4 ms·

Wow I was JUST thinking about this today: Can there be a hardware random number generator that solely relies on such cosmic particles etc. hitting it? Bonus:

Wow I was JUST thinking about this today: Can there be a hardware random number generator that solely relies on such cosmic particles etc. hitting it? Bonus: Use it as signs from God (reminiscing of Terry Davis of TempleOS)

defrost 4y ago
Sure .. although you'll find it will have a (perhaps surprisingly) consistant distribution of energies and timings and here on earth will fluctuate by density of atmosphere above (height, humidity, tempreture) and relationship to earths magnetic flux lines with a partial coupling to solar output. Airborne radiometric ground surveys run calibration flights at varying altitude to build an estimate of cosmic activity in order to subtract that from ground events originating from Uranium, Potassium, Thorium, Radon, etc.
- sebzim4500 4y ago
  Those kind of trends don't matter very much if you e.g. only look at the least significant bits of the detection count.
  - defrost 4y ago
    They might suggest more interesting applications such as using cosmic rays to map the interior of pyramids though.
Bayart 4y ago
As far as I know, the counts per minute for background radiation you get with cheap compact captors (say the stuff you find on Geiger counters) is pretty low, a dozen to a hundred counts per minute. That's not a lot of entropy. You could much more precise captors, but then you couldn't just plug it into a PCIe slot. At this scale, you probably get more entropy from just jitter on the electrical circuit. And it's pointless to have one huge centralized RNG, at least from a security standpoint.
- tgflynn 4y ago
  > You could much more precise captors What do you mean by that ? There are only so many particles of ionizing radiation traversing a given surface per unit time (fortunately for us).
  - Bayart 4y ago
    I meant bigger. But it doesn't sound quite as nice as "precise".
    - idiocrat 4y ago
      You can open up a cheap USB camera to get the nacked CCD sensor and put a radioactive source (Americium-241) from a smoke detector directly onto the chip. The CCD sensor, connected as USB camera, will record thousands of flashes/sec capturing the alpha radiation.
idiocrat 4y ago
For increased entropy, you can use a thermal noise from a cheap camera or a static noise from a microphone.
V__ 4y ago
This is what random.org does: > A binary digit (bit) can be either 0 or 1. There are several Random.org radios located in Copenhagen, Dublin, and Ballsbridge, each generating 12,000 bits per second[8] from the atmospheric noise picked up.[9] The generators produce a continuous string of random bits which are converted into the form requested (integer, Gaussian distribution, etc.) [1] https://en.wikipedia.org/wiki/Random.org https://en.wikipedia.org/wiki/Random.org
- dmurray 4y ago
  Should that read "Ballsbridge, Dublin and Copenhagen"?
shagie 4y ago
Hotbits uses radioactive decay as its source https://www.fourmilab.ch/hotbits/ https://www.fourmilab.ch/hotbits/ It measures the time between two events (call this T1) and then the time between the next two events (call this T2). If T1 > T2, you've got a 1. If T1 < T2, you've got a 0. If T1 = T2 throw it out. As this is measuring the time between events rather than the rate of events, a decaying source just gives less bits over time rather than less randomness. > The trick I use was dreamed up in a conversation in 1985 with John Nagle, who is doing some fascinating things these days with artificial animals. Since the time of any given decay is random, then the interval between two consecutive decays is also random. What we do, then, is measure a pair of these intervals, and emit a zero or one bit based on the relative length of the two intervals. If we measure the same interval for the two decays, we discard the measurement and try again, to avoid the risk of inducing bias due to the resolution of our clock.
- dmurray 4y ago
  Doesn't the time between events increase over time as there are fewer radioactive atoms left to decay? So E[T1] < E[T2] and you get slightly more 0 bits than 1s. I'm sure the device is on a scale where this effect is tiny, but the description sounds like the creator is aiming for absolute theoretical correctness rather than "good enough" randomness which is not so hard to come by.
  - shagie 4y ago
    If you've got a mole of cesium (137 grams), that's 10^23 atoms. The difference between 10^23 and (10^23) - 1 would be lost in the clock resolution of the computer it is hooked up to. The statistical tests of randomness are described at https://www.fourmilab.ch/hotbits/statistical_testing/stattest.html https://www.fourmilab.ch/hotbits/statistical_testing/stattes... from ent ( https://www.fourmilab.ch/random/ https://www.fourmilab.ch/random/ ) Entropy = 7.999975 bits per byte. Optimum compression would reduce the size of this 11468800 byte file by 0 percent. Chi square distribution for 11468800 samples is 402.53, and randomly would exceed this value 0.01 percent of the times. Arithmetic mean value of data bytes is 127.5423 (127.5 = random). Monte Carlo value for Pi is 3.141486168 (error 0.00 percent). Serial correlation coefficient is -0.000053 (totally uncorrelated = 0.0). I'd be impressed to find any other data source that is more random than hotbits (autocorrect keeps wanting to make this hobbits). ---- (late edit) https://www.fourmilab.ch/hotbits/how3.html https://www.fourmilab.ch/hotbits/how3.html specifically addresses this though: > For example, you might worry about the fact that the intensity of the radiation source is slowly decreasing over time. Cæsium-137's 30.17 year half-life isn't all that long. One half-life in the future, we'll measure T1 and T2 intervals, on the average, twice as long as today. This means, then, that even on consecutive measurements there is a small bias in favour of T2 being longer than T1. How serious is this? Well, expressed in seconds, the half-life is about 9.5×108 and we receive count pulses at a rate of 1000 per second or so. So the time needed to perform the measurements to produce one random bit is on the order of 10−12 half-lives, and T2 will then tend to be longer by a factor of the same magnitude. Since the inter-count interval is around a millisecond, this means T2 will be, on average, 10−15 seconds longer than T1. This is comparable to the long-term accuracy of the best atomic time standards and is entirely negligible for our purposes. The crystal oscillator which provides the time base for the computer making the measurement is only accurate to 100 parts per million, or one part in ten thousand, and thus can induce errors ten million times as large as those due to the slow decay of the source. (This is, again, unlikely to be a real problem because most computer clocks, while prone to drifting as temperature and supply voltage vary, do not change significantly on the millisecond scale. Still, jitter due to where the clock generator happens to trigger on the oscillator waveform will still dwarf the effects of decay of the source during one measurement.)

