diff --git a/src/repetitive-interval.cpp b/src/repetitive-interval.cpp
new file mode 100644
index 0000000..2a441b5
--- /dev/null
+++ b/src/repetitive-interval.cpp
@@ -0,0 +1,275 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2014-2015,  Regents of the University of California
+ *
+ * This file is part of ndn-group-encrypt (Group-based Encryption Protocol for NDN).
+ * See AUTHORS.md for complete list of ndn-group-encrypt authors and contributors.
+ *
+ * ndn-group-encrypt is free software: you can redistribute it and/or modify it under the terms
+ * of the GNU General Public License as published by the Free Software Foundation,
+ * either version 3 of the License, or (at your option) any later version.
+ *
+ * ndn-group-encrypt is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
+ * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
+ * PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * ndn-group-encrypt, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * @author Zhiyi Zhang <dreamerbarrychang@gmail.com>
+ */
+
+#include "repetitive-interval.hpp"
+#include "tlv.hpp"
+
+#include <ndn-cxx/encoding/block-helpers.hpp>
+#include <ndn-cxx/util/concepts.hpp>
+#include <boost/date_time/posix_time/posix_time.hpp>
+
+namespace ndn {
+namespace gep {
+
+static const TimeStamp DEFAULT_TIME = boost::posix_time::from_iso_string("14000101T000000");
+
+BOOST_CONCEPT_ASSERT((WireEncodable<RepetitiveInterval>));
+BOOST_CONCEPT_ASSERT((WireDecodable<RepetitiveInterval>));
+
+RepetitiveInterval::RepetitiveInterval()
+  : m_startDate(DEFAULT_TIME)
+  , m_endDate(DEFAULT_TIME)
+  , m_intervalStartHour(0)
+  , m_intervalEndHour(24)
+  , m_nRepeats(0)
+  , m_unit(RepeatUnit::NONE)
+{
+}
+
+RepetitiveInterval::RepetitiveInterval(const Block& block)
+{
+  wireDecode(block);
+}
+
+RepetitiveInterval::RepetitiveInterval(const TimeStamp& startDate,
+                                       const TimeStamp& endDate,
+                                       size_t intervalStartHour,
+                                       size_t intervalEndHour,
+                                       size_t nRepeats,
+                                       RepeatUnit unit)
+  : m_startDate(startDate)
+  , m_endDate(endDate)
+  , m_intervalStartHour(intervalStartHour)
+  , m_intervalEndHour(intervalEndHour)
+  , m_nRepeats(nRepeats)
+  , m_unit(unit)
+{
+  BOOST_ASSERT(m_intervalStartHour < m_intervalEndHour);
+  BOOST_ASSERT(m_startDate.date() <= m_endDate.date());
+  BOOST_ASSERT(m_intervalEndHour <= 24);
+  if (unit == RepeatUnit::NONE)
+    BOOST_ASSERT(m_startDate.date() == m_endDate.date());
+}
+
+template<encoding::Tag TAG>
+size_t
+RepetitiveInterval::wireEncode(EncodingImpl<TAG>& encoder) const
+{
+  using namespace boost::posix_time;
+
+  size_t totalLength = 0;
+
+  // RepeatUnit
+  totalLength += prependNonNegativeIntegerBlock(encoder, tlv::RepeatUnit,
+                                                  static_cast<size_t>(m_unit));
+  // NRepeat
+  totalLength += prependNonNegativeIntegerBlock(encoder, tlv::NRepeats, m_nRepeats);
+  // IntervalEndHour
+  totalLength += prependNonNegativeIntegerBlock(encoder, tlv::IntervalEndHour, m_intervalEndHour);
+  // IntervalStartHour
+  totalLength += prependNonNegativeIntegerBlock(encoder, tlv::IntervalStartHour,
+                                                m_intervalStartHour);
+  // EndDate
+  totalLength += prependStringBlock(encoder, tlv::EndDate, to_iso_string(m_endDate));
+  // StartDate
+  totalLength += prependStringBlock(encoder, tlv::StartDate, to_iso_string(m_startDate));
+
+  totalLength += encoder.prependVarNumber(totalLength);
+  totalLength += encoder.prependVarNumber(tlv::RepetitiveInterval);
+
+  return totalLength;
+}
+
+const Block&
+RepetitiveInterval::wireEncode() const
+{
+  if (m_wire.hasWire())
+    return m_wire;
+
+  EncodingEstimator estimator;
+  size_t estimatedSize = wireEncode(estimator);
+
+  EncodingBuffer buffer(estimatedSize, 0);
+  wireEncode(buffer);
+
+  this->m_wire = buffer.block();
+  return m_wire;
+}
+
+void
+RepetitiveInterval::wireDecode(const Block& wire)
+{
+  using namespace boost::posix_time;
+
+  if (wire.type() != tlv::RepetitiveInterval)
+    BOOST_THROW_EXCEPTION(tlv::Error("Unexpected TLV type when decoding RepetitiveInterval"));
+
+  m_wire = wire;
+  m_wire.parse();
+
+  if (m_wire.elements_size() != 6)
