diff --git a/include/ndn-cpp/security/identity/identity-storage.hpp b/include/ndn-cpp/security/identity/identity-storage.hpp
deleted file mode 100644
index 87d93fd..0000000
--- a/include/ndn-cpp/security/identity/identity-storage.hpp
+++ /dev/null
@@ -1,211 +0,0 @@
-/* -*- 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_IDENTITY_STORAGE_HPP
-#define NDN_IDENTITY_STORAGE_HPP
-
-#include "../../name.hpp"
-#include "../security-common.hpp"
-#include "../certificate/public-key.hpp"
-
-namespace ndn {
-
-class Certificate;
-class IdentityCertificate;
-class Data;
-
-/**
- * IdentityStorage is a base class for the storage of identity, public keys and certificates. 
- * Private keys are stored in PrivateKeyStorage.
- * This is an abstract base class.  A subclass must implement the methods.
- */
-class IdentityStorage {
-public:
-  struct Error : public std::runtime_error { Error(const std::string &what) : std::runtime_error(what) {} };
-
-  /**
-   * The virtual Destructor.
-   */
-  virtual 
-  ~IdentityStorage() {}
-
-  /**
-   * Check if the specified identity already exists.
-   * @param identityName The identity name.
-   * @return true if the identity exists, otherwise false.
-   */
-  virtual bool 
-  doesIdentityExist(const Name& identityName) = 0;
-
-  /**
-   * Add a new identity. An exception will be thrown if the identity already exists.
-   * @param identityName The identity name to be added.
-   */
-  virtual void
-  addIdentity(const Name& identityName) = 0;
-
-  /**
-   * Revoke the identity.
-   * @return true if the identity was revoked, false if not.
-   */
-  virtual bool 
-  revokeIdentity() = 0;
-
-  /**
-   * Generate a name for a new key belonging to the identity.
-   * @param identityName The identity name.
-   * @param useKsk If true, generate a KSK name, otherwise a DSK name.
-   * @return The generated key name.
-   */
-  Name 
-  getNewKeyName(const Name& identityName, bool useKsk);
-
-  /**
-   * Check if the specified key already exists.
-   * @param keyName The name of the key.
-   * @return true if the key exists, otherwise false.
-   */
-  virtual bool 
-  doesKeyExist(const Name& keyName) = 0;
-
-  /**
-   * Add a public key to the identity storage.
-   * @param keyName The name of the public key to be added.
-   * @param keyType Type of the public key to be added.
-   * @param publicKeyDer A blob of the public key DER to be added.
-   */
-  virtual void 
-  addKey(const Name& keyName, KeyType keyType, const PublicKey& publicKeyDer) = 0;
-
-  /**
-   * Get the public key DER blob from the identity storage.
-   * @param keyName The name of the requested public key.
-   * @return The DER Blob.  If not found, return a Blob with a null pointer.
-   */
-  virtual ptr_lib::shared_ptr<PublicKey>
-  getKey(const Name& keyName) = 0;
-
-  /**
-   * Activate a key.  If a key is marked as inactive, its private part will not be used in packet signing.
-   * @param keyName name of the key
-   */
-  virtual void 
-  activateKey(const Name& keyName) = 0;
-
-  /**
-   * Deactivate a key. If a key is marked as inactive, its private part will not be used in packet signing.
-   * @param keyName name of the key
-   */
-  virtual void 
-  deactivateKey(const Name& keyName) = 0;
-
-  /**
-   * Check if the specified certificate already exists.
-   * @param certificateName The name of the certificate.
-   * @return true if the certificate exists, otherwise false.
-   */
-  virtual bool
-  doesCertificateExist(const Name& certificateName) = 0;
-
-  /**
-   * Add a certificate to the identity storage.
-   * @param certificate The certificate to be added.  This makes a copy of the certificate.
-   */
-  virtual void 
-  addCertificate(const IdentityCertificate& certificate) = 0;
-
-  /**
-   * Get a certificate from the identity storage.
-   * @param certificateName The name of the requested certificate.
-   * @param allowAny If false, only a valid certificate will be returned, otherwise validity is disregarded.
-   * @return The requested certificate.  If not found, return a shared_ptr with a null pointer.
-   */
-  virtual ptr_lib::shared_ptr<IdentityCertificate> 
-  getCertificate(const Name &certificateName, bool allowAny = false) = 0;
-
-
-  /*****************************************
-   *           Get/Set Default             *
-   *****************************************/
-
-  /**
-   * Get the default identity. 
-   * @param return The name of default identity, or an empty name if there is no default.
