diff --git a/src/security/key-chain.cpp b/src/security/key-chain.cpp
index 22a25b3..a04e58b 100644
--- a/src/security/key-chain.cpp
+++ b/src/security/key-chain.cpp
@@ -38,6 +38,8 @@
 // Use a GUID as a magic number of KeyChain::DEFAULT_PREFIX identifier
 const Name KeyChain::DEFAULT_PREFIX("/723821fd-f534-44b3-80d9-44bf5f58bbbb");
 
+const RsaKeyParams KeyChain::DEFAULT_KEY_PARAMS;
+
 KeyChain::KeyChain()
   : m_pib(0)
   , m_tpm(0)
@@ -120,6 +122,49 @@
     throw Error("TPM type '" + tpmName + "' is not supported");
 }
 
+Name
+KeyChain::createIdentity(const Name& identityName, const KeyParams& params)
+{
+  m_pib->addIdentity(identityName);
+
+  Name keyName;
+  try
+    {
+      keyName = m_pib->getDefaultKeyNameForIdentity(identityName);
+    }
+  catch (SecPublicInfo::Error& e)
+    {
+      keyName = generateKeyPair(identityName, true, params);
+      m_pib->setDefaultKeyNameForIdentity(keyName);
+    }
+
+  Name certName;
+  try
+    {
+      certName = m_pib->getDefaultCertificateNameForKey(keyName);
+    }
+  catch (SecPublicInfo::Error& e)
+    {
+      shared_ptr<IdentityCertificate> selfCert = selfSign(keyName);
+      m_pib->addCertificateAsIdentityDefault(*selfCert);
+      certName = selfCert->getName();
+    }
+
+  return certName;
+}
+
+Name
+KeyChain::generateRsaKeyPairAsDefault(const Name& identityName, bool isKsk, int keySize)
+{
+  RsaKeyParams params(keySize);
+
+  Name keyName = generateKeyPair(identityName, isKsk, params);
+
+  m_pib->setDefaultKeyNameForIdentity(keyName);
+
+  return keyName;
+}
+
 shared_ptr<IdentityCertificate>
 KeyChain::prepareUnsignedIdentityCertificate(const Name& keyName,
   const Name& signingIdentity,
@@ -199,6 +244,7 @@
 
   if (subjectDescription.empty())
     {
+      // OID 2.5.4.41 is the oid of subject name.
       CertificateSubjectDescription subjectName("2.5.4.41", keyName.getPrefix(-1).toUri());
       certificate->addSubjectDescription(subjectName);
     }
@@ -221,8 +267,8 @@
 KeyChain::sign(const uint8_t* buffer, size_t bufferLength, const Name& certificateName)
 {
   if (!m_pib->doesCertificateExist(certificateName))
-    throw SecPublicInfo::Error("Requested certificate ["
-                               + certificateName.toUri() + "] doesn't exist");
+    throw SecPublicInfo::Error("Requested certificate [" +
+                               certificateName.toUri() + "] doesn't exist");
 
   Name keyName = IdentityCertificate::certificateNameToPublicKeyName(certificateName);
 
@@ -269,7 +315,7 @@
 {
   Name keyName = IdentityCertificate::certificateNameToPublicKeyName(cert.getName());
   if (!m_tpm->doesKeyExistInTpm(keyName, KEY_CLASS_PRIVATE))
-    throw SecTpm::Error("private key does not exist!");
+    throw SecTpm::Error("Private key does not exist");
 
   SignatureSha256WithRsa signature;
   signature.setKeyLocator(cert.getName().getPrefix(-1)); // implicit conversion should take care
@@ -282,7 +328,7 @@
 KeyChain::exportIdentity(const Name& identity, const std::string& passwordStr)
 {
   if (!m_pib->doesIdentityExist(identity))
-    throw SecPublicInfo::Error("Identity does not exist!");
+    throw SecPublicInfo::Error("Identity does not exist");
 
   Name keyName = m_pib->getDefaultKeyNameForIdentity(identity);
 
@@ -362,4 +408,146 @@
     }
 }
 
+Name
+KeyChain::generateKeyPair(const Name& identityName, bool isKsk, const KeyParams& params)
+{
+  Name keyName = m_pib->getNewKeyName(identityName, isKsk);
+
+  m_tpm->generateKeyPairInTpm(keyName.toUri(), params);
+
+  shared_ptr<PublicKey> pubKey = m_tpm->getPublicKeyFromTpm(keyName.toUri());
+  m_pib->addKey(keyName, *pubKey);
+
+  return keyName;
+}
+
+void
+KeyChain::signPacketWrapper(Data& data, const SignatureSha256WithRsa& signature,
+                            const Name& keyName, DigestAlgorithm digestAlgorithm)
+{
+  data.setSignature(signature);
+
+  EncodingBuffer encoder;
+  data.wireEncode(encoder, true);
+
+  Block signatureValue = m_tpm->signInTpm(encoder.buf(), encoder.size(),
+                                          keyName, digestAlgorithm);
+  data.wireEncode(encoder, signatureValue);
+}
+
+void
+KeyChain::signPacketWrapper(Interest& interest, const SignatureSha256WithRsa& signature,
+                            const Name& keyName, DigestAlgorithm digestAlgorithm)
+{
+  time::milliseconds timestamp = time::toUnixTimestamp(time::system_clock::now());
+  if (timestamp <= m_lastTimestamp)
+    {
+      timestamp = m_lastTimestamp + time::milliseconds(1);
+    }
+
+  Name signedName = interest.getName();
+  signedName
+    .append(name::Component::fromNumber(timestamp.count()))        // timestamp
+    .append(name::Component::fromNumber(random::generateWord64())) // nonce
+    .append(signature.getInfo());                                  // signatureInfo
+
+  Block sigValue = m_tpm->signInTpm(signedName.wireEncode().value(),
+                                    signedName.wireEncode().value_size(),
+                                    keyName,
+                                    digestAlgorithm);
+  sigValue.encode();
+  signedName.append(sigValue);                                     // signatureValue
+  interest.setName(signedName);
+}
+
+Signature
+KeyChain::signByIdentity(const uint8_t* buffer, size_t bufferLength, const Name& identityName)
+{
+  Name signingCertificateName;
+  try
+    {
+      signingCertificateName = m_pib->getDefaultCertificateNameForIdentity(identityName);
+    }
+  catch (SecPublicInfo::Error& 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);
+}
+
+void
+KeyChain::signWithSha256(Data& data)
+{
+  DigestSha256 sig;
+  data.setSignature(sig);
+
+  Block sigValue(Tlv::SignatureValue,
+                 crypto::sha256(data.wireEncode().value(),
+                                data.wireEncode().value_size() -
+                                data.getSignature().getValue().size()));
+  data.setSignatureValue(sigValue);
+}
+
+void
+KeyChain::deleteCertificate(const Name& certificateName)
+{
+  try
+    {
+      if (m_pib->getDefaultCertificateName() == certificateName)
+        return;
+    }
+  catch (SecPublicInfo::Error& e)
+    {
+      // Not a real error, just try to delete the certificate
+    }
+
+  m_pib->deleteCertificateInfo(certificateName);
+}
+
+void
+KeyChain::deleteKey(const Name& keyName)
+{
+  try
+    {
+      if (m_pib->getDefaultKeyNameForIdentity(m_pib->getDefaultIdentity()) == keyName)
+        return;
+    }
+  catch (SecPublicInfo::Error& e)
+    {
+      // Not a real error, just try to delete the key
+    }
+
+  m_pib->deletePublicKeyInfo(keyName);
+  m_tpm->deleteKeyPairInTpm(keyName);
+}
+
+void
+KeyChain::deleteIdentity(const Name& identity)
+{
+  try
+    {
+      if (m_pib->getDefaultIdentity() == identity)
+        return;
+    }
+  catch (SecPublicInfo::Error& e)
+    {
+      // Not a real error, just try to delete the identity
+    }
+
+  std::vector<Name> nameList;
+  m_pib->getAllKeyNamesOfIdentity(identity, nameList, true);
+  m_pib->getAllKeyNamesOfIdentity(identity, nameList, false);
+
+  m_pib->deleteIdentityInfo(identity);
+
+  std::vector<Name>::const_iterator it = nameList.begin();
+  for(; it != nameList.end(); it++)
+    m_tpm->deleteKeyPairInTpm(*it);
+}
+
 }
diff --git a/src/security/key-chain.hpp b/src/security/key-chain.hpp
index 2b6da41..44ff1de 100644
--- a/src/security/key-chain.hpp
+++ b/src/security/key-chain.hpp
@@ -26,6 +26,7 @@
 
