File Coverage

blib/lib/Crypt/OpenPGP/Ciphertext.pm

Criterion	Covered	Total	%
statement	79	84	94.0
branch	20	26	76.9
condition	6	11	54.5
subroutine	14	15	93.3
pod	4	7	57.1
total	123	143	86.0

package Crypt::OpenPGP::Ciphertext;
use strict;
use warnings;

our $VERSION = '1.19'; # VERSION

use Crypt::OpenPGP::Util;
use Crypt::OpenPGP::Cipher;
use Crypt::OpenPGP::Constants qw( DEFAULT_CIPHER
                                  PGP_PKT_ENCRYPTED
                                  PGP_PKT_ENCRYPTED_MDC );
use Crypt::OpenPGP::ErrorHandler;
use base qw( Crypt::OpenPGP::ErrorHandler );

use constant MDC_TRAILER => chr(0xd3) . chr(0x14);

sub pkt_type { $_[0]->{is_mdc} ? PGP_PKT_ENCRYPTED_MDC : PGP_PKT_ENCRYPTED }

sub new {
    my $class = shift;
    my $enc = bless { }, $class;
    $enc->init(@_);
}

sub init {
    my $enc = shift;
    my %param = @_;
    if ((my $key = $param{SymKey}) && (my $data = $param{Data})) {
        $enc->{is_mdc} = $param{MDC} || 0;
        $enc->{version} = 1;
        my $alg = $param{Cipher} || DEFAULT_CIPHER;
        my $cipher = Crypt::OpenPGP::Cipher->new($alg, $key);
        my $bs = $cipher->blocksize;
        my $pad = Crypt::OpenPGP::Util::get_random_bytes($bs);
        $pad .= substr $pad, -2, 2;
        $enc->{ciphertext} = $cipher->encrypt($pad);
        $cipher->sync unless $enc->{is_mdc};
        $enc->{ciphertext} .= $cipher->encrypt($data);

        if ($enc->{is_mdc}) {
            require Crypt::OpenPGP::MDC;
            my $mdc = Crypt::OpenPGP::MDC->new(
                Data => $pad . $data . MDC_TRAILER );
            my $mdc_buf = Crypt::OpenPGP::PacketFactory->save($mdc);
            $enc->{ciphertext} .= $cipher->encrypt($mdc_buf);
        }
    }
    $enc;
}

sub parse {
    my $class = shift;
    my($buf, $is_mdc) = @_;
    my $enc = $class->new;
    $enc->{is_mdc} = $is_mdc;
    if ($is_mdc) {
        $enc->{version} = $buf->get_int8;
    }
    $enc->{ciphertext} = $buf->get_bytes($buf->length - $buf->offset);
    $enc;
}

sub save {
    my $enc = shift;
    my $buf = Crypt::OpenPGP::Buffer->new;
    if ($enc->{is_mdc}) {
        $buf->put_int8($enc->{version});
    }
    $buf->put_bytes($enc->{ciphertext});
    $buf->bytes;
}

sub display {
    my $enc = shift;
    my $str = ":encrypted data packet:\n" .
              "        length: " . length($enc->{ciphertext}) . "\n";
    if ($enc->{is_mdc}) {
        $str .= "        is_mdc: $enc->{version}\n";
    }
    $str;
}

sub decrypt {
    my $enc = shift;
    my($key, $sym_alg) = @_;
    my $cipher = Crypt::OpenPGP::Cipher->new($sym_alg, $key) or
        return $enc->error( Crypt::OpenPGP::Cipher->errstr );
    my $padlen = $cipher->blocksize + 2;
    my $pt = $enc->{prefix} =
        $cipher->decrypt(substr $enc->{ciphertext}, 0, $padlen);
    return $enc->error("Bad checksum")
        unless substr($pt, -4, 2) eq substr($pt, -2, 2);
    $cipher->sync unless $enc->{is_mdc};
    $pt = $cipher->decrypt(substr $enc->{ciphertext}, $padlen);
    if ($enc->{is_mdc}) {
        my $mdc_buf = Crypt::OpenPGP::Buffer->new_with_init(substr $pt,-22,22);
        $pt = substr $pt, 0, -22;
        my $mdc = Crypt::OpenPGP::PacketFactory->parse($mdc_buf);
        return $enc->error("Encrypted MDC packet without MDC")
            unless $mdc && ref($mdc) eq 'Crypt::OpenPGP::MDC';
        require Crypt::OpenPGP::Digest;
        my $dgst = Crypt::OpenPGP::Digest->new('SHA1');
        my $hash = $dgst->hash($enc->{prefix} . $pt . chr(0xd3) . chr(0x14));
        return $enc->error("SHA-1 hash of plaintext does not match MDC body")
            unless $mdc->digest eq $hash;
    }
    $pt;
}

1;
__END__