-   */
-  virtual Name 
-  getDefaultIdentity() = 0;
-
-  /**
-   * Get the default key name for the specified identity.
-   * @param identityName The identity name.
-   * @return The default key name.
-   */
-  virtual Name 
-  getDefaultKeyNameForIdentity(const Name& identityName) = 0;
-
-  /**
-   * Get the default certificate name for the specified identity.
-   * @param identityName The identity name.
-   * @return The default certificate name.
-   */
-  Name 
-  getDefaultCertificateNameForIdentity(const Name& identityName);
-
-  /**
-   * Get the default certificate name for the specified key.
-   * @param keyName The key name.
-   * @return The default certificate name.
-   */
-  virtual Name 
-  getDefaultCertificateNameForKey(const Name& keyName) = 0;
-
-  /**
-   * Set the default identity.  If the identityName does not exist, then clear the default identity
-   * so that getDefaultIdentity() returns an empty name.
-   * @param identityName The default identity name.
-   */
-  virtual void 
-  setDefaultIdentity(const Name& identityName) = 0;
-
-  /**
-   * Set the default key name for the specified identity.
-   * @param keyName The key name.
-   * @param identityNameCheck (optional) The identity name to check the keyName.
-   */
-  virtual void 
-  setDefaultKeyNameForIdentity(const Name& keyName, const Name& identityNameCheck = Name()) = 0;
-
-  /**
-   * Set the default key name for the specified identity.
-   * @param keyName The key name.
-   * @param certificateName The certificate name.
-   */
-  virtual void 
-  setDefaultCertificateNameForKey(const Name& keyName, const Name& certificateName) = 0;  
-
-  
-  virtual std::vector<Name>
-  getAllIdentities(bool isDefault) = 0;
-
-  virtual std::vector<Name>
-  getAllKeyNames(bool isDefault) = 0;
-
-  virtual std::vector<Name>
-  getAllKeyNamesOfIdentity(const Name& identity, bool isDefault) = 0;
-    
-  virtual std::vector<Name>
-  getAllCertificateNames(bool isDefault) = 0;
-    
-  virtual std::vector<Name>
-  getAllCertificateNamesOfKey(const Name& keyName, bool isDefault) = 0;
-
-};
-
-}
-
-#endif
diff --git a/include/ndn-cpp/security/identity/sec-public-info.hpp b/include/ndn-cpp/security/identity/sec-public-info.hpp
new file mode 100644
index 0000000..3a46310
--- /dev/null
+++ b/include/ndn-cpp/security/identity/sec-public-info.hpp
@@ -0,0 +1,362 @@
+/* -*- 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_SEC_PUBLIC_INFO_HPP
+#define NDN_SEC_PUBLIC_INFO_HPP
+
+#include "../../name.hpp"
+#include "../security-common.hpp"
+#include "../certificate/public-key.hpp"
+#include "../certificate/identity-certificate.hpp"
+
+namespace ndn {
+
+/**
+ * SecPublicInfo is a base class for the storage of identity, public keys and certificates. 
+ * Private keys are stored in SecTpm.
+ * This is an abstract base class.  A subclass must implement the methods.
+ */
+class SecPublicInfo {
+public:
+  struct Error : public std::runtime_error { Error(const std::string &what) : std::runtime_error(what) {} };
+
+  /**
+   * The virtual Destructor.
+   */
+  virtual 
+  ~SecPublicInfo() {}
+
+  /**
+   * Check if the specified identity already exists.
+   * @param identityName The identity name.
+   * @return true if the identity exists, otherwise false.
+   */
+  virtual bool 
+  doesIdentityExist(const Name& identityName) = 0;
+
+  /**
+   * Add a new identity. An exception will be thrown if the identity already exists.
+   * @param identityName The identity name to be added.
+   */
+  virtual void
+  addIdentity(const Name& identityName) = 0;
+
+  /**
+   * Revoke the identity.
+   * @return true if the identity was revoked, false if not.
+   */
+  virtual bool 
+  revokeIdentity() = 0;
+
+  /**
+   * Check if the specified key already exists.
+   * @param keyName The name of the key.
+   * @return true if the key exists, otherwise false.
+   */
+  virtual bool 
+  doesPublicKeyExist(const Name& keyName) = 0;
+
+  /**
+   * Add a public key to the identity storage.
+   * @param keyName The name of the public key to be added.
+   * @param keyType Type of the public key to be added.
+   * @param publicKeyDer A blob of the public key DER to be added.
+   */
+  virtual void 
+  addPublicKey(const Name& keyName, KeyType keyType, const PublicKey& publicKeyDer) = 0;
+
+  /**
+   * Get the public key DER blob from the identity storage.
+   * @param keyName The name of the requested public key.
