diff --git a/include/ndn-cpp/encoding/oid.hpp b/include/ndn-cpp/encoding/oid.hpp
index f89339c..e755c05 100644
--- a/include/ndn-cpp/encoding/oid.hpp
+++ b/include/ndn-cpp/encoding/oid.hpp
@@ -22,6 +22,8 @@
   {
   }
     
+  OID(const char *oid);
+
   OID(const std::string& oid);
 
   OID(const std::vector<int>& oid)
@@ -58,10 +60,16 @@
 
   void
   decode(CryptoPP::BufferedTransformation &in);
-  
-private:
-  bool equal(const OID& oid) const;
 
+
+private:
+  void
+  construct(const std::string &value);
+  
+  bool
+  equal(const OID& oid) const;
+
+private:
   std::vector<int> oid_;
 };
 
diff --git a/include/ndn-cpp/security/certificate/certificate-extension.hpp b/include/ndn-cpp/security/certificate/certificate-extension.hpp
index 697993c..d979d44 100644
--- a/include/ndn-cpp/security/certificate/certificate-extension.hpp
+++ b/include/ndn-cpp/security/certificate/certificate-extension.hpp
@@ -27,17 +27,6 @@
   {
     decode(in);
   }
-  
-  /**
-   * Create a new CertificateExtension.
-   * @param oid The oid of subject description entry.
-   * @param isCritical If true, the extension must be handled.
-   * @param value The extension value.
-   */
-  CertificateExtension(const std::string& oid, const bool isCritical, const Buffer& value)
-  : extensionId_(oid), isCritical_(isCritical), extensionValue_(value)
-  {
-  }
 
   /**
    * Create a new CertificateExtension.
@@ -46,10 +35,15 @@
    * @param value The extension value.
    */
   CertificateExtension(const OID& oid, const bool isCritical, const Buffer& value)
-  : extensionId_(oid), isCritical_(isCritical), extensionValue_(value)
+    : extensionId_(oid), isCritical_(isCritical), extensionValue_(value)
   {
   }
 
+  CertificateExtension(const OID& oid, const bool isCritical, const uint8_t* value, size_t valueSize)
+    : extensionId_(oid), isCritical_(isCritical), extensionValue_(value, valueSize)
+  {
+  }
+  
   /**
    * The virtual destructor.
    */
diff --git a/include/ndn-cpp/security/certificate/certificate-subject-description.hpp b/include/ndn-cpp/security/certificate/certificate-subject-description.hpp
index 9576e0d..5717920 100644
--- a/include/ndn-cpp/security/certificate/certificate-subject-description.hpp
+++ b/include/ndn-cpp/security/certificate/certificate-subject-description.hpp
@@ -31,16 +31,6 @@
    * @param oid The oid of the subject description entry.
    * @param value The value of the subject description entry.
    */
-  CertificateSubjectDescription(const std::string &oid, const std::string &value)
-  : oid_(oid), value_(value)
-  {
-  }
-
-  /**
-   * Create a new CertificateSubjectDescription.
-   * @param oid The oid of the subject description entry.
-   * @param value The value of the subject description entry.
-   */
   CertificateSubjectDescription(const OID &oid, const std::string &value)
   : oid_(oid), value_(value)
   {