Random Number Generator
Use cryptographically strong random. The computer world has different randoms, but they all have one thing in common, they are not really random. There is always an algorithm in the background that generates pseudo random numbers.
If you see a rnd() or random() function somewhere, it's very likely that there is a simple algorithm in the background that does not provide a sufficient level of randomness.
This page uses another method based on the implementation of the cryptographic services which generates very strong random numbers.
You can trust the randomness of these numbers, and for example, you can use them as the basis for creating symmetric encryption keys.