security: Make addKey/Cert behavior of PibImpl consistent

Change-Id: I30c6dd0007e9095ee07f7a8eda3b20db4c34c513
Refs: #3351
diff --git a/src/security/pib/pib-sqlite3.hpp b/src/security/pib/pib-sqlite3.hpp
index 806a29c..8c47176 100644
--- a/src/security/pib/pib-sqlite3.hpp
+++ b/src/security/pib/pib-sqlite3.hpp
@@ -134,6 +134,16 @@
   getDefaultCertificateOfKey(const Name& keyName) const final;
 
 private:
+  bool
+  hasDefaultIdentity() const;
+
+  bool
+  hasDefaultKeyOfIdentity(const Name& identity) const;
+
+  bool
+  hasDefaultCertificateOfKey(const Name& keyName) const;
+
+private:
   sqlite3* m_database;
 };