This module maintains a concept of a current selection of entropy
source. Algorithms that require entropy can use the source nominated
by this module, avoiding the need for entropy source objects to be
explicitly passed around. This is convenient because usually one
entropy source will be used for an entire program run and so an
explicit entropy source parameter would rarely vary. There is also a
default entropy source, avoiding the need to explicitly configure a
source at all.

If nothing is done to set a source then it defaults to the use of
Rijndael (AES) in counter mode (see
Data::Entropy::RawSource::CryptCounter and Crypt::Rijndael), keyed
using Perl's built-in rand function. This gives a data stream that
looks like concentrated entropy, but really only has at most the
entropy of the rand seed. Within a single run it is cryptographically
difficult to detect the correlation between parts of the
pseudo-entropy stream. If more true entropy is required then it is
necessary to configure a different entropy source.

WWW:	http://search.cpan.org/dist/Data-Entropy/