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.