src/security/key-chain.hpp

/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/**
 * Copyright (c) 2013-2016 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.
 *
 * @author Yingdi Yu <http://irl.cs.ucla.edu/~yingdi/>
 */

#ifndef NDN_SECURITY_KEY_CHAIN_HPP
#define NDN_SECURITY_KEY_CHAIN_HPP

#include "sec-public-info.hpp"
#include "sec-tpm.hpp"
#include "key-params.hpp"
#include "secured-bag.hpp"
#include "signature-sha256-with-rsa.hpp"
#include "signature-sha256-with-ecdsa.hpp"
#include "digest-sha256.hpp"
#include "signing-info.hpp"

#include "../interest.hpp"
#include "../util/crypto.hpp"
#include "../util/random.hpp"
#include <initializer_list>

namespace ndn {
namespace security {

/**
 * @brief The packet signing interface.
 */
class KeyChain : noncopyable
{
public:
  class Error : public std::runtime_error
  {
  public:
    explicit
    Error(const std::string& what)
      : std::runtime_error(what)
    {
    }
  };

  /**
   * @brief Error thrown when the supplied TPM locator to KeyChain constructor does not match
   *        the locator stored in PIB
   */
  class MismatchError : public Error
  {
  public:
    explicit
    MismatchError(const std::string& what)
      : Error(what)
    {
    }
  };

  typedef function<unique_ptr<SecPublicInfo> (const std::string&)> PibCreateFunc;
  typedef function<unique_ptr<SecTpm>(const std::string&)> TpmCreateFunc;

  /**
   * @brief Register a new PIB
   * @param aliases List of schemes with which this PIB will be associated.
   *        The first alias in the list is considered a canonical name of the PIB instance.
   */
  template<class PibType>
  static void
  registerPib(std::initializer_list<std::string> aliases);

  /**
   * @brief Register a new TPM
   * @param aliases List of schemes with which this TPM will be associated
   *        The first alias in the list is considered a canonical name of the TPM instance.
   */
  template<class TpmType>
  static void
  registerTpm(std::initializer_list<std::string> aliases);

  /**
   * @brief Get default PIB locator
   */
  static std::string
  getDefaultPibLocator();

  /**
    * @brief Create a PIB according to @p pibLocator
    */
  static unique_ptr<SecPublicInfo>
  createPib(const std::string& pibLocator);

  /**
   * @brief Get default TPM locator
   */
  static std::string
  getDefaultTpmLocator();

  /**
    * @brief Create a TPM according to @p tpmLocator
    */
  static unique_ptr<SecTpm>
  createTpm(const std::string& tpmLocator);

  /**
   * @brief Constructor to create KeyChain with default PIB and TPM
   *
   * Default PIB and TPM are platform-dependent and can be overriden system-wide or on
   * per-use basis.
   *
   * @todo Add detailed description about config file behavior here
   */
  KeyChain();

  /**
   * @brief KeyChain constructor
   *
   * @sa  http://redmine.named-data.net/issues/2260
   *
   * @param pibLocator PIB locator
   * @param tpmLocator TPM locator
   * @param allowReset if true, the PIB will be reset when the supplied tpmLocator
   *        mismatches the one in PIB
   */
  KeyChain(const std::string& pibLocator,
           const std::string& tpmLocator,
           bool allowReset = false);

  virtual
  ~KeyChain();

  /**
   * @brief Create an identity by creating a pair of Key-Signing-Key (KSK) for this identity and a
   *        self-signed certificate of the KSK.
   *
   * @param identityName The name of the identity.
   * @param params The key parameter if a key needs to be generated for the identity.
   * @return The name of the default certificate of the identity.
   */
  Name
  createIdentity(const Name& identityName, const KeyParams& params = DEFAULT_KEY_PARAMS);

  /**
   * @brief Generate a pair of RSA keys for the specified identity.
   *
   * @param identityName The name of the identity.
   * @param isKsk true for generating a Key-Signing-Key (KSK), false for a Data-Signing-Key (KSK).
   * @param keySize The size of the key.
   * @return The generated key name.
   * @see generateEcdsaKeyPair
   */
  Name
  generateRsaKeyPair(const Name& identityName, bool isKsk = false, uint32_t keySize = 2048);

