Secure Boot Device Using Dual Public Key Verification
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Solution Overview
Problem
Existing secure boot systems for electronic devices face challenges in verifying the integrity of firmware during the manufacturing process, particularly when the public key has not yet been written, leaving the firmware vulnerable to forgery or alteration.
Innovation Solution
An electronic device is configured with a first memory area for storing firmware signed with a private key, a second memory area for the boot loader to verify integrity using a public key, and a third memory area for storing a public key, where the boot loader verifies firmware integrity using either the stored public key or an embedded public key depending on its presence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the public key is not written during manufacturing, then the firmware can be installed and tested, but the firmware becomes vulnerable to forgery or alteration
Solution Approach 1:
The system performs preliminary integrity verification using a temporary public key embedded in the boot loader before the formal public key is written. This preliminary action allows firmware to be installed and tested during manufacturing while maintaining integrity protection through the embedded key that verifies the firmware signature.
Solution Approach 2:
The embedded public key in the boot loader acts as an intermediary verification mechanism. It temporarily mediates the firmware verification process during manufacturing before the formal public key is written, enabling both firmware installation and integrity protection simultaneously.
2Reliability
If the public key is embedded in the boot loader, then firmware integrity can be verified during manufacturing, but the device complexity increases
Solution Approach 1:
The system segments public key storage into two distinct areas: an embedded public key stored in the boot loader for manufacturing-time verification, and a formal public key stored in a separate memory area for post-manufacturing verification. This segmentation allows different verification needs to be met without compromising system security.
Solution Approach 2:
Different parts of the system have different quality requirements: the boot loader requires an embedded public key for immediate verification during manufacturing, while the firmware storage area requires a formal public key for subsequent verification. Each memory area is configured with the appropriate public key type for its specific function.
3Reliability
If firmware verification is performed during manufacturing, then unauthorized changes are prevented, but the manufacturing process time increases
Solution Approach 1:
Firmware integrity verification is performed as a preliminary action during the boot process using the embedded public key before the formal public key is written. This allows manufacturing to proceed with verification already in place without adding significant time overhead to the manufacturing process.
Data Source
AI summary
Disclosed is an electronic device configured to perform a secure boot. The electronic device according to an embodiment disclosed herein may include: a first memory area for storing a firmware signed with a private key; a second memory area for storing a boot loader configured to verify integrity of the firmware and executing the firmware of which integrity has been verified; and a third memory area for storing a first public key paired with the private key, wherein the second memory area may store a second public key paired with the private key. The boot loader may verify the integrity of the firmware with the first public key when there is the first public key in the third memory area and verify the integrity of the firmware with the second public key when there is no first public key is in the third memory area.