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.