diff --git a/src/configuration.cpp b/src/configuration.cpp
new file mode 100644
index 0000000..c4f2c72
--- /dev/null
+++ b/src/configuration.cpp
@@ -0,0 +1,198 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2017-2020, Regents of the University of California.
+ *
+ * This file is part of ndncert, a certificate management system based on NDN.
+ *
+ * ndncert 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.
+ *
+ * ndncert 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 copies of the GNU General Public License along with
+ * ndncert, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * See AUTHORS.md for complete list of ndncert authors and contributors.
+ */
+
+#include "configuration.hpp"
+#include "challenge-module.hpp"
+#include <ndn-cxx/util/io.hpp>
+#include <boost/filesystem.hpp>
+
+namespace ndn {
+namespace ndncert {
+
+void
+CaConfigItem::parse(const JsonSection& configJson)
+{
+  // CA prefix
+  m_caPrefix = Name(configJson.get(CONFIG_CA_PREFIX, ""));
+  if (m_caPrefix.empty()) {
+    BOOST_THROW_EXCEPTION(std::runtime_error("Cannot parse ca-prefix from the config file"));
+  }
+  // CA info
+  m_caInfo = configJson.get(CONFIG_CA_INFO, "");
+  // CA max validity period
+  m_maxValidityPeriod = time::seconds(configJson.get(CONFIG_MAX_VALIDITY_PERIOD, 86400));
+  // CA max suffix length
+  m_maxSuffixLength = configJson.get_optional<size_t>(CONFIG_MAX_SUFFIX_LENGTH);
+  // probe parameter keys
+  m_probeParameterKeys.clear();
+  auto probeParametersJson = configJson.get_child_optional(CONFIG_PROBE_PARAMETERS);
+  if (probeParametersJson) {
+    for (const auto item : *probeParametersJson) {
+      auto probeParameter = item.second.get(CONFIG_PROBE_PARAMETER, "");
+      probeParameter = boost::algorithm::to_lower_copy(probeParameter);
+      if (probeParameter == "") {
+        BOOST_THROW_EXCEPTION(std::runtime_error("Probe parameter key cannot be empty."));
+      }
+      m_probeParameterKeys.push_back(probeParameter);
+    }
+  }
+  // supported challenges
+  m_supportedChallenges.clear();
+  auto challengeListJson = configJson.get_child_optional(CONFIG_SUPPORTED_CHALLENGES);
+  if (challengeListJson) {
+    for (const auto item : *challengeListJson) {
+      auto challengeType = item.second.get(CONFIG_CHALLENGE, "");
+      challengeType = boost::algorithm::to_lower_copy(challengeType);
+      if (challengeType == "") {
+        BOOST_THROW_EXCEPTION(std::runtime_error("Challenge type canont be empty."));
+      }
+      if (!ChallengeModule::isChallengeSupported(challengeType)) {
+        BOOST_THROW_EXCEPTION(std::runtime_error("Challenge " + challengeType + " is not supported."));
+      }
+      m_supportedChallenges.push_back(challengeType);
+    }
+  }
+  // anchor certificate
+  m_cert = nullptr;
+  auto certificateStr = configJson.get("certificate", "");
+  if (certificateStr != "") {
+    std::istringstream ss(certificateStr);
+    m_cert = io::load<security::v2::Certificate>(ss);
+  }
+}
+
+JsonSection
+CaConfigItem::toJson() const
+{
+  JsonSection caItem;
+  caItem.put(CONFIG_CA_PREFIX, m_caPrefix.toUri());
+  caItem.put(CONFIG_CA_INFO, m_caInfo);
+  caItem.put(CONFIG_MAX_VALIDITY_PERIOD, m_maxValidityPeriod.count());
+  caItem.put(CONFIG_MAX_SUFFIX_LENGTH, m_maxSuffixLength);
+  if (!m_probeParameterKeys.empty()) {
+    JsonSection probeParametersJson;
+    for (const auto& key : m_probeParameterKeys) {
+      JsonSection keyJson;
+      keyJson.put(CONFIG_PROBE_PARAMETER, key);
+      probeParametersJson.push_back(std::make_pair("", keyJson));
+    }
+    caItem.add_child("", probeParametersJson);
+  }
+  if (!m_supportedChallenges.empty()) {
+    JsonSection challengeListJson;
+    for (const auto& challenge : m_supportedChallenges) {
+      JsonSection challengeJson;
+      challengeJson.put(CONFIG_CHALLENGE, challenge);
+      challengeListJson.push_back(std::make_pair("", challengeJson));
+    }
+    caItem.add_child("", challengeListJson);
+  }
+  if (m_cert != nullptr) {
+    std::stringstream ss;
+    io::save(*m_cert, ss);
+    caItem.put("certificate", ss.str());
+  }
+  return caItem;
+}
+
+void
+CaConfig::load(const std::string& fileName)
+{
+  JsonSection configJson;
+  try {
+    boost::property_tree::read_json(fileName, configJson);
+  }
+  catch (const std::exception& error) {
+    BOOST_THROW_EXCEPTION(std::runtime_error("Failed to parse configuration file " + fileName + ", " + error.what()));
+  }
+  if (configJson.begin() == configJson.end()) {
+    BOOST_THROW_EXCEPTION(std::runtime_error("No JSON configuration found in file: " + fileName));
+  }
+  m_caItem.parse(configJson);
+  if (m_caItem.m_supportedChallenges.size() == 0) {
+    BOOST_THROW_EXCEPTION(std::runtime_error("At least one challenge should be specified."));
+  }
+}
+
+void
+CaConfig::save(const std::string& fileName) const
+{
+  std::stringstream ss;
+  boost::property_tree::write_json(ss, m_caItem.toJson());
+  std::ofstream configFile;
+  configFile.open(fileName);
+  configFile << ss.str();
+  configFile.close();
+}
+
+void
+ClientConfig::load(const std::string& fileName)
+{
+  JsonSection configJson;
+  try {
+    boost::property_tree::read_json(fileName, configJson);
+  }
+  catch (const std::exception& error) {
+    BOOST_THROW_EXCEPTION(std::runtime_error("Failed to parse configuration file " + fileName + ", " + error.what()));
+  }
+  if (configJson.begin() == configJson.end()) {
+    BOOST_THROW_EXCEPTION(std::runtime_error("No JSON configuration found in file: " + fileName));
+  }
+  load(configJson);
+}
+
+void
+ClientConfig::load(const JsonSection& configSection)
+{
+  m_caItems.clear();
+  auto caList = configSection.get_child("ca-list");
+  for (auto item : caList) {
+    CaConfigItem caItem;
+    caItem.parse(item.second);
+    if (caItem.m_cert == nullptr) {
+      BOOST_THROW_EXCEPTION(std::runtime_error("No CA certificate is loaded from JSON configuration."));
+    }
+    m_caItems.push_back(std::move(caItem));
+  }
+}
+
+void
+ClientConfig::save(const std::string& fileName) const
+{
+  JsonSection configJson;
+  for (const auto& caItem : m_caItems) {
+    configJson.push_back(std::make_pair("", caItem.toJson()));
+  }
+  std::stringstream ss;
+  boost::property_tree::write_json(ss, configJson);
+  std::ofstream configFile;
+  configFile.open(fileName);
+  configFile << ss.str();
+  configFile.close();
+}
+
+void
+ClientConfig::removeCaItem(const Name& caName)
+{
+  m_caItems.remove_if([&](const CaConfigItem& item) { return item.m_caPrefix == caName; });
+}
+
+}  // namespace ndncert
+}  // namespace ndn