 #include "sec-public-info.hpp"
 #include "sec-tpm.hpp"
+#include "key-params.hpp"
 #include "secured-bag.hpp"
 #include "signature-sha256-with-rsa.hpp"
 #include "digest-sha256.hpp"
@@ -60,6 +61,9 @@
 
   static const Name DEFAULT_PREFIX;
 
+  // RsaKeyParams is set to be default for backward compatibility.
+  static const RsaKeyParams DEFAULT_KEY_PARAMS;
+
   KeyChain();
 
   template<class KeyChainTraits>
@@ -84,10 +88,11 @@
    *        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.
    */
-  inline Name
-  createIdentity(const Name& identityName);
+  Name
+  createIdentity(const Name& identityName, const KeyParams& params = DEFAULT_KEY_PARAMS);
 
   /**
    * @brief Generate a pair of RSA keys for the specified identity.
@@ -109,7 +114,7 @@
    * @param keySize The size of the key.
    * @return The generated key name.
    */
-  inline Name
+  Name
   generateRsaKeyPairAsDefault(const Name& identityName, bool isKsk = false, int keySize = 2048);
 
   /**
@@ -217,13 +222,13 @@
    * @param identityName The identity name.
    * @return The Signature.
    */
-  inline Signature
+  Signature
   signByIdentity(const uint8_t* buffer, size_t bufferLength, const Name& identityName);
 
   /**
    * @brief Set Sha256 weak signature for @param data
    */
-  inline void
+  void
   signWithSha256(Data& data);
 
   /**
@@ -252,7 +257,7 @@
    *
    * @param certificateName The certificate to be deleted.
    */
-  inline void
+  void
   deleteCertificate(const Name& certificateName);
 
   /**
@@ -263,7 +268,7 @@
    *
    * @param keyName The key to be deleted.
    */
-  inline void
+  void
   deleteKey(const Name& keyName);
 
   /**
@@ -274,7 +279,7 @@
    *
    * @param identity The identity to be deleted.
    */
-  inline void
+  void
   deleteIdentity(const Name& identity);
 
   /**
@@ -348,6 +353,12 @@
     return m_pib->addPublicKey(keyName, keyType, publicKeyDer);
   }
 
+  void
+  addKey(const Name& keyName, const PublicKey& publicKeyDer)
+  {
+    return m_pib->addKey(keyName, publicKeyDer);
+  }
+
   shared_ptr<PublicKey>
   getPublicKey(const Name& keyName) const
   {
@@ -547,9 +558,9 @@
   }
 
   void
-  generateKeyPairInTpm(const Name& keyName, KeyType keyType, int keySize)
+  generateKeyPairInTpm(const Name& keyName, const KeyParams& params)
   {
-    return m_tpm->generateKeyPairInTpm(keyName, keyType, keySize);
+    return m_tpm->generateKeyPairInTpm(keyName, params);
   }
 
   void
@@ -585,9 +596,9 @@
   }
 
   void
-  generateSymmetricKeyInTpm(const Name& keyName, KeyType keyType, int keySize)
+  generateSymmetricKeyInTpm(const Name& keyName, const KeyParams& params)
   {
-    return m_tpm->generateSymmetricKeyInTpm(keyName, keyType, keySize);
+    return m_tpm->generateSymmetricKeyInTpm(keyName, params);
   }
 
   bool
@@ -644,13 +655,12 @@
    *
    * @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.
+   * @param params The parameter of the key.
    * @return The name of the generated key.
    */
-  inline Name
+  Name
   generateKeyPair(const Name& identityName, bool isKsk = false,
-                  KeyType keyType = KEY_TYPE_RSA, int keySize = 2048);
+                  const KeyParams& params = DEFAULT_KEY_PARAMS);
 
   /**
    * @brief Sign the data using a particular key.
@@ -661,7 +671,7 @@
    * @param digestAlgorithm the digest algorithm.
    * @throws Tpm::Error
    */
-  inline void
+  void
   signPacketWrapper(Data& data, const SignatureSha256WithRsa& signature,
                     const Name& keyName, DigestAlgorithm digestAlgorithm);
 
@@ -674,7 +684,7 @@
    * @param digestAlgorithm the digest algorithm.
    * @throws Tpm::Error
    */
-  inline void
+  void
   signPacketWrapper(Interest& interest, const SignatureSha256WithRsa& signature,
                     const Name& keyName, DigestAlgorithm digestAlgorithm);
 
@@ -695,49 +705,10 @@
 }
 
 inline Name
-KeyChain::createIdentity(const Name& identityName)
-{
-  m_pib->addIdentity(identityName);
-
-  Name keyName;
-  try
-    {
-      keyName = m_pib->getDefaultKeyNameForIdentity(identityName);
-    }
-  catch (SecPublicInfo::Error& e)
-    {
-      keyName = generateRsaKeyPairAsDefault(identityName, true);
-    }
-
-  Name certName;
-  try
-    {
-      certName = m_pib->getDefaultCertificateNameForKey(keyName);
-    }
-  catch (SecPublicInfo::Error& e)
-    {
-      shared_ptr<IdentityCertificate> selfCert = selfSign(keyName);
-      m_pib->addCertificateAsIdentityDefault(*selfCert);
-      certName = selfCert->getName();
-    }
-
-  return certName;
-}
-
-inline Name
 KeyChain::generateRsaKeyPair(const Name& identityName, bool isKsk, int keySize)
 {
-  return generateKeyPair(identityName, isKsk, KEY_TYPE_RSA, keySize);
-}
-
-inline Name
-KeyChain::generateRsaKeyPairAsDefault(const Name& identityName, bool isKsk, int keySize)
-{
-  Name keyName = generateKeyPair(identityName, isKsk, KEY_TYPE_RSA, keySize);
-
-  m_pib->setDefaultKeyNameForIdentity(keyName);
-
-  return keyName;
+  RsaKeyParams params(keySize);
+  return generateKeyPair(identityName, isKsk, params);
 }
 
 template<typename T>
@@ -789,96 +760,6 @@
   sign(packet, signingCertificateName);
 }
 
