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Comment by lll-o-lll | Hacker News Reader

What an interesting talk, and an interesting concept also. Open source hardware security; get the security researchers interested and fix the security defects.

The “read the data out with a super expensive microscope” remained. Is there any way to defeat that attack I wonder? I suppose the hsm model of “destructive tamper detection” is one way.

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I patented something that had a countermeasure for this, which was a bit impractical but fun to think about. Basically you put the sensitive data in an eeprom layered with a chemical that emits UV when exposed to air or, optionally, visible light - chemically more entertaining, hard to manufacture. But it's a just an arms race at that point.

Cool idea, but seems pretty straightforward to bypass and definitely an arms race

The current solution is obfuscation. They make the mapping from physical state to actual key complicated enough that you have to reverse engineer a lot of the logic.

You can also bury the fuse array inside the chip. So in addition to the microscope, you will also have to non-destructively etch or mill the chip to expose the fuses. This also renders the chip non-functional, so if the secret is unique per chip, then the leaked secret can't be used to bootstrap to other secrets on the die.

> The “read the data out with a super expensive microscope” remained. Is there any way to defeat that attack I wonder?

Get your chip made with the latest TSMC process and get features so small nobody else, even superpowers and trillion-dollar tech companies working together, can manipulate them :)

A good scanning electron microscope costs at most a few million? And is pretty common in a decently funded lab pretty much anywhere? Resolutions of 5nm is not uncommon. A scanning tunnelling microscope can go much lower (single atom types) and isn’t all that much more expensive either (comparatively I mean).

I think it’s common knowledge by now that the smallest feature in a 5nm chip isn’t really 5nm. So that’s not (yet?) a viable strategy.

Manipulating features smaller than what TSMC manufacture is possible in many places (just at great expense), TSMC's special sauce is being able to manufacture it in quantity and economically. Ultimately it's always going to be difficult to completely protect storage at rest, because it is possible to take something apart atom by atom, but it does raise the cost of the attack substantially.

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