+   * @return The DER Blob.  If not found, return a Blob with a null pointer.
+   */
+  virtual ptr_lib::shared_ptr<PublicKey>
+  getPublicKey(const Name& keyName) = 0;
+
+  /**
+   * Activate a key.  If a key is marked as inactive, its private part will not be used in packet signing.
+   * @param keyName name of the key
+   */
+  virtual void 
+  activatePublicKey(const Name& keyName) = 0;
+
+  /**
+   * Deactivate a key. If a key is marked as inactive, its private part will not be used in packet signing.
+   * @param keyName name of the key
+   */
+  virtual void 
+  deactivatePublicKey(const Name& keyName) = 0;
+
+  /**
+   * Check if the specified certificate already exists.
+   * @param certificateName The name of the certificate.
+   * @return true if the certificate exists, otherwise false.
+   */
+  virtual bool
+  doesCertificateExist(const Name& certificateName) = 0;
+
+  /**
+   * Add a certificate to the identity storage.
+   * @param certificate The certificate to be added.  This makes a copy of the certificate.
+   */
+  virtual void 
+  addCertificate(const IdentityCertificate& certificate) = 0;
+
+  /**
+   * Get a certificate from the identity storage.
+   * @param certificateName The name of the requested certificate.
+   * @param allowAny If false, only a valid certificate will be returned, otherwise validity is disregarded.
+   * @return The requested certificate.  If not found, return a shared_ptr with a null pointer.
+   */
+  virtual ptr_lib::shared_ptr<IdentityCertificate> 
+  getCertificate(const Name &certificateName, bool allowAny = false) = 0;
+
+
+  /*****************************************
+   *            Default Getter             *
+   *****************************************/
+
+  /**
+   * Get the default identity. 
+   * @param return The name of default identity, or an empty name if there is no default.
+   */
+  virtual Name 
+  getDefaultIdentity() = 0;
+
+  /**
+   * Get the default key name for the specified identity.
+   * @param identityName The identity name.
+   * @return The default key name.
+   */
+  virtual Name 
+  getDefaultKeyNameForIdentity(const Name& identityName) = 0;
+
+  /**
+   * Get the default certificate name for the specified key.
+   * @param keyName The key name.
+   * @return The default certificate name.
+   */
+  virtual Name 
+  getDefaultCertificateNameForKey(const Name& keyName) = 0;
+
+  virtual std::vector<Name>
+  getAllIdentities(bool isDefault) = 0;
+
+  virtual std::vector<Name>
+  getAllKeyNames(bool isDefault) = 0;
+
+  virtual std::vector<Name>
+  getAllKeyNamesOfIdentity(const Name& identity, bool isDefault) = 0;
+    
+  virtual std::vector<Name>
+  getAllCertificateNames(bool isDefault) = 0;
+    
+  virtual std::vector<Name>
+  getAllCertificateNamesOfKey(const Name& keyName, bool isDefault) = 0;
+
+protected:
+
+  /*****************************************
+   *            Default Setter             *
+   *****************************************/
+  
+  /**
+   * Set the default identity.  If the identityName does not exist, then clear the default identity
+   * so that getDefaultIdentity() returns an empty name.
+   * @param identityName The default identity name.
+   */
+  virtual void 
+  setDefaultIdentityInternal(const Name& identityName) = 0;
+  
+  /**
+   * Set the default key name for the corresponding identity.
+   * @param keyName The key name.
+   */
+  virtual void
+  setDefaultKeyNameForIdentityInternal(const Name& keyName) = 0;
+
+  /**
+   * Set the default certificate name for the corresponding key.
+   * @param certificateName The certificate name.
+   */
+  virtual void 
+  setDefaultCertificateNameForKeyInternal(const Name& certificateName) = 0; 
+
+public:
+  
+  /*****************************************
+   *            Helper Methods             *
+   *****************************************/
+
+  /**
+   * Set the default identity.  If the identityName does not exist, then clear the default identity
+   * so that getDefaultIdentity() returns an empty name.
+   * @param identityName The default identity name.
+   */
+  inline void 
+  setDefaultIdentity(const Name& identityName);
+
+  /**
+   * Set the default key name for the corresponding identity.
+   * @param keyName The key name.
+   */
+  inline void 
+  setDefaultKeyNameForIdentity(const Name& keyName);
+
+  /**
+   * Set the default certificate name for the corresponding key.
+   * @param certificateName The certificate name.
+   */
+  inline void 
