HMAC is used for message integrity checks between two parties that
share a secret key, and works in combination with some other Digest
algorithm, usually MD5 or SHA-1.  The HMAC mechanism is described in
RFC 2104.

The Digest::HMAC module follow the common Digest:: interface, but the
constructor takes the secret key and the name of some other simple
Digest:: module as argument.

You will need perl version 5.004 or better to install these modules.
The Digest::MD5 module and Digest::SHA1 module must be installed.

Copyright 1998-2001 Gisle Aas.
Copyright 1998 Graham Barr.

This library is free software; you can redistribute it and/or
modify it under the same terms as Perl itself.