  /**
   * @brief Generate a pair of ECDSA keys for the specified identity.
   *
   * @param identityName The name of the identity.
   * @param isKsk true for generating a Key-Signing-Key (KSK), false for a Data-Signing-Key (KSK).
   * @param keySize The size of the key.
   * @return The generated key name.
   * @see generateRsaKeyPair
   */
  Name
  generateEcdsaKeyPair(const Name& identityName, bool isKsk = false, uint32_t keySize = 256);

  /**
   * @brief Generate a pair of RSA keys for the specified identity and set it as default key for
   *        the identity.
   *
   * @param identityName The name of the identity.
   * @param isKsk true for generating a Key-Signing-Key (KSK), false for a Data-Signing-Key (KSK).
   * @param keySize The size of the key.
   * @return The generated key name.
   * @see generateRsaKeyPair, generateEcdsaKeyPair, generateEcdsaKeyPairAsDefault
   */
  Name
  generateRsaKeyPairAsDefault(const Name& identityName, bool isKsk = false, uint32_t keySize = 2048);

  /**
   * @brief Generate a pair of ECDSA keys for the specified identity and set it as default key for
   *        the identity.
   *
   * @param identityName The name of the identity.
   * @param isKsk true for generating a Key-Signing-Key (KSK), false for a Data-Signing-Key (KSK).
   * @param keySize The size of the key.
   * @return The generated key name.
   * @see generateRsaKeyPair, generateEcdsaKeyPair, generateRsaKeyPairAsDefault
   */
  Name
  generateEcdsaKeyPairAsDefault(const Name& identityName, bool isKsk = false, uint32_t keySize = 256);

  /**
   * @brief prepare an unsigned identity certificate
   *
   * @param keyName Key name, e.g., `/<identity_name>/ksk-123456`.
   * @param signingIdentity The signing identity.
   * @param notBefore Refer to v1::IdentityCertificate.
   * @param notAfter Refer to v1::IdentityCertificate.
   * @param subjectDescription Refer to v1::IdentityCertificate.
   * @param certPrefix Prefix before `KEY` component. By default, KeyChain will infer the
   *                   certificate name according to the relation between the signingIdentity and
   *                   the subject identity. If signingIdentity is a prefix of the subject identity,
   *                   `KEY` will be inserted after the signingIdentity, otherwise `KEY` is inserted
   *                   after subject identity (i.e., before `ksk-....`).
   * @return v1::IdentityCertificate.
   */
  shared_ptr<v1::IdentityCertificate>
  prepareUnsignedIdentityCertificate(const Name& keyName,
    const Name& signingIdentity,
    const time::system_clock::TimePoint& notBefore,
    const time::system_clock::TimePoint& notAfter,
    const std::vector<security::v1::CertificateSubjectDescription>& subjectDescription,
    const Name& certPrefix = DEFAULT_PREFIX);

  /**
   * @brief prepare an unsigned identity certificate
   *
   * @param keyName Key name, e.g., `/<identity_name>/ksk-123456`.
   * @param publicKey Public key to sign.
   * @param signingIdentity The signing identity.
   * @param notBefore Refer to v1::IdentityCertificate.
   * @param notAfter Refer to v1::IdentityCertificate.
   * @param subjectDescription Refer to v1::IdentityCertificate.
   * @param certPrefix Prefix before `KEY` component. By default, KeyChain will infer the
   *                   certificate name according to the relation between the signingIdentity and
   *                   the subject identity. If signingIdentity is a prefix of the subject identity,
   *                   `KEY` will be inserted after the signingIdentity, otherwise `KEY` is inserted
   *                   after subject identity (i.e., before `ksk-....`).
   * @return v1::IdentityCertificate.
   */
  shared_ptr<v1::IdentityCertificate>
  prepareUnsignedIdentityCertificate(const Name& keyName,
    const v1::PublicKey& publicKey,
    const Name& signingIdentity,
    const time::system_clock::TimePoint& notBefore,
    const time::system_clock::TimePoint& notAfter,
    const std::vector<security::v1::CertificateSubjectDescription>& subjectDescription,
    const Name& certPrefix = DEFAULT_PREFIX);

