NAME

       Digest::HMAC - Keyed-Hashing for Message Authentication

SYNOPSIS

        # Functional style
        use Digest::HMAC qw(hmac hmac_hex);
        $digest = hmac($data, $key, \&myhash);
        print hmac_hex($data, $key, \&myhash);

        # OO style
        use Digest::HMAC;
        $hmac = Digest::HMAC->new($key, "Digest::MyHash");

        $hmac->add($data);
        $hmac->addfile(*FILE);

        $digest = $hmac->digest;
        $digest = $hmac->hexdigest;
        $digest = $hmac->b64digest;

DESCRIPTION

       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.

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

       The hmac() and hmac_hex() functions and the Digest::HMAC->new() constructor takes an
       optional $blocksize argument as well.  The HMAC algorithm assumes the digester to hash by
       iterating a basic compression function on blocks of data and the $blocksize should match
       the byte-length of such blocks.

       The default $blocksize is 64 which is suitable for the MD5 and SHA-1 digest functions.
       For stronger algorithms the blocksize probably needs to be increased.

SEE ALSO

       Digest::HMAC_MD5, Digest::HMAC_SHA1

       RFC 2104

MAINTAINER

       Andrew Rodland <arodland@cpan.org>

ORIGINAL AUTHORS

       Graham Barr <gbarr@ti.com>, Gisle Aas <gisle@aas.no>