Becoming a tyrant: Implementing secure boot in embedded devices

on YouTube ↗42m

" summary

Describes implementing secure boot on embedded SoMs by trusting vendor boot ROM, burning e-fuses burned to lock stages, using signed U-Boot FIT image to verify kernel and device tree, adding a TPM for key storage and TPM parameter encryption, and protecting rootfs with dm-verity and signed update images. Advises multiple hardware kits (one sacrificial for fuses), blow JTAG fuses, design factory programming and key separation, and expect higher dev cost and bricking risk; solution works but remains vulnerable to physical attacks like logic analyzers and unpatchable hardware bugs.

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" chapters (24)

1. 0:00Intro
2. 0:14Becoming a tyrant: Implementing secure boot in embedded devices
3. 2:15Hi, I'm Irving . I want to talk about secure boot
4. 3:18Chain of trust mechanism • Verify integrity of next component before executing . Can use hashes or public keys . Can provide some protection against tampering (incl. physical)
5. 4:17The Tyrant . Whoever controls the keys/hashes, controls everything
6. 4:56Who is your adversary? . Can be used in a variety of scenarios • Important to determine who has control and who has none
7. 5:39Hyphothetical scenario 3
8. 7:31Anything involving financial transactions
9. 8:59Automotive ECU / Industrial controls • Some devices control heavy and powerful things · Cars, cranes, industrial equipments, steam turbines · Tampering can cause injury, death, and legal liabilities
10. 9:18But I should be able to modify my devices!
11. 10:50What about fixing bugs in ECUs?
12. 12:09Vendor lock-in · Tamperproofing can be used to lock out competitors eg generic spare parts, consumables, self-repair
13. 13:51What kind of secrets? • User data
14. 14:27What kind of protection? · Physical attacks
15. 15:46Why do we need secure boot for this? • Blob / Filesystem/Full disk encryption is not enough
16. 16:29Trusted Platform Modules?
17. 18:25TPM pitfalls · Enable parameter encryption
18. 18:38Encryption with secure boot
19. 19:52Is it worth it?
20. 23:41First stage (hardware-specific) · Always vendor-specific, so start with vendor instructions • Get multiple hardware kits - You will need to burn e-fuse and test different signed builds
21. 26:41Firmware updates . You should use signed images
22. 27:21Mass manufacturing • Locking software/interfaces can limit manufacturing flexibility
23. 30:19U-boot verified boot • Secure and flexible boot with U-Boot bootloader by Marek Vasut
24. 31:21Real-world examples

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