src/security/key-chain.hpp - ndn-cxx - Gitiles

 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil -*- */
 /**
  * Copyright (C) 2013 Regents of the University of California.
  * @author: Yingdi Yu <yingdi@cs.ucla.edu>
  * @author: Jeff Thompson <jefft0@remap.ucla.edu>
  * See COPYING for copyright and distribution information.
  */

 #ifndef NDN_SECURITY_KEY_CHAIN_HPP
 #define NDN_SECURITY_KEY_CHAIN_HPP

 #include "identity-certificate.hpp"
 #include "public-key.hpp"
 #include "signature-sha256-with-rsa.hpp"
 #include "signature-sha256.hpp"
 #include "secured-bag.hpp"
 #include "../interest.hpp"
 #include "../util/random.hpp"
 #include "../util/crypto.hpp"

 //PublicInfo
 #include "sec-public-info-sqlite3.hpp"
 #include "sec-public-info-memory.hpp"
 //TPM
 #include "sec-tpm-file.hpp"
 #include "sec-tpm-memory.hpp"

 #ifdef NDN_CPP_HAVE_OSX_SECURITY
 #include "sec-tpm-osx.hpp"
 #endif


 namespace ndn {

 /**
  * @brief KeyChain is one of the main classes of the security library.
  *
  * The KeyChain class provides a set of interfaces of identity management and private key related operations.
  */
 template<class Info, class Tpm>
 class KeyChainImpl : public Info, public Tpm
 {
   typedef SecPublicInfo::Error InfoError;
   typedef SecTpm::Error TpmError;
 public:
   /**
    * @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.
    * @return The name of the default certificate of the identity.
    */
   Name
   createIdentity(const Name& identityName)
   {
     Info::addIdentity(identityName);

     Name keyName;
     try
       {
         keyName = Info::getDefaultKeyNameForIdentity(identityName);
       }
     catch(InfoError& e)
       {
         keyName = generateRSAKeyPairAsDefault(identityName, true);
       }

     Name certName;
     try
       {
         certName = Info::getDefaultCertificateNameForKey(keyName);
       }
     catch(InfoError& e)
       {
         shared_ptr<IdentityCertificate> selfCert = selfSign(keyName);
         Info::addCertificateAsIdentityDefault(*selfCert);
         certName = selfCert->getName();
       }

     return certName;
   }

   /**
    * @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.
    */
   Name
   generateRSAKeyPair(const Name& identityName, bool isKsk = false, int keySize = 2048)
   {
     return generateKeyPair(identityName, isKsk, KEY_TYPE_RSA, keySize);
   }

   /**
    * @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.
    */
   Name
   generateRSAKeyPairAsDefault(const Name& identityName, bool isKsk = false, int keySize = 2048)
   {
     Name keyName = generateKeyPair(identityName, isKsk, KEY_TYPE_RSA, keySize);

     Info::setDefaultKeyNameForIdentity(keyName);

     return keyName;
   }

   /**
    * @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 IdentityCertificate.
    * @param notAfter Refer to IdentityCertificate.
    * @param subjectDescription Refer to IdentityCertificate.
    * @return IdentityCertificate.
    */
   shared_ptr<IdentityCertificate>
   prepareUnsignedIdentityCertificate(const Name& keyName,
                                      const Name& signingIdentity,
                                      const time::system_clock::TimePoint& notBefore,
                                      const time::system_clock::TimePoint& notAfter,
                                      const std::vector<CertificateSubjectDescription>& subjectDescription)

   {
     if(keyName.size() < 1)
       return shared_ptr<IdentityCertificate>();

     std::string keyIdPrefix = keyName.get(-1).toEscapedString().substr(0, 4);
     if(keyIdPrefix != "ksk-" && keyIdPrefix != "dsk-")
       return shared_ptr<IdentityCertificate>();

     shared_ptr<IdentityCertificate> certificate = make_shared<IdentityCertificate>();
     Name certName;

     if(signingIdentity.isPrefixOf(keyName))
       {
         certName.append(signingIdentity).append("KEY").append(keyName.getSubName(signingIdentity.size())).append("ID-CERT").appendVersion();
       }
     else
       {
         certName.append(keyName.getPrefix(-1)).append("KEY").append(keyName.get(-1)).append("ID-CERT").appendVersion();
       }

     certificate->setName(certName);
     certificate->setNotBefore(notBefore);
     certificate->setNotAfter(notAfter);

