The random number generator gathers environmental noise from device drivers and other sources into
       an entropy pool.  The generator also keeps an estimate of the number  of  bits  of  noise  in  the
       entropy pool.  From this entropy pool random numbers are created.

       When  read,  the  /dev/random  device will only return random bytes within the estimated number of
       bits of noise in the entropy pool.  /dev/random should be suitable for uses that  need  very  high
       quality  randomness such as one-time pad or key generation.  When the entropy pool is empty, reads
       from /dev/random will block until additional environmental noise is gathered.