4 ms·

Here's the fraction of 1s for each bit position output by MD5 and SHA-256 using the first million integers as inputs: https://pastebin.com/aVR3u8Vv https://past

Here's the fraction of 1s for each bit position output by MD5 and SHA-256 using the first million integers as inputs: https://pastebin.com/aVR3u8Vv https://pastebin.com/aVR3u8Vv

withinboredom 4y ago
I quickly threw a few into excel with a pareto graph to show distribution. Granted, it is only the first 10,000 integers % 1000: https://imgur.com/a/HypGWP1 https://imgur.com/a/HypGWP1 To my untrained eye, md5 and sha1 (and not shown, sha256) look remarkably similar to random. If you want truly even distributions, then going with a nieve "X % Y" approach looks better.
- FreakLegion 4y ago
  If you do % 1000 there'll be a bit of bias from the modulus, but not anything meaningful for the use case, and it affects MD5 and SHA both. No argument that for simple incrementing integers a raw modulus is better, though. Even if hashing is needed, a cryptographic hash function probably isn't (depending on threat model, e.g. whether user inputs are involved).
  - withinboredom 4y ago
    MD5 and ShaX are available in almost every language. Things that are probably better (like Murmur3) might not be, or may even have different hashes for the same thing (C# vs JS with Murmur3, for example). I had to reimplement Murmur3 in C# to get the hashes to match from JS, it boiled down to the C# version using longs and eventually casting to an int while JS can’t or didn’t do that final cast.
    - FreakLegion 4y ago
      I wasn't thinking of anything exotic, just the built-in functions used for hash tables and random number generators (for integers and other inputs that can be interpreted as seeds, a random number generator is also a hash function, and of course in your case the hash function was a random number generator all along anyway!).
jimmywetnips 4y ago
soooo basically there is no bias
- withinboredom 4y ago
  Looks like it. Though I think md5 is faster, which is maybe what I’m remembering, now that I think about it. This was years ago, funny how memory gets tainted.
  - jimmywetnips 4y ago
    I think that's probably true of lots of masters of crafts, sometimes you have a gut feeling and don't even remember the formative moments that created the conclusion haha

Here's the fraction of 1s for each bit position output by MD5 and SHA-256 using the first million integers as inputs: https://pastebin.com/aVR3u8Vv https://pastebin.com/aVR3u8Vv

withinboredom 4y ago

I quickly threw a few into excel with a pareto graph to show distribution. Granted, it is only the first 10,000 integers % 1000: https://imgur.com/a/HypGWP1 https://imgur.com/a/HypGWP1 To my untrained eye, md5 and sha1 (and not shown, sha256) look remarkably similar to random. If you want truly even distributions, then going with a nieve "X % Y" approach looks better.

FreakLegion 4y ago
If you do % 1000 there'll be a bit of bias from the modulus, but not anything meaningful for the use case, and it affects MD5 and SHA both. No argument that for simple incrementing integers a raw modulus is better, though. Even if hashing is needed, a cryptographic hash function probably isn't (depending on threat model, e.g. whether user inputs are involved).
- withinboredom 4y ago
  MD5 and ShaX are available in almost every language. Things that are probably better (like Murmur3) might not be, or may even have different hashes for the same thing (C# vs JS with Murmur3, for example). I had to reimplement Murmur3 in C# to get the hashes to match from JS, it boiled down to the C# version using longs and eventually casting to an int while JS can’t or didn’t do that final cast.
  - FreakLegion 4y ago
    I wasn't thinking of anything exotic, just the built-in functions used for hash tables and random number generators (for integers and other inputs that can be interpreted as seeds, a random number generator is also a hash function, and of course in your case the hash function was a random number generator all along anyway!).

jimmywetnips 4y ago

soooo basically there is no bias

withinboredom 4y ago
Looks like it. Though I think md5 is faster, which is maybe what I’m remembering, now that I think about it. This was years ago, funny how memory gets tainted.
- jimmywetnips 4y ago
  I think that's probably true of lots of masters of crafts, sometimes you have a gut feeling and don't even remember the formative moments that created the conclusion haha