CSPRNG
PHP Manual

導入

The » cryptographically secure pseudo-random number generator (CSPRNG) API provides an easy and reliable way to generate crypto-strong random integers and bytes for use within cryptographic contexts.

これが使えるようになった PHP のバージョンは 7.0.0 but there is also a » userland implementation for PHP >= 5.2.0.


CSPRNG
PHP Manual