  /**
   * @brief Sign data according to the supplied signing information
   *
   * This method uses the supplied signing information @p params to create the SignatureInfo block:
   * - it selects a private key and its certificate to sign the packet
   * - sets the KeyLocator field with the certificate name, and
   * - adds other requested information to the SignatureInfo block).
   *
   * After that, the method assigns the created SignatureInfo to the data packets, generate a
   * signature and sets as part of the SignatureValue block.
   *
   * @param data The data to sign
   * @param params The signing parameters.
   * @throws Error if signing fails.
   * @see SigningInfo
   */
  void
  sign(Data& data, const SigningInfo& params = DEFAULT_SIGNING_INFO);

  /**
   * @brief Sign interest according to the supplied signing information
   *
   * This method uses the supplied signing information @p params to create the SignatureInfo block:
   * - it selects a private key and its certificate to sign the packet
   * - sets the KeyLocator field with the certificate name, and
   * - adds other requested information to the SignatureInfo block).
   *
   * After that, the method appends the created SignatureInfo to the interest name, generate a
   * signature and appends it as part of the SignatureValue block to the interest name.
   *
   * @param interest The interest to sign
   * @param params The signing parameters.
   * @throws Error if signing fails.
   * @see SigningInfo
   */
  void
  sign(Interest& interest, const SigningInfo& params = DEFAULT_SIGNING_INFO);

  /**
   * @brief Sign buffer according to the supplied signing information
   *
   * @param buffer The buffer to sign
   * @param bufferLength The buffer size
   * @param params The signing parameters.
   * @return a SignatureValue TLV block
   * @throws Error if signing fails.
   * @see SigningInfo
   */
  Block
  sign(const uint8_t* buffer, size_t bufferLength, const SigningInfo& params);

  /**
   * @deprecated use sign sign(T&, const SigningInfo&)
   * @brief Sign packet with a particular certificate.
   *
   * @param packet The packet to be signed.
   * @param certificateName The certificate name of the key to use for signing.
   * @throws SecPublicInfo::Error if certificate does not exist.
   */
  template<typename T>
  void
  sign(T& packet, const Name& certificateName);

  /**
   * @deprecated Use sign(const uint8_t*, size_t, const SigningInfo&) instead
   * @brief Sign the byte array using a particular certificate.
   *
   * @param buffer The byte array to be signed.
   * @param bufferLength the length of buffer.
   * @param certificateName The certificate name of the signing key.
   * @return The Signature.
   * @throws SecPublicInfo::Error if certificate does not exist.
   */
  Signature
  sign(const uint8_t* buffer, size_t bufferLength, const Name& certificateName);

  /**
   * @deprecated use sign sign(T&, const SigningInfo&)
   * @brief Sign packet using the default certificate of a particular identity.
   *
   * If there is no default certificate of that identity, this method will create a self-signed
   * certificate.
   *
   * @param packet The packet to be signed.
   * @param identityName The signing identity name.
   */
  template<typename T>
  void
  signByIdentity(T& packet, const Name& identityName);

  /**
   * @deprecated use sign(const uint8_t*, size_t, const SigningInfo&) instead
   * @brief Sign the byte array using the default certificate of a particular identity.
   *
   * @param buffer The byte array to be signed.
   * @param bufferLength the length of buffer.
   * @param identityName The identity name.
   * @return The Signature.
   */
  Signature
  signByIdentity(const uint8_t* buffer, size_t bufferLength, const Name& identityName);

  /**
   * @deprecated use sign(Data&, SigningInfo(SigningInfo::SIGNER_TYPE_SHA256))
   * @brief Set Sha256 weak signature for @p data
   */
  void
  signWithSha256(Data& data);

  /**
   * @deprecated use sign(Interest&, SigningInfo(SigningInfo::SIGNER_TYPE_SHA256))
   * @brief Set Sha256 weak signature for @p interest
   */
  void
  signWithSha256(Interest& interest);

  /**
   * @brief Generate a self-signed certificate for a public key.
   *
   * @param keyName The name of the public key
   * @return The generated certificate, shared_ptr<v1::IdentityCertificate>() if selfSign fails
   */
  shared_ptr<v1::IdentityCertificate>
  selfSign(const Name& keyName);

