Decrypt secret key

lib/openpgp.php

@@ -1454,15 +1454,15 @@ class OpenPGP_PublicSubkeyPacket extends OpenPGP_PublicKeyPacket {
  * @see http://tools.ietf.org/html/rfc4880#section-12
  */
 class OpenPGP_SecretKeyPacket extends OpenPGP_PublicKeyPacket {
-  public $s2k_useage, $s2k, $symmetric_type, $private_hash, $encrypted_data;
+  public $s2k_useage, $s2k, $symmetric_algorithm, $private_hash, $encrypted_data;
   function read() {
     parent::read(); // All the fields from PublicKey
     $this->s2k_useage = ord($this->read_byte());
     if($this->s2k_useage == 255 || $this->s2k_useage == 254) {
-      $this->symmetric_type = ord($this->read_byte());
+      $this->symmetric_algorithm = ord($this->read_byte());
       $this->s2k = OpenPGP_S2k::parse($this->input);
     } else if($this->s2k_useage > 0) {
-      $this->symmetric_type = $this->s2k_useage;
+      $this->symmetric_algorithm = $this->s2k_useage;
     }
     if($this->s2k_useage > 0) {
       // TODO: IV of the same length as cipher's block size
@@ -1503,7 +1503,7 @@ class OpenPGP_SecretKeyPacket extends OpenPGP_PublicKeyPacket {
     $bytes = parent::body() . chr($this->s2k_useage);
     $secret_material = NULL;
     if($this->s2k_useage == 255 || $this->s2k_useage == 254) {
-      $bytes .= chr($this->symmetric_type);
+      $bytes .= chr($this->symmetric_algorithm);
       $bytes .= $this->s2k->to_bytes();
     }
     if($this->s2k_useage > 0) {

lib/openpgp_crypt_aes_tripledes.php

@@ -30,6 +30,44 @@ class OpenPGP_Crypt_AES_TripleDES {
     return NULL; /* If we get here, we failed */
   }
 
+  public static function decryptSecretKey($pass, $packet) {
+    $packet = clone $packet; // Do not mutate orinigal
+
+    list($cipher, $key_bytes, $key_block_bytes) = self::getCipher($packet->symmetric_algorithm);
+    $cipher->setKey($packet->s2k->make_key($pass, $key_bytes));
+    $cipher->setIV(substr($packet->encrypted_data, 0, $key_block_bytes));
+    $material = $cipher->decrypt(substr($packet->encrypted_data, $key_block_bytes));
+
+    if($packet->s2k_useage == 254) {
+      $chk = substr($material, -20);
+      $material = substr($material, 0, -20);
+      if($chk != hash('sha1', $material)) return NULL;
+    } else {
+      $chk = unpack('n', substr($material, -2));
+      $chk = reset($chk);
+      $material = substr($material, 0, -2);
+
+      $mkChk = 0;
+      for($i = 0; $i < strlen($material); $i++) {
+        $mkChk = ($mkChk + ord($material{$i})) % 65536;
+      }
+      if($chk != $mkChk) return NULL;
+    }
+
+    $packet->s2k_useage = 0;
+    $packet->symmetric_algorithm = 0;
+    $packet->encrypted_data = NULL;
+
+    foreach($packet::$secret_key_fields[$packet->algorithm] as $f) {
+      $length = unpack('n', substr($material, 0, 2)); // in bits
+      $length = (int)floor((reset($length) + 7) / 8); // in bytes
+      $packet->key[$f] = substr($material, 2, $length);
+      $material = substr($material, 2 + $length);
+    }
+
+    return $packet;
+  }
+
   public static function decryptPacket($epacket, $symmetric_algorithm, $key) {
     list($cipher, $key_bytes, $key_block_bytes) = self::getCipher($symmetric_algorithm);
     if(!$cipher) return NULL;

tests/phpseclib_suite.php

@@ -104,4 +104,10 @@ class Decryption extends PHPUnit_Framework_TestCase {
       }
     }
   }
+
+  public function testDecryptSecretKey() {
+    $key = OpenPGP_Message::parse(file_get_contents(dirname(__FILE__) . '/data/encryptedSecretKey.gpg'));
+    $skey = OpenPGP_Crypt_AES_TripleDES::decryptSecretKey("hello", $key[0]);
+    $this->assertSame(!!$skey, true);
+  }
 }