diff --git a/src/detail/ca-storage.hpp b/src/detail/ca-storage.hpp
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+++ b/src/detail/ca-storage.hpp
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+/* -*- 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.
+ */
+
+#ifndef NDNCERT_CA_STORAGE_HPP
+#define NDNCERT_CA_STORAGE_HPP
+
+#include "detail/ca-state.hpp"
+
+namespace ndn {
+namespace ndncert {
+
+class CaStorage : noncopyable
+{
+public: // request related
+  /**
+   * @throw if request cannot be fetched from underlying data storage
+   */
+  virtual CaState
+  getRequest(const std::string& requestId) = 0;
+
+  /**
+   * @throw if there is an existing request with the same request ID
+   */
+  virtual void
+  addRequest(const CaState& request) = 0;
+
+  virtual void
+  updateRequest(const CaState& request) = 0;
+
+  virtual void
+  deleteRequest(const std::string& requestId) = 0;
+
+  virtual std::list<CaState>
+  listAllRequests() = 0;
+
+  virtual std::list<CaState>
+  listAllRequests(const Name& caName) = 0;
+
+public: // factory
+  template<class CaStorageType>
+  static void
+  registerCaStorage(const std::string& caStorageType = CaStorageType::STORAGE_TYPE)
+  {
+    CaStorageFactory& factory = getFactory();
+    BOOST_ASSERT(factory.count(caStorageType) == 0);
+    factory[caStorageType] = [] (const Name& caName, const std::string& path) {
+      return std::make_unique<CaStorageType>(caName, path);
+    };
+  }
+
+  static unique_ptr<CaStorage>
+  createCaStorage(const std::string& caStorageType, const Name& caName, const std::string& path);
+
+  virtual
+  ~CaStorage() = default;
+
+private:
+  using CaStorageCreateFunc = function<unique_ptr<CaStorage> (const Name&, const std::string&)>;
+  using CaStorageFactory = std::map<std::string, CaStorageCreateFunc>;
+
+  static CaStorageFactory&
+  getFactory();
+};
+
+#define NDNCERT_REGISTER_CA_STORAGE(C)                           \
+static class NdnCert ## C ## CaStorageRegistrationClass          \
+{                                                                \
+public:                                                          \
+  NdnCert ## C ## CaStorageRegistrationClass()                   \
+  {                                                              \
+    ::ndn::ndncert::CaStorage::registerCaStorage<C>();           \
+  }                                                              \
+} g_NdnCert ## C ## CaStorageRegistrationVariable
+
+} // namespace ndncert
+} // namespace ndn
+
+#endif // NDNCERT_CA_STORAGE_HPP