use openssl as alternate decryptor if available

this update also removes 'mcrypt' as compulsory dependency allowing the user to use the script on unencrypted streams when both libraries ('mcrypt' and 'openssl') are not available.
K-S-V · May 28, 2016 · 3a9b748 · 3a9b748
1 parent a3fc2e4
commit 3a9b748
Showing 1 changed file with 37 additions and 11 deletions.
diff --git a/AdobeHDS.php b/AdobeHDS.php
@@ -354,12 +354,25 @@ function error($error)
   class AkamaiDecryptor
     {
       var $ecmID, $ecmTimestamp, $ecmVersion, $kdfVersion, $dccAccReserved, $prevEcmID;
-      var $aes_cbc, $debug, $decryptBytes, $decryptorTest, $lastKeyUrl, $sessionID, $sessionKey, $sessionKeyUrl;
+      var $aes_cbc, $debug, $decryptBytes, $decryptorTest, $encryptor, $lastKeyUrl, $sessionID, $sessionKey, $sessionKeyUrl;
       var $packetIV, $packetKey, $packetSalt, $saltAesKey;
 
       function __construct()
         {
-          $this->aes_cbc       = mcrypt_module_open('rijndael-128', '', 'cbc', '');
+          if (extension_loaded("openssl"))
+            {
+              $this->encryptor = "openssl";
+            }
+          else if (extension_loaded("mcrypt"))
+            {
+              $this->encryptor = "mcrypt";
+              $this->aes_cbc   = mcrypt_module_open('rijndael-128', '', 'cbc', '');
+            }
+          else
+            {
+              $this->encryptor = false;
+              LogInfo("You need to install either 'mcrypt' or 'openssl' extension to decrypt some encrypted streams.");
+            }
           $this->debug         = false;
           $this->decryptorTest = false;
           $this->lastKeyUrl    = "";
@@ -382,6 +395,26 @@ function InitDecryptor()
           $this->saltAesKey     = null;
         }
 
+      function AesDecrypt($cipherData, $key, $iv)
+        {
+          $decrypted = "";
+          if ($this->encryptor == "openssl")
+            {
+              $decrypted = openssl_decrypt(base64_encode($cipherData), "aes-128-cbc", $key, OPENSSL_ZERO_PADDING, $iv);
+            }
+          else if ($this->encryptor == "mcrypt")
+            {
+              mcrypt_generic_init($this->aes_cbc, $key, $iv);
+              $decrypted = mdecrypt_generic($this->aes_cbc, $cipherData);
+              mcrypt_generic_deinit($this->aes_cbc);
+            }
+          else
+            {
+              LogError("Failed to find suitable decryption library");
+            }
+          return $decrypted;
+        }
+
       function KDF()
         {
           $debug = $this->debug;
@@ -402,11 +435,9 @@ function KDF()
               LogDebug("SaltAesKey   : " . hexlify($this->saltAesKey), $debug);
               $this->prevEcmID = $this->ecmID;
             }
-          mcrypt_generic_init($this->aes_cbc, $this->saltAesKey, $this->packetIV);
           LogDebug("EncryptedSalt: " . hexlify($this->packetSalt), $debug);
-          $decryptedSalt = mdecrypt_generic($this->aes_cbc, $this->packetSalt);
+          $decryptedSalt = $this->AesDecrypt($this->packetSalt, $this->saltAesKey, $this->packetIV);
           LogDebug("DecryptedSalt: " . hexlify($decryptedSalt), $debug);
-          mcrypt_generic_deinit($this->aes_cbc);
           $this->decryptBytes = ReadInt32($decryptedSalt, 0);
           LogDebug("DecryptBytes : " . $this->decryptBytes, $debug);
           $decryptedSalt = substr($decryptedSalt, 4, 16);
@@ -508,11 +539,7 @@ function Decrypt($data, $pos, $opt = array())
           $encryptedData = substr($encryptedData, 0, $this->decryptBytes);
           $decryptedData = "";
           if ($this->decryptBytes > 0)
-            {
-              mcrypt_generic_init($this->aes_cbc, $this->packetKey, $this->packetIV);
-              $decryptedData = mdecrypt_generic($this->aes_cbc, $encryptedData);
-              mcrypt_generic_deinit($this->aes_cbc);
-            }
+              $decryptedData = $this->AesDecrypt($encryptedData, $this->packetKey, $this->packetIV);
           $decryptedData .= $lastBlockData;
           LogDebug("DecryptedData: " . hexlify(substr($decryptedData, 0, 64)), $debug);
 
@@ -2081,7 +2108,6 @@ function value_in_array_field($needle, $needle_field, $value_field, $haystack, $
   $required_extensions = array(
       "bcmath",
       "curl",
-      "mcrypt",
       "SimpleXML"
   );
   $missing_extensions  = array_diff($required_extensions, get_loaded_extensions());