Fix for issue #509. Check symmetric key length once decrypted, to make sure it...

Fix for issue #509. Check symmetric key length once decrypted, to make sure it is the same size as expected.

git-svn-id: https://simplesamlphp.googlecode.com/svn/trunk@3145 44740490-163a-0410-bde0-09ae8108e29a

lib/SAML2/Utils.php

@@ -398,6 +398,10 @@ class SAML2_Utils {
 
 			try {
 				$key = $encKey->decryptKey($symmetricKeyInfo);
+				if (strlen($key) != $keySize) {
+					throw new Exception('Unexpected key size (' . strlen($key) * 8 . 'bits) for encryption algorithm: ' .
+										var_export($symmetricKey->type, TRUE));
+				}
 			} catch (Exception $e) {
 				/* We failed to decrypt this key. Log it, and substitute a "random" key. */
 				SimpleSAML_Logger::error('Failed to decrypt symmetric key: ' . $e->getMessage());