diff --git a/src/security/pib-impl.hpp b/src/security/pib-impl.hpp
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+/* -*- 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.
+ */
+
+#ifndef NDN_SECURITY_PIB_IMPL_HPP
+#define NDN_SECURITY_PIB_IMPL_HPP
+
+#include <set>
+#include "identity-certificate.hpp"
+
+namespace ndn {
+namespace security {
+
+/**
+ * @brief Abstract class of PIB implementation
+ *
+ * This class defines the interface that an actual PIB (e.g., one based on sqlite3)
+ * implementation should provide.
+ */
+class PibImpl
+{
+public:
+  /**
+   * @brief represents a non-semantic error
+   *
+   * A subclass of PibImpl may throw a subclass of this type when
+   * there's a non-semantic error, such as a storage problem.
+  */
+  class Error : public std::runtime_error
+  {
+  public:
+    explicit
+    Error(const std::string& what)
+      : std::runtime_error(what)
+    {
+    }
+  };
+
+public:
+
+  virtual
+  ~PibImpl()
+  {
+  }
+
+public: // TpmLocator management
+
+  /**
+   * @brief Set the corresponding TPM information to @p tpmLocator.
+   *
+   * If the provided @p tpmLocator is different from the existing one, the
+   * content in PIB will be cleaned up, otherwise nothing will be changed.
+   *
+   * @param tmpLocator The name for the new tmpLocator
+   */
+  virtual void
+  setTpmLocator(const std::string& tpmLocator) = 0;
+
+  /**
+   * @brief Get TPM Locator
+   */
+  virtual std::string
+  getTpmLocator() const = 0;
+
+public: // Identity management
+
+  /**
+   * @brief Check the existence of an identity.
+   *
+   * @param identity The name of the identity.
+   * @return true if the identity exists, otherwise false.
+   */
+  virtual bool
+  hasIdentity(const Name& identity) const = 0;
+
+  /**
+   * @brief Add an identity.
+   *
+   * If the identity already exists, do nothing.
+   *
+   * @param identity The name of the identity to add.
+   */
+  virtual void
+  addIdentity(const Name& identity) = 0;
+
+  /**
+   * @brief Remove an identity
+   *
+   * If the identity does not exist, do nothing.
+   *
+   * @param identity The name of the identity to remove.
+   */
+  virtual void
+  removeIdentity(const Name& identity) = 0;
+
+  /// @brief Get the name of all the identities
+  virtual std::set<Name>
+  getIdentities() const = 0;
+
+  /**
+   * @brief Set an identity with name @p identityName as the default identity.
+   *
+   * Since adding an identity only requires the identity name, create the
+   * identity if it does not exist.
+   *
+   * @param identityName The name for the default identity.
+   */
+  virtual void
+  setDefaultIdentity(const Name& identityName) = 0;
+
+  /**
+   * @brief Get the default identity.
+   *
+   * @return The name for the default identity.
+   * @throws Pib::Error if no default identity.
+   */
+  virtual Name
+  getDefaultIdentity() const = 0;
+
+public: // Key management
+
+  /**
+   * @brief Check the existence of a key.
+   *
+   * @param identity The name of the belonged identity.
+   * @param keyId The key id component.
+   * @return true if the key exists, otherwise false. Return false if the identity does not exist
+   */
+  virtual bool
+  hasKey(const Name& identity, const name::Component& keyId) const = 0;
+
+  /**
+   * @brief Add a key.
+   *
+   * If the key already exists, do nothing.
+   * If the identity does not exist, add the identity as well.
+   *
+   * @param identity The name of the belonged identity.
+   * @param keyId The key id component.
+   * @param publicKey The public key bits.
+   */
+  virtual void
+  addKey(const Name& identity, const name::Component& keyId, const PublicKey& publicKey) = 0;
+
+  /**
+   * @brief Remove a key.
+   *
+   * If the key does not exist, do nothing.
+   *
+   * @param identity The name of the belonged identity.
+   * @param keyId The key id component.
+   */
+  virtual void
+  removeKey(const Name& identity, const name::Component& keyId) = 0;
+
+  /**
+   * @brief Get the key bits of a key.
