4 ms·

I'm trying to remember a technique based on listening to static or whitenoise and taking the least significant bit. You then take that stream of bits and postp

I'm trying to remember a technique based on listening to static or whitenoise and taking the least significant bit. You then take that stream of bits and postprocess it by looking for bit changes and don't use them directly. That's a vague and I'm sure inaccurate description, but it isn't enough for me to google it ... anyone know what I'm referring to?

chipuni 5y ago
That sounds a lot like what https://www.random.org/ https://www.random.org/ does to create random numbers.
- rrauenza 5y ago
  Perhaps -- I can't find their description behind the process and I'm now curious about the math behind it. I think they would take a series of 0's and 1's.. 0010001110100100011 ...and map that into 0's and 1's based on the changes, not the numbers themselves. Maybe like 00 or 11 mapped to 0 and 10 or 01 mapped to 1? I can't recall.
  - denton-scratch 5y ago
    This sounds like the Von Neumann Extractor. https://en.wikipedia.org/wiki/Randomness_extractor https://en.wikipedia.org/wiki/Randomness_extractor It's purpose is to remove bias: the propensity of physical random processes to produce more 1s than 0s (or v.v.). Unlike some whiteners (AES?) it can be implemented with a handful of gates.
    - rrauenza 5y ago
      Yes, that's it. And it's used to eliminate bias. I found a good explanation at https://www.youtube.com/watch?v=xquB4rDbsvc https://www.youtube.com/watch?v=xquB4rDbsvc at about 14min.
  - chipuni 5y ago
    random.org definitely uses that process. See: https://www.random.org/statistics/source-purity/ https://www.random.org/statistics/source-purity/