defrost 4y ago

Sure .. although you'll find it will have a (perhaps surprisingly) consistant distribution of energies and timings and here on earth will fluctuate by density of atmosphere above (height, humidity, tempreture) and relationship to earths magnetic flux lines with a partial coupling to solar output. Airborne radiometric ground surveys run calibration flights at varying altitude to build an estimate of cosmic activity in order to subtract that from ground events originating from Uranium, Potassium, Thorium, Radon, etc.

sebzim4500 4y ago
Those kind of trends don't matter very much if you e.g. only look at the least significant bits of the detection count.
- defrost 4y ago
  They might suggest more interesting applications such as using cosmic rays to map the interior of pyramids though.

Bayart 4y ago

As far as I know, the counts per minute for background radiation you get with cheap compact captors (say the stuff you find on Geiger counters) is pretty low, a dozen to a hundred counts per minute. That's not a lot of entropy. You could much more precise captors, but then you couldn't just plug it into a PCIe slot. At this scale, you probably get more entropy from just jitter on the electrical circuit. And it's pointless to have one huge centralized RNG, at least from a security standpoint.

tgflynn 4y ago
> You could much more precise captors What do you mean by that ? There are only so many particles of ionizing radiation traversing a given surface per unit time (fortunately for us).
- Bayart 4y ago
  I meant bigger. But it doesn't sound quite as nice as "precise".
  - idiocrat 4y ago
    You can open up a cheap USB camera to get the nacked CCD sensor and put a radioactive source (Americium-241) from a smoke detector directly onto the chip. The CCD sensor, connected as USB camera, will record thousands of flashes/sec capturing the alpha radiation.

idiocrat 4y ago

For increased entropy, you can use a thermal noise from a cheap camera or a static noise from a microphone.