  /**
   * @brief Self-sign the supplied identity certificate.
   *
   * @param cert The supplied cert.
   * @throws SecTpm::Error if the private key does not exist.
   */
  void
  selfSign(v1::IdentityCertificate& cert);

  /**
   * @brief delete a certificate.
   *
   * @param certificateName The certificate to be deleted.
   * @throws KeyChain::Error if certificate cannot be deleted.
   */
  void
  deleteCertificate(const Name& certificateName);

  /**
   * @brief delete a key.
   *
   * @param keyName The key to be deleted.
   * @throws KeyChain::Error if key cannot be deleted.
   */
  void
  deleteKey(const Name& keyName);

  /**
   * @brief delete an identity.
   *
   * @param identity The identity to be deleted.
   * @throws KeyChain::Error if identity cannot be deleted.
   */
  void
  deleteIdentity(const Name& identity);

  /**
   * @brief export an identity.
   *
   * @param identity The identity to export.
   * @param passwordStr The password to secure the private key.
   * @return The encoded export data.
   * @throws SecPublicInfo::Error if anything goes wrong in exporting.
   */
  shared_ptr<SecuredBag>
  exportIdentity(const Name& identity, const std::string& passwordStr);

  /**
   * @brief import an identity.
   *
   * @param securedBag The encoded import data.
   * @param passwordStr The password to secure the private key.
   */
  void
  importIdentity(const SecuredBag& securedBag, const std::string& passwordStr);

  SecPublicInfo&
  getPib()
  {
    return *m_pib;
  }

  const SecPublicInfo&
  getPib() const
  {
    return *m_pib;
  }

  SecTpm&
  getTpm()
  {
    return *m_tpm;
  }

  const SecTpm&
  getTpm() const
  {
    return *m_tpm;
  }

  /*******************************
   *  Wrapper of SecPublicInfo   *
   *******************************/
  bool
  doesIdentityExist(const Name& identityName) const
  {
    return m_pib->doesIdentityExist(identityName);
  }

  void
  addIdentity(const Name& identityName)
  {
    return m_pib->addIdentity(identityName);
  }

  bool
  doesPublicKeyExist(const Name& keyName) const
  {
    return m_pib->doesPublicKeyExist(keyName);
  }

  void
  addPublicKey(const Name& keyName, KeyType keyType, const v1::PublicKey& publicKeyDer)
  {
    return m_pib->addKey(keyName, publicKeyDer);
  }

  void
  addKey(const Name& keyName, const v1::PublicKey& publicKeyDer)
  {
    return m_pib->addKey(keyName, publicKeyDer);
  }

  shared_ptr<v1::PublicKey>
  getPublicKey(const Name& keyName) const
  {
    return m_pib->getPublicKey(keyName);
  }

  bool
  doesCertificateExist(const Name& certificateName) const
  {
    return m_pib->doesCertificateExist(certificateName);
  }

  void
  addCertificate(const v1::IdentityCertificate& certificate)
  {
    return m_pib->addCertificate(certificate);
  }

  shared_ptr<v1::IdentityCertificate>
  getCertificate(const Name& certificateName) const
  {
    return m_pib->getCertificate(certificateName);
  }

  Name
  getDefaultIdentity() const
  {
    return m_pib->getDefaultIdentity();
  }

  Name
  getDefaultKeyNameForIdentity(const Name& identityName) const
  {
    return m_pib->getDefaultKeyNameForIdentity(identityName);
  }

  /**
   * @brief Get default key parameters for the specified identity
   *
   * If identity has a previously generated key, the returned parameters
   * will include the same type of the key.  If there are no existing
   * keys, DEFAULT_KEY_PARAMS is used.
   */
  const KeyParams&
  getDefaultKeyParamsForIdentity(const Name& identityName) const;

