nthdimtech / signet-cad Goto Github PK

During device initialization the user should be allowed to set a "security level". For any value other than the lowest security level firmware updates will have to have a correct digital signature. In a medium security level setting the signing key would bet set at initialization but could be changed later. At a high security level the signing key would be fixed for the lifetime of the device after initialization.

How do you protect the content of the storage (i.e. flash memory) against HW attacks?

Mainly against reading it out e.g. by connecting to appropriate pins on the PCB and messing up with the signals (including clock/crystal). I could not find you're burning some internal transistors to protect against such attacks nor you're allowing the user to lock the flash memory (before any reading or writing can start) by a very long unique key submitted before any use. I'm not sure which locking features the chosen MCU has, but for me this is a very important question.

I wonder whether I can put Signet into a salty water, leave it there for two weeks, put it out, let it dry (at least a bit) and connect to a computer. It sounds pretty extreme, but it's a time-condensed test for e.g. United Arabic Emirates (yeah, I'm in that country more and more often and the salty humidity of 95% is really an electronics killer).

Is there any water-resistant coating on the PCB and possibly some finish of the PCB with already all components mounted?