     shared_ptr<PublicKey> publicKey;
     try
       {
         publicKey = Info::getPublicKey(keyName);
       }
     catch(InfoError& e)
       {
         return shared_ptr<IdentityCertificate>();
       }
     certificate->setPublicKeyInfo(*publicKey);

     if(subjectDescription.empty())
       {
         CertificateSubjectDescription subDescryptName("2.5.4.41", keyName.getPrefix(-1).toUri());
         certificate->addSubjectDescription(subDescryptName);
       }
     else
       {
         std::vector<CertificateSubjectDescription>::const_iterator sdIt = subjectDescription.begin();
         std::vector<CertificateSubjectDescription>::const_iterator sdEnd = subjectDescription.end();
         for(; sdIt != sdEnd; sdIt++)
           certificate->addSubjectDescription(*sdIt);
       }

     certificate->encode();

     return certificate;
   }

   /**
    * @brief Sign packet with default identity
    *
    * On return, signatureInfo and signatureValue in the packet are set.
    * If default identity does not exist,
    * a temporary identity will be created and set as default.
    *
    * @param packet The packet to be signed
    */
   template<typename T>
   void
   sign(T& packet)
   {
     if (!static_cast<bool>(Info::defaultCertificate()))
       {
         Info::refreshDefaultCertificate();

         if (!static_cast<bool>(Info::defaultCertificate()))
           {
             Name defaultIdentity;
             try
               {
                 defaultIdentity = Info::getDefaultIdentity();
               }
             catch (InfoError& e)
               {
                 uint32_t random = random::generateWord32();
                 defaultIdentity.append("tmp-identity")
                   .append(reinterpret_cast<uint8_t*>(&random), 4);
               }
             createIdentity(defaultIdentity);
             Info::setDefaultIdentity(defaultIdentity);
             Info::refreshDefaultCertificate();
           }
       }

     sign(packet, *Info::defaultCertificate());
   }

   /**
    * @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)
   {
     if (!Info::doesCertificateExist(certificateName))
       throw InfoError("Requested certificate [" + certificateName.toUri() + "] doesn't exist");

     SignatureSha256WithRsa signature;
     signature.setKeyLocator(certificateName.getPrefix(-1)); // implicit conversion should take care

     // For temporary usage, we support RSA + SHA256 only, but will support more.
     signPacketWrapper(packet, signature,
                       IdentityCertificate::certificateNameToPublicKeyName(certificateName),
                       DIGEST_ALGORITHM_SHA256);
   }

   /**
    * @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)
   {
     if (!Info::doesCertificateExist(certificateName))
       throw InfoError("Requested certificate [" + certificateName.toUri() + "] doesn't exist");

     SignatureSha256WithRsa signature;
     signature.setKeyLocator(certificateName.getPrefix(-1)); // implicit conversion should take care

     // For temporary usage, we support RSA + SHA256 only, but will support more.
     signature.setValue(Tpm::signInTpm(buffer, bufferLength,
                                       IdentityCertificate::certificateNameToPublicKeyName(certificateName),
                                       DIGEST_ALGORITHM_SHA256));
     return signature;
   }

   /**
    * @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)
   {
     Name signingCertificateName;
     try
       {
         signingCertificateName = Info::getDefaultCertificateNameForIdentity(identityName);
       }
     catch(InfoError& e)
       {
         signingCertificateName = createIdentity(identityName);
         // Ideally, no exception will be thrown out, unless something goes wrong in the TPM, which is a fatal error.
       }

     // We either get or create the signing certificate, sign packet! (no exception unless fatal error in TPM)
     sign(packet, signingCertificateName);
   }

   /**
    * @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)
   {
     Name signingCertificateName;
     try
       {
         signingCertificateName = Info::getDefaultCertificateNameForIdentity(identityName);
       }
     catch(InfoError& e)
       {
         signingCertificateName = createIdentity(identityName);
         // Ideally, no exception will be thrown out, unless something goes wrong in the TPM, which is a fatal error.
       }

     // We either get or create the signing certificate, sign data! (no exception unless fatal error in TPM)
     return sign(buffer, bufferLength, signingCertificateName);
   }

   /**
    * @brief Set Sha256 weak signature.
    *
    * @param data.
    */
   void
   signWithSha256(Data& data)
   {
     SignatureSha256 sig;
     data.setSignature(sig);