V__ 4y ago

This is what random.org does: > A binary digit (bit) can be either 0 or 1. There are several Random.org radios located in Copenhagen, Dublin, and Ballsbridge, each generating 12,000 bits per second[8] from the atmospheric noise picked up.[9] The generators produce a continuous string of random bits which are converted into the form requested (integer, Gaussian distribution, etc.) [1] https://en.wikipedia.org/wiki/Random.org https://en.wikipedia.org/wiki/Random.org

dmurray 4y ago
Should that read "Ballsbridge, Dublin and Copenhagen"?

shagie 4y ago

Hotbits uses radioactive decay as its source https://www.fourmilab.ch/hotbits/ https://www.fourmilab.ch/hotbits/ It measures the time between two events (call this T1) and then the time between the next two events (call this T2). If T1 > T2, you've got a 1. If T1 < T2, you've got a 0. If T1 = T2 throw it out. As this is measuring the time between events rather than the rate of events, a decaying source just gives less bits over time rather than less randomness. > The trick I use was dreamed up in a conversation in 1985 with John Nagle, who is doing some fascinating things these days with artificial animals. Since the time of any given decay is random, then the interval between two consecutive decays is also random. What we do, then, is measure a pair of these intervals, and emit a zero or one bit based on the relative length of the two intervals. If we measure the same interval for the two decays, we discard the measurement and try again, to avoid the risk of inducing bias due to the resolution of our clock.

dmurray 4y ago
Doesn't the time between events increase over time as there are fewer radioactive atoms left to decay? So E[T1] < E[T2] and you get slightly more 0 bits than 1s. I'm sure the device is on a scale where this effect is tiny, but the description sounds like the creator is aiming for absolute theoretical correctness rather than "good enough" randomness which is not so hard to come by.
- shagie 4y ago
  If you've got a mole of cesium (137 grams), that's 10^23 atoms. The difference between 10^23 and (10^23) - 1 would be lost in the clock resolution of the computer it is hooked up to. The statistical tests of randomness are described at https://www.fourmilab.ch/hotbits/statistical_testing/stattest.html https://www.fourmilab.ch/hotbits/statistical_testing/stattes... from ent ( https://www.fourmilab.ch/random/ https://www.fourmilab.ch/random/ ) Entropy = 7.999975 bits per byte. Optimum compression would reduce the size of this 11468800 byte file by 0 percent. Chi square distribution for 11468800 samples is 402.53, and randomly would exceed this value 0.01 percent of the times. Arithmetic mean value of data bytes is 127.5423 (127.5 = random). Monte Carlo value for Pi is 3.141486168 (error 0.00 percent). Serial correlation coefficient is -0.000053 (totally uncorrelated = 0.0). I'd be impressed to find any other data source that is more random than hotbits (autocorrect keeps wanting to make this hobbits). ---- (late edit) https://www.fourmilab.ch/hotbits/how3.html https://www.fourmilab.ch/hotbits/how3.html specifically addresses this though: > For example, you might worry about the fact that the intensity of the radiation source is slowly decreasing over time. Cæsium-137's 30.17 year half-life isn't all that long. One half-life in the future, we'll measure T1 and T2 intervals, on the average, twice as long as today. This means, then, that even on consecutive measurements there is a small bias in favour of T2 being longer than T1. How serious is this? Well, expressed in seconds, the half-life is about 9.5×108 and we receive count pulses at a rate of 1000 per second or so. So the time needed to perform the measurements to produce one random bit is on the order of 10−12 half-lives, and T2 will then tend to be longer by a factor of the same magnitude. Since the inter-count interval is around a millisecond, this means T2 will be, on average, 10−15 seconds longer than T1. This is comparable to the long-term accuracy of the best atomic time standards and is entirely negligible for our purposes. The crystal oscillator which provides the time base for the computer making the measurement is only accurate to 100 parts per million, or one part in ten thousand, and thus can induce errors ten million times as large as those due to the slow decay of the source. (This is, again, unlikely to be a real problem because most computer clocks, while prone to drifting as temperature and supply voltage vary, do not change significantly on the millisecond scale. Still, jitter due to where the clock generator happens to trigger on the oscillator waveform will still dwarf the effects of decay of the source during one measurement.)