diff --git a/src/detail/request-encoder.hpp b/src/detail/request-encoder.hpp
new file mode 100644
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+++ b/src/detail/request-encoder.hpp
@@ -0,0 +1,50 @@
+/* -*- 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_DETAIL_REQUEST_ENCODER_HPP
+#define NDNCERT_DETAIL_REQUEST_ENCODER_HPP
+
+#include "detail/ca-request-state.hpp"
+
+namespace ndn {
+namespace ndncert {
+namespace requesttlv {
+
+Block
+encodeApplicationParameters(RequestType requestType, const std::vector<uint8_t>& ecdhPub,
+                            const security::Certificate& certRequest);
+
+void
+decodeApplicationParameters(const Block& block, RequestType requestType, std::vector<uint8_t>& ecdhPub,
+                            shared_ptr<security::Certificate>& certRequest);
+
+Block
+encodeDataContent(const std::vector<uint8_t>& ecdhKey, const std::array<uint8_t, 32>& salt,
+                  const RequestId& requestId, const std::vector<std::string>& challenges);
+
+std::list<std::string>
+decodeDataContent(const Block& content, std::vector<uint8_t>& ecdhKey,
+                  std::array<uint8_t, 32>& salt, RequestId& requestId);
+
+} // namespace requesttlv
+} // namespace ndncert
+} // namespace ndn
+
+#endif // NDNCERT_DETAIL_NEW_RENEW_REVOKE_ENCODER_HPP
\ No newline at end of file