Digest::HMAC - Keyed-Hashing for Message Authentication
# 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;
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.
Graham Barr <firstname.lastname@example.org>, Gisle Aas <email@example.com>