     Block sigValue(Tlv::SignatureValue,
                    crypto::sha256(data.wireEncode().value(),
                                   data.wireEncode().value_size() - data.getSignature().getValue().size()));
     data.setSignatureValue(sigValue);

   }

   /**
    * @brief Generate a self-signed certificate for a public key.
    *
    * @param keyName The name of the public key.
    * @return The generated certificate, NULL if selfSign fails.
    */
   shared_ptr<IdentityCertificate>
   selfSign(const Name& keyName)
   {
     shared_ptr<PublicKey> pubKey;
     try
       {
         pubKey = Info::getPublicKey(keyName); // may throw an exception.
       }
     catch(InfoError& e)
       {
         return shared_ptr<IdentityCertificate>();
       }

     shared_ptr<IdentityCertificate> certificate = make_shared<IdentityCertificate>();

     Name certificateName = keyName.getPrefix(-1);
     certificateName.append("KEY").append(keyName.get(-1)).append("ID-CERT").appendVersion();

     certificate->setName(certificateName);
     certificate->setNotBefore(time::system_clock::now());
     certificate->setNotAfter(time::system_clock::now() + time::days(7300)/* ~20 years*/);
     certificate->setPublicKeyInfo(*pubKey);
     certificate->addSubjectDescription(CertificateSubjectDescription("2.5.4.41", keyName.toUri()));
     certificate->encode();

     selfSign(*certificate);
     return certificate;
   }

   /**
    * @brief Self-sign the supplied identity certificate.
    *
    * @param cert The supplied cert.
    * @throws SecTpm::Error if the private key does not exist.
    */
   void
   selfSign (IdentityCertificate& cert)
   {
     Name keyName = IdentityCertificate::certificateNameToPublicKeyName(cert.getName());
     if(!Tpm::doesKeyExistInTpm(keyName, KEY_CLASS_PRIVATE))
       throw TpmError("private key does not exist!");

     SignatureSha256WithRsa signature;
     signature.setKeyLocator(cert.getName().getPrefix(-1)); // implicit conversion should take care

     // For temporary usage, we support RSA + SHA256 only, but will support more.
     signPacketWrapper(cert, signature, keyName, DIGEST_ALGORITHM_SHA256);
   }

   /**
    * @brief delete a certificate.
    *
    * If the certificate to be deleted is current default system default,
    * the method will not delete the certificate and return immediately.
    *
    * @param certificateName The certificate to be deleted.
    */
   void
   deleteCertificate (const Name& certificateName)
   {
     try
       {
         if(Info::getDefaultCertificateName() == certificateName)
           return;
       }
     catch(InfoError& e)
       {
         // Not a real error, just try to delete the certificate
       }

     Info::deleteCertificateInfo(certificateName);
   }

   /**
    * @brief delete a key.
    *
    * If the key to be deleted is current default system default,
    * the method will not delete the key and return immediately.
    *
    * @param keyName The key to be deleted.
    */
   void
   deleteKey (const Name& keyName)
   {
     try
       {
         if(Info::getDefaultKeyNameForIdentity(Info::getDefaultIdentity()) == keyName)
           return;
       }
     catch(InfoError& e)
       {
         // Not a real error, just try to delete the key
       }

     Info::deletePublicKeyInfo(keyName);
     Tpm::deleteKeyPairInTpm(keyName);
   }

   /**
    * @brief delete an identity.
    *
    * If the identity to be deleted is current default system default,
    * the method will not delete the identity and return immediately.
    *
    * @param identity The identity to be deleted.
    */
   void
   deleteIdentity (const Name& identity)
   {
     try
       {
         if(Info::getDefaultIdentity() == identity)
           return;
       }
     catch(InfoError& e)
       {
         // Not a real error, just try to delete the identity
       }

     std::vector<Name> nameList;
     Info::getAllKeyNamesOfIdentity(identity, nameList, true);
     Info::getAllKeyNamesOfIdentity(identity, nameList, false);

     Info::deleteIdentityInfo(identity);

     std::vector<Name>::const_iterator it = nameList.begin();
     for(; it != nameList.end(); it++)
       Tpm::deleteKeyPairInTpm(*it);
   }

   /**
    * @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 InfoError if anything goes wrong in exporting.
    */
   shared_ptr<SecuredBag>
   exportIdentity(const Name& identity, const std::string& passwordStr)
   {
     if (!Info::doesIdentityExist(identity))
       throw InfoError("Identity does not exist!");

