The Digest::MD5 module allows you to use the RSA Data Security Inc.
MD5 Message Digest algorithm from within Perl programs.  The algorithm
takes as input a message of arbitrary length and produces as output
a 128-bit "fingerprint" or "message digest" of the input.

The Digest::MD5 module provide a procedural interface for simple
use, as well as an object oriented interface that can handle messages
of arbitrary length and which can read files directly.

Further documentation is embedded in the individual modules.