  Name
  getDefaultCertificateNameForKey(const Name& keyName) const
  {
    return m_pib->getDefaultCertificateNameForKey(keyName);
  }

  void
  getAllIdentities(std::vector<Name>& nameList, bool isDefault) const
  {
    return m_pib->getAllIdentities(nameList, isDefault);
  }

  void
  getAllKeyNames(std::vector<Name>& nameList, bool isDefault) const
  {
    return m_pib->getAllKeyNames(nameList, isDefault);
  }

  void
  getAllKeyNamesOfIdentity(const Name& identity, std::vector<Name>& nameList, bool isDefault) const
  {
    return m_pib->getAllKeyNamesOfIdentity(identity, nameList, isDefault);
  }

  void
  getAllCertificateNames(std::vector<Name>& nameList, bool isDefault) const
  {
    return m_pib->getAllCertificateNames(nameList, isDefault);
  }

  void
  getAllCertificateNamesOfKey(const Name& keyName,
                              std::vector<Name>& nameList,
                              bool isDefault) const
  {
    return m_pib->getAllCertificateNamesOfKey(keyName, nameList, isDefault);
  }

  void
  deleteCertificateInfo(const Name& certificateName)
  {
    return m_pib->deleteCertificateInfo(certificateName);
  }

  void
  deletePublicKeyInfo(const Name& keyName)
  {
    return m_pib->deletePublicKeyInfo(keyName);
  }

  void
  deleteIdentityInfo(const Name& identity)
  {
    return m_pib->deleteIdentityInfo(identity);
  }

  void
  setDefaultIdentity(const Name& identityName)
  {
    return m_pib->setDefaultIdentity(identityName);
  }

  void
  setDefaultKeyNameForIdentity(const Name& keyName)
  {
    return m_pib->setDefaultKeyNameForIdentity(keyName);
  }

  void
  setDefaultCertificateNameForKey(const Name& certificateName)
  {
    return m_pib->setDefaultCertificateNameForKey(certificateName);
  }

  Name
  getNewKeyName(const Name& identityName, bool useKsk)
  {
    return m_pib->getNewKeyName(identityName, useKsk);
  }

  Name
  getDefaultCertificateNameForIdentity(const Name& identityName) const
  {
    return m_pib->getDefaultCertificateNameForIdentity(identityName);
  }

  Name
  getDefaultCertificateName() const
  {
    return m_pib->getDefaultCertificateName();
  }

  void
  addCertificateAsKeyDefault(const v1::IdentityCertificate& certificate)
  {
    return m_pib->addCertificateAsKeyDefault(certificate);
  }

  void
  addCertificateAsIdentityDefault(const v1::IdentityCertificate& certificate)
  {
    return m_pib->addCertificateAsIdentityDefault(certificate);
  }

  void
  addCertificateAsSystemDefault(const v1::IdentityCertificate& certificate)
  {
    return m_pib->addCertificateAsSystemDefault(certificate);
  }

  shared_ptr<v1::IdentityCertificate>
  getDefaultCertificate() const
  {
    if (!static_cast<bool>(m_pib->getDefaultCertificate()))
      const_cast<KeyChain*>(this)->setDefaultCertificateInternal();

    return m_pib->getDefaultCertificate();
  }

  void
  refreshDefaultCertificate()
  {
    return m_pib->refreshDefaultCertificate();
  }

  /*******************************
   *  Wrapper of SecTpm          *
   *******************************/

  void
  setTpmPassword(const uint8_t* password, size_t passwordLength)
  {
    return m_tpm->setTpmPassword(password, passwordLength);
  }

  void
  resetTpmPassword()
  {
    return m_tpm->resetTpmPassword();
  }

  void
  setInTerminal(bool inTerminal)
  {
    return m_tpm->setInTerminal(inTerminal);
  }

  bool
  getInTerminal() const
  {
    return m_tpm->getInTerminal();
  }

  bool
  isLocked() const
  {
    return m_tpm->isLocked();
  }

  bool
  unlockTpm(const char* password, size_t passwordLength, bool usePassword)
  {
    return m_tpm->unlockTpm(password, passwordLength, usePassword);
  }

  void
  generateKeyPairInTpm(const Name& keyName, const KeyParams& params)
  {
    return m_tpm->generateKeyPairInTpm(keyName, params);
  }

  void
  deleteKeyPairInTpm(const Name& keyName)
  {
    return m_tpm->deleteKeyPairInTpm(keyName);
  }

  shared_ptr<v1::PublicKey>
  getPublicKeyFromTpm(const Name& keyName) const
  {
    return m_tpm->getPublicKeyFromTpm(keyName);
  }

