DER encoding: implement Certificate::printCertificate().
diff --git a/ndn-cpp/encoding/der/visitor/certificate-data-visitor.hpp b/ndn-cpp/encoding/der/visitor/certificate-data-visitor.hpp
index 3df60be..ec73bd7 100644
--- a/ndn-cpp/encoding/der/visitor/certificate-data-visitor.hpp
+++ b/ndn-cpp/encoding/der/visitor/certificate-data-visitor.hpp
@@ -19,27 +19,27 @@
   virtual void visit(DerSequence&,         ndnboost::any);
 };
 
-class CertValidityVisitor : public VoidVisitor {
+class CertificateValidityVisitor : public VoidVisitor {
 public:
   virtual void visit(DerSequence&,         ndnboost::any);
 };
 
-class CertSubDescryptVisitor : public VoidVisitor {
+class CertificateSubjectDescriptionVisitor : public VoidVisitor {
 public:
   virtual void visit(DerSequence&,         ndnboost::any);
 };
 
-class CertSubjectVisitor : public VoidVisitor {
+class CertificateSubjectVisitor : public VoidVisitor {
 public:
   virtual void visit(DerSequence&,         ndnboost::any);
 };
 
-class CertExtnEntryVisitor : public VoidVisitor {
+class CertificateExtensionEntryVisitor : public VoidVisitor {
 public:
   virtual void visit(DerSequence&,         ndnboost::any);
 };
 
-class CertExtensionVisitor : public VoidVisitor {
+class CertificateExtensionVisitor : public VoidVisitor {
 public:
   virtual void visit(DerSequence&,         ndnboost::any);
 };