Maynard Handley (name99.delete@this.name99.org) on December 11, 2018 7:20 am wrote:
>......
> The crypto has to be appropriate to the problem. This is NOT the equivalent of network crypto.
> For example, suppose the equivalent of a random key burned into the device is XOR'd with everything
> going into and out of an MRAM cache (maybe also XOR-in the relevant addresses).
> Is that good enough? On the off-chance that someone could extract the contents
> of the MRAM cache (which may or may not be true?) the assumption is always
> that they CANNOT extract the contents of these sorts of hardware keys.

Such a scheme would be about as secure as writing a key on a yellow postit on your monitor.

Unfortunately the fact is that good encryption is hard, and somewhat computationally involved.

Not to mention the fact that with a static key, both ends need that key, as as soon as it leaks, its game over.

Real security is about reducing threat envelopes, and adding complexity rarely does that - moving the secure data to its own completely separate physical device with the simplest possible interface, dedicated to just that function is generally a good start, but securing a high complexity shared resource such as a modern cloud server? good luck.. Securing something where a bad actor has physical access enough to remove memory? good lucky..