diff --git a/src/group-manager-db.cpp b/src/group-manager-db.cpp
index 6b0eb2d..57a3697 100644
--- a/src/group-manager-db.cpp
+++ b/src/group-manager-db.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /**
- * Copyright (c) 2014-2017,  Regents of the University of California
+ * Copyright (c) 2014-2018,  Regents of the University of California
  *
  * This file is part of ndn-group-encrypt (Group-based Encryption Protocol for NDN).
  * See AUTHORS.md for complete list of ndn-group-encrypt authors and contributors.
@@ -16,55 +16,54 @@
  * You should have received a copy of the GNU General Public License along with
  * ndn-group-encrypt, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
  *
- * @author Zhiyi Zhang <dreamerbarrychang@gmail.com>
+ * @author Zhiyi Zhang <zhiyi@cs.ucla.edu>
  */
 
 #include "group-manager-db.hpp"
 #include "algo/rsa.hpp"
-
-#include <sqlite3.h>
-#include <boost/filesystem.hpp>
 #include <ndn-cxx/util/sqlite3-statement.hpp>
-#include <ndn-cxx/security/identity-certificate.hpp>
+#include <boost/filesystem.hpp>
+#include <sqlite3.h>
+#include <ndn-cxx/util/string-helper.hpp>
 
 namespace ndn {
 namespace gep {
 
 using util::Sqlite3Statement;
 
-static const std::string INITIALIZATION =
-  "CREATE TABLE IF NOT EXISTS                         \n"
-  "  schedules(                                       \n"
-  "    schedule_id         INTEGER PRIMARY KEY,       \n"
-  "    schedule_name       TEXT NOT NULL,             \n"
-  "    schedule            BLOB NOT NULL              \n"
-  "  );                                               \n"
-  "CREATE UNIQUE INDEX IF NOT EXISTS                  \n"
-  "   scheduleNameIndex ON schedules(schedule_name);  \n"
-  "                                                   \n"
-  "CREATE TABLE IF NOT EXISTS                         \n"
-  "  members(                                         \n"
-  "    member_id           INTEGER PRIMARY KEY,       \n"
-  "    schedule_id         INTEGER NOT NULL,          \n"
-  "    member_name         BLOB NOT NULL,             \n"
-  "    key_name            BLOB NOT NULL,             \n"
-  "    pubkey              BLOB NOT NULL,             \n"
-  "    FOREIGN KEY(schedule_id)                       \n"
-  "      REFERENCES schedules(schedule_id)            \n"
-  "      ON DELETE CASCADE                            \n"
-  "      ON UPDATE CASCADE                            \n"
-  "  );                                               \n"
-  "CREATE UNIQUE INDEX IF NOT EXISTS                  \n"
-  "   memNameIndex ON members(member_name);           \n"
-  "                                                   \n"
-  "CREATE TABLE IF NOT EXISTS                         \n"
-  "  ekeys(                                           \n"
-  "    ekey_id             INTEGER PRIMARY KEY,       \n"
-  "    ekey_name           BLOB NOT NULL,             \n"
-  "    pub_key             BLOB NOT NULL              \n"
-  "  );                                               \n"
-  "CREATE UNIQUE INDEX IF NOT EXISTS                  \n"
-  "   ekeyNameIndex ON ekeys(ekey_name);              \n";
+static const std::string INITIALIZATION = R"_DBTEXT_(
+CREATE TABLE IF NOT EXISTS
+  schedules(
+    schedule_id         INTEGER PRIMARY KEY,
+    schedule_name       TEXT NOT NULL,
+    schedule            BLOB NOT NULL
+  );
+CREATE UNIQUE INDEX IF NOT EXISTS
+   scheduleNameIndex ON schedules(schedule_name);
+
+CREATE TABLE IF NOT EXISTS
+  members(
+    member_id           INTEGER PRIMARY KEY,
+    schedule_id         INTEGER NOT NULL,
+    member_name         BLOB NOT NULL,
+    key_name            BLOB NOT NULL,
+    pubkey              BLOB NOT NULL,
+    FOREIGN KEY(schedule_id)
+      REFERENCES schedules(schedule_id)
+      ON DELETE CASCADE
+      ON UPDATE CASCADE
+  );
+CREATE UNIQUE INDEX IF NOT EXISTS
+   memNameIndex ON members(member_name);
+
+CREATE TABLE IF NOT EXISTS
+  ekeys(
+    ekey_id             INTEGER PRIMARY KEY,
+    ekey_name           BLOB NOT NULL,
+    pub_key             BLOB NOT NULL
+  );
+CREATE UNIQUE INDEX IF NOT EXISTS
+   ekeyNameIndex ON ekeys(ekey_name);)_DBTEXT_";
 