+  setDefaultCertificateNameForKey(const Name& certificateName); 
+
+  /**
+   * Generate a name for a new key belonging to the identity.
+   * @param identityName The identity name.
+   * @param useKsk If true, generate a KSK name, otherwise a DSK name.
+   * @return The generated key name.
+   */
+  inline Name 
+  getNewKeyName(const Name& identityName, bool useKsk);
+
+    /**
+   * Get the default certificate name for the specified identity.
+   * @param identityName The identity name.
+   * @return The default certificate name.
+   */
+  inline Name 
+  getDefaultCertificateNameForIdentity(const Name& identityName);
+
+  /**
+   * Get the default certificate name of the default identity, which will be used when signing is based on identity and 
+   * the identity is not specified.
+   * @return The requested certificate name.
+   */
+  inline Name
+  getDefaultCertificateName();
+
+  /**
+   * Add a certificate and set the certificate as the default of its corresponding key.
+   * @param certificate The certificate to be added.  This makes a copy of the certificate.
+   */
+  inline void
+  addCertificateAsKeyDefault(const IdentityCertificate& certificate);
+
+  /**
+   * Add a certificate into the public key identity storage and set the certificate as the default for its corresponding identity.
+   * @param certificate The certificate to be added.  This makes a copy of the certificate.
+   */
+  inline void
+  addCertificateAsIdentityDefault(const IdentityCertificate& certificate);
+
+  inline ptr_lib::shared_ptr<IdentityCertificate>
+  defaultCertificate();
+  
+  inline void
+  refreshDefaultCertificate();
+
+protected:
+  ptr_lib::shared_ptr<IdentityCertificate> defaultCertificate_;
+
+};
+
+void
+SecPublicInfo::setDefaultIdentity(const Name& identityName)
+{
+  setDefaultIdentityInternal(identityName);
+  refreshDefaultCertificate();
+}
+
+void
+SecPublicInfo::setDefaultKeyNameForIdentity(const Name& keyName)
+{
+  setDefaultKeyNameForIdentityInternal(keyName);
+  refreshDefaultCertificate();
+}
+
+void 
+SecPublicInfo::setDefaultCertificateNameForKey(const Name& certificateName)
+{
+  setDefaultCertificateNameForKeyInternal(certificateName);
+  refreshDefaultCertificate();
+}
+
+Name 
+SecPublicInfo::getDefaultCertificateNameForIdentity(const Name& identityName)
+{
+  return getDefaultCertificateNameForKey(getDefaultKeyNameForIdentity(identityName));
+}
+
+Name
+SecPublicInfo::getNewKeyName (const Name& identityName, bool useKsk)
+{
+  MillisecondsSince1970 ti = getNow();
+  // Get the number of seconds.
+  std::ostringstream oss;
+  oss << floor(ti / 1000.0);  
+
+  std::string keyIdStr;
+    
+  if (useKsk)
+    keyIdStr = ("KSK-" + oss.str());
+  else
+    keyIdStr = ("DSK-" + oss.str());
+
+  Name keyName = Name(identityName).append(keyIdStr);
+
+  if (doesPublicKeyExist(keyName))
+    throw Error("Key name already exists");
+
+  return keyName;
+}
+
+Name
+SecPublicInfo::getDefaultCertificateName()
+{
+  if(!static_cast<bool>(defaultCertificate_))
+    refreshDefaultCertificate();
+
+  if(!static_cast<bool>(defaultCertificate_))
+    return Name();
+
+  return defaultCertificate_->getName();
+}
+
+void
+SecPublicInfo::addCertificateAsKeyDefault(const IdentityCertificate& certificate)
+{
+  addCertificate(certificate);
+  setDefaultCertificateNameForKeyInternal(certificate.getName());
+  refreshDefaultCertificate();
+}
+
+void
+SecPublicInfo::addCertificateAsIdentityDefault(const IdentityCertificate& certificate)
+{
+  addCertificate(certificate);
+  setDefaultKeyNameForIdentityInternal(certificate.getPublicKeyName());
+  setDefaultCertificateNameForKeyInternal(certificate.getName());
+  refreshDefaultCertificate();
+}
+
+ptr_lib::shared_ptr<IdentityCertificate>
+SecPublicInfo::defaultCertificate()
+{
+  return defaultCertificate_;
+}
+
+void
+SecPublicInfo::refreshDefaultCertificate()
+{
+  defaultCertificate_ = getCertificate(getDefaultCertificateNameForIdentity(getDefaultIdentity()));
+}
+
+
+}
+
+#endif
diff --git a/include/ndn-cpp/security/identity/private-key-storage.hpp b/include/ndn-cpp/security/identity/sec-tpm.hpp
similarity index 79%
rename from include/ndn-cpp/security/identity/private-key-storage.hpp
rename to include/ndn-cpp/security/identity/sec-tpm.hpp
index 5446484..9452f9f 100644
--- a/include/ndn-cpp/security/identity/private-key-storage.hpp
+++ b/include/ndn-cpp/security/identity/sec-tpm.hpp
@@ -6,19 +6,18 @@
  * See COPYING for copyright and distribution information.
  */
 
