How to test a random generator

Question

I need to test a random number generator which produces numbers randomly. How to make sure the numbers generated are random.

Answer 1

You can only test statistical randomness anyway, and that does not prove whether the number sequence is cryptographically strong. Statistically testing a PRNG requires quite a lot (10 or even 100Gbytes) of the generated bits.

Dieharder is a very good testing suite.

http://www.phy.duke.edu/~rgb/General/dieharder.php

And TestU01 is also well-known.

http://www.iro.umontreal.ca/~simardr/testu01/tu01.html