security: change enum to enum class in security-common.hpp

Change-Id: I5565c845cd57f3457c8120b11399a105fa83418d
Refs: #3083
diff --git a/tools/ndnsec/delete.hpp b/tools/ndnsec/delete.hpp
index 9b36fba..0c96af4 100644
--- a/tools/ndnsec/delete.hpp
+++ b/tools/ndnsec/delete.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /**
- * Copyright (c) 2013-2015 Regents of the University of California.
+ * Copyright (c) 2013-2016 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -96,7 +96,7 @@
     }
     else if (isDeleteKey) {
       if (!keyChain.doesPublicKeyExist(name) &&
-          !keyChain.doesKeyExistInTpm(name, KEY_CLASS_PRIVATE)) {
+          !keyChain.doesKeyExistInTpm(name, KeyClass::PRIVATE)) {
         std::cerr << "ERROR: Key does not exist: " << name << std::endl;
         return 1;
       }