     Name keyName = Info::getDefaultKeyNameForIdentity(identity);

     ConstBufferPtr pkcs8;
     try
       {
         pkcs8 = Tpm::exportPrivateKeyPkcs8FromTpm(keyName, passwordStr);
       }
     catch(TpmError& e)
       {
         throw InfoError("Fail to export PKCS8 of private key");
       }

     shared_ptr<IdentityCertificate> cert;
     try
       {
         cert = Info::getCertificate(Info::getDefaultCertificateNameForKey(keyName));
       }
     catch(InfoError& e)
       {
         cert = selfSign(keyName);
         Info::addCertificateAsIdentityDefault(*cert);
       }

     shared_ptr<SecuredBag> secureBag = make_shared<SecuredBag>(boost::cref(*cert), boost::cref(pkcs8));

     return secureBag;
   }

   /**
    * @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)
   {
     Name keyName = IdentityCertificate::certificateNameToPublicKeyName(securedBag.getCertificate().getName());
     Name identity = keyName.getPrefix(-1);

     // Add identity
     Info::addIdentity(identity);

     // Add key
     Tpm::importPrivateKeyPkcs8IntoTpm(keyName, securedBag.getKey()->buf(), securedBag.getKey()->size(), passwordStr);
     shared_ptr<PublicKey> pubKey = Tpm::getPublicKeyFromTpm(keyName.toUri());
     Info::addPublicKey(keyName, KEY_TYPE_RSA, *pubKey); // HACK! We should set key type according to the pkcs8 info.
     Info::setDefaultKeyNameForIdentity(keyName);

     // Add cert
     Info::addCertificateAsIdentityDefault(securedBag.getCertificate());
   }


 private:
   /**
    * @brief sign a packet using a pariticular certificate.
    *
    * @param packet The packet to be signed.
    * @param certificate The signing certificate.
    */
   template<typename T>
   void
   sign(T& packet, const IdentityCertificate& certificate)
   {
     SignatureSha256WithRsa signature;
     signature.setKeyLocator(certificate.getName().getPrefix(-1));

     // For temporary usage, we support RSA + SHA256 only, but will support more.
     signPacketWrapper(packet, signature, certificate.getPublicKeyName(), DIGEST_ALGORITHM_SHA256);
   }

   /**
    * @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 keyType The type of the key pair, e.g. KEY_TYPE_RSA.
    * @param keySize The size of the key pair.
    * @return The name of the generated key.
    */
   Name
   generateKeyPair(const Name& identityName, bool isKsk = false, KeyType keyType = KEY_TYPE_RSA, int keySize = 2048)
   {
     Name keyName = Info::getNewKeyName(identityName, isKsk);

     Tpm::generateKeyPairInTpm(keyName.toUri(), keyType, keySize);

     shared_ptr<PublicKey> pubKey = Tpm::getPublicKeyFromTpm(keyName.toUri());
     Info::addPublicKey(keyName, keyType, *pubKey);

     return keyName;
   }

   /**
    * @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 SignatureSha256WithRsa& signature, const Name& keyName, DigestAlgorithm digestAlgorithm)
   {
     data.setSignature(signature);
     data.setSignatureValue
       (Tpm::signInTpm(data.wireEncode().value(),
                       data.wireEncode().value_size() - data.getSignature().getValue().size(),
                       keyName, 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 SignatureSha256WithRsa& signature, const Name& keyName, DigestAlgorithm digestAlgorithm)
   {
     Name signedName = Name(interest.getName()).append(signature.getInfo());

     Block sigValue = Tpm::signInTpm(signedName.wireEncode().value(),
                                     signedName.wireEncode().value_size(),
                                     keyName,
                                     DIGEST_ALGORITHM_SHA256);
     sigValue.encode();
     signedName.append(sigValue);
     interest.setName(signedName);
   }


 };

 } // namespace ndn


 #if defined(NDN_CPP_HAVE_OSX_SECURITY) and defined(NDN_CPP_WITH_OSX_KEYCHAIN)

 namespace ndn
 {
 typedef KeyChainImpl<SecPublicInfoSqlite3, SecTpmOsx> KeyChain;
 };

 #else

 namespace ndn
 {
 typedef KeyChainImpl<SecPublicInfoSqlite3, SecTpmFile> KeyChain;
 };

