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NumWorks open source calculator
08-31-2017, 09:55 PM
Post: #27
RE: NumWorks open source calculator
Without a form of secure boot, upgrading will be possible. It could be very hard.

I'd expect there to be a small boot loader which runs the calculator firmware. If this boot loader is properly checking for cryptographic signatures, you're not loading a new image onto the device while it is there.

This doesn't stop you necessarily, it might be possible to attach debugging headers to the board and to then replace the boot loader with your own. Soldering will be required and the case will have to be opened. Even if the debug pins aren't run out somewhere nice (they almost always are), it could still be possible to hook them up -- I've seen loose wires pushed under a BGA chip to contact an internal pin before.

If this approach isn't possible, the processor can be replaced by another which you've programmed specially.

Far more likely is the boot loader doesn't implement the cryptography properly and there is an exploitable hole.

The real question is: is it worth the effort? The answer is most likely no. If you are up to doing the kinds of things required, you are probably up to learning the exam material.


Pauli
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Messages In This Thread
NumWorks open source calculator - BobVA - 08-28-2017, 10:33 PM
RE: NumWorks open source calculator - Dan - 08-29-2017, 02:37 AM
RE: NumWorks open source calculator - Paul Dale - 08-31-2017 09:55 PM
NumWorks User manual!!!!!!!!!! - Namir - 09-06-2017, 08:10 PM
RE: NumWorks open source calculator - JDW - 07-07-2018, 10:30 PM
RE: NumWorks open source calculator - JDW - 07-08-2018, 12:55 PM
RE: NumWorks open source calculator - JDW - 07-09-2018, 12:03 AM
RE: NumWorks open source calculator - JDW - 07-10-2018, 12:04 AM
RE: NumWorks open source calculator - JDW - 07-15-2018, 01:11 PM
RE: NumWorks open source calculator - JDW - 07-12-2018, 12:03 AM
RE: NumWorks open source calculator - JDW - 07-14-2018, 01:41 PM



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