The arc4random family of functions provides a cryptographic pseudorandom
number generator automatically seeded from the system entropy pool and
safe to use from multiple threads.  arc4random is designed to prevent an
adversary from guessing outputs, unlike rand(3) and random(3), and is
faster and more convenient than reading from /dev/urandom directly.

This is a Lua wrapper for arc4random(3), portable to systems that
do and don't have it natively in libc. On systems where arc4random
may be insecure it provides a replacement.