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  • Hash : 3c53796c
    Author : Edward Thomson
    Date : 2022-02-07T19:38:32

    rand: introduce git_rand PRNG Introduce `git_rand`, a PRNG based on xoroshiro256**, a fast, all-purpose pseudo-random number generator: https://prng.di.unimi.it The PRNG will be seeded by the system's entropy store when possible, falling back to current time and system data (pid, uptime, etc). Inspiration for this was taken from libressl, but since our PRNG is not used for cryptographic purposes (and indeed currently only generates a unique temp file name that is written in a protected directory), this should be more than sufficient. Our implementation of xoroshiro256** was taken almost strictly from the original author's sources, but was tested against PractRand to ensure that there were no foolish mistranslations: ``` RNG_test using PractRand version 0.94 RNG = RNG_stdin64, seed = unknown test set = core, folding = standard (64 bit) rng=RNG_stdin64, seed=unknown length= 256 megabytes (2^28 bytes), time= 2.9 seconds no anomalies in 210 test result(s) rng=RNG_stdin64, seed=unknown length= 512 megabytes (2^29 bytes), time= 6.2 seconds no anomalies in 226 test result(s) rng=RNG_stdin64, seed=unknown length= 1 gigabyte (2^30 bytes), time= 12.7 seconds no anomalies in 243 test result(s) rng=RNG_stdin64, seed=unknown length= 2 gigabytes (2^31 bytes), time= 25.4 seconds no anomalies in 261 test result(s) rng=RNG_stdin64, seed=unknown length= 4 gigabytes (2^32 bytes), time= 50.6 seconds no anomalies in 277 test result(s) rng=RNG_stdin64, seed=unknown length= 8 gigabytes (2^33 bytes), time= 104 seconds no anomalies in 294 test result(s) ```