diff --git a/src/ca-config.cpp b/src/ca-config.cpp
index b8b0d59..3165b2d 100644
--- a/src/ca-config.cpp
+++ b/src/ca-config.cpp
@@ -66,7 +66,7 @@
   std::list<std::string> result;
   auto it = section.begin();
   for (; it != section.end(); it++) {
-    result.push_back(it->second.get<std::string>("type"));
+    result.push_back(boost::algorithm::to_lower_copy(it->second.get<std::string>("type")));
   }
   return result;
 }
diff --git a/src/ca-module.cpp b/src/ca-module.cpp
index 20761e0..89bf8a7 100644
--- a/src/ca-module.cpp
+++ b/src/ca-module.cpp
@@ -189,11 +189,9 @@
   }
   // generate salt for HKDF
   auto saltInt = random::generateSecureWord64();
-  uint8_t salt[sizeof(saltInt)];
-  std::memcpy(salt, &saltInt, sizeof(saltInt));
   // hkdf
   hkdf(m_ecdh.context->sharedSecret, m_ecdh.context->sharedSecretLen,
-       salt, sizeof(saltInt), m_aesKey, 32);
+       (uint8_t*)&saltInt, sizeof(saltInt), m_aesKey, sizeof(m_aesKey));
 
   // parse certificate request
   std::string certRequestStr = parameterJson.get(JSON_CLIENT_CERT_REQ, "");
@@ -319,7 +317,7 @@
   // decrypt the parameters
   Buffer paramJsonPayload;
   try {
-    paramJsonPayload = parseEncBlock(m_aesKey, 32,
+    paramJsonPayload = parseEncBlock(m_aesKey, sizeof(m_aesKey),
                                      request.getApplicationParameters());
   }
   catch (const std::exception& e) {
@@ -403,7 +401,7 @@
   std::stringstream ss2;
   boost::property_tree::write_json(ss2, contentJson);
   auto payload = ss2.str();
-  auto contentBlock = genEncBlock(tlv::Content, m_aesKey, 32,
+  auto contentBlock = genEncBlock(tlv::Content, m_aesKey, sizeof(m_aesKey),
                                   (const uint8_t*)payload.c_str(), payload.size());
   result.setContent(contentBlock);
   m_keyChain.sign(result, signingByIdentity(m_config.m_caName));
diff --git a/src/challenge-module/challenge-email.cpp b/src/challenge-module/challenge-email.cpp
index e475b24..b22ec93 100644
--- a/src/challenge-module/challenge-email.cpp
+++ b/src/challenge-module/challenge-email.cpp
@@ -28,7 +28,7 @@
 
 _LOG_INIT(ndncert.ChallengeEmail);
 
-NDNCERT_REGISTER_CHALLENGE(ChallengeEmail, "Email");
+NDNCERT_REGISTER_CHALLENGE(ChallengeEmail, "email");
 
 const std::string ChallengeEmail::NEED_CODE = "need-code";
 const std::string ChallengeEmail::WRONG_CODE = "wrong-code";
@@ -39,7 +39,7 @@
 ChallengeEmail::ChallengeEmail(const std::string& scriptPath,
                                const size_t& maxAttemptTimes,
                                const time::seconds secretLifetime)
-  : ChallengeModule("Email")
+  : ChallengeModule("email")
   , m_sendEmailScript(scriptPath)
   , m_maxAttemptTimes(maxAttemptTimes)
   , m_secretLifetime(secretLifetime)
diff --git a/src/challenge-module/challenge-pin.cpp b/src/challenge-module/challenge-pin.cpp
index 7de32f0..9534b21 100644
--- a/src/challenge-module/challenge-pin.cpp
+++ b/src/challenge-module/challenge-pin.cpp
@@ -27,14 +27,14 @@
 
 _LOG_INIT(ndncert.challenge-pin);
 
-NDNCERT_REGISTER_CHALLENGE(ChallengePin, "PIN");
+NDNCERT_REGISTER_CHALLENGE(ChallengePin, "pin");
 
 const std::string ChallengePin::NEED_CODE = "need-code";
 const std::string ChallengePin::WRONG_CODE = "wrong-code";
 const std::string ChallengePin::JSON_PIN_CODE = "pin-code";
 
 ChallengePin::ChallengePin(const size_t& maxAttemptTimes, const time::seconds& secretLifetime)
-  : ChallengeModule("PIN")
+  : ChallengeModule("pin")
   , m_secretLifetime(secretLifetime)
   , m_maxAttemptTimes(maxAttemptTimes)
 {
diff --git a/src/client-module.cpp b/src/client-module.cpp
index 28e535b..12d835d 100644
--- a/src/client-module.cpp
+++ b/src/client-module.cpp
@@ -194,12 +194,11 @@
   const auto& peerKeyBase64Str = contentJson.get<std::string>(JSON_CA_ECDH, "");
   const auto& saltStr = contentJson.get<std::string>(JSON_CA_SALT, "");
   uint64_t saltInt = std::stoull(saltStr);
-  uint8_t salt[sizeof(saltInt)];
-  std::memcpy(salt, &saltInt, sizeof(saltInt));
   m_ecdh.deriveSecret(peerKeyBase64Str);
 
   // HKDF
-  hkdf(m_ecdh.context->sharedSecret, m_ecdh.context->sharedSecretLen, salt, sizeof(saltInt), m_aesKey, 32);
+  hkdf(m_ecdh.context->sharedSecret, m_ecdh.context->sharedSecretLen,
+       (uint8_t*)&saltInt, sizeof(saltInt), m_aesKey, sizeof(m_aesKey));
 
   // update state
   m_status = contentJson.get<int>(JSON_CA_STATUS);
@@ -228,7 +227,7 @@
   std::stringstream ss;
   boost::property_tree::write_json(ss, paramJson);
   auto payload = ss.str();
-  auto paramBlock = genEncBlock(tlv::ApplicationParameters, m_aesKey, 32,
+  auto paramBlock = genEncBlock(tlv::ApplicationParameters, m_aesKey, sizeof(m_aesKey),
                                 (const uint8_t*)payload.c_str(), payload.size());
   interest->setApplicationParameters(paramBlock);
 
@@ -243,7 +242,7 @@
     _LOG_ERROR("Cannot verify data signature from " << m_ca.m_caName.toUri());
     return;
   }
-  auto result = parseEncBlock(m_aesKey, 32, reply.getContent());
+  auto result = parseEncBlock(m_aesKey, sizeof(m_aesKey), reply.getContent());
   std::string payload((const char*)result.data(), result.size());
   std::istringstream ss(payload);
   JsonSection contentJson;