security: Implement BasicIdentityStorage::getCertificate
diff --git a/include/ndn-cpp/security/identity/basic-identity-storage.hpp b/include/ndn-cpp/security/identity/basic-identity-storage.hpp
index d841548..488d95a 100644
--- a/include/ndn-cpp/security/identity/basic-identity-storage.hpp
+++ b/include/ndn-cpp/security/identity/basic-identity-storage.hpp
@@ -138,7 +138,7 @@
    * @param allowAny If false, only a valid certificate will be returned, otherwise validity is disregarded.
    * @return The requested certificate.  If not found, return a shared_ptr with a null pointer.
    */
-  virtual ptr_lib::shared_ptr<Certificate> 
+  virtual ptr_lib::shared_ptr<Data> 
   getCertificate(const Name &certificateName, bool allowAny = false);
 
 
diff --git a/include/ndn-cpp/security/identity/identity-storage.hpp b/include/ndn-cpp/security/identity/identity-storage.hpp
index d9b5e1a..fdf3d0c 100644
--- a/include/ndn-cpp/security/identity/identity-storage.hpp
+++ b/include/ndn-cpp/security/identity/identity-storage.hpp
@@ -129,7 +129,7 @@
    * @param allowAny If false, only a valid certificate will be returned, otherwise validity is disregarded.
    * @return The requested certificate.  If not found, return a shared_ptr with a null pointer.
    */
-  virtual ptr_lib::shared_ptr<Certificate> 
+  virtual ptr_lib::shared_ptr<Data> 
   getCertificate(const Name &certificateName, bool allowAny = false) = 0;
 
 
diff --git a/include/ndn-cpp/security/identity/memory-identity-storage.hpp b/include/ndn-cpp/security/identity/memory-identity-storage.hpp
index 9b7dd5f..0fb09c0 100644
--- a/include/ndn-cpp/security/identity/memory-identity-storage.hpp
+++ b/include/ndn-cpp/security/identity/memory-identity-storage.hpp
@@ -124,7 +124,7 @@
    * @param allowAny If false, only a valid certificate will be returned, otherwise validity is disregarded.
    * @return The requested certificate.  If not found, return a shared_ptr with a null pointer.
    */
-  virtual ptr_lib::shared_ptr<Certificate> 
+  virtual ptr_lib::shared_ptr<Data> 
   getCertificate(const Name &certificateName, bool allowAny = false);