Php/docs/intro.csprng
来自菜鸟教程
The [https://en.wikipedia.org/wiki/Cryptographically_secure_pseudorandom_number_generator » 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.
自以下版本起 PHP 7.0.0 but there is also a » userland implementation for PHP >= 5.2.0.