-inline Signature
-KeyChain::signByIdentity(const uint8_t* buffer, size_t bufferLength, const Name& identityName)
-{
-  Name signingCertificateName;
-  try
-    {
-      signingCertificateName = m_pib->getDefaultCertificateNameForIdentity(identityName);
-    }
-  catch (SecPublicInfo::Error& 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);
-}
-
-inline void
-KeyChain::signWithSha256(Data& data)
-{
-  DigestSha256 sig;
-  data.setSignature(sig);
-
-  Block sigValue(Tlv::SignatureValue,
-                 crypto::sha256(data.wireEncode().value(),
-                                data.wireEncode().value_size() -
-                                data.getSignature().getValue().size()));
-  data.setSignatureValue(sigValue);
-}
-
-inline void
-KeyChain::deleteCertificate(const Name& certificateName)
-{
-  try
-    {
-      if (m_pib->getDefaultCertificateName() == certificateName)
-        return;
-    }
-  catch (SecPublicInfo::Error& e)
-    {
-      // Not a real error, just try to delete the certificate
-    }
-
-  m_pib->deleteCertificateInfo(certificateName);
-}
-
-inline void
-KeyChain::deleteKey(const Name& keyName)
-{
-  try
-    {
-      if (m_pib->getDefaultKeyNameForIdentity(m_pib->getDefaultIdentity()) == keyName)
-        return;
-    }
-  catch (SecPublicInfo::Error& e)
-    {
-      // Not a real error, just try to delete the key
-    }
-
-  m_pib->deletePublicKeyInfo(keyName);
-  m_tpm->deleteKeyPairInTpm(keyName);
-}
-
-inline void
-KeyChain::deleteIdentity(const Name& identity)
-{
-  try
-    {
-      if (m_pib->getDefaultIdentity() == identity)
-        return;
-    }
-  catch (SecPublicInfo::Error& e)
-    {
-      // Not a real error, just try to delete the identity
-    }
-
-  std::vector<Name> nameList;
-  m_pib->getAllKeyNamesOfIdentity(identity, nameList, true);
-  m_pib->getAllKeyNamesOfIdentity(identity, nameList, false);
-
-  m_pib->deleteIdentityInfo(identity);
-
-  std::vector<Name>::const_iterator it = nameList.begin();
-  for(; it != nameList.end(); it++)
-    m_tpm->deleteKeyPairInTpm(*it);
-}
-
 template<typename T>
 void
 KeyChain::sign(T& packet, const IdentityCertificate& certificate)
@@ -890,58 +771,6 @@
   signPacketWrapper(packet, signature, certificate.getPublicKeyName(), DIGEST_ALGORITHM_SHA256);
 }
 
-inline Name
-KeyChain::generateKeyPair(const Name& identityName, bool isKsk, KeyType keyType, int keySize)
-{
-  Name keyName = m_pib->getNewKeyName(identityName, isKsk);
-
-  m_tpm->generateKeyPairInTpm(keyName.toUri(), keyType, keySize);
-
-  shared_ptr<PublicKey> pubKey = m_tpm->getPublicKeyFromTpm(keyName.toUri());
-  m_pib->addPublicKey(keyName, keyType, *pubKey);
-
-  return keyName;
-}
-
-inline void
-KeyChain::signPacketWrapper(Data& data, const SignatureSha256WithRsa& signature,
-                            const Name& keyName, DigestAlgorithm digestAlgorithm)
-{
-  data.setSignature(signature);
-
-  EncodingBuffer encoder;
-  data.wireEncode(encoder, true);
-
-  Block signatureValue = m_tpm->signInTpm(encoder.buf(), encoder.size(),
-                                          keyName, digestAlgorithm);
-  data.wireEncode(encoder, signatureValue);
-}
-
-inline void
-KeyChain::signPacketWrapper(Interest& interest, const SignatureSha256WithRsa& signature,
-                            const Name& keyName, DigestAlgorithm digestAlgorithm)
-{
-  time::milliseconds timestamp = time::toUnixTimestamp(time::system_clock::now());
-  if (timestamp <= m_lastTimestamp)
-    {
-      timestamp = m_lastTimestamp + time::milliseconds(1);
-    }
-
-  Name signedName = interest.getName();
-  signedName
-    .append(name::Component::fromNumber(timestamp.count()))        // timestamp
-    .append(name::Component::fromNumber(random::generateWord64())) // nonce
-    .append(signature.getInfo());                                  // signatureInfo
-
-  Block sigValue = m_tpm->signInTpm(signedName.wireEncode().value(),
-                                    signedName.wireEncode().value_size(),
-                                    keyName,
-                                    digestAlgorithm);
-  sigValue.encode();
-  signedName.append(sigValue);                                     // signatureValue
-  interest.setName(signedName);
-}
-
 }
 
