diff --git a/tests/key-chain-fixture.cpp b/tests/key-chain-fixture.cpp
new file mode 100644
index 0000000..e65ff42
--- /dev/null
+++ b/tests/key-chain-fixture.cpp
@@ -0,0 +1,116 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/*
+ * Copyright (c) 2014-2022,  Regents of the University of California,
+ *                           Arizona Board of Regents,
+ *                           Colorado State University,
+ *                           University Pierre & Marie Curie, Sorbonne University,
+ *                           Washington University in St. Louis,
+ *                           Beijing Institute of Technology,
+ *                           The University of Memphis.
+ *
+ * This file is part of NLSR (Named-data Link State Routing).
+ * See AUTHORS.md for complete list of NLSR authors and contributors.
+ *
+ * NLSR 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.
+ *
+ * NLSR 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
+ * NLSR, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "tests/key-chain-fixture.hpp"
+
+#include <ndn-cxx/util/io.hpp>
+
+#include <boost/filesystem/operations.hpp>
+
+namespace nlsr {
+namespace test {
+
+using namespace ndn::security;
+
+KeyChainFixture::KeyChainFixture()
+  : m_keyChain("pib-memory:", "tpm-memory:")
+{
+}
+
+KeyChainFixture::~KeyChainFixture()
+{
+  boost::system::error_code ec;
+  for (const auto& certFile : m_certFiles) {
+    boost::filesystem::remove(certFile, ec); // ignore error
+  }
+}
+
+bool
+KeyChainFixture::saveCert(const ndn::Data& cert, const std::string& filename)
+{
+  m_certFiles.push_back(filename);
+  try {
+    ndn::io::save(cert, filename);
+    return true;
+  }
+  catch (const ndn::io::Error&) {
+    return false;
+  }
+}
+
+bool
+KeyChainFixture::saveIdentityCert(const Identity& identity, const std::string& filename)
+{
+  Certificate cert;
+  try {
+    cert = identity.getDefaultKey().getDefaultCertificate();
+  }
+  catch (const Pib::Error&) {
+    return false;
+  }
+
+  return saveCert(cert, filename);
+}
+
+bool
+KeyChainFixture::saveIdentityCert(const ndn::Name& identityName, const std::string& filename,
+                                  bool allowCreate)
+{
+  Identity id;
+  try {
+    id = m_keyChain.getPib().getIdentity(identityName);
+  }
+  catch (const Pib::Error&) {
+    if (allowCreate) {
+      id = m_keyChain.createIdentity(identityName);
+    }
+  }
+
+  if (!id) {
+    return false;
+  }
+
+  return saveIdentityCert(id, filename);
+}
+
+Identity
+KeyChainFixture::addSubCertificate(const ndn::Name& subIdentityName,
+                                   const Identity& issuer,
+                                   const ndn::KeyParams& params)
+{
+  auto subIdentity = m_keyChain.createIdentity(subIdentityName, params);
+
+  auto request = subIdentity.getDefaultKey().getDefaultCertificate();
+  ndn::security::MakeCertificateOptions opts;
+  opts.issuerId = ndn::name::Component::fromEscapedString("parent");
+  m_keyChain.makeCertificate(request, ndn::signingByIdentity(issuer), opts);
+
+  m_keyChain.setDefaultCertificate(subIdentity.getDefaultKey(), request);
+
+  return subIdentity;
+}
+
+} // namespace test
+} // namespace nlsr