> If you've tested the implementation of rand that you're using and
determined that it isn't good enough for what you're doing then you need
to look at other generators. In particular, you ought to look at the
Mersenne Twister: it's big (the most common form of the generator stores
624 32-bit values), but it's fast and it has a long period.
The OP said his application is cryptography. I don't know if that
means a toy project or a "real" software project. I hope the OP is
working on a toy project. Otherwise, they need to learn MUCH more
about random number generators and particularly those that are crypto
secure and this topic seems off topic here.
OP, neither rand nor Mersenne are suitable for cryptography. You need
to be using something such as Blum Blum Shub for example.
L. Blum, M. Blum, and M. Shub.
A Simple Unpredictable Pseudo-Random Number Generator.
SIAM Journal on Computing, volume 15, pages 364-383, May 1986
But more importantly, if this isn't a toy, please take the time to
learn the field as well as you can. I'm sure anyone that uses your
software will appreciate having a decent crypto system.
If it is a toy, well have fun with whichever generator you choose :)