+    BOOST_THROW_EXCEPTION(tlv::Error("RepetitiveInterval tlv does not have six sub-TLVs"));
+
+  Block::element_const_iterator it = m_wire.elements_begin();
+  // StartDate
+  if (it->type() == tlv::StartDate) {
+    m_startDate = ptime(from_iso_string(readString(*it)));
+    it++;
+  }
+  else
+    BOOST_THROW_EXCEPTION(tlv::Error("First element must be StartDate"));
+
+  // EndDate
+  if (it->type() == tlv::EndDate) {
+    m_endDate = ptime(from_iso_string(readString(*it)));
+    it++;
+  }
+  else
+    BOOST_THROW_EXCEPTION(tlv::Error("Second element must be EndDate"));
+
+  // IntervalStartHour
+  if (it->type() == tlv::IntervalStartHour) {
+    m_intervalStartHour = readNonNegativeInteger(*it);
+    it++;
+  }
+  else
+    BOOST_THROW_EXCEPTION(tlv::Error("Third element must be IntervalStartHour"));
+
+  // IntervalEndHour
+  if (it->type() == tlv::IntervalEndHour) {
+    m_intervalEndHour = readNonNegativeInteger(*it);
+    it++;
+  }
+  else
+    BOOST_THROW_EXCEPTION(tlv::Error("Fourth element must be IntervalEndHour"));
+
+  // NRepeats
+  if (it->type() == tlv::NRepeats) {
+    m_nRepeats = readNonNegativeInteger(*it);
+    it++;
+  }
+  else
+    BOOST_THROW_EXCEPTION(tlv::Error("Fifth element must be NRepeats"));
+
+  // RepeatUnit
+  if (it->type() == tlv::RepeatUnit) {
+    m_unit = static_cast<RepeatUnit>(readNonNegativeInteger(*it));
+    it++;
+  }
+  else
+    BOOST_THROW_EXCEPTION(tlv::Error("The last element must be RepeatUnit"));
+}
+
+std::tuple<bool, Interval>
+RepetitiveInterval::getInterval(const TimeStamp& tp) const
+{
+  TimeStamp startTime;
+  TimeStamp endTime;
+  bool isPositive;
+
+  if (!this->hasIntervalOnDate(tp)) {
+    // there is no interval on the date of tp
+    startTime = TimeStamp(tp.date(), boost::posix_time::hours(0));
+    endTime = TimeStamp(tp.date(), boost::posix_time::hours(24));
+    isPositive = false;
+  }
+  else {
+    // there is an interval on the date of tp
+    startTime = TimeStamp(tp.date(), boost::posix_time::hours(m_intervalStartHour));
+    endTime = TimeStamp(tp.date(), boost::posix_time::hours(m_intervalEndHour));
+
+    // check if in the time duration
+    if (tp < startTime) {
+      endTime = startTime;
+      startTime = TimeStamp(tp.date(), boost::posix_time::hours(0));
+      isPositive = false;
+    }
+    else if (tp > endTime) {
+      startTime = endTime;
+      endTime = TimeStamp(tp.date(), boost::posix_time::hours(24));
+      isPositive = false;
+    }
+    else {
+      isPositive = true;
+    }
+  }
+  return std::make_tuple(isPositive, Interval(startTime, endTime));
+}
+
+bool
+RepetitiveInterval::hasIntervalOnDate(const TimeStamp& tp) const
+{
+  namespace bg = boost::gregorian;
+
+  // check if in the bound of the interval
+  if (tp.date() < m_startDate.date() || tp.date() > m_endDate.date()) {
+    return false;
+  }
+
+  if (m_unit == RepeatUnit::NONE) {
+    return true;
+  }
+
+  // check if in the matching date
+  bg::date dateA = tp.date();
+  bg::date dateB = m_startDate.date();
+  if (m_unit == RepeatUnit::DAY) {
+    bg::date_duration duration = dateA - dateB;
+    if (static_cast<size_t>(duration.days()) % m_nRepeats == 0)
+      return true;
+  }
+  else if (m_unit == RepeatUnit::MONTH && dateA.day() == dateB.day()) {
+    size_t yearDiff = static_cast<size_t>(dateA.year() - dateB.year());
+    size_t monthDiff = 12 * yearDiff + dateA.month().as_number() - dateB.month().as_number();
+    if (monthDiff % m_nRepeats == 0)
+      return true;
+  }
+  else if (m_unit == RepeatUnit::YEAR &&
+           dateA.day().as_number() == dateB.day().as_number() &&
+           dateA.month().as_number() == dateB.month().as_number()) {
+    size_t diff = static_cast<size_t>(dateA.year() - dateB.year());
+    if (diff % m_nRepeats == 0)
+      return true;
+  }
+
+  return false;
+}
+
+bool
+RepetitiveInterval::operator<(const RepetitiveInterval& interval) const
+{
+  if (m_startDate < interval.getStartDate())
+    return true;
+  if (m_endDate < interval.getEndDate())
+    return true;
+  if (m_intervalStartHour < interval.getIntervalStartHour())
+    return true;
+  if (m_intervalEndHour < interval.getIntervalEndHour())
+    return true;
+  if (m_nRepeats < interval.getNRepeats())
+    return true;
+  if (static_cast<size_t>(m_unit) < static_cast<size_t>(interval.getRepeatUnit()))
+    return true;
+  return false;
+}
+
+} // namespace gep
+} // namespace ndn