why- Open BSD .rocks

arc4random(3) (∞)

OpenBSD has its own cryptographic random number generator.

Wherever random input is needed, arc4random is used. arc4random is an abstraction layer for currently considered as safe ciphers and produces ChaCha20 ciphers at the moment

Arc4random is “A Replacement Call For Random”, to generate very quickly high quality 32-bit pseudo-random numbers.