 class GroupManagerDB::Impl
 {
@@ -73,14 +72,10 @@
   {
     // open Database
 
-    int result = sqlite3_open_v2(dbPath.c_str(), &m_database,
+    int result = sqlite3_open_v2(dbPath.c_str(),
+                                 &m_database,
                                  SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE,
-#ifdef NDN_CXX_DISABLE_SQLITE3_FS_LOCKING
-                                 "unix-dotfile"
-#else
-                                 nullptr
-#endif
-                                 );
+                                 nullptr);
 
     if (result != SQLITE_OK)
       BOOST_THROW_EXCEPTION(Error("GroupManager DB cannot be opened/created: " + dbPath));
@@ -106,7 +101,8 @@
   getScheduleId(const std::string& name) const
   {
     Sqlite3Statement statement(m_database,
-                               "SELECT schedule_id FROM schedules WHERE schedule_name=?");
+                               R"_DBTEXT_(SELECT schedule_id FROM schedules
+                               WHERE schedule_name=?)_DBTEXT_");
     statement.bind(1, name, SQLITE_TRANSIENT);
 
     int result = -1;
@@ -131,7 +127,8 @@
 GroupManagerDB::hasSchedule(const std::string& name) const
 {
   Sqlite3Statement statement(m_impl->m_database,
-                             "SELECT schedule_id FROM schedules where schedule_name=?");
+                             R"_DBTEXT_(SELECT schedule_id FROM schedules
+                             WHERE schedule_name=?)_DBTEXT_");
   statement.bind(1, name, SQLITE_TRANSIENT);
   return (statement.step() == SQLITE_ROW);
 }
@@ -141,7 +138,7 @@
 {
   std::list<std::string> result;
   Sqlite3Statement statement(m_impl->m_database,
-                             "SELECT schedule_name FROM schedules");
+                             R"_DBTEXT_(SELECT schedule_name FROM schedules)_DBTEXT_");
 
   result.clear();
   while (statement.step() == SQLITE_ROW) {
@@ -154,7 +151,7 @@
 GroupManagerDB::getSchedule(const std::string& name) const
 {
   Sqlite3Statement statement(m_impl->m_database,
-                             "SELECT schedule FROM schedules where schedule_name=?");
+                             R"_DBTEXT_(SELECT schedule FROM schedules where schedule_name=?)_DBTEXT_");
   statement.bind(1, name, SQLITE_TRANSIENT);
 
   Schedule result;
@@ -172,10 +169,10 @@
 {
   std::map<Name, Buffer> result;
   Sqlite3Statement statement(m_impl->m_database,
-                             "SELECT key_name, pubkey\
-                              FROM members JOIN schedules\
-                              ON members.schedule_id=schedules.schedule_id\
-                              WHERE schedule_name=?");
+                             R"_DBTEXT_(SELECT key_name, pubkey
+                             FROM members JOIN schedules
+                             ON members.schedule_id=schedules.schedule_id
+                             WHERE schedule_name=?)_DBTEXT_");
   statement.bind(1, name, SQLITE_TRANSIENT);
   result.clear();
 
@@ -195,8 +192,8 @@
   BOOST_ASSERT(name.length() != 0);
 
   Sqlite3Statement statement(m_impl->m_database,
-                             "INSERT INTO schedules (schedule_name, schedule)\
-                              values (?, ?)");
+                             R"_DBTEXT_(INSERT INTO schedules (schedule_name, schedule)
+                             values (?, ?))_DBTEXT_");
   statement.bind(1, name, SQLITE_TRANSIENT);
   statement.bind(2, schedule.wireEncode(), SQLITE_TRANSIENT);
   if (statement.step() != SQLITE_DONE)
@@ -207,7 +204,7 @@
 GroupManagerDB::deleteSchedule(const std::string& name)
 {
   Sqlite3Statement statement(m_impl->m_database,
-                             "DELETE FROM schedules WHERE schedule_name=?");
+                             R"_DBTEXT_(DELETE FROM schedules WHERE schedule_name=?)_DBTEXT_");
   statement.bind(1, name, SQLITE_TRANSIENT);
   statement.step();
 }
@@ -218,7 +215,8 @@
   BOOST_ASSERT(newName.length() != 0);
 