 #endif // NDN_SECURITY_KEY_CHAIN_HPP
diff --git a/src/security/key-params.cpp b/src/security/key-params.cpp
new file mode 100644
index 0000000..7ee2e1e
--- /dev/null
+++ b/src/security/key-params.cpp
@@ -0,0 +1,83 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2013-2014 Regents of the University of California.
+ *
+ * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
+ *
+ * ndn-cxx library is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU Lesser General Public License as published by the Free Software
+ * Foundation, either version 3 of the License, or (at your option) any later version.
+ *
+ * ndn-cxx library is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+ * PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more details.
+ *
+ * You should have received copies of the GNU General Public License and GNU Lesser
+ * General Public License along with ndn-cxx, e.g., in COPYING.md file.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
+ */
+
+#include "key-params.hpp"
+
+namespace ndn {
+
+static const uint32_t RSA_KEY_SIZES[] = {2048, 1024};
+static const uint32_t ECDSA_KEY_SIZES[] = {256, 384};
+static const uint32_t AES_KEY_SIZES[] = {64, 128, 256};
+
+uint32_t
+RsaKeyParamsInfo::checkKeySize(uint32_t size)
+{
+  for (size_t i = 0; i < (sizeof(RSA_KEY_SIZES) / sizeof(uint32_t)); i++)
+    {
+      if (RSA_KEY_SIZES[i] == size)
+        return size;
+    }
+  return getDefaultSize();
+}
+
+uint32_t
+RsaKeyParamsInfo::getDefaultSize()
+{
+  return RSA_KEY_SIZES[0];
+}
+
+uint32_t
+EcdsaKeyParamsInfo::checkKeySize(uint32_t size)
+{
+
+  for (size_t i = 0; i < (sizeof(ECDSA_KEY_SIZES) / sizeof(uint32_t)); i++)
+    {
+      if (ECDSA_KEY_SIZES[i] == size)
+        return size;
+    }
+  return getDefaultSize();
+}
+
+uint32_t
+EcdsaKeyParamsInfo::getDefaultSize()
+{
+  return ECDSA_KEY_SIZES[0];
+}
+
+
+uint32_t
+AesKeyParamsInfo::checkKeySize(uint32_t size)
+{
+  for (size_t i = 0; i < (sizeof(AES_KEY_SIZES) / sizeof(uint32_t)); i++)
+    {
+      if (AES_KEY_SIZES[i] == size)
+        return size;
+    }
+  return getDefaultSize();
+}
+
+uint32_t
+AesKeyParamsInfo::getDefaultSize()
+{
+  return AES_KEY_SIZES[0];
+}
+
+} // namespace ndn
diff --git a/src/security/key-params.hpp b/src/security/key-params.hpp
new file mode 100644
index 0000000..2cac26a
--- /dev/null
+++ b/src/security/key-params.hpp
@@ -0,0 +1,235 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2013-2014 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_KEY_PARAMS_HPP
+#define NDN_SECURITY_KEY_PARAMS_HPP
+
+#include "security-common.hpp"
+
+namespace ndn {
+
+/**
+ * @brief Base class of key parameters.
+ *
+ * Its subclasses are used to store parameters for key generation.
+ */
+class KeyParams
+{
+public:
+  class Error : public std::runtime_error
+  {
+  public:
+    explicit
+    Error(const std::string& what)
+      : std::runtime_error(what)
+    {
+    }
+  };
+
+  virtual
+  ~KeyParams()
+  {
+  }
+
+  KeyType
+  getKeyType() const
+  {
+    return m_keyType;
+  }
+
+protected:
+  explicit
+  KeyParams(KeyType keyType)
+    : m_keyType(keyType)
+  {
+  }
+
+private:
+  KeyType m_keyType;
+};
+
+
+/// @brief RsaKeyParamInfo is used to initialize a SimplePublicKeyParams template for RSA key.
+class RsaKeyParamsInfo
+{
+public:
+  static KeyType
+  getType()
+  {
+    return KEY_TYPE_RSA;
+  }
+
+  /// @brief check if size is qualified, otherwise return the default key size.
+  static uint32_t
+  checkKeySize(uint32_t size);
+
+  static uint32_t
+  getDefaultSize();
+};
+
+/// @brief EcdsaKeyParamInfo is used to initialize a SimplePublicKeyParams template for ECDSA key.
+class EcdsaKeyParamsInfo
+{
+public:
+  static KeyType
+  getType()
+  {
+    return KEY_TYPE_ECDSA;
+  }
+
+  /// @brief check if size is qualified, otherwise return the default key size.
+  static uint32_t
+  checkKeySize(uint32_t size);
+
+  static uint32_t
+  getDefaultSize();
+};
+
+
+/// @brief SimplePublicKeyParams is a template for public keys with only one parameter: size.
+template<typename KeyParamsInfo>
+class SimplePublicKeyParams : public KeyParams
+{
+public:
+  explicit
+  SimplePublicKeyParams(uint32_t size = KeyParamsInfo::getDefaultSize())
+    : KeyParams(KeyParamsInfo::getType())
+  {
+    setKeySize(size);
+  }
+
+  explicit
+  SimplePublicKeyParams(const SimplePublicKeyParams& params)
+    : KeyParams(params)
+    , m_size(params.m_size)
+  {
+  }
+
+  explicit
+  SimplePublicKeyParams(const KeyParams& params)
+    : KeyParams(params.getKeyType())
+  {
+    throw KeyParams::Error("Incorrect key parameters (incompatible key type)");
+  }
+
+  uint32_t
+  getKeySize() const
+  {
+    return m_size;
+  }
+
+private:
+  void
+  setKeySize(uint32_t size)
+  {
+    m_size = KeyParamsInfo::checkKeySize(size);
+  }
+
+  uint32_t
+  getDefaultKeySize() const
+  {
+    return KeyParamsInfo::getDefaultSize();
+  }
+
+private:
+  uint32_t m_size;
+};
+
+/// @brief RsaKeyParams carries parameters for RSA key.
+typedef SimplePublicKeyParams<RsaKeyParamsInfo> RsaKeyParams;
+
+/// @brief EcdsaKeyParams carries parameters for ECDSA key.
+typedef SimplePublicKeyParams<EcdsaKeyParamsInfo> EcdsaKeyParams;
+
+
+/// @brief AesKeyParamsInfo is used to initialize a SimpleSymmetricKeyParams template for AES key.
+class AesKeyParamsInfo
+{
+public:
+  static KeyType
+  getType()
+  {
+    return KEY_TYPE_AES;
+  }
+
+  /// @brief check if size is qualified, otherwise return the default key size.
+  static uint32_t
+  checkKeySize(uint32_t size);
+
+  static uint32_t
+  getDefaultSize();
+};
+
+
+/// @brief SimpleSymmetricKeyParams is a template for symmetric keys with only one parameter: size.
+template<typename KeyParamsInfo>
+class SimpleSymmetricKeyParams : public KeyParams
+{
+public:
+  explicit
+  SimpleSymmetricKeyParams(uint32_t size = KeyParamsInfo::getDefaultSize())
+    : KeyParams(KeyParamsInfo::getType())
+  {
+    setKeySize(size);
+  }
+
+  explicit
+  SimpleSymmetricKeyParams(const SimpleSymmetricKeyParams& params)
+    : KeyParams(params)
+    , m_size(params.m_size)
+  {
+  }
+
+  explicit
+  SimpleSymmetricKeyParams(const KeyParams& params)
+  {
+    throw KeyParams::Error("Incorrect key parameters (incompatible key type)");
+  }
+
+  uint32_t
+  getKeySize() const
+  {
+    return m_size;
+  }
+
+private:
+  void
+  setKeySize(uint32_t size)
+  {
+    m_size = KeyParamsInfo::checkKeySize(size);
+  }
+
+  uint32_t
+  getDefaultKeySize() const
+  {
+    return KeyParamsInfo::getDefaultSize();
+  }
+
+private:
+  uint32_t m_size;
+
+};
+
+typedef SimpleSymmetricKeyParams<AesKeyParamsInfo> AesKeyParams;
+
+} // namespace ndn
+
+#endif // NDN_SECURITY_KEY_PARAMS_HPP
diff --git a/src/security/sec-tpm-file.cpp b/src/security/sec-tpm-file.cpp
index c8b460c..6634f68 100644
--- a/src/security/sec-tpm-file.cpp
+++ b/src/security/sec-tpm-file.cpp
@@ -38,13 +38,16 @@
 
 #include <algorithm>
 
-using namespace std;
-
 namespace ndn {
 
+using std::string;
+using std::ostringstream;
+using std::ofstream;
+
 class SecTpmFile::Impl
 {
 public:
+  explicit
   Impl(const string& dir)
   {
     if (dir.empty())
@@ -52,11 +55,11 @@
     else
       m_keystorePath = dir;
 
-    boost::filesystem::create_directories (m_keystorePath);
+    boost::filesystem::create_directories(m_keystorePath);
   }
 
   boost::filesystem::path
-  nameTransform(const string& keyName, const string& extension)
+  transformName(const string& keyName, const string& extension)
   {
     using namespace CryptoPP;
     string digest;
@@ -75,7 +78,7 @@
   string
   maintainMapping(const string& keyName)
   {
-    string keyFileName = nameTransform(keyName, "").string();
+    string keyFileName = transformName(keyName, "").string();
 
     ofstream outfile;
     string dirFile = (m_keystorePath / "mapping.txt").string();
@@ -95,10 +98,11 @@
 SecTpmFile::SecTpmFile(const string& dir)
   : m_impl(new Impl(dir))
   , m_inTerminal(false)
-{}
+{
+}
 
 void
-SecTpmFile::generateKeyPairInTpm(const Name& keyName, KeyType keyType, int keySize)
+SecTpmFile::generateKeyPairInTpm(const Name& keyName, const KeyParams& params)
 {
   string keyURI = keyName.toUri();
 
@@ -111,15 +115,16 @@
 
   try
     {
-      switch (keyType)
+      switch (params.getKeyType())
         {
         case KEY_TYPE_RSA:
           {
             using namespace CryptoPP;
-            AutoSeededRandomPool rng;
 
