Use of gen-random

[Robert J. Hansen]

> So I am curious, how might I _lose_ entropy by _generating_ random
> numbers? What do each of the three methods do?

Without knowing your OS and various other finicky details, it's hard  
to say.

On many UNIX systems, the system keeps track of unpredictable inputs,  
does various mathemagic to them, and stores the results as a source of  
high quality random bits.  These are as close to truly random as can  
easily be obtained with computers.  Since they're the result of  
physical processes, there are only a finite number of them available.   
Using these random bits profligately can result in high quality  
randomness being unavailable to other applications that need it.

Most systems also include a fairly good PRNG (pseudo-random number  
generator) which is good for most purposes.  But for crypto, you want  
the best quality randomness you can get.