security: Add IdentityCertificate copy constructor.
diff --git a/include/ndn-cpp/security/certificate/identity-certificate.hpp b/include/ndn-cpp/security/certificate/identity-certificate.hpp
index f2b585f..4d3a9db 100644
--- a/include/ndn-cpp/security/certificate/identity-certificate.hpp
+++ b/include/ndn-cpp/security/certificate/identity-certificate.hpp
@@ -32,6 +32,11 @@
   IdentityCertificate(const Data& data);
   
   /**
+   * The copy constructor. 
+   */
+  IdentityCertificate(const IdentityCertificate& identityCertificate);
+  
+  /**
    * The virtual destructor.
    */
   virtual