Start work on decryption

This commit is contained in:
Stephen Paul Weber 2013-01-21 18:18:13 -05:00
parent 06cf887846
commit bf8201f432
3 changed files with 118 additions and 1 deletions

View File

@ -128,7 +128,7 @@ class OpenPGP_S2K {
case 3: case 3:
$s2k->hash_algorithm = ord($input{1}); $s2k->hash_algorithm = ord($input{1});
$s2k->salt = substr($input, 2, 8); $s2k->salt = substr($input, 2, 8);
$s2k->count = OpenPGP::decode_s2k_count($input{9}); $s2k->count = OpenPGP::decode_s2k_count(ord($input{10}));
$input = substr($input, 11); $input = substr($input, 11);
break; break;
} }
@ -154,6 +154,37 @@ class OpenPGP_S2K {
} }
return $bytes; return $bytes;
} }
function raw_hash($s) {
return hash(strtolower(OpenPGP_SignaturePacket::$hash_algorithms[$this->hash_algorithm]), $s, true);
}
function sized_hash($s, $size) {
$hash = $this->raw_hash($s);
while(strlen($hash) < $size) {
$s = "\0" . $s;
$hash .= $this->raw_hash($s);
}
return substr($hash, 0, $size);
}
function iterate($s) {
if(strlen($s) >= $this->count) return $s;
$s = str_repeat($s, ceil($this->count / strlen($s)));
return substr($s, 0, $this->count);
}
function make_key($pass, $size) {
switch($this->type) {
case 0:
return $this->sized_hash($pass, $size);
case 1:
return $this->sized_hash($this->salt . $pass, $size);
case 3:
return $this->sized_hash($this->iterate($this->salt . $pass), $size);
}
}
} }
////////////////////////////////////////////////////////////////////////////// //////////////////////////////////////////////////////////////////////////////

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@ -0,0 +1,57 @@
<?php
require_once dirname(__FILE__).'/openpgp.php';
require_once 'Crypt/AES.php';
class OpenPGP_phpseclib_Crypt {
public static function decryptSymmetric($pass, $m) {
foreach($m as $p) {
if($p instanceof OpenPGP_SymmetricSessionKeyPacket) {
switch($p->symmetric_algorithm) {
case 7:
$cipher = new Crypt_AES(CRYPT_AES_MODE_CFB);
$cipher->setKeyLength(128);
break;
case 8:
$cipher = new Crypt_AES(CRYPT_AES_MODE_CFB);
$cipher->setKeyLength(192);
break;
case 9:
$cipher = new Crypt_AES(CRYPT_AES_MODE_CFB);
$cipher->setKeyLength(256);
break;
}
if(!$cipher) continue; // Unsupported cipher
$cipher->setKey($p->s2k->make_key($pass, $cipher->key_size));
$epacket = self::getEncryptedData($m);
$padAmount = $cipher->block_size - (strlen($epacket->data) % $cipher->block_size);
if(strlen($p->encrypted_data) < 1) {
if($epacket instanceof OpenPGP_IntegrityProtectedDataPacket) {
$data = substr($cipher->decrypt($epacket->data . str_repeat("\0", $padAmount)), 0, strlen($epacket->data));
$prefix = substr($data, 0, $cipher->block_size + 2);
$mdc = substr(substr($data, -22, 22), 2);
$data = substr($data, $cipher->block_size + 2, -22);
$mkMDC = hash("sha1", $prefix . $data . "\xD3\x14", true);
if($mkMDC !== $mdc) return false;
return OpenPGP_Message::parse($data);
} else {
// TODO (resync)
}
} else {
// TODO
}
}
}
}
public static function getEncryptedData($m) {
foreach($m as $p) {
if($p instanceof OpenPGP_EncryptedDataPacket) return $p;
}
throw new Exception("Can only decrypt EncryptedDataPacket");
}
}

View File

@ -4,6 +4,7 @@
require_once dirname(__FILE__).'/../lib/openpgp.php'; require_once dirname(__FILE__).'/../lib/openpgp.php';
require_once dirname(__FILE__).'/../lib/openpgp_crypt_rsa.php'; require_once dirname(__FILE__).'/../lib/openpgp_crypt_rsa.php';
require_once dirname(__FILE__).'/../lib/openpgp_phpseclib_crypt.php';
class MessageVerification extends PHPUnit_Framework_TestCase { class MessageVerification extends PHPUnit_Framework_TestCase {
public function oneMessageRSA($pkey, $path) { public function oneMessageRSA($pkey, $path) {
@ -61,3 +62,31 @@ class KeyVerification extends PHPUnit_Framework_TestCase {
$this->oneKeyRSA("helloKey.gpg"); $this->oneKeyRSA("helloKey.gpg");
} }
} }
class Decryption extends PHPUnit_Framework_TestCase {
public function oneSymmetric($pass, $cnt, $path) {
$m = OpenPGP_Message::parse(file_get_contents(dirname(__FILE__) . '/data/' . $path));
$m2 = OpenPGP_phpseclib_Crypt::decryptSymmetric($pass, $m);
while($m2[0] instanceof OpenPGP_CompressedDataPacket) $m2 = $m2[0]->data;
foreach($m2 as $p) {
if($p instanceof OpenPGP_LiteralDataPacket) {
$this->assertEquals($p->data, $cnt);
}
}
}
public function testDecryptAES() {
$this->oneSymmetric("hello", "PGP\n", "symmetric-aes.gpg");
}
/* TODO
public function testDecryptSessionKey() {
$this->oneSymmetric("hello", "PGP\n", "symmetric-with-session-key.gpg");
}
public function testDecryptNoMDC() {
$this->oneSymmetric("hello", "PGP\n", "symmetric-no-mdc.gpg");
}
*/
}