security: Fix bug in PrivateKeyStorage: Make public.
diff --git a/ndn-cpp/security/identity/private-key-storage.hpp b/ndn-cpp/security/identity/private-key-storage.hpp
index 246bd91..4bc91b9 100644
--- a/ndn-cpp/security/identity/private-key-storage.hpp
+++ b/ndn-cpp/security/identity/private-key-storage.hpp
@@ -15,6 +15,7 @@
 namespace ndn {
 
 class PrivateKeyStorage {
+public:
   /**
    * The virtual destructor
    */