5 ms·

User inputs are not random but they certainly can be entropic. It is crucial to inform the user of this, as software has. "Generating random numbers, please m

User inputs are not random but they certainly can be entropic. It is crucial to inform the user of this, as software has. "Generating random numbers, please move your mouse around randomly" is suitable for literally all use cases.

betwixthewires 5y ago
Yeah, you're right, I guess I should've been more clear, using user inputs naively as an RNG is a bad idea, using it as a source of entropy can be useful. I would never entirely rely on it though, noise is a must, all it can really do is speed up true random number generation, and then only if the implementation is right, combining the sources of entropy naively can lead to reduction in security also, to me the risk of that added complexity is not worth the speed up in anything critical, I'd rather not use user inputs at all.
- tinus_hn 5y ago
  In many cases the next problem would be what to use instead. The alternatives aren’t too great either.
  - IntrepidWorm 5y ago
    Suggestion: Every device has a built in lava lamp that we process into visual noise... Bring the 70's back in a big way.
    - tinus_hn 5y ago
      Many devices already have hardware sources of randomness built in. The problem is just that they are unverifiable and built by companies that have shown themselves to be untrustworthy.
      - catlifeonmars 5y ago
        No, the problem is that the built in sources aren’t funky enough ;) In all seriousness, though, yes and guaranteeing that the manufacturing process itself can “bake” in the randomness is a super interesting area of research. It’s like 99% of the manufacturing process is an exercise in reducing variability, and then there’s PUFs, where you’re basically trying to maximize variability, but in such a way that you maintain computational precision.
  - betwixthewires 5y ago
    There are great alternatives in principle. The problem is incentives to sabotage alternatives by governments and manufacturers. There are chips that produce real entropy, and processors come with integrated hardware for this purpose. The problem is that you don't know if the hardware is deliberately flawed in some way.
hinkley 5y ago
Specifically, PRNGs based on cryptographic algorithms (CSPRNGs) resist loss of existing entropy from having new, low entropy sources appended to the stream. To my thinking, what is more important is that you don’t fool yourself about the amount of entropy from one source, or among sources. Two entropy sources that are dependent variables may be good separately but not together. Like the timings of keystrokes and network packets may be affected by the scheduler, or the fact that you are typing into a remote editor session which is bouncing ACKs back, or auto saving every time you hit enter or change focus.

betwixthewires 5y ago

Yeah, you're right, I guess I should've been more clear, using user inputs naively as an RNG is a bad idea, using it as a source of entropy can be useful. I would never entirely rely on it though, noise is a must, all it can really do is speed up true random number generation, and then only if the implementation is right, combining the sources of entropy naively can lead to reduction in security also, to me the risk of that added complexity is not worth the speed up in anything critical, I'd rather not use user inputs at all.

tinus_hn 5y ago
In many cases the next problem would be what to use instead. The alternatives aren’t too great either.
- IntrepidWorm 5y ago
  Suggestion: Every device has a built in lava lamp that we process into visual noise... Bring the 70's back in a big way.
  - tinus_hn 5y ago
    Many devices already have hardware sources of randomness built in. The problem is just that they are unverifiable and built by companies that have shown themselves to be untrustworthy.
    - catlifeonmars 5y ago
      No, the problem is that the built in sources aren’t funky enough ;) In all seriousness, though, yes and guaranteeing that the manufacturing process itself can “bake” in the randomness is a super interesting area of research. It’s like 99% of the manufacturing process is an exercise in reducing variability, and then there’s PUFs, where you’re basically trying to maximize variability, but in such a way that you maintain computational precision.
- betwixthewires 5y ago
  There are great alternatives in principle. The problem is incentives to sabotage alternatives by governments and manufacturers. There are chips that produce real entropy, and processors come with integrated hardware for this purpose. The problem is that you don't know if the hardware is deliberately flawed in some way.

hinkley 5y ago

Specifically, PRNGs based on cryptographic algorithms (CSPRNGs) resist loss of existing entropy from having new, low entropy sources appended to the stream. To my thinking, what is more important is that you don’t fool yourself about the amount of entropy from one source, or among sources. Two entropy sources that are dependent variables may be good separately but not together. Like the timings of keystrokes and network packets may be affected by the scheduler, or the fact that you are typing into a remote editor session which is bouncing ACKs back, or auto saving every time you hit enter or change focus.