3 ms·
If you're only worried that your PRNG doesn't look random, there's TestU01: http://www.iro.umontreal.ca/~simardr/testu01/tu01.html http://www.iro.umontreal.ca/~
by pbsd 13y ago
If you're only worried that your PRNG doesn't look random, there's TestU01: http://www.iro.umontreal.ca/~simardr/testu01/tu01.html http://www.iro.umontreal.ca/~simardr/testu01/tu01.html
However these are just statistical tests; they tell you nothing about how much actual entropy you're actually getting (cf. Debian). That said, it probably would have caught the Cryptocat bias.
- mistercow 13y ago>they tell you nothing about how much actual entropy you're actually getting I'm not actually sure what "actual entropy" would mean in this context if not "the number of bits in the seed".
- pbsd 13y agoNot only the number of bits in the seed, but also their unpredictability. There are many things that can go wrong. Some examples: - the seed is timer-based and has far less entropy (information) than its bit size - the seed is OK, but the generator is somehow weak (e.g., only made with linear components, or throws away parts of the seed, or outputs too much of its internal state) - Bugs, bugs everywhere (cute example: an RC4-based generator that uses the XOR trick to swap elements) No standard statistical test would catch those (it would catch the latter, actually), even though the security of the generator would be gravely diminished.