diff --git a/src/security/key.cpp b/src/security/key.cpp
new file mode 100644
index 0000000..d7a1a6f
--- /dev/null
+++ b/src/security/key.cpp
@@ -0,0 +1,201 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2013-2015 Regents of the University of California.
+ *
+ * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
+ *
+ * ndn-cxx library is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU Lesser General Public License as published by the Free Software
+ * Foundation, either version 3 of the License, or (at your option) any later version.
+ *
+ * ndn-cxx library 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 Lesser General Public License for more details.
+ *
+ * You should have received copies of the GNU General Public License and GNU Lesser
+ * General Public License along with ndn-cxx, e.g., in COPYING.md file.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
+ */
+
+#include "key.hpp"
+#include "pib-impl.hpp"
+#include "pib.hpp"
+
+namespace ndn {
+namespace security {
+
+Key::Key()
+  : m_hasDefaultCertificate(false)
+  , m_needRefreshCerts(false)
+  , m_impl(nullptr)
+{
+}
+
+Key::Key(const Name& identityName, const name::Component& keyId,
+         const PublicKey& publicKey, shared_ptr<PibImpl> impl)
+  : m_id(identityName)
+  , m_keyId(keyId)
+  , m_key(publicKey)
+  , m_hasDefaultCertificate(false)
+  , m_needRefreshCerts(true)
+  , m_impl(impl)
+{
+  validityCheck();
+
+  m_keyName = m_id;
+  m_keyName.append(m_keyId);
+
+  m_impl->addIdentity(m_id);
+  m_impl->addKey(m_id, m_keyId, publicKey);
+}
+
+Key::Key(const Name& identityName, const name::Component& keyId,
+         shared_ptr<PibImpl> impl)
+  : m_id(identityName)
+  , m_keyId(keyId)
+  , m_hasDefaultCertificate(false)
+  , m_needRefreshCerts(true)
+  , m_impl(impl)
+{
+  validityCheck();
+
+  m_keyName = m_id;
+  m_keyName.append(m_keyId);
+
+  m_key = m_impl->getKeyBits(m_id, m_keyId);
+}
+
+const Name&
+Key::getName() const
+{
+  validityCheck();
+
+  return m_keyName;
+}
+
+const Name&
+Key::getIdentity() const
+{
+  validityCheck();
+
+  return m_id;
+}
+
+const name::Component&
+Key::getKeyId() const
+{
+  validityCheck();
+
+  return m_keyId;
+}
+
+const PublicKey&
+Key::getPublicKey() const
+{
+  validityCheck();
+
+  return m_key;
+}
+
+void
+Key::addCertificate(const IdentityCertificate& certificate)
+{
+  validityCheck();
+
+  if (!m_needRefreshCerts &&
+      m_certificates.find(certificate.getName()) == m_certificates.end()) {
+    // if we have already loaded all the certificate, but the new certificate is not one of them
+    // the CertificateContainer should be refreshed
+    m_needRefreshCerts = true;
+  }
+
+  m_impl->addCertificate(certificate);
+}
+
+void
+Key::removeCertificate(const Name& certName)
+{
+  validityCheck();
+
+  if (m_hasDefaultCertificate && m_defaultCertificate.getName() == certName)
+    m_hasDefaultCertificate = false;
+
+  m_impl->removeCertificate(certName);
+  m_needRefreshCerts = true;
+}
+
+IdentityCertificate
+Key::getCertificate(const Name& certName)
+{
+  validityCheck();
+
+  return m_impl->getCertificate(certName);
+}
+
+CertificateContainer
+Key::getCertificates()
+{
+  validityCheck();
+
+  if (m_needRefreshCerts) {
+    m_certificates = std::move(CertificateContainer(m_impl->getCertificatesOfKey(m_id, m_keyId),
+                                                    m_impl));
+    m_needRefreshCerts = false;
+  }
+
+  return m_certificates;
+}
+
+const IdentityCertificate&
+Key::setDefaultCertificate(const Name& certName)
+{
+  validityCheck();
+
+  m_defaultCertificate = m_impl->getCertificate(certName);
+  m_impl->setDefaultCertificateOfKey(m_id, m_keyId, certName);
+  m_hasDefaultCertificate = true;
+  return m_defaultCertificate;
+}
+
+const IdentityCertificate&
+Key::setDefaultCertificate(const IdentityCertificate& certificate)
+{
+  addCertificate(certificate);
+  return setDefaultCertificate(certificate.getName());
+}
+
+const IdentityCertificate&
+Key::getDefaultCertificate()
+{
+  validityCheck();
+
+  if (!m_hasDefaultCertificate) {
+    m_defaultCertificate = m_impl->getDefaultCertificateOfKey(m_id, m_keyId);
+    m_hasDefaultCertificate = true;
+  }
+
+  return m_defaultCertificate;
+}
+
+Key::operator bool() const
+{
+  return !(this->operator!());
+}
+
+bool
+Key::operator!() const
+{
+  return (m_impl == nullptr);
+}
+
+void
+Key::validityCheck() const
+{
+  if (m_impl == nullptr)
+    throw std::domain_error("Invalid Key instance");
+}
+
+} // namespace security
+} // namespace ndn