   Sqlite3Statement statement(m_impl->m_database,
-                             "UPDATE schedules SET schedule_name=? WHERE schedule_name=?");
+                             R"_DBTEXT_(UPDATE schedules SET schedule_name=?
+                             WHERE schedule_name=?)_DBTEXT_");
   statement.bind(1, newName, SQLITE_TRANSIENT);
   statement.bind(2, oldName, SQLITE_TRANSIENT);
   if (statement.step() != SQLITE_DONE)
@@ -234,7 +232,8 @@
   }
 
   Sqlite3Statement statement(m_impl->m_database,
-                             "UPDATE schedules SET schedule=? WHERE schedule_name=?");
+                             R"_DBTEXT_(UPDATE schedules SET schedule=?
+                             WHERE schedule_name=?)_DBTEXT_");
   statement.bind(1, schedule.wireEncode(), SQLITE_TRANSIENT);
   statement.bind(2, name, SQLITE_TRANSIENT);
   statement.step();
@@ -244,7 +243,7 @@
 GroupManagerDB::hasMember(const Name& identity) const
 {
   Sqlite3Statement statement(m_impl->m_database,
-                             "SELECT member_id FROM members WHERE member_name=?");
+                             R"_DBTEXT_(SELECT member_id FROM members WHERE member_name=?)_DBTEXT_");
   statement.bind(1, identity.wireEncode(), SQLITE_TRANSIENT);
   return (statement.step() == SQLITE_ROW);
 }
@@ -254,7 +253,7 @@
 {
   std::list<Name> result;
   Sqlite3Statement statement(m_impl->m_database,
-                             "SELECT member_name FROM members");
+                             R"_DBTEXT_(SELECT member_name FROM members)_DBTEXT_");
 
   result.clear();
   while (statement.step() == SQLITE_ROW) {
@@ -267,10 +266,10 @@
 GroupManagerDB::getMemberSchedule(const Name& identity) const
 {
   Sqlite3Statement statement(m_impl->m_database,
-                             "SELECT schedule_name\
-                              FROM schedules JOIN members\
-                              ON schedules.schedule_id = members.schedule_id\
-                              WHERE member_name=?");
+                             R"_DBTEXT_(SELECT schedule_name
+                             FROM schedules JOIN members
+                             ON schedules.schedule_id = members.schedule_id
+                             WHERE member_name=?)_DBTEXT_");
   statement.bind(1, identity.wireEncode(), SQLITE_TRANSIENT);
 
   std::string result = "";
@@ -284,8 +283,7 @@
 }
 
 void
-GroupManagerDB::addMember(const std::string& scheduleName, const Name& keyName,
-                          const Buffer& key)
+GroupManagerDB::addMember(const std::string& scheduleName, const Name& keyName, const Buffer& key)
 {
   int scheduleId = m_impl->getScheduleId(scheduleName);
   if (scheduleId == -1)
@@ -295,12 +293,12 @@
   Name memberName = keyName.getPrefix(-1);
 
   Sqlite3Statement statement(m_impl->m_database,
-                             "INSERT INTO members(schedule_id, member_name, key_name, pubkey)\
-                              values (?, ?, ?, ?)");
+                             R"_DBTEXT_(INSERT INTO members(schedule_id, member_name, key_name, pubkey)
+                             values (?, ?, ?, ?))_DBTEXT_");
   statement.bind(1, scheduleId);
   statement.bind(2, memberName.wireEncode(), SQLITE_TRANSIENT);
   statement.bind(3, keyName.wireEncode(), SQLITE_TRANSIENT);
-  statement.bind(4, key.buf(), key.size(), SQLITE_TRANSIENT);
+  statement.bind(4, key.data(), key.size(), SQLITE_TRANSIENT);
 
   if (statement.step() != SQLITE_DONE)
     BOOST_THROW_EXCEPTION(Error("Cannot add the member to database"));
@@ -314,7 +312,8 @@
     BOOST_THROW_EXCEPTION(Error("The schedule dose not exist"));
 
