Support 3DES

2013-01-26 11:08:18 -05:00
parent bf8201f432
commit 567b18c1b2
3 changed files with 19 additions and 7 deletions
--- a/lib/openpgp_crypt_aes_tripledes.php
+++ b/lib/openpgp_crypt_aes_tripledes.php
@@ -0,0 +1,65 @@
+<?php
+
+require_once dirname(__FILE__).'/openpgp.php';
+require_once 'Crypt/AES.php';
+require_once 'Crypt/TripleDES.php';
+
+class OpenPGP_Crypt_AES_TripleDES {
+  public static function decryptSymmetric($pass, $m) {
+    foreach($m as $p) {
+      if($p instanceof OpenPGP_SymmetricSessionKeyPacket) {
+        switch($p->symmetric_algorithm) {
+          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);
+            $cipher->setKeyLength(256);
+            break;
+        }
+        if(!$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));
+        $epacket = self::getEncryptedData($m);
+        $padAmount = $key_block_bytes - (strlen($epacket->data) % $key_block_bytes);
+
+        if(strlen($p->encrypted_data) < 1) {
+          if($epacket instanceof OpenPGP_IntegrityProtectedDataPacket) {
+				 $data = substr($cipher->decrypt($epacket->data . str_repeat("\0", $padAmount)), 0, strlen($epacket->data));
+				 $prefix = substr($data, 0, $key_block_bytes + 2);
+				 $mdc = substr(substr($data, -22, 22), 2);
+				 $data = substr($data, $key_block_bytes + 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");
+  }
+}