+            const RsaKeyParams& rsaParams = static_cast<const RsaKeyParams&>(params);
+            AutoSeededRandomPool rng;
             InvertibleRSAFunction privateKey;
-            privateKey.Initialize(rng, keySize);
+            privateKey.Initialize(rng, rsaParams.getKeySize());
 
             string privateKeyFileName = keyFileName + ".pri";
             Base64Encoder privateKeySink(new FileSink(privateKeyFileName.c_str()));
@@ -141,6 +146,10 @@
           throw Error("Unsupported key type!");
         }
     }
+  catch (KeyParams::Error& e)
+    {
+      throw Error(e.what());
+    }
   catch (CryptoPP::Exception& e)
     {
       throw Error(e.what());
@@ -150,8 +159,8 @@
 void
 SecTpmFile::deleteKeyPairInTpm(const Name& keyName)
 {
-  boost::filesystem::path publicKeyPath(m_impl->nameTransform(keyName.toUri(), ".pub"));
-  boost::filesystem::path privateKeyPath(m_impl->nameTransform(keyName.toUri(), ".pri"));
+  boost::filesystem::path publicKeyPath(m_impl->transformName(keyName.toUri(), ".pub"));
+  boost::filesystem::path privateKeyPath(m_impl->transformName(keyName.toUri(), ".pri"));
 
   if (boost::filesystem::exists(publicKeyPath))
     boost::filesystem::remove(publicKeyPath);
@@ -172,7 +181,7 @@
   try
     {
       using namespace CryptoPP;
-      FileSource(m_impl->nameTransform(keyURI, ".pub").string().c_str(),
+      FileSource(m_impl->transformName(keyURI, ".pub").string().c_str(),
                  true,
                  new Base64Decoder(new FileSink(os)));
     }
@@ -189,7 +198,7 @@
 SecTpmFile::exportPrivateKeyPkcs8FromTpm(const Name& keyName)
 {
   OBufferStream privateKeyOs;
-  CryptoPP::FileSource(m_impl->nameTransform(keyName.toUri(), ".pri").string().c_str(), true,
+  CryptoPP::FileSource(m_impl->transformName(keyName.toUri(), ".pri").string().c_str(), true,
                        new CryptoPP::Base64Decoder(new CryptoPP::FileSink(privateKeyOs)));
 
   return privateKeyOs.buf();
@@ -251,7 +260,7 @@
 
       //Read private key
       ByteQueue bytes;
-      FileSource file(m_impl->nameTransform(keyURI, ".pri").string().c_str(),
+      FileSource file(m_impl->transformName(keyURI, ".pri").string().c_str(),
                       true, new Base64Decoder);
       file.TransferTo(bytes);
       bytes.MessageEnd();
@@ -300,7 +309,7 @@
 
   //       //Read private key
   //       ByteQueue bytes;
-  //       FileSource file(m_impl->nameTransform(keyURI, ".pri").string().c_str(), true, new Base64Decoder);
+  //       FileSource file(m_impl->transformName(keyURI, ".pri").string().c_str(), true, new Base64Decoder);
   //       file.TransferTo(bytes);
   //       bytes.MessageEnd();
   //       RSA::PrivateKey privateKey;
@@ -320,27 +329,27 @@
   //   {
   //     throw Error("Symmetric encryption is not implemented!");
   //     // if (!doesKeyExistInTpm(keyName, KEY_CLASS_SYMMETRIC))
-  //     // 	throw Error("symmetric key doesn't exist");
+  //     //     throw Error("symmetric key doesn't exist");
 
   //     // try{
-  //     // 	string keyBits;
-  //     // 	string symKeyFileName = m_impl->nameTransform(keyURI, ".key");
-  //     // 	FileSource(symKeyFileName, true, new HexDecoder(new StringSink(keyBits)));
+  //     //     string keyBits;
+  //     //     string symKeyFileName = m_impl->transformName(keyURI, ".key");
+  //     //     FileSource(symKeyFileName, true, new HexDecoder(new StringSink(keyBits)));
 
-  //     // 	using CryptoPP::AES;
-  //     // 	AutoSeededRandomPool rnd;
-  //     // 	byte iv[AES::BLOCKSIZE];
-  //     // 	rnd.GenerateBlock(iv, AES::BLOCKSIZE);
+  //     //     using CryptoPP::AES;
+  //     //     AutoSeededRandomPool rnd;
+  //     //     byte iv[AES::BLOCKSIZE];
+  //     //     rnd.GenerateBlock(iv, AES::BLOCKSIZE);
 
-  //     // 	CFB_Mode<AES>::Decryption decryptor;
-  //     // 	decryptor.SetKeyWithIV(reinterpret_cast<const uint8_t*>(keyBits.c_str()), keyBits.size(), iv);
+  //     //     CFB_Mode<AES>::Decryption decryptor;
+  //     //     decryptor.SetKeyWithIV(reinterpret_cast<const uint8_t*>(keyBits.c_str()), keyBits.size(), iv);
 
-  //     // 	OBufferStream os;
-  //     // 	StringSource(data, dataLength, true, new StreamTransformationFilter(decryptor,new FileSink(os)));
-  //     // 	return os.buf();
+  //     //     OBufferStream os;
+  //     //     StringSource(data, dataLength, true, new StreamTransformationFilter(decryptor,new FileSink(os)));
+  //     //     return os.buf();
 
   //     // }catch (CryptoPP::Exception& e){
-  //     // 	throw Error(e.what());
+  //     //     throw Error(e.what());
   //     // }
   //   }
 }
@@ -363,7 +372,7 @@
 
   //         //Read private key
   //         ByteQueue bytes;
-  //         FileSource file(m_impl->nameTransform(keyURI, ".pub").string().c_str(), true, new Base64Decoder);
+  //         FileSource file(m_impl->transformName(keyURI, ".pub").string().c_str(), true, new Base64Decoder);
   //         file.TransferTo(bytes);
   //         bytes.MessageEnd();
   //         RSA::PublicKey publicKey;
@@ -383,33 +392,33 @@
   //   {
   //     throw Error("Symmetric encryption is not implemented!");
   //     // if (!doesKeyExistInTpm(keyName, KEY_CLASS_SYMMETRIC))
-  //     // 	throw Error("symmetric key doesn't exist");
+  //     //     throw Error("symmetric key doesn't exist");
 
   //     // try{
-  //     // 	string keyBits;
-  //     // 	string symKeyFileName = m_impl->nameTransform(keyURI, ".key");
-  //     // 	FileSource(symKeyFileName, true, new HexDecoder(new StringSink(keyBits)));
+  //     //     string keyBits;
+  //     //     string symKeyFileName = m_impl->transformName(keyURI, ".key");
+  //     //     FileSource(symKeyFileName, true, new HexDecoder(new StringSink(keyBits)));
 
-  //     // 	using CryptoPP::AES;
-  //     // 	AutoSeededRandomPool rnd;
-  //     // 	byte iv[AES::BLOCKSIZE];
-  //     // 	rnd.GenerateBlock(iv, AES::BLOCKSIZE);
+  //     //     using CryptoPP::AES;
+  //     //     AutoSeededRandomPool rnd;
+  //     //     byte iv[AES::BLOCKSIZE];
+  //     //     rnd.GenerateBlock(iv, AES::BLOCKSIZE);
 
-  //     // 	CFB_Mode<AES>::Encryption encryptor;
-  //     // 	encryptor.SetKeyWithIV(reinterpret_cast<const uint8_t*>(keyBits.c_str()), keyBits.size(), iv);
+  //     //     CFB_Mode<AES>::Encryption encryptor;
+  //     //     encryptor.SetKeyWithIV(reinterpret_cast<const uint8_t*>(keyBits.c_str()), keyBits.size(), iv);
 
