File Coverage

blib/lib/Digest/EMAC.pm

Criterion	Covered	Total	%
statement	18	50	36.0
branch	0	6	0.0
condition			n/a
subroutine	6	11	54.5
pod	0	5	0.0
total	24	72	33.3

package Digest::EMAC;

#use diagnostics;
use strict;
#use warnings;
use Carp;
use Crypt::CBC;
use MIME::Base64;
use Exporter;
use vars qw($VERSION @EXPORT_OK @ISA);
$VERSION = '1.2';
@ISA = ('Exporter');
@EXPORT_OK = qw(emac hexdigest base64digest);

sub createcipher
{
    my ($key, $iv, $cipher) = @_;
    my $cipher_obj = Crypt::CBC->new({'key' => $key,
                                      'cipher' => $cipher,
                                      'iv' => $iv,
                                      'regenerate_key' => 1,
                                      'padding' => 'standard',
                                      'prepend_iv' => 0});
    return $cipher_obj;
}

sub createsubkey
{
    my ($key, $iv, $cipher, $data) = @_;
    my $tempcipher = &createcipher($key, $iv, $cipher);
    return $tempcipher->encrypt($data);
}

sub emac
{
    my ($key, $cipher, $inputdata) = @_;

    my $DATASIZE = length $inputdata;
    my $data = pack "a$DATASIZE", $inputdata;

    $cipher = $cipher=~/^Crypt::/ ? $cipher : "Crypt::$cipher";
    eval "require $cipher";
    if ($@) {
        print "Can't load cipher $cipher.\n";
        print "You must install $cipher first!\n";
        exit 0;
    }

    $cipher =~ s/^Crypt::// unless $cipher->can('blocksize');

    my $BLOCKSIZE = eval {$cipher->blocksize};
    my $iv = pack "x$BLOCKSIZE", 0;

    my $subkey1 = &createsubkey($key, $iv, $cipher, 0);
    my $subkey2 = &createsubkey($key, $iv, $cipher, 1);

    my $cipher1 = &createcipher($subkey1, $iv, $cipher);
    my $ciphertext = $cipher1->encrypt($data);
    my $mac1 = substr $ciphertext, -$BLOCKSIZE;

    my $cipher2 = &createcipher($subkey2, $iv, $cipher);
    my $mac2 = $cipher2->encrypt($mac1);

    my $final_mac = substr $mac2, -$BLOCKSIZE;
    return $final_mac;
}

sub hexdigest
{
    my ($data) = @_;
    return unpack("H*", $data);
}

sub base64digest
{
    my ($data) = @_;
    return encode_base64($data, "");
}

1;

__END__