   Sqlite3Statement statement(m_impl->m_database,
-                             "UPDATE members SET schedule_id=? WHERE member_name=?");
+                             R"_DBTEXT_(UPDATE members SET schedule_id=?
+                             WHERE member_name=?)_DBTEXT_");
   statement.bind(1, scheduleId);
   statement.bind(2, identity.wireEncode(), SQLITE_TRANSIENT);
   statement.step();
@@ -324,7 +323,7 @@
 GroupManagerDB::deleteMember(const Name& identity)
 {
   Sqlite3Statement statement(m_impl->m_database,
-                             "DELETE FROM members WHERE member_name=?");
+                             R"_DBTEXT_(DELETE FROM members WHERE member_name=?)_DBTEXT_");
   statement.bind(1, identity.wireEncode(), SQLITE_TRANSIENT);
   statement.step();
 }
@@ -333,7 +332,7 @@
 GroupManagerDB::hasEKey(const Name& eKeyName)
 {
   Sqlite3Statement statement(m_impl->m_database,
-                             "SELECT ekey_id FROM ekeys where ekey_name=?");
+                             R"_DBTEXT_(SELECT ekey_id FROM ekeys where ekey_name=?)_DBTEXT_");
   statement.bind(1, eKeyName.wireEncode(), SQLITE_TRANSIENT);
   return (statement.step() == SQLITE_ROW);
 }
@@ -342,9 +341,10 @@
 GroupManagerDB::addEKey(const Name& eKeyName, const Buffer& pubKey, const Buffer& priKey)
 {
   Sqlite3Statement statement(m_impl->m_database,
-                             "INSERT INTO ekeys(ekey_name, pub_key) values (?, ?)");
+                             R"_DBTEXT_(INSERT INTO ekeys(ekey_name, pub_key)
+                             values (?, ?))_DBTEXT_");
   statement.bind(1, eKeyName.wireEncode(), SQLITE_TRANSIENT);
-  statement.bind(2, pubKey.buf(), pubKey.size(), SQLITE_TRANSIENT);
+  statement.bind(2, pubKey.data(), pubKey.size(), SQLITE_TRANSIENT);
   if (statement.step() != SQLITE_DONE)
     BOOST_THROW_EXCEPTION(Error("Cannot add the EKey to database"));
 
@@ -355,7 +355,7 @@
 GroupManagerDB::getEKey(const Name& eKeyName)
 {
   Sqlite3Statement statement(m_impl->m_database,
-                             "SELECT * FROM ekeys where ekey_name=?");
+                             R"_DBTEXT_(SELECT * FROM ekeys where ekey_name=?)_DBTEXT_");
   statement.bind(1, eKeyName.wireEncode(), SQLITE_TRANSIENT);
 
   Buffer pubKey, priKey;
@@ -371,7 +371,8 @@
 void
 GroupManagerDB::cleanEKeys()
 {
-  Sqlite3Statement statement(m_impl->m_database, "DELETE FROM ekeys");
+  Sqlite3Statement statement(m_impl->m_database,
+                             R"_DBTEXT_(DELETE FROM ekeys)_DBTEXT_");
   statement.step();
   m_impl->m_priKeyBase.clear();
 }
@@ -380,12 +381,14 @@
 GroupManagerDB::deleteEKey(const Name& eKeyName)
 {
   Sqlite3Statement statement(m_impl->m_database,
-                             "DELETE FROM ekeys WHERE ekey_name=?");
+                             R"_DBTEXT_(DELETE FROM ekeys WHERE ekey_name=?)_DBTEXT_");
   statement.bind(1, eKeyName.wireEncode(), SQLITE_TRANSIENT);
   statement.step();
 
   auto search = m_impl->m_priKeyBase.find(eKeyName);
-  m_impl->m_priKeyBase.erase(search);
+  if (search != m_impl->m_priKeyBase.end()) {
+    m_impl->m_priKeyBase.erase(search);
+  }
 }
 
 } // namespace gep