Support session keys

lib/openpgp_crypt_aes_tripledes.php

@@ -8,62 +8,46 @@ class OpenPGP_Crypt_AES_TripleDES {
   public static function decryptSymmetric($pass, $m) {
     foreach($m as $p) {
       if($p instanceof OpenPGP_SymmetricSessionKeyPacket) {
-        switch($p->symmetric_algorithm) {
+        list($cipher, $key_bytes, $key_block_bytes) = self::getCipher($p->symmetric_algorithm);
-          case 2:
+        if(!$cipher) continue;
-            $cipher = new Crypt_TripleDES(CRYPT_DES_MODE_CFB);
-            $key_bytes = 24;
-            $key_block_bytes = 8;
-            break;
-          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
-        if(!isset($key_bytes)) $key_bytes = $cipher->key_size;
-        if(!isset($key_block_bytes)) $key_block_bytes = $cipher->block_size;
-
         $cipher->setKey($p->s2k->make_key($pass, $key_bytes));
+
+        if(strlen($p->encrypted_data) > 0) {
+          $padAmount = $key_block_bytes - (strlen($p->encrypted_data) % $key_block_bytes);
+          $data = substr($cipher->decrypt($p->encrypted_data . str_repeat("\0", $padAmount)), 0, strlen($p->encrypted_data));
+          list($cipher, $key_bytes, $key_block_bytes) = self::getCipher(ord($data{0}));
+          if(!$cipher) continue;
+          $cipher->setKey(substr($data, 1));
+        }
+
         $epacket = self::getEncryptedData($m);
         $padAmount = $key_block_bytes - (strlen($epacket->data) % $key_block_bytes);
 
-        if(strlen($p->encrypted_data) < 1) {
+        if($epacket instanceof OpenPGP_IntegrityProtectedDataPacket) {
-          if($epacket instanceof OpenPGP_IntegrityProtectedDataPacket) {
+           $data = substr($cipher->decrypt($epacket->data . str_repeat("\0", $padAmount)), 0, strlen($epacket->data));
-             $data = substr($cipher->decrypt($epacket->data . str_repeat("\0", $padAmount)), 0, strlen($epacket->data));
+           $prefix = substr($data, 0, $key_block_bytes + 2);
-             $prefix = substr($data, 0, $key_block_bytes + 2);
+           $mdc = substr(substr($data, -22, 22), 2);
-             $mdc = substr(substr($data, -22, 22), 2);
+           $data = substr($data, $key_block_bytes + 2, -22);
-             $data = substr($data, $key_block_bytes + 2, -22);
 
-             $mkMDC = hash("sha1", $prefix . $data . "\xD3\x14", true);
+           $mkMDC = hash("sha1", $prefix . $data . "\xD3\x14", true);
-             if($mkMDC !== $mdc) return false;
+           if($mkMDC !== $mdc) return false;
 
-             try {
+           try {
-               $msg = OpenPGP_Message::parse($data);
+             $msg = OpenPGP_Message::parse($data);
-             } catch (Exception $ex) { $msg = NULL; }
+           } catch (Exception $ex) { $msg = NULL; }
-             if($msg) return $msg; /* Otherwise keep trying */
+           if($msg) return $msg; /* Otherwise keep trying */
-          } else {
-             // No MDC mean decrypt with resync
-             $iv = substr($epacket->data, 2, $key_block_bytes);
-             $edata = substr($epacket->data, $key_block_bytes + 2);
-
-             $cipher->setIV($iv);
-             $data = substr($cipher->decrypt($edata . str_repeat("\0", $padAmount)), 0, strlen($edata));
-
-             try {
-               $msg = OpenPGP_Message::parse($data);
-             } catch (Exception $ex) { $msg = NULL; }
-             if($msg) return $msg; /* Otherwise keep trying */
-          }
         } else {
-          // TODO
+           // No MDC mean decrypt with resync
+           $iv = substr($epacket->data, 2, $key_block_bytes);
+           $edata = substr($epacket->data, $key_block_bytes + 2);
+
+           $cipher->setIV($iv);
+           $data = substr($cipher->decrypt($edata . str_repeat("\0", $padAmount)), 0, strlen($edata));
+
+           try {
+             $msg = OpenPGP_Message::parse($data);
+           } catch (Exception $ex) { $msg = NULL; }
+           if($msg) return $msg; /* Otherwise keep trying */
         }
       }
     }
@@ -71,6 +55,34 @@ class OpenPGP_Crypt_AES_TripleDES {
     return NULL; /* If we get here, we failed */
   }
 
+  public static function getCipher($algo) {
+    switch($algo) {
+      case 2:
+        $cipher = new Crypt_TripleDES(CRYPT_DES_MODE_CFB);
+        $key_bytes = 24;
+        $key_block_bytes = 8;
+        break;
+      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;
+      default:
+        $cipher = NULL;
+    }
+    if(!$cipher) return array(NULL, NULL, NULL); // Unsupported cipher
+    if(!isset($key_bytes)) $key_bytes = $cipher->key_size;
+    if(!isset($key_block_bytes)) $key_block_bytes = $cipher->block_size;
+    return array($cipher, $key_bytes, $key_block_bytes);
+  }
+
   public static function getEncryptedData($m) {
     foreach($m as $p) {
       if($p instanceof OpenPGP_EncryptedDataPacket) return $p;

tests/phpseclib_suite.php

@@ -84,11 +84,9 @@ class Decryption extends PHPUnit_Framework_TestCase {
     $this->oneSymmetric("hello", "PGP\n", "symmetric-3des.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");