 #endif //NDN_CPP_HAVE_OSX_SECURITY

 #endif //NDN_SECURITY_KEY_CHAIN_HPP
	/* -- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil -- */
	/**
	* Copyright (C) 2013 Regents of the University of California.
	* @author: Yingdi Yu <yingdi@cs.ucla.edu>
	* @author: Jeff Thompson <jefft0@remap.ucla.edu>
	* See COPYING for copyright and distribution information.
	*/

	#ifndef NDN_SECURITY_KEY_CHAIN_HPP
	#define NDN_SECURITY_KEY_CHAIN_HPP

	#include "identity-certificate.hpp"
	#include "public-key.hpp"
	#include "signature-sha256-with-rsa.hpp"
	#include "signature-sha256.hpp"
	#include "secured-bag.hpp"
	#include "../interest.hpp"
	#include "../util/random.hpp"
	#include "../util/crypto.hpp"

	//PublicInfo
	#include "sec-public-info-sqlite3.hpp"
	#include "sec-public-info-memory.hpp"
	//TPM
	#include "sec-tpm-file.hpp"
	#include "sec-tpm-memory.hpp"

	#ifdef NDN_CPP_HAVE_OSX_SECURITY
	#include "sec-tpm-osx.hpp"
	#endif


	namespace ndn {

	/**
	* @brief KeyChain is one of the main classes of the security library.
	*
	* The KeyChain class provides a set of interfaces of identity management and private key related operations.
	*/
	template<class Info, class Tpm>
	class KeyChainImpl : public Info, public Tpm
	{
	typedef SecPublicInfo::Error InfoError;
	typedef SecTpm::Error TpmError;
	public:
	/**
	* @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.
	* @return The name of the default certificate of the identity.
	*/
	Name
	createIdentity(const Name& identityName)
	{
	Info::addIdentity(identityName);

	Name keyName;
	try
	{
	keyName = Info::getDefaultKeyNameForIdentity(identityName);
	}
	catch(InfoError& e)
	{
	keyName = generateRSAKeyPairAsDefault(identityName, true);
	}

	Name certName;
	try
	{
	certName = Info::getDefaultCertificateNameForKey(keyName);
	}
	catch(InfoError& e)
	{
	shared_ptr<IdentityCertificate> selfCert = selfSign(keyName);
	Info::addCertificateAsIdentityDefault(*selfCert);
	certName = selfCert->getName();
	}

	return certName;
	}

	/**
	* @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.
	*/
	Name
	generateRSAKeyPair(const Name& identityName, bool isKsk = false, int keySize = 2048)
	{
	return generateKeyPair(identityName, isKsk, KEY_TYPE_RSA, keySize);
	}

	/**
	* @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.
	*/
	Name
	generateRSAKeyPairAsDefault(const Name& identityName, bool isKsk = false, int keySize = 2048)
	{
	Name keyName = generateKeyPair(identityName, isKsk, KEY_TYPE_RSA, keySize);

	Info::setDefaultKeyNameForIdentity(keyName);

	return keyName;
	}

	/**
	* @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 IdentityCertificate.
	* @param notAfter Refer to IdentityCertificate.
	* @param subjectDescription Refer to IdentityCertificate.
	* @return IdentityCertificate.
	*/
	shared_ptr<IdentityCertificate>
	prepareUnsignedIdentityCertificate(const Name& keyName,
	const Name& signingIdentity,
	const time::system_clock::TimePoint& notBefore,
	const time::system_clock::TimePoint& notAfter,
	const std::vector<CertificateSubjectDescription>& subjectDescription)

	{
	if(keyName.size() < 1)
	return shared_ptr<IdentityCertificate>();

	std::string keyIdPrefix = keyName.get(-1).toEscapedString().substr(0, 4);
	if(keyIdPrefix != "ksk-" && keyIdPrefix != "dsk-")
	return shared_ptr<IdentityCertificate>();

	shared_ptr<IdentityCertificate> certificate = make_shared<IdentityCertificate>();
	Name certName;

	if(signingIdentity.isPrefixOf(keyName))
	{
	certName.append(signingIdentity).append("KEY").append(keyName.getSubName(signingIdentity.size())).append("ID-CERT").appendVersion();
	}
	else
	{
	certName.append(keyName.getPrefix(-1)).append("KEY").append(keyName.get(-1)).append("ID-CERT").appendVersion();
	}

	certificate->setName(certName);
	certificate->setNotBefore(notBefore);
	certificate->setNotAfter(notAfter);

