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Digest
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HMAC.pm
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package Digest::HMAC; $VERSION = "1.03"; use strict; # OO interface sub new { my($class, $key, $hasher, $block_size) = @_; $block_size ||= 64; $key = $hasher->new->add($key)->digest if length($key) > $block_size; my $self = bless {}, $class; $self->{k_ipad} = $key ^ (chr(0x36) x $block_size); $self->{k_opad} = $key ^ (chr(0x5c) x $block_size); $self->{hasher} = $hasher->new->add($self->{k_ipad}); $self; } sub reset { my $self = shift; $self->{hasher}->reset->add($self->{k_ipad}); $self; } sub add { my $self = shift; $self->{hasher}->add(@_); $self; } sub addfile { my $self = shift; $self->{hasher}->addfile(@_); $self; } sub _digest { my $self = shift; my $inner_digest = $self->{hasher}->digest; $self->{hasher}->reset->add($self->{k_opad}, $inner_digest); } sub digest { shift->_digest->digest; } sub hexdigest { shift->_digest->hexdigest; } sub b64digest { shift->_digest->b64digest; } # Functional interface require Exporter; *import = \&Exporter::import; use vars qw(@EXPORT_OK); @EXPORT_OK = qw(hmac hmac_hex); sub hmac { my($data, $key, $hash_func, $block_size) = @_; $block_size ||= 64; $key = &$hash_func($key) if length($key) > $block_size; my $k_ipad = $key ^ (chr(0x36) x $block_size); my $k_opad = $key ^ (chr(0x5c) x $block_size); &$hash_func($k_opad, &$hash_func($k_ipad, $data)); } sub hmac_hex { unpack("H*", &hmac); } 1; __END__ =head1 NAME Digest::HMAC - Keyed-Hashing for Message Authentication =head1 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; =head1 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 C<Digest::> interface, but the constructor takes the secret key and the name of some other simple C<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. =head1 SEE ALSO L<Digest::HMAC_MD5>, L<Digest::HMAC_SHA1> RFC 2104 =head1 AUTHORS Graham Barr <gbarr@ti.com>, Gisle Aas <gisle@aas.no> =cut