-  //     // 	OBufferStream os;
-  //     // 	StringSource(data, dataLength, true, new StreamTransformationFilter(encryptor, new FileSink(os)));
-  //     // 	return os.buf();
+  //     //     OBufferStream os;
+  //     //     StringSource(data, dataLength, true, new StreamTransformationFilter(encryptor, new FileSink(os)));
+  //     //     return os.buf();
   //     // }catch (CryptoPP::Exception& e){
-  //     // 	throw Error(e.what());
+  //     //     throw Error(e.what());
   //     // }
   //   }
 }
 
 
 void
-SecTpmFile::generateSymmetricKeyInTpm(const Name& keyName, KeyType keyType, int keySize)
+SecTpmFile::generateSymmetricKeyInTpm(const Name& keyName, const KeyParams& params)
 {
   throw Error("SecTpmFile::generateSymmetricKeyInTpm is not supported!");
   // string keyURI = keyName.toUri();
@@ -449,21 +458,21 @@
   string keyURI = keyName.toUri();
   if (keyClass == KEY_CLASS_PUBLIC)
     {
-      if (boost::filesystem::exists(m_impl->nameTransform(keyURI, ".pub")))
+      if (boost::filesystem::exists(m_impl->transformName(keyURI, ".pub")))
         return true;
       else
         return false;
     }
   if (keyClass == KEY_CLASS_PRIVATE)
     {
-      if (boost::filesystem::exists(m_impl->nameTransform(keyURI, ".pri")))
+      if (boost::filesystem::exists(m_impl->transformName(keyURI, ".pri")))
         return true;
       else
         return false;
     }
   if (keyClass == KEY_CLASS_SYMMETRIC)
     {
-      if (boost::filesystem::exists(m_impl->nameTransform(keyURI, ".key")))
+      if (boost::filesystem::exists(m_impl->transformName(keyURI, ".key")))
         return true;
       else
         return false;
diff --git a/src/security/sec-tpm-file.hpp b/src/security/sec-tpm-file.hpp
index d878ad6..3c97e4e 100644
--- a/src/security/sec-tpm-file.hpp
+++ b/src/security/sec-tpm-file.hpp
@@ -88,7 +88,7 @@
   }
 
   virtual void
-  generateKeyPairInTpm(const Name& keyName, KeyType keyType, int keySize);
+  generateKeyPairInTpm(const Name& keyName, const KeyParams& params);
 
   virtual void
   deleteKeyPairInTpm(const Name& keyName);
@@ -107,7 +107,7 @@
   encryptInTpm(const uint8_t* data, size_t dataLength, const Name& keyName, bool isSymmetric);
 
   virtual void
-  generateSymmetricKeyInTpm(const Name& keyName, KeyType keyType, int keySize);
+  generateSymmetricKeyInTpm(const Name& keyName, const KeyParams& params);
 
   virtual bool
   doesKeyExistInTpm(const Name& keyName, KeyClass keyClass);
@@ -121,9 +121,10 @@
   }
 
 protected:
-  /******************************
-   * From TrustedPlatformModule *
-   ******************************/
+  ////////////////////////////////
+  // From TrustedPlatformModule //
+  ////////////////////////////////
+
   virtual ConstBufferPtr
   exportPrivateKeyPkcs8FromTpm(const Name& keyName);
 
diff --git a/src/security/sec-tpm-osx.cpp b/src/security/sec-tpm-osx.cpp
index a5a7159..031632d 100644
--- a/src/security/sec-tpm-osx.cpp
+++ b/src/security/sec-tpm-osx.cpp
@@ -41,10 +41,10 @@
 
 #include <Security/SecDigestTransform.h>
 
-using namespace std;
-
 namespace ndn {
 
+using std::string;
+
 /**
  * @brief Helper class to wrap CoreFoundation object pointers
  *
@@ -256,7 +256,7 @@
 SecTpmOsx::setTpmPassword(const uint8_t* password, size_t passwordLength)
 {
   m_impl->m_passwordSet = true;
-  memset(const_cast<char*>(m_impl->m_password.c_str()), 0, m_impl->m_password.size());
+  std::fill(m_impl->m_password.begin(), m_impl->m_password.end(), 0);
   m_impl->m_password.clear();
   m_impl->m_password.append(reinterpret_cast<const char*>(password), passwordLength);
 }
@@ -265,7 +265,7 @@
 SecTpmOsx::resetTpmPassword()
 {
   m_impl->m_passwordSet = false;
-  memset(const_cast<char*>(m_impl->m_password.c_str()), 0, m_impl->m_password.size());
+  std::fill(m_impl->m_password.begin(), m_impl->m_password.end(), 0);
   m_impl->m_password.clear();
 }
 
@@ -363,8 +363,9 @@
 }
 
 void
-SecTpmOsx::generateKeyPairInTpmInternal(const Name& keyName, KeyType keyType,
-                                        int keySize, bool needRetry)
+SecTpmOsx::generateKeyPairInTpmInternal(const Name& keyName,
+                                        const KeyParams& params,
+                                        bool needRetry)
 {
 
   if (doesKeyExistInTpm(keyName, KEY_CLASS_PUBLIC))
@@ -385,6 +386,20 @@
                               &kCFTypeDictionaryKeyCallBacks,
                               0);
 
+  KeyType keyType = params.getKeyType();
+  uint32_t keySize;
+  switch (keyType)
+    {
+    case KEY_TYPE_RSA:
+      {
+        const RsaKeyParams& rsaParams = static_cast<const RsaKeyParams&>(params);
+        keySize = rsaParams.getKeySize();
+        break;
+      }
+    default:
+      throw Error("Fail to create a key pair: Unsupported key type");
+    }
+
   CFReleaser<CFNumberRef> cfKeySize = CFNumberCreate(0, kCFNumberIntType, &keySize);
 
   CFDictionaryAddValue(attrDict.get(), kSecAttrKeyType, m_impl->getAsymKeyType(keyType));
@@ -392,6 +407,7 @@
   CFDictionaryAddValue(attrDict.get(), kSecAttrLabel, keyLabel.get());
 
   CFReleaser<SecKeyRef> publicKey, privateKey;
+  // C-style cast is used as per Apple convention
   OSStatus res = SecKeyGeneratePair((CFDictionaryRef)attrDict.get(),
                                     &publicKey.get(), &privateKey.get());
 
@@ -403,7 +419,7 @@
   if (res == errSecAuthFailed && !needRetry)
     {
       if (unlockTpm(0, 0, false))
-        generateKeyPairInTpmInternal(keyName, keyType, keySize, true);
+        generateKeyPairInTpmInternal(keyName, params, true);
       else
         throw Error("Fail to unlock the keychain");
     }
@@ -442,7 +458,7 @@
 }
 
 void
-SecTpmOsx::generateSymmetricKeyInTpm(const Name& keyName, KeyType keyType, int keySize)
+SecTpmOsx::generateSymmetricKeyInTpm(const Name& keyName, const KeyParams& params)
 {
   throw Error("SecTpmOsx::generateSymmetricKeyInTpm is not supported");
   // if (doesKeyExistInTpm(keyName, KEY_CLASS_SYMMETRIC))
@@ -537,7 +553,7 @@
   FileSink sink(pkcs1Os);
 
   uint32_t version = 0;
-  OID algorithm("1.2.840.113549.1.1.1");
+  OID algorithm("1.2.840.113549.1.1.1"); // "RSA encryption"
   SecByteBlock rawKeyBits;
   // PrivateKeyInfo ::= SEQUENCE {
   //   version              INTEGER,
@@ -645,6 +661,7 @@
         return false;
     }
 
+  // C-style cast is used as per Apple convention
   SecKeychainItemRef privateKey = (SecKeychainItemRef)CFArrayGetValueAtIndex(outItems.get(), 0);
   SecKeychainAttribute attrs[1]; // maximum number of attributes
   SecKeychainAttributeList attrList = { 0, attrs };
@@ -652,7 +669,7 @@
   {
     attrs[attrList.count].tag = kSecKeyPrintName;
     attrs[attrList.count].length = keyUri.size();
-    attrs[attrList.count].data = (void *)keyUri.c_str();
+    attrs[attrList.count].data = const_cast<char*>(keyUri.c_str());
     attrList.count++;
   }
 
@@ -697,6 +714,7 @@
   if (res != errSecSuccess)
     return false;
 