	shared_ptr<PublicKey> publicKey;
	try
	{
	publicKey = Info::getPublicKey(keyName);
	}
	catch(InfoError& e)
	{
	return shared_ptr<IdentityCertificate>();
	}
	certificate->setPublicKeyInfo(*publicKey);

	if(subjectDescription.empty())
	{
	CertificateSubjectDescription subDescryptName("2.5.4.41", keyName.getPrefix(-1).toUri());
	certificate->addSubjectDescription(subDescryptName);
	}
	else
	{
	std::vector<CertificateSubjectDescription>::const_iterator sdIt = subjectDescription.begin();
	std::vector<CertificateSubjectDescription>::const_iterator sdEnd = subjectDescription.end();
	for(; sdIt != sdEnd; sdIt++)
	certificate->addSubjectDescription(*sdIt);
	}

	certificate->encode();

	return certificate;
	}

	/**
	* @brief Sign packet with default identity
	*
	* On return, signatureInfo and signatureValue in the packet are set.
	* If default identity does not exist,
	* a temporary identity will be created and set as default.
	*
	* @param packet The packet to be signed
	*/
	template<typename T>
	void
	sign(T& packet)
	{
	if (!static_cast<bool>(Info::defaultCertificate()))
	{
	Info::refreshDefaultCertificate();

	if (!static_cast<bool>(Info::defaultCertificate()))
	{
	Name defaultIdentity;
	try
	{
	defaultIdentity = Info::getDefaultIdentity();
	}
	catch (InfoError& e)
	{
	uint32_t random = random::generateWord32();
	defaultIdentity.append("tmp-identity")
	.append(reinterpret_cast<uint8_t*>(&random), 4);
	}
	createIdentity(defaultIdentity);
	Info::setDefaultIdentity(defaultIdentity);
	Info::refreshDefaultCertificate();
	}
	}

	sign(packet, *Info::defaultCertificate());
	}

	/**
	* @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)
	{
	if (!Info::doesCertificateExist(certificateName))
	throw InfoError("Requested certificate [" + certificateName.toUri() + "] doesn't exist");

	SignatureSha256WithRsa signature;
	signature.setKeyLocator(certificateName.getPrefix(-1)); // implicit conversion should take care

	// For temporary usage, we support RSA + SHA256 only, but will support more.
	signPacketWrapper(packet, signature,
	IdentityCertificate::certificateNameToPublicKeyName(certificateName),
	DIGEST_ALGORITHM_SHA256);
	}

	/**
	* @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)
	{
	if (!Info::doesCertificateExist(certificateName))
	throw InfoError("Requested certificate [" + certificateName.toUri() + "] doesn't exist");

	SignatureSha256WithRsa signature;
	signature.setKeyLocator(certificateName.getPrefix(-1)); // implicit conversion should take care

	// For temporary usage, we support RSA + SHA256 only, but will support more.
	signature.setValue(Tpm::signInTpm(buffer, bufferLength,
	IdentityCertificate::certificateNameToPublicKeyName(certificateName),
	DIGEST_ALGORITHM_SHA256));
	return signature;
	}

	/**
	* @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)
	{
	Name signingCertificateName;
	try
	{
	signingCertificateName = Info::getDefaultCertificateNameForIdentity(identityName);
	}
	catch(InfoError& e)
	{
	signingCertificateName = createIdentity(identityName);
	// Ideally, no exception will be thrown out, unless something goes wrong in the TPM, which is a fatal error.
	}

	// We either get or create the signing certificate, sign packet! (no exception unless fatal error in TPM)
	sign(packet, signingCertificateName);
	}

	/**
	* @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)
	{
	Name signingCertificateName;
	try
	{
	signingCertificateName = Info::getDefaultCertificateNameForIdentity(identityName);
	}
	catch(InfoError& e)
	{
	signingCertificateName = createIdentity(identityName);
	// Ideally, no exception will be thrown out, unless something goes wrong in the TPM, which is a fatal error.
	}

	// We either get or create the signing certificate, sign data! (no exception unless fatal error in TPM)
	return sign(buffer, bufferLength, signingCertificateName);
	}

	/**
	* @brief Set Sha256 weak signature.
	*
	* @param data.
	*/
	void
	signWithSha256(Data& data)
	{
	SignatureSha256 sig;
	data.setSignature(sig);

