroller with Active Management Technology (AMT) capabilities to securely store and validate signature keys and certificates, ensuring they are inaccessible to the host processor and allowing for remote validation and revocation through out-of-band communication, thereby enhancing the UEFI secure boot protocol.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If public keys and certificates are stored on the firmware for secure boot, then digital signature verification can be performed on EFI drivers and OS loaders, but the security is compromised because the platform cannot securely store the public keys and revocation at boot time is not possible
Solution Approach 1:
The system separates the secure key storage function from the main firmware by implementing a dedicated key storage area within the ROM that is inaccessible to the host processor. This segmentation isolates the critical security function (public key storage) from the potentially vulnerable firmware environment, allowing secure boot validation while preventing key compromise.
Solution Approach 2:
A secondary processor or secure execution environment acts as an intermediary between the boot process and the stored public keys. This intermediary validates digital signatures on EFI drivers and OS loaders without exposing the private keys or allowing direct modification, enabling revocation at boot time while maintaining security.
2Adaptability or versatility
If the firmware stores public keys to enable secure boot, then authentication of boot components can be performed, but the device complexity increases and security vulnerabilities arise from the inability to revoke keys
Solution Approach 1:
The system implements dynamic key management by enabling revocation of public keys at boot time through a secondary processor or secure execution environment. This allows the system to adapt security policies in real-time without requiring hardware changes, achieving boot time revocation capability while managing complexity through software-based solutions.
Solution Approach 2:
The ROM with embedded public keys is designed to serve multiple functions: storing authentication keys for secure boot, enabling revocation at boot time, and providing a secure foundation for future security updates. This multi-functionality reduces the need for separate dedicated hardware components, managing device complexity while enhancing adaptability.
Data Source
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AI summary
In some embodiments, the invention involves a system and method relating to secure booting of a platform. In at least one embodiment, the present invention is intended to securely boot a platform using one or more signature keys stored in a secure location on the platform, where access to the signature is by a microcontroller on the platform and the host processor has no direct access to alter the signature key. Other embodiments are described and claimed.