+  // C-style cast is used as per Apple convention
   SecKeychainItemRef publicKey = (SecKeychainItemRef)CFArrayGetValueAtIndex(outItems.get(), 0);
   SecKeychainAttribute attrs[1]; // maximum number of attributes
   SecKeychainAttributeList attrList = { 0, attrs };
@@ -704,7 +722,7 @@
   {
     attrs[attrList.count].tag = kSecKeyPrintName;
     attrs[attrList.count].length = keyUri.size();
-    attrs[attrList.count].data = (void *)keyUri.c_str();
+    attrs[attrList.count].data = const_cast<char*>(keyUri.c_str());
     attrList.count++;
   }
 
@@ -735,16 +753,17 @@
     }
 
   CFReleaser<CFErrorRef> error;
+  // C-style cast is used as per Apple convention
   CFReleaser<SecTransformRef> signer = SecSignTransformCreate((SecKeyRef)privateKey.get(),
                                                               &error.get());
   if (error.get() != 0)
     throw Error("Fail to create signer");
 
   // Set input
-  Boolean set_res = SecTransformSetAttribute(signer.get(),
-                                             kSecTransformInputAttributeName,
-                                             dataRef.get(),
-                                             &error.get());
+  SecTransformSetAttribute(signer.get(),
+                           kSecTransformInputAttributeName,
+                           dataRef.get(),
+                           &error.get());
   if (error.get() != 0)
     throw Error("Fail to configure input of signer");
 
@@ -757,24 +776,25 @@
     throw Error("Fail to configure digest algorithm of signer");
 
   // Set padding type
-  set_res = SecTransformSetAttribute(signer.get(),
-                                     kSecDigestTypeAttribute,
-                                     m_impl->getDigestAlgorithm(digestAlgorithm),
-                                     &error.get());
+  SecTransformSetAttribute(signer.get(),
+                           kSecDigestTypeAttribute,
+                           m_impl->getDigestAlgorithm(digestAlgorithm),
+                           &error.get());
   if (error.get() != 0)
     throw Error("Fail to configure digest algorithm of signer");
 
   // Set padding attribute
   long digestSize = m_impl->getDigestSize(digestAlgorithm);
   CFReleaser<CFNumberRef> cfDigestSize = CFNumberCreate(0, kCFNumberLongType, &digestSize);
-  set_res = SecTransformSetAttribute(signer.get(),
-                                     kSecDigestLengthAttribute,
-                                     cfDigestSize.get(),
-                                     &error.get());
+  SecTransformSetAttribute(signer.get(),
+                           kSecDigestLengthAttribute,
+                           cfDigestSize.get(),
+                           &error.get());
   if (error.get() != 0)
     throw Error("Fail to configure digest size of signer");
 
   // Actually sign
+  // C-style cast is used as per Apple convention
   CFReleaser<CFDataRef> signature = (CFDataRef)SecTransformExecute(signer.get(), &error.get());
   if (error.get() != 0)
     {
@@ -856,37 +876,38 @@
         }
 
       CFReleaser<SecAccessRef> accRef;
-      OSStatus acc_res = SecKeychainItemCopyAccess(privateKey.get(), &accRef.get());
+      SecKeychainItemCopyAccess(privateKey.get(), &accRef.get());
 
       CFReleaser<CFArrayRef> signACL = SecAccessCopyMatchingACLList(accRef.get(),
                                                                     kSecACLAuthorizationSign);
 
+      // C-style cast is used as per Apple convention
       SecACLRef aclRef = (SecACLRef)CFArrayGetValueAtIndex(signACL.get(), 0);
 
       CFReleaser<CFArrayRef> appList;
       CFReleaser<CFStringRef> description;
       SecKeychainPromptSelector promptSelector;
-      OSStatus acl_res = SecACLCopyContents(aclRef,
-                                            &appList.get(),
-                                            &description.get(),
-                                            &promptSelector);
+      SecACLCopyContents(aclRef,
+                         &appList.get(),
+                         &description.get(),
+                         &promptSelector);
 
       CFReleaser<CFMutableArrayRef> newAppList = CFArrayCreateMutableCopy(0,
                                                                           0,
                                                                           appList.get());
 
       CFReleaser<SecTrustedApplicationRef> trustedApp;
-      acl_res = SecTrustedApplicationCreateFromPath(appPath.c_str(),
-                                                    &trustedApp.get());
+      SecTrustedApplicationCreateFromPath(appPath.c_str(),
+                                          &trustedApp.get());
 
       CFArrayAppendValue(newAppList.get(), trustedApp.get());
 
-      acl_res = SecACLSetContents(aclRef,
-                                  newAppList.get(),
-                                  description.get(),
-                                  promptSelector);
+      SecACLSetContents(aclRef,
+                        newAppList.get(),
+                        description.get(),
+                        promptSelector);
 
-      acc_res = SecKeychainItemSetAccess(privateKey.get(), accRef.get());
+      SecKeychainItemSetAccess(privateKey.get(), accRef.get());
     }
 }
 
@@ -951,6 +972,7 @@
   CFDictionaryAddValue(attrDict.get(), kSecReturnRef, kCFBooleanTrue);
 
   CFReleaser<SecKeychainItemRef> itemRef;
+  // C-style cast is used as per Apple convention
   OSStatus res = SecItemCopyMatching((CFDictionaryRef)attrDict.get(), (CFTypeRef*)&itemRef.get());
 
   if (res == errSecSuccess)
@@ -963,7 +985,7 @@
 bool
 SecTpmOsx::generateRandomBlock(uint8_t* res, size_t size)
 {
-  return (SecRandomCopyBytes(kSecRandomDefault, size, res) == 0);
+  return SecRandomCopyBytes(kSecRandomDefault, size, res) == 0;
 }
 
 ////////////////////////////////
@@ -991,6 +1013,7 @@
   CFDictionaryAddValue(attrDict.get(), kSecReturnRef, kCFBooleanTrue);
 
   CFReleaser<SecKeychainItemRef> keyItem;
+  // C-style cast is used as per Apple convention
   OSStatus res = SecItemCopyMatching((CFDictionaryRef)attrDict.get(), (CFTypeRef*)&keyItem.get());
 
   if (res != errSecSuccess)
@@ -1013,7 +1036,7 @@
 CFTypeRef
 SecTpmOsx::Impl::getAsymKeyType(KeyType keyType)
 {
-  switch (keyType){
+  switch (keyType) {
   case KEY_TYPE_RSA:
     return kSecAttrKeyTypeRSA;
   default:
@@ -1024,7 +1047,7 @@
 CFTypeRef
 SecTpmOsx::Impl::getSymKeyType(KeyType keyType)
 {
-  switch (keyType){
+  switch (keyType) {
   case KEY_TYPE_AES:
     return kSecAttrKeyTypeAES;
   default:
@@ -1035,7 +1058,7 @@
 CFTypeRef
 SecTpmOsx::Impl::getKeyClass(KeyClass keyClass)
 {
-  switch (keyClass){
+  switch (keyClass) {
   case KEY_CLASS_PRIVATE:
     return kSecAttrKeyClassPrivate;
   case KEY_CLASS_PUBLIC:
@@ -1050,13 +1073,7 @@
 CFStringRef
 SecTpmOsx::Impl::getDigestAlgorithm(DigestAlgorithm digestAlgo)
 {
-  switch (digestAlgo){
-    // case DIGEST_MD2:
-    //   return kSecDigestMD2;
-    // case DIGEST_MD5:
-    //   return kSecDigestMD5;
-    // case DIGEST_SHA1:
-    //   return kSecDigestSHA1;
+  switch (digestAlgo) {
   case DIGEST_ALGORITHM_SHA256:
     return kSecDigestSHA2;
   default:
@@ -1067,13 +1084,9 @@
 long
 SecTpmOsx::Impl::getDigestSize(DigestAlgorithm digestAlgo)
 {
-  switch (digestAlgo){
+  switch (digestAlgo) {
   case DIGEST_ALGORITHM_SHA256:
     return 256;
-    // case DIGEST_SHA1:
-    // case DIGEST_MD2:
-    // case DIGEST_MD5:
-    //   return 0;
   default:
     return -1;
   }
diff --git a/src/security/sec-tpm-osx.hpp b/src/security/sec-tpm-osx.hpp
index 306e417..fca8dda 100644
--- a/src/security/sec-tpm-osx.hpp
+++ b/src/security/sec-tpm-osx.hpp
@@ -53,9 +53,7 @@
   ~SecTpmOsx();
 
