4 ms·

You can audit the code, compile, synthesise, place and route the design, tape out masks, send it to a fab, decap a few of the chips you get back and look at it

You can audit the code, compile, synthesise, place and route the design, tape out masks, send it to a fab, decap a few of the chips you get back and look at it under a microscope. You should be able to compare that to the masks to verify the design hasn't been tampered with. It's harder to audit ASICs that other people have had fabricated without having the exact same standard cell libraries, tooling versions (optimisations change over time), knowing what optimisation settings they used, etc. to be able to prove the masks came from the same code.

brianwawok 10y ago
Is spot checking good enough? Wouldnt you need to follow every trace?
- olympus 10y ago
  In hardware, implementing a backdoor that provides a reasonable level of functionality is probably going to cause a visible change to the layout/routing, kind of like a software backdoor is going to change the hash. I say probably because it's possible that advanced actors like the USA and China have developed tools that add features (backdoors) while making the visual layout look very similar. Then you would probably only find the backdoors by "fuzzing" the chip like you would a piece of software.
  - ashitlerferad 10y ago
    There are hardware backdoors that require only dopant-level changes, see the second comment here: https://lwn.net/Articles/688751/ https://lwn.net/Articles/688751/
    - digi_owl 10y ago
      It feels like trying to fend of anything but automated drive-by attacks online will be a fools errand.
  - jevinskie 10y ago
    You can do it with a single gate and a handful of passive parts. http://ieee-security.org/TC/SP2016/papers/0824a018.pdf http://ieee-security.org/TC/SP2016/papers/0824a018.pdf
- kevin_thibedeau 10y ago
  The masks can be converted back into a netlist and then a formal Logic Equivalence Checker can verify correspondence with the original HDL.
  - analognoise 10y ago
    That won't protect against the dopant level attacks, but you could have an automated test run to ascertain dopant levels on chips that you decapped - if you want to take paranoia to the absolute limits. That would take serious time and money to setup computer controlled micropositioners and expensive source measurement units, etc. Iirc, there was a group from the CCC working on using image recognition algorithms to extract netlists from decapped chips. I'll have to look that up...
DigitalJack 10y ago
The weak link there is the masks. It's rare for the company creating the design to make the masks unless they are their own foundry. And many foundries themselves outsource masks due to equipment costs.

brianwawok 10y ago

Is spot checking good enough? Wouldnt you need to follow every trace?

olympus 10y ago
In hardware, implementing a backdoor that provides a reasonable level of functionality is probably going to cause a visible change to the layout/routing, kind of like a software backdoor is going to change the hash. I say probably because it's possible that advanced actors like the USA and China have developed tools that add features (backdoors) while making the visual layout look very similar. Then you would probably only find the backdoors by "fuzzing" the chip like you would a piece of software.
- ashitlerferad 10y ago
  There are hardware backdoors that require only dopant-level changes, see the second comment here: https://lwn.net/Articles/688751/ https://lwn.net/Articles/688751/
  - digi_owl 10y ago
    It feels like trying to fend of anything but automated drive-by attacks online will be a fools errand.
- jevinskie 10y ago
  You can do it with a single gate and a handful of passive parts. http://ieee-security.org/TC/SP2016/papers/0824a018.pdf http://ieee-security.org/TC/SP2016/papers/0824a018.pdf
kevin_thibedeau 10y ago
The masks can be converted back into a netlist and then a formal Logic Equivalence Checker can verify correspondence with the original HDL.
- analognoise 10y ago
  That won't protect against the dopant level attacks, but you could have an automated test run to ascertain dopant levels on chips that you decapped - if you want to take paranoia to the absolute limits. That would take serious time and money to setup computer controlled micropositioners and expensive source measurement units, etc. Iirc, there was a group from the CCC working on using image recognition algorithms to extract netlists from decapped chips. I'll have to look that up...

DigitalJack 10y ago

The weak link there is the masks. It's rare for the company creating the design to make the masks unless they are their own foundry. And many foundries themselves outsource masks due to equipment costs.