Re:Show HN: The SC4-HSM, a fully open USB hardware secure mo...
by lisper on Friday July 08, 2016 @04:08AM
(#12054160)
The RDP on the F4 is more capable than the F1. The F1 only has level 1 RDP, the F4 has level 2 as well. If you can break level 2 without decapping the chip that would be big news (and probably result in a class action lawsuit against STM). Can you describe how you did it? [EDIT: Never mind, I see you already answered that in the other branch of this thread.]
Re:Show HN: The SC4-HSM, a fully open USB hardware secure mo...
by kosma on Sunday July 10, 2016 @05:37AM
(#12065085)
I had a look at the documentation and it seems they finally made it a JTAG fuse and not just a value in program memory. Nice move.
Re:Show HN: The SC4-HSM, a fully open USB hardware secure mo...
by mkj on Friday July 08, 2016 @03:55AM
(#12054118)
Nice, I'd wondered how hard that would be. Could you share details?
Re:Show HN: The SC4-HSM, a fully open USB hardware secure mo...
by kosma on Friday July 08, 2016 @04:12AM
(#12054168)
The FPB (flash patch and breakpoint) peripheral on Cortex-M3 allows live-patching the flash contents; this allows you to temporarily change the reset vector. That, plus careful supply voltage glitching to reset some peripherals but not other, and the device is pwned.
I have managed to bypass readout protection on STM32F1 with just a few nights of hacking and $2 in parts; I suspect F4 isn't much different. I wouldn't trust any general purpose MCU in this regard.