 
-  /******************************
-   * From TrustedPlatformModule *
-   ******************************/
+  // Following methods are inherited from SecTpm
 
   virtual void
   setTpmPassword(const uint8_t* password, size_t passwordLength);
@@ -76,9 +74,9 @@
   unlockTpm(const char* password, size_t passwordLength, bool usePassword);
 
   virtual void
-  generateKeyPairInTpm(const Name& keyName, KeyType keyType, int keySize)
+  generateKeyPairInTpm(const Name& keyName, const KeyParams& params)
   {
-    generateKeyPairInTpmInternal(keyName, keyType, keySize, false);
+    generateKeyPairInTpmInternal(keyName, params, false);
   }
 
   virtual void
@@ -104,7 +102,7 @@
   encryptInTpm(const uint8_t* data, size_t dataLength, const Name& keyName, bool isSymmetric);
 
   virtual void
-  generateSymmetricKeyInTpm(const Name& keyName, KeyType keyType, int keySize);
+  generateSymmetricKeyInTpm(const Name& keyName, const KeyParams& params);
 
   virtual bool
   doesKeyExistInTpm(const Name& keyName, KeyClass keyClass);
@@ -116,9 +114,7 @@
   addAppToAcl(const Name& keyName, KeyClass keyClass, const std::string& appPath, AclType acl);
 
 protected:
-  /******************************
-   * From TrustedPlatformModule *
-   ******************************/
+  // Following methods are inherited from SecTpm
   virtual ConstBufferPtr
   exportPrivateKeyPkcs8FromTpm(const Name& keyName)
   {
@@ -134,11 +130,9 @@
   virtual bool
   importPublicKeyPkcs1IntoTpm(const Name& keyName, const uint8_t* buf, size_t size);
 
-  /******************************
-   *       OSX-specifics        *
-   ******************************/
+  // Following methods are OSX-specific
   void
-  generateKeyPairInTpmInternal(const Name& keyName, KeyType keyType, int keySize, bool needRetry);
+  generateKeyPairInTpmInternal(const Name& keyName, const KeyParams& params, bool needRetry);
 
   void
   deleteKeyPairInTpmInternal(const Name& keyName, bool needRetry);
diff --git a/src/security/sec-tpm.cpp b/src/security/sec-tpm.cpp
index 2c3d976..2011a95 100644
--- a/src/security/sec-tpm.cpp
+++ b/src/security/sec-tpm.cpp
@@ -295,5 +295,40 @@
   return true;
 }
 
+bool
+SecTpm::getImpExpPassWord(std::string& password, const std::string& prompt)
+{
+  bool isInitialized = false;
+
+  char* pw0 = 0;
+
+  pw0 = getpass(prompt.c_str());
+  if (0 == pw0)
+    return false;
+  std::string password1 = pw0;
+  memset(pw0, 0, strlen(pw0));
+
+  pw0 = getpass("Confirm:");
+  if (0 == pw0)
+    {
+      std::fill(password1.begin(), password1.end(), 0);
+      return false;
+    }
+
+  if (0 == password1.compare(pw0))
+    {
+      isInitialized = true;
+      password.swap(password1);
+    }
+
+  std::fill(password1.begin(), password1.end(), 0);
+  memset(pw0, 0, strlen(pw0));
+
+  if (password.empty())
+    return false;
+
+  return isInitialized;
+}
+
 
 } // namespace ndn
diff --git a/src/security/sec-tpm.hpp b/src/security/sec-tpm.hpp
index 8acb1b5..031aa2b 100644
--- a/src/security/sec-tpm.hpp
+++ b/src/security/sec-tpm.hpp
@@ -29,6 +29,7 @@
 #include "../name.hpp"
 #include "../data.hpp"
 #include "public-key.hpp"
+#include "key-params.hpp"
 
 namespace ndn {
 
@@ -110,12 +111,11 @@
    * @brief Generate a pair of asymmetric keys.
    *
    * @param keyName The name of the key pair.
-   * @param keyType The type of the key pair, e.g. KEY_TYPE_RSA.
-   * @param keySize The size of the key pair.
+   * @param params The parameters of key.
    * @throws SecTpm::Error if fails.
    */
   virtual void
-  generateKeyPairInTpm(const Name& keyName, KeyType keyType, int keySize) = 0;
+  generateKeyPairInTpm(const Name& keyName, const KeyParams& params) = 0;
 
   /**
    * @brief Delete a key pair of asymmetric keys.
@@ -180,12 +180,11 @@
    * @brief Generate a symmetric key.
    *
    * @param keyName The name of the key.
-   * @param keyType The type of the key, e.g. KEY_TYPE_AES.
-   * @param keySize The size of the key.
+   * @param params The parameter of the key.
    * @throws SecTpm::Error if key generating fails.
    */
   virtual void
-  generateSymmetricKeyInTpm(const Name& keyName, KeyType keyType, int keySize) = 0;
+  generateSymmetricKeyInTpm(const Name& keyName, const KeyParams& params) = 0;
 
   /**
    * @brief Check if a particular key exists.
@@ -287,47 +286,10 @@
    * @param prompt Prompt for password, i.e., "Password for key:"
    * @return true if password has been obtained.
    */
-  inline virtual bool
+  virtual bool
   getImpExpPassWord(std::string& password, const std::string& prompt);
 };
 
-inline bool
-SecTpm::getImpExpPassWord(std::string& password, const std::string& prompt)
-{
-  int result = false;
-
-  char* pw0 = NULL;
-
-  pw0 = getpass(prompt.c_str());
-  if (!pw0)
-    return false;
-  std::string password1 = pw0;
-  memset(pw0, 0, strlen(pw0));
-
-  pw0 = getpass("Confirm:");
-  if (!pw0)
-    {
-      char* pw1 = const_cast<char*>(password1.c_str());
-      memset(pw1, 0, password1.size());
-      return false;
-    }
-
-  if (!password1.compare(pw0))
-    {
-      result = true;
-      password.swap(password1);
-    }
-
-  char* pw1 = const_cast<char*>(password1.c_str());
-  memset(pw1, 0, password1.size());
-  memset(pw0, 0, strlen(pw0));
-
-  if (password.empty())
-    return false;
-
-  return result;
-}
-
 } // namespace ndn
 
 #endif //NDN_SECURITY_SEC_TPM_HPP
diff --git a/src/security/security-common.hpp b/src/security/security-common.hpp
index b6b3119..ad3f671 100644
--- a/src/security/security-common.hpp
+++ b/src/security/security-common.hpp
@@ -55,9 +55,6 @@
 };
 
 enum DigestAlgorithm {
-  // DIGEST_ALGORITHM_MD2,
-  // DIGEST_ALGORITHM_MD5,
-  // DIGEST_ALGORITHM_SHA1,
   DIGEST_ALGORITHM_SHA256
 };