Commands tagged rng (2)

  • True random number generator in pure ZSH

    Do not use this in production! This is a true hardware random number generator using your system as the entropy source. It models flipping a coin by pitting a fast clock (the CPU) against a slow clock (the RTC). The CPU models the coin flipping head over tails during flight and the RTC models the duration of the coin's flight in the air. A timer is set 1 millisecond into the future and a bit is flipped as fast as possible before the timer expires. 256 bits are collected then hashed with SHA-256 to whiten the data and ensure uniformity. This makes some assumptions however. It assumes that your system is not compromised. It assumes your system is generating enough interrupts for the kernel scheduler to be unpredictable on what gets CPU priority. It assumes that your installed sha256sum(1) command is correctly implemented. Just because you can, doesn't mean you should. Use your system's RNG (EG, /dev/urandom) instead. Show Sample Output


    1
    trng() { zmodload zsh/datetime; local flips=""; while ((${#flips}<256)); do local coin=0; local t=$((EPOCHREALTIME+0.001)); while (($EPOCHREALTIME<$t)); do ((coin^=1)); done; flips+=$coin; done; local h=($(print "$flips"|sha256sum));
    atoponce · 2025-11-24 18:13:40 0
  • xorshift32 RNG in Bash

    The xorshift32 PRNG written by George Marsaglia in Bash, code golfed. Bash already has the $RANDOM and $SRANDOM environment variables, so this isn't all that useful. The seed "s" must be non-zero. Show Sample Output


    0
    n(){ s=$[s^s<<13];s=$[s^s>>17];s=$[s^s<<5];echo $[s&2**32-1]; }
    atoponce · 2026-07-31 03:42:35 0

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