BasicDistributionTest is a test function to run a basic statistic test on `randf` output.

computes a bijection from the set of all permutations into the the set [0, n!-1] (where `n` is the size of input `perm`).

EvaluateDistributionUniformity evaluates if the input distribution is close to uniform through a basic quick test.

NewChacha20PRG returns a new Chacha20-based PRG, seeded with the input seed (32 bytes) and a customizer (up to 12 bytes).

RestoreChacha20PRG creates a chacha20 base PRG based on a previously stored state.

Chacha20CustomizerMaxLen is the maximum length of the nonce used as a PRG customizer, it is fixed to 24 bytes.

Chacha20SeedLen is the seed length of the Chacha based PRG, it is fixed to 32 bytes.

Rand is a pseudo random number generator All methods update the internal state of the PRG which makes the PRGs implementing this interface non concurrent-safe.