3 ms·

Given that the microscope inspection saw the individual bits in the microcode tables, I wonder how possible it would be to visually extract crypto keys baked in

Given that the microscope inspection saw the individual bits in the microcode tables, I wonder how possible it would be to visually extract crypto keys baked into the processor for newer models. I doubt they'd be in a nice orderly addressed ROM area like this, but they still have to be hardcoded somewhere.

madez 9y ago
There are techniques to prevent reading stored data in chips. Smartcards often have some of those protections.
- marcosdumay 9y ago
  Good luck protecting against offline reading with a microscope. The only defense is that this thing is expensive.
userbinator 9y ago
I wonder how possible it would be to visually extract crypto keys baked into the processor for newer models AFAIK the Intel ones use public-key encryption[1], so you would not really gain anything. They obviously thought of this. [1] http://inertiawar.com/microcode/ http://inertiawar.com/microcode/ - 2048-bit RSA too, so not really breakable in the near future either.
- solotronics 9y ago
  I wonder if there will be a point that machine learning algorithms can hack better than humans? Already they can play certain games and find solutions that seem alien to us. Perhaps this is already occuring?
rft 9y ago
As was already pointed out, any protection scheme would most likely use asymetric crypto, so you can only dump the public key anyway. However there is a more pressing problem, that you would even have if symetric crypto was used: In order to extract the key you would need to know how it is encoded, which you only know once you know the plaintext of the microcode (which requires the encryption key to read the microcode updates). You run into a chicken-egg problem. Without the processor oracle, it would have been hard to impossible to start guessing the semantics of bitstrings. Also the physical ROM bits are not in the same order as the bits the CPU actually excutes during runtime. The mapping function is non trivial and we do not fully understand it yet. Finding this function required knowing what valid, plaintext microcode looks like so we could match the bitstrings from the ROM to it.

madez 9y ago

There are techniques to prevent reading stored data in chips. Smartcards often have some of those protections.

marcosdumay 9y ago
Good luck protecting against offline reading with a microscope. The only defense is that this thing is expensive.

userbinator 9y ago

I wonder how possible it would be to visually extract crypto keys baked into the processor for newer models AFAIK the Intel ones use public-key encryption[1], so you would not really gain anything. They obviously thought of this. [1] http://inertiawar.com/microcode/ http://inertiawar.com/microcode/ - 2048-bit RSA too, so not really breakable in the near future either.

solotronics 9y ago
I wonder if there will be a point that machine learning algorithms can hack better than humans? Already they can play certain games and find solutions that seem alien to us. Perhaps this is already occuring?

rft 9y ago

As was already pointed out, any protection scheme would most likely use asymetric crypto, so you can only dump the public key anyway. However there is a more pressing problem, that you would even have if symetric crypto was used: In order to extract the key you would need to know how it is encoded, which you only know once you know the plaintext of the microcode (which requires the encryption key to read the microcode updates). You run into a chicken-egg problem. Without the processor oracle, it would have been hard to impossible to start guessing the semantics of bitstrings. Also the physical ROM bits are not in the same order as the bits the CPU actually excutes during runtime. The mapping function is non trivial and we do not fully understand it yet. Finding this function required knowing what valid, plaintext microcode looks like so we could match the bitstrings from the ROM to it.