diff --git a/src/security/certificate-cache-ttl.hpp b/src/security/certificate-cache-ttl.hpp
new file mode 100644
index 0000000..6d5194b
--- /dev/null
+++ b/src/security/certificate-cache-ttl.hpp
@@ -0,0 +1,54 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil -*- */
+/**
+ * Copyright (C) 2013 Regents of the University of California.
+ * @author: Yingdi Yu <yingdi@cs.ucla.edu>
+ * See COPYING for copyright and distribution information.
+ */
+
+#ifndef NDN_CERTIFICATE_CACHE_TTL_HPP
+#define NDN_CERTIFICATE_CACHE_TTL_HPP
+
+#include "certificate-cache.hpp"
+#include "../util/scheduler.hpp"
+#include "../util/time.hpp"
+
+#include <unistd.h>
+#include <map>
+
+namespace ndn
+{
+ 
+class CertificateCacheTtl : public CertificateCache
+{
+public:
+  CertificateCacheTtl(shared_ptr<boost::asio::io_service> io, int defaultTtl = 3600);
+  
+  virtual
+  ~CertificateCacheTtl();
+    
+  virtual void
+  insertCertificate(ptr_lib::shared_ptr<const IdentityCertificate> certificate);
+  
+  virtual ptr_lib::shared_ptr<const IdentityCertificate> 
+  getCertificate(const Name & certificateNameWithoutVersion);
+
+private:  
+  void
+  insert(ptr_lib::shared_ptr<const IdentityCertificate> certificate);
+  
+  void
+  remove(const Name &certificateName);
+
+protected:
+  typedef std::map<Name, ptr_lib::shared_ptr<const IdentityCertificate> > Cache;
+  typedef std::map<Name, EventId> EventTracker;
+
+  int m_defaultTtl;
+  Cache m_cache;
+  EventTracker m_tracker;
+  Scheduler m_scheduler;
+};
+
+}//ndn
+
+#endif