random_bytes(
length) ->bytes
Read cryptographically secure random bytes
Returns length bytes from the kernel CSPRNG (getrandom(2), falling
back to /dev/urandom). Accepts 0 to 65536 bytes.
This is the only randomness in this module fit for keys, tokens and
salts. math.random backs everything else here, and its state is
recoverable from a handful of outputs however well it was seeded.