File Coverage

blib/lib/Crypt/Keyczar/Crypter.pm

Criterion	Covered	Total	%
statement	34	38	89.4
branch	6	10	60.0
condition			n/a
subroutine	6	6	100.0
pod	0	1	0.0
total	46	55	83.6

package Crypt::Keyczar::Crypter;
use base 'Crypt::Keyczar::Encrypter';
use strict;
use warnings;
use Crypt::Keyczar qw(HEADER_SIZE KEY_HASH_SIZE FORMAT_VERSION);
use Carp;


sub decrypt {
    my $self = shift;
    my $data = shift;

    if (length $data < HEADER_SIZE()) {
        croak "signature is short";
    }
    my $hash_size = KEY_HASH_SIZE();
    my ($v, $hash, $body) = unpack "C1 a$hash_size a*", $data;
    if ($v != FORMAT_VERSION()) {
        croak "bad format version: $v";
    }
    my $key = $self->get_key($hash);
    if (!$key) {
        croak "key not found";
    }

    my $engine = $key->get_engine();
    my $mac    = $key->get_sign_engine();
    my $cipher_body = substr $body, 0, $mac->digest_size()*-1;
    my $signature   = substr $body, $mac->digest_size()*-1;
    my $iv = $engine->init($cipher_body);
    my $cipher_text = length $iv > 0 ? substr($cipher_body, length $iv) : $body;
    my $plain_text = $engine->decrypt($cipher_text);
    my $signed_text = substr $data, 0, $mac->digest_size()*-1;
    $mac->update($signed_text);
    if (!$mac->verify($signature)) {
        croak "invalid signature";
    }

    return $plain_text;
}

1;
__END__