Digest-hmac is a project mainly written in Perl, it's free.
The Digest::HMAC Perl module
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.