Entropy

View available entropy

cat /proc/sys/kernel/random/entropy_avail

Increase available entropy

This is applicable to non-interactive machines such as servers, and useful when generating a lot of keys.

Install the haveged package

"The haveged project is an attempt to provide an easy-to-use, unpredictable random number generator based upon an adaptation of the HAVEGE algorithm. Haveged was created to remedy low-entropy conditions in the Linux random device that can occur under some workloads, especially on headless servers. Current development of haveged is directed towards improving overall reliablity and adaptability while minimizing the barriers to using haveged for other tasks."

emerge -av haveged

and start it. It will use CPU execution timings (which are very irregular) to seed the system's RNG.