	Block sigValue(Tlv::SignatureValue,
	crypto::sha256(data.wireEncode().value(),
	data.wireEncode().value_size() - data.getSignature().getValue().size()));
	data.setSignatureValue(sigValue);

	}

	/**
	* @brief Generate a self-signed certificate for a public key.
	*
	* @param keyName The name of the public key.
	* @return The generated certificate, NULL if selfSign fails.
	*/
	shared_ptr<IdentityCertificate>
	selfSign(const Name& keyName)
	{
	shared_ptr<PublicKey> pubKey;
	try
	{
	pubKey = Info::getPublicKey(keyName); // may throw an exception.
	}
	catch(InfoError& e)
	{
	return shared_ptr<IdentityCertificate>();
	}

	shared_ptr<IdentityCertificate> certificate = make_shared<IdentityCertificate>();

	Name certificateName = keyName.getPrefix(-1);
	certificateName.append("KEY").append(keyName.get(-1)).append("ID-CERT").appendVersion();

	certificate->setName(certificateName);
	certificate->setNotBefore(time::system_clock::now());
	certificate->setNotAfter(time::system_clock::now() + time::days(7300)/* ~20 years*/);
	certificate->setPublicKeyInfo(*pubKey);
	certificate->addSubjectDescription(CertificateSubjectDescription("2.5.4.41", keyName.toUri()));
	certificate->encode();

	selfSign(*certificate);
	return certificate;
	}

	/**
	* @brief Self-sign the supplied identity certificate.
	*
	* @param cert The supplied cert.
	* @throws SecTpm::Error if the private key does not exist.
	*/
	void
	selfSign (IdentityCertificate& cert)
	{
	Name keyName = IdentityCertificate::certificateNameToPublicKeyName(cert.getName());
	if(!Tpm::doesKeyExistInTpm(keyName, KEY_CLASS_PRIVATE))
	throw TpmError("private key does not exist!");

	SignatureSha256WithRsa signature;
	signature.setKeyLocator(cert.getName().getPrefix(-1)); // implicit conversion should take care

	// For temporary usage, we support RSA + SHA256 only, but will support more.
	signPacketWrapper(cert, signature, keyName, DIGEST_ALGORITHM_SHA256);
	}

	/**
	* @brief delete a certificate.
	*
	* If the certificate to be deleted is current default system default,
	* the method will not delete the certificate and return immediately.
	*
	* @param certificateName The certificate to be deleted.
	*/
	void
	deleteCertificate (const Name& certificateName)
	{
	try
	{
	if(Info::getDefaultCertificateName() == certificateName)
	return;
	}
	catch(InfoError& e)
	{
	// Not a real error, just try to delete the certificate
	}

	Info::deleteCertificateInfo(certificateName);
	}

	/**
	* @brief delete a key.
	*
	* If the key to be deleted is current default system default,
	* the method will not delete the key and return immediately.
	*
	* @param keyName The key to be deleted.
	*/
	void
	deleteKey (const Name& keyName)
	{
	try
	{
	if(Info::getDefaultKeyNameForIdentity(Info::getDefaultIdentity()) == keyName)
	return;
	}
	catch(InfoError& e)
	{
	// Not a real error, just try to delete the key
	}

	Info::deletePublicKeyInfo(keyName);
	Tpm::deleteKeyPairInTpm(keyName);
	}

	/**
	* @brief delete an identity.
	*
	* If the identity to be deleted is current default system default,
	* the method will not delete the identity and return immediately.
	*
	* @param identity The identity to be deleted.
	*/
	void
	deleteIdentity (const Name& identity)
	{
	try
	{
	if(Info::getDefaultIdentity() == identity)
	return;
	}
	catch(InfoError& e)
	{
	// Not a real error, just try to delete the identity
	}

	std::vector<Name> nameList;
	Info::getAllKeyNamesOfIdentity(identity, nameList, true);
	Info::getAllKeyNamesOfIdentity(identity, nameList, false);

	Info::deleteIdentityInfo(identity);

	std::vector<Name>::const_iterator it = nameList.begin();
	for(; it != nameList.end(); it++)
	Tpm::deleteKeyPairInTpm(*it);
	}

	/**
	* @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 InfoError if anything goes wrong in exporting.
	*/
	shared_ptr<SecuredBag>
	exportIdentity(const Name& identity, const std::string& passwordStr)
	{
	if (!Info::doesIdentityExist(identity))
	throw InfoError("Identity does not exist!");