+   *
+   * @param identity The name of the belonged identity.
+   * @param keyId The key id component.
+   * @return key bits
+   * @throws Pib::Error if the key does not exist.
+   */
+  virtual PublicKey
+  getKeyBits(const Name& identity, const name::Component& keyId) const = 0;
+
+  /**
+   * @brief Get all the key ids of an identity with name @p identity
+   *
+   * The returned key ids can be used to create a KeyContainer.
+   * With key id, identity name, backend implementation, one can create a Key frontend instance.
+   *
+   * @return the key id name component set. If the identity does not exist, return an empty set.
+   */
+  virtual std::set<name::Component>
+  getKeysOfIdentity(const Name& identity) const = 0;
+
+  /**
+   * @brief Set an key with id @p keyId as the default key of an identity with name @p identity.
+   *
+   * @param identity The name of the belonged identity.
+   * @param keyId The key id component.
+   * @throws Pib::Error if the key does not exist.
+   */
+  virtual void
+  setDefaultKeyOfIdentity(const Name& identity, const name::Component& keyId) = 0;
+
+  /**
+   * @brief Get the id of the default key of an identity with name @p identity.
+   *
+   * @param identity The name of the belonged identity.
+   * @throws Pib::Error if no default key or the identity does not exist.
+   */
+  virtual name::Component
+  getDefaultKeyOfIdentity(const Name& identity) const = 0;
+
+public: // Certificate Management
+
+  /**
+   * @brief Check the existence of a certificate with name @p certName.
+   *
+   * @param certName The name of the certificate.
+   * @return true if the certificate exists, otherwise false.
+   */
+  virtual bool
+  hasCertificate(const Name& certName) const = 0;
+
+  /**
+   * @brief Add a certificate.
+   *
+   * If the certificate already exists, do nothing.
+   * If the key or identity do not exist, add them as well.
+   *
+   * @param certificate The certificate to add.
+   */
+  virtual void
+  addCertificate(const IdentityCertificate& certificate) = 0;
+
+  /**
+   * @brief Remove a certificate with name @p certName.
+   *
+   * If the certificate does not exist, do nothing.
+   *
+   * @param certName The name of the certificate.
+   */
+  virtual void
+  removeCertificate(const Name& certName) = 0;
+
+  /**
+   * @brief Get a certificate with name @p certName.
+   *
+   * @param certName The name of the certificate.
+   * @return the certificate.
+   * @throws Pib::Error if the certificate does not exist.
+   */
+  virtual IdentityCertificate
+  getCertificate(const Name& certName) const = 0;
+
+  /**
+   * @brief Get a list of certificate names of a key with id @p keyId of @p identity.
+   *
+   * The returned certificate names can be used to create a CertificateContainer.
+   * With certificate name and backend implementation, one can obtain the certificate directly.
+   *
+   * @param identity The name of the belonging identity.
+   * @param keyId The key id.
+   * @return The certificate name set. If the key does not exist, return an empty set.
+   */
+  virtual std::set<Name>
+  getCertificatesOfKey(const Name& identity, const name::Component& keyId) const = 0;
+
+  /**
+   * @brief Set a cert with name @p certName as the default of a key with id @keyId of @identity.
+   *
+   * @param identity The name of the belonging identity.
+   * @param keyId The key id.
+   * @param certName The name of the certificate.
+   * @throws Pib::Error if the certificate with name @p certName does not exist.
+   */
+  virtual void
+  setDefaultCertificateOfKey(const Name& identity, const name::Component& keyId,
+                             const Name& certName) = 0;
+
+  /**
+   * @brief Get the default certificate of a key with id @keyId of @identity.
+   *
+   * @param identity The name of the belonging identity.
+   * @param keyId The key id.
+   * @return a pointer to the certificate, null if no default certificate for the key.
+   * @throws Pib::Error if the default certificate does not exist.
+   */
+  virtual IdentityCertificate
+  getDefaultCertificateOfKey(const Name& identity, const name::Component& keyId) const = 0;
+
+};
+
+} // namespace security
+} // namespace ndn
+
+#endif // NDN_SECURITY_PIB_IMPL_HPP