-#ifndef NDN_PRIVATE_KEY_STORAGE_HPP
-#define NDN_PRIVATE_KEY_STORAGE_HPP
+#ifndef NDN_SEC_TPM_HPP
+#define NDN_SEC_TPM_HPP
 
 #include <string>
 #include "../security-common.hpp"
 #include "../../name.hpp"
 #include "../../data.hpp"
+#include "../certificate/public-key.hpp"
 
 namespace ndn {
 
-class PublicKey;
-
-class PrivateKeyStorage {
+class SecTpm {
 public:
   struct Error : public std::runtime_error { Error(const std::string &what) : std::runtime_error(what) {} };
 
@@ -26,7 +25,7 @@
    * The virtual destructor.
    */    
   virtual 
-  ~PrivateKeyStorage() {}
+  ~SecTpm() {}
 
   /**
    * Generate a pair of asymmetric keys.
@@ -35,7 +34,7 @@
    * @param keySize The size of the key pair.
    */
   virtual void 
-  generateKeyPair(const Name& keyName, KeyType keyType = KEY_TYPE_RSA, int keySize = 2048) = 0;
+  generateKeyPairInTpm(const Name& keyName, KeyType keyType, int keySize) = 0;
 
   /**
    * Get the public key
@@ -43,7 +42,7 @@
    * @return The public key.
    */
   virtual ptr_lib::shared_ptr<PublicKey> 
-  getPublicKey(const Name& keyName) = 0;
+  getPublicKeyFromTpm(const Name& keyName) = 0;
   
   /**
    * Fetch the private key for keyName and sign the data, returning a signature Blob.
@@ -54,12 +53,10 @@
    * @return The signature, or a null pointer if signing fails.
    */  
   virtual Block
-  sign(const uint8_t *data, size_t dataLength,
-       const Name& keyName, DigestAlgorithm digestAlgorithm = DIGEST_ALGORITHM_SHA256) = 0;
+  sign(const uint8_t *data, size_t dataLength, const Name& keyName, DigestAlgorithm digestAlgorithm) = 0;
 
   virtual void
-  sign(Data &data,
-       const Name& keyName, DigestAlgorithm digestAlgorithm = DIGEST_ALGORITHM_SHA256) = 0;
+  sign(Data &data, const Name& keyName, DigestAlgorithm digestAlgorithm) = 0;
   
   /**
    * Decrypt data.
@@ -70,7 +67,7 @@
    * @return The decrypted data.
    */
   virtual ConstBufferPtr 
-  decrypt(const Name& keyName, const uint8_t* data, size_t dataLength, bool isSymmetric = false) = 0;
+  decrypt(const Name& keyName, const uint8_t* data, size_t dataLength, bool isSymmetric) = 0;
 
   /**
    * Encrypt data.
@@ -81,7 +78,7 @@
    * @return The encrypted data.
    */
   virtual ConstBufferPtr
-  encrypt(const Name& keyName, const uint8_t* data, size_t dataLength, bool isSymmetric = false) = 0;
+  encrypt(const Name& keyName, const uint8_t* data, size_t dataLength, bool isSymmetric) = 0;
 
   /**
    * @brief Generate a symmetric key.
@@ -90,7 +87,7 @@
    * @param keySize The size of the key.
    */
   virtual void 
-  generateKey(const Name& keyName, KeyType keyType = KEY_TYPE_AES, int keySize = 256) = 0;
+  generateSymmetricKey(const Name& keyName, KeyType keyType, int keySize) = 0;
 
   /**
    * Check if a particular key exists.