	Name keyName = Info::getDefaultKeyNameForIdentity(identity);

	ConstBufferPtr pkcs8;
	try
	{
	pkcs8 = Tpm::exportPrivateKeyPkcs8FromTpm(keyName, passwordStr);
	}
	catch(TpmError& e)
	{
	throw InfoError("Fail to export PKCS8 of private key");
	}

	shared_ptr<IdentityCertificate> cert;
	try
	{
	cert = Info::getCertificate(Info::getDefaultCertificateNameForKey(keyName));
	}
	catch(InfoError& e)
	{
	cert = selfSign(keyName);
	Info::addCertificateAsIdentityDefault(*cert);
	}

	shared_ptr<SecuredBag> secureBag = make_shared<SecuredBag>(boost::cref(*cert), boost::cref(pkcs8));

	return secureBag;
	}

	/**
	* @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)
	{
	Name keyName = IdentityCertificate::certificateNameToPublicKeyName(securedBag.getCertificate().getName());
	Name identity = keyName.getPrefix(-1);

	// Add identity
	Info::addIdentity(identity);

	// Add key
	Tpm::importPrivateKeyPkcs8IntoTpm(keyName, securedBag.getKey()->buf(), securedBag.getKey()->size(), passwordStr);
	shared_ptr<PublicKey> pubKey = Tpm::getPublicKeyFromTpm(keyName.toUri());
	Info::addPublicKey(keyName, KEY_TYPE_RSA, *pubKey); // HACK! We should set key type according to the pkcs8 info.
	Info::setDefaultKeyNameForIdentity(keyName);

	// Add cert
	Info::addCertificateAsIdentityDefault(securedBag.getCertificate());
	}


	private:
	/**
	* @brief sign a packet using a pariticular certificate.
	*
	* @param packet The packet to be signed.
	* @param certificate The signing certificate.
	*/
	template<typename T>
	void
	sign(T& packet, const IdentityCertificate& certificate)
	{
	SignatureSha256WithRsa signature;
	signature.setKeyLocator(certificate.getName().getPrefix(-1));

	// For temporary usage, we support RSA + SHA256 only, but will support more.
	signPacketWrapper(packet, signature, certificate.getPublicKeyName(), DIGEST_ALGORITHM_SHA256);
	}

	/**
	* @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 keyType The type of the key pair, e.g. KEY_TYPE_RSA.
	* @param keySize The size of the key pair.
	* @return The name of the generated key.
	*/
	Name
	generateKeyPair(const Name& identityName, bool isKsk = false, KeyType keyType = KEY_TYPE_RSA, int keySize = 2048)
	{
	Name keyName = Info::getNewKeyName(identityName, isKsk);

	Tpm::generateKeyPairInTpm(keyName.toUri(), keyType, keySize);

	shared_ptr<PublicKey> pubKey = Tpm::getPublicKeyFromTpm(keyName.toUri());
	Info::addPublicKey(keyName, keyType, *pubKey);

	return keyName;
	}

	/**
	* @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 SignatureSha256WithRsa& signature, const Name& keyName, DigestAlgorithm digestAlgorithm)
	{
	data.setSignature(signature);
	data.setSignatureValue
	(Tpm::signInTpm(data.wireEncode().value(),
	data.wireEncode().value_size() - data.getSignature().getValue().size(),
	keyName, 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 SignatureSha256WithRsa& signature, const Name& keyName, DigestAlgorithm digestAlgorithm)
	{
	Name signedName = Name(interest.getName()).append(signature.getInfo());

	Block sigValue = Tpm::signInTpm(signedName.wireEncode().value(),
	signedName.wireEncode().value_size(),
	keyName,
	DIGEST_ALGORITHM_SHA256);
	sigValue.encode();
	signedName.append(sigValue);
	interest.setName(signedName);
	}


	};

	} // namespace ndn



	#if defined(NDN_CPP_HAVE_OSX_SECURITY) and defined(NDN_CPP_WITH_OSX_KEYCHAIN)

	namespace ndn
	{
	typedef KeyChainImpl<SecPublicInfoSqlite3, SecTpmOsx> KeyChain;
	};

	#else

	namespace ndn
	{
	typedef KeyChainImpl<SecPublicInfoSqlite3, SecTpmFile> KeyChain;
	};

	#endif //NDN_CPP_HAVE_OSX_SECURITY

	#endif //NDN_SECURITY_KEY_CHAIN_HPP