diff --git a/src/util/time.cpp b/src/util/time.cpp
index 15ac925..b652a7b 100644
--- a/src/util/time.cpp
+++ b/src/util/time.cpp
@@ -20,11 +20,112 @@
  */
 
 #include "time.hpp"
+#include "time-custom-clock.hpp"
+
 #include <boost/date_time/posix_time/posix_time.hpp>
 
 namespace ndn {
 namespace time {
 
+static shared_ptr<CustomSystemClock> g_systemClock;
+static shared_ptr<CustomSteadyClock> g_steadyClock;
+
+// this method is defined in time-custom-clock.hpp
+void
+setCustomClocks(shared_ptr<CustomSteadyClock> steadyClock,
+                shared_ptr<CustomSystemClock> systemClock)
+{
+  g_systemClock = systemClock;
+  g_steadyClock = steadyClock;
+}
+
+/////////////////////////////////////////////////////////////////////////////////////////////
+
+system_clock::time_point
+system_clock::now() noexcept
+{
+  if (g_systemClock == nullptr) {
+    // optimized default version
+    return time_point(boost::chrono::system_clock::now().time_since_epoch());
+  }
+  else {
+    return g_systemClock->getNow();
+  }
+}
+
+std::time_t
+system_clock::to_time_t(const time_point& t) noexcept
+{
+  return duration_cast<seconds>(t.time_since_epoch()).count();
+}
+
+system_clock::time_point
+system_clock::from_time_t(std::time_t t) noexcept
+{
+  return time_point(seconds(t));
+}
+
+/////////////////////////////////////////////////////////////////////////////////////////////
+
+#ifdef __APPLE__
+  // Note that on OS X platform boost::steady_clock is not truly monotonic, so we use
+  // system_clock instead.  Refer to https://svn.boost.org/trac/boost/ticket/7719)
+  typedef boost::chrono::system_clock base_steady_clock;
+#else
+  typedef boost::chrono::steady_clock base_steady_clock;
+#endif
+
+steady_clock::time_point
+steady_clock::now() noexcept
+{
+  if (g_steadyClock == nullptr) {
+    // optimized default version
+    return time_point(base_steady_clock::now().time_since_epoch());
+  }
+  else {
+    return g_steadyClock->getNow();
+  }
+}
+
+boost::posix_time::time_duration
+steady_clock::to_posix_duration(const duration& duration)
+{
+  if (g_steadyClock == nullptr) {
+    // optimized default version
+    return
+#ifdef BOOST_DATE_TIME_HAS_NANOSECONDS
+      boost::posix_time::nanoseconds(duration_cast<nanoseconds>(duration).count())
+#else
+      boost::posix_time::microseconds(duration_cast<microseconds>(duration).count())
+#endif
+      ;
+  }
+  else {
+    return g_steadyClock->toPosixDuration(duration);
+  }
+}
+
+/////////////////////////////////////////////////////////////////////////////////////////////
+
+const system_clock::TimePoint&
+getUnixEpoch()
+{
+  static system_clock::TimePoint epoch = system_clock::from_time_t(0);
+  return epoch;
+}
+
+milliseconds
+toUnixTimestamp(const system_clock::TimePoint& point)
+{
+  return duration_cast<milliseconds>(point - getUnixEpoch());
+}
+
+system_clock::TimePoint
+fromUnixTimestamp(const milliseconds& duration)
+{
+  return getUnixEpoch() + duration;
+}
+
 std::string
 toIsoString(const system_clock::TimePoint& timePoint)
 {
@@ -100,3 +201,45 @@
 
 } // namespace time
 } // namespace ndn
+
+namespace boost {
+namespace chrono {
+
+/////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class CharT>
+std::basic_string<CharT>
+clock_string<ndn::time::system_clock, CharT>::since()
+{
+  if (ndn::time::g_systemClock == nullptr) {
+    // optimized default version
+    return clock_string<system_clock, CharT>::since();
+  }
+  else {
+    return ndn::time::g_systemClock->getSince();
+  }
+}
+
+template
+struct clock_string<ndn::time::system_clock, char>;
+
+/////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class CharT>
+std::basic_string<CharT>
+clock_string<ndn::time::steady_clock, CharT>::since()
+{
+  if (ndn::time::g_steadyClock == nullptr) {
+    // optimized default version
+    return clock_string<ndn::time::base_steady_clock, CharT>::since();
+  }
+  else {
+    return ndn::time::g_steadyClock->getSince();
+  }
+}
+
+template
+struct clock_string<ndn::time::steady_clock, char>;
+
+} // namespace chrono
+} // namespace boost