  Block
  signInTpm(const uint8_t* data, size_t dataLength,
            const Name& keyName,
            DigestAlgorithm digestAlgorithm)
  {
    return m_tpm->signInTpm(data, dataLength, keyName, digestAlgorithm);
  }

  ConstBufferPtr
  decryptInTpm(const uint8_t* data, size_t dataLength, const Name& keyName, bool isSymmetric)
  {
    return m_tpm->decryptInTpm(data, dataLength, keyName, isSymmetric);
  }

  ConstBufferPtr
  encryptInTpm(const uint8_t* data, size_t dataLength, const Name& keyName, bool isSymmetric)
  {
    return m_tpm->encryptInTpm(data, dataLength, keyName, isSymmetric);
  }

  void
  generateSymmetricKeyInTpm(const Name& keyName, const KeyParams& params)
  {
    return m_tpm->generateSymmetricKeyInTpm(keyName, params);
  }

  bool
  doesKeyExistInTpm(const Name& keyName, KeyClass keyClass) const
  {
    return m_tpm->doesKeyExistInTpm(keyName, keyClass);
  }

  bool
  generateRandomBlock(uint8_t* res, size_t size) const
  {
    return m_tpm->generateRandomBlock(res, size);
  }

  void
  addAppToAcl(const Name& keyName, KeyClass keyClass, const std::string& appPath, AclType acl)
  {
    return m_tpm->addAppToAcl(keyName, keyClass, appPath, acl);
  }

  ConstBufferPtr
  exportPrivateKeyPkcs5FromTpm(const Name& keyName, const std::string& password)
  {
    return m_tpm->exportPrivateKeyPkcs5FromTpm(keyName, password);
  }

  bool
  importPrivateKeyPkcs5IntoTpm(const Name& keyName,
                               const uint8_t* buf, size_t size,
                               const std::string& password)
  {
    return m_tpm->importPrivateKeyPkcs5IntoTpm(keyName, buf, size, password);
  }

private:
  void
  initialize(const std::string& pibLocatorUri,
             const std::string& tpmLocatorUri,
             bool needReset);

  /**
   * @brief Prepare a SignatureInfo TLV according to signing information and return the signing key name
   *
   * @param params The signing parameters.
   * @return The signing key name and prepared SignatureInfo.
   * @throw Error when the requested signing method cannot be satisfied.
   */
  std::tuple<Name, SignatureInfo>
  prepareSignatureInfo(const SigningInfo& params);

  /**
   * @brief Internal abstraction of packet signing.
   *
   * @param packet The packet to sign
   * @param params The signing parameters.
   * @throw Error when the signing fails.
   */
  template<typename T>
  void
  signImpl(T& packet, const SigningInfo& params);

  /**
   * @brief Set default certificate if it is not initialized
   */
  void
  setDefaultCertificateInternal();

  /**
   * @brief Generate a key pair for the specified identity.
   *
   * @param identityName The name of the specified identity.
   * @param isKsk true for generating a Key-Signing-Key (KSK), false for a Data-Signing-Key (KSK).
   * @param params The parameter of the key.
   * @return The name of the generated key.
   */
  Name
  generateKeyPair(const Name& identityName, bool isKsk = false,
                  const KeyParams& params = DEFAULT_KEY_PARAMS);

  /**
   * @brief Sign the data using a particular key.
   *
   * @param data Reference to the data packet.
   * @param signature Signature to be added.
   * @param keyName The name of the signing key.
   * @param digestAlgorithm the digest algorithm.
   * @throws Tpm::Error
   */
  void
  signPacketWrapper(Data& data, const Signature& signature,
                    const Name& keyName, DigestAlgorithm digestAlgorithm);

  /**
   * @brief Sign the interest using a particular key.
   *
   * @param interest Reference to the interest packet.
   * @param signature Signature to be added.
   * @param keyName The name of the signing key.
   * @param digestAlgorithm the digest algorithm.
   * @throws Tpm::Error
   */
  void
  signPacketWrapper(Interest& interest, const Signature& signature,
                    const Name& keyName, DigestAlgorithm digestAlgorithm);

