4 ms·

To print all the chips on your own mini-fab - maybe. Eventually.

by snaky 8y ago

RcouF1uZ4gsC 8y ago
But your mini-fab might be backdoored and create chips with backdoors.
- responseguy 8y ago
  More likely that the schematics will contain backdoors, that aren't easily understood to be backdoors. EDIT: have - contains
  - 0xcde4c3db 8y ago
    It could conceivably be done even below the schematic level, though I'm not sure how much room modern processes have for this sort of thing now that we're talking about how many atoms wide a transistor is. I've been told that there was a period of a few years in which a kind of "copy protection" proliferated in IC layouts. The layouts would be tweaked to exploit quirks of the originating company's fabrication process (e.g. a pattern might look like a diode but actually function as a resistor when fabricated), and this would sabotage attempts by other companies to clone the chip (at the time, Japanese and Soviet clones were major concerns).
    - snaky 8y ago
      The lower a level, the easier to add a backdoor, the harder to audit. To add the backdoor to the handwritten assembly code is much easier than to do this with (reasonably clean style) C, and both are easier than add it to Standard ML or Haskell code. The same is true with verified formal hardware description specifications, Verilog and lithographic mask. So the path toward trustworthy computing, besides cheap fabs, is higher level tools, projects like Kami and CakeML, proof checking, automatic verification and synthesis.
- snaky 8y ago
  That's harder thing to do on every iteration down to the first principles. So in theory you maybe could do the hammer, which is made so as to specifically clog nails with a deviation of 5.2 degrees to the left, which leads to the light bulbs distortions in the chip designer room which eventually leads to particular backdoor in the chip he designed - but this is really hard.
  - BuildTheRobots 8y ago
    Isn't this just the physical manifestation of "Trusting Trust" - the seminal paper on backdooring compilers? It might be difficult, but who really inspects their own prints at a 100-micron resolution? https://www.archive.ece.cmu.edu/~ganger/712.fall02/papers/p761-thompson.pdf https://www.archive.ece.cmu.edu/~ganger/712.fall02/papers/p7... - there's plenty of HN discussions to be found too.
    - snaky 8y ago
      That's why we are talking about cheap small mini-fabs instead of just placing the order to any Chinese fab. The mini-fabs would use open-source community-driven software which is easy to audit for backdoors. That's not easy, but the trend is toward that, for sure - e.g. pick and place systems driven by OpenPNP is a step in this direction.
    - floren 8y ago
      The example in Trusting Trust was a very specific case: he modified the C compiler to replace a known bit of code in the login program. Along those same lines, you could possibly set up your minifab such that it inserts a backdoor into a particular RISC-V implementation. However, if I sat down and made my own chip, how would the fab figure out how to insert a backdoor? If you have code which can analyze a processor layout and seamlessly insert a backdoor, please come forward and collect your Turing Award.
      - groby_b 8y ago
        "made my own chip" You are aware that making a chip with any reasonable processing power either requires using existing designs, or teams of hundreds of people for several years, yes? You're back to trusting trust. Or using toy computers.

To print all the chips on your own mini-fab - maybe. Eventually.

by snaky 8y ago

To print all the chips on your own mini-fab - maybe. Eventually.

RcouF1uZ4gsC 8y ago

But your mini-fab might be backdoored and create chips with backdoors.

responseguy 8y ago
More likely that the schematics will contain backdoors, that aren't easily understood to be backdoors. EDIT: have - contains
- 0xcde4c3db 8y ago
  It could conceivably be done even below the schematic level, though I'm not sure how much room modern processes have for this sort of thing now that we're talking about how many atoms wide a transistor is. I've been told that there was a period of a few years in which a kind of "copy protection" proliferated in IC layouts. The layouts would be tweaked to exploit quirks of the originating company's fabrication process (e.g. a pattern might look like a diode but actually function as a resistor when fabricated), and this would sabotage attempts by other companies to clone the chip (at the time, Japanese and Soviet clones were major concerns).
  - snaky 8y ago
    The lower a level, the easier to add a backdoor, the harder to audit. To add the backdoor to the handwritten assembly code is much easier than to do this with (reasonably clean style) C, and both are easier than add it to Standard ML or Haskell code. The same is true with verified formal hardware description specifications, Verilog and lithographic mask. So the path toward trustworthy computing, besides cheap fabs, is higher level tools, projects like Kami and CakeML, proof checking, automatic verification and synthesis.
snaky 8y ago
That's harder thing to do on every iteration down to the first principles. So in theory you maybe could do the hammer, which is made so as to specifically clog nails with a deviation of 5.2 degrees to the left, which leads to the light bulbs distortions in the chip designer room which eventually leads to particular backdoor in the chip he designed - but this is really hard.
- BuildTheRobots 8y ago
  Isn't this just the physical manifestation of "Trusting Trust" - the seminal paper on backdooring compilers? It might be difficult, but who really inspects their own prints at a 100-micron resolution? https://www.archive.ece.cmu.edu/~ganger/712.fall02/papers/p761-thompson.pdf https://www.archive.ece.cmu.edu/~ganger/712.fall02/papers/p7... - there's plenty of HN discussions to be found too.
  - snaky 8y ago
    That's why we are talking about cheap small mini-fabs instead of just placing the order to any Chinese fab. The mini-fabs would use open-source community-driven software which is easy to audit for backdoors. That's not easy, but the trend is toward that, for sure - e.g. pick and place systems driven by OpenPNP is a step in this direction.
  - floren 8y ago
    The example in Trusting Trust was a very specific case: he modified the C compiler to replace a known bit of code in the login program. Along those same lines, you could possibly set up your minifab such that it inserts a backdoor into a particular RISC-V implementation. However, if I sat down and made my own chip, how would the fab figure out how to insert a backdoor? If you have code which can analyze a processor layout and seamlessly insert a backdoor, please come forward and collect your Turing Award.
    - groby_b 8y ago
      "made my own chip" You are aware that making a chip with any reasonable processing power either requires using existing designs, or teams of hundreds of people for several years, yes? You're back to trusting trust. Or using toy computers.