  /**
   * @brief Generate a SignatureValue block for a buffer @p buf with size @p size using
   *        a key with name @p keyName and digest algorithm @p digestAlgorithm.
   */
  Block
  pureSign(const uint8_t* buf, size_t size, const Name& keyName, DigestAlgorithm digestAlgorithm) const;

  static void
  registerPibImpl(const std::string& canonicalName,
                  std::initializer_list<std::string> aliases, PibCreateFunc createFunc);

  static void
  registerTpmImpl(const std::string& canonicalName,
                  std::initializer_list<std::string> aliases, TpmCreateFunc createFunc);

public:
  static tlv::SignatureTypeValue
  getSignatureType(KeyType keyType, DigestAlgorithm digestAlgorithm);

public:
  static const Name DEFAULT_PREFIX;
  static const SigningInfo DEFAULT_SIGNING_INFO;

  /**
   * @brief A localhost identity which indicates that signature is generated using SHA-256.
   * @todo Passing this as identity is not implemented.
   */
  static const Name DIGEST_SHA256_IDENTITY;

  // RsaKeyParams is set to be default for backward compatibility.
  static const RsaKeyParams DEFAULT_KEY_PARAMS;

  typedef std::map<std::string, Block> SignParams;

private:
  std::unique_ptr<SecPublicInfo> m_pib;
  std::unique_ptr<SecTpm> m_tpm;
  time::milliseconds m_lastTimestamp;
};

template<typename T>
void
KeyChain::signImpl(T& packet, const SigningInfo& params)
{
  Name keyName;
  SignatureInfo sigInfo;
  std::tie(keyName, sigInfo) = prepareSignatureInfo(params);

  signPacketWrapper(packet, Signature(sigInfo),
                    keyName, params.getDigestAlgorithm());
}

template<typename T>
void
KeyChain::sign(T& packet, const Name& certificateName)
{
  signImpl(packet, SigningInfo(SigningInfo::SIGNER_TYPE_CERT, certificateName));
}

template<typename T>
void
KeyChain::signByIdentity(T& packet, const Name& identityName)
{
  signImpl(packet, SigningInfo(SigningInfo::SIGNER_TYPE_ID, identityName));
}

template<class PibType>
inline void
KeyChain::registerPib(std::initializer_list<std::string> aliases)
{
  registerPibImpl(*aliases.begin(), aliases, [] (const std::string& locator) {
      return make_unique<PibType>(locator);
    });
}

template<class TpmType>
inline void
KeyChain::registerTpm(std::initializer_list<std::string> aliases)
{
  registerTpmImpl(*aliases.begin(), aliases, [] (const std::string& locator) {
      return make_unique<TpmType>(locator);
    });
}

/**
 * \brief Register SecPib class in ndn-cxx KeyChain
 *
 * This macro should be placed once in the implementation file of the
 * SecPib type within the namespace where the type is declared.
 */
#define NDN_CXX_KEYCHAIN_REGISTER_PIB(PibType, ...)     \
static class NdnCxxAuto ## PibType ## PibRegistrationClass    \
{                                                             \
public:                                                       \
  NdnCxxAuto ## PibType ## PibRegistrationClass()             \
  {                                                           \
    ::ndn::KeyChain::registerPib<PibType>({__VA_ARGS__});     \
  }                                                           \
} ndnCxxAuto ## PibType ## PibRegistrationVariable

/**
 * \brief Register SecTpm class in ndn-cxx KeyChain
 *
 * This macro should be placed once in the implementation file of the
 * SecTpm type within the namespace where the type is declared.
 */
#define NDN_CXX_KEYCHAIN_REGISTER_TPM(TpmType, ...)     \
static class NdnCxxAuto ## TpmType ## TpmRegistrationClass    \
{                                                             \
public:                                                       \
  NdnCxxAuto ## TpmType ## TpmRegistrationClass()             \
  {                                                           \
    ::ndn::KeyChain::registerTpm<TpmType>({__VA_ARGS__});     \
  }                                                           \
} ndnCxxAuto ## TpmType ## TpmRegistrationVariable

} // namespace security

using security::KeyChain;

} // namespace ndn

#endif // NDN_SECURITY_KEY_CHAIN_HPP