diff --git a/src/logic.cpp b/src/logic.cpp
index f584da5..4c3fc55 100644
--- a/src/logic.cpp
+++ b/src/logic.cpp
@@ -49,6 +49,8 @@
 int Logic::m_instanceCounter = 0;
 #endif
 
+const ndn::Name Logic::DEFAULT_NAME;
+const ndn::shared_ptr<ndn::Validator> Logic::DEFAULT_VALIDATOR;
 const time::steady_clock::Duration Logic::DEFAULT_RESET_TIMER = time::seconds(0);
 const time::steady_clock::Duration Logic::DEFAULT_CANCEL_RESET_TIMER = time::milliseconds(500);
 const time::milliseconds Logic::DEFAULT_RESET_INTEREST_LIFETIME(1000);
@@ -62,6 +64,8 @@
              const Name& syncPrefix,
              const Name& userPrefix,
              const UpdateCallback& onUpdate,
+             const Name& signingId,
+             ndn::shared_ptr<ndn::Validator> validator,
              const time::steady_clock::Duration& resetTimer,
              const time::steady_clock::Duration& cancelResetTimer,
              const time::milliseconds& resetInterestLifetime,
@@ -84,6 +88,8 @@
   , m_resetInterestLifetime(resetInterestLifetime)
   , m_syncInterestLifetime(syncInterestLifetime)
   , m_syncReplyFreshness(syncReplyFreshness)
+  , m_signingId(signingId)
+  , m_validator(validator)
 {
 #ifdef _DEBUG
   m_instanceId = m_instanceCounter++;
@@ -250,8 +256,12 @@
 Logic::onSyncData(const Interest& interest, Data& data)
 {
   _LOG_DEBUG_ID(">> Logic::onSyncData");
-  // Place holder for validator.
-  onSyncDataValidated(data.shared_from_this());
+  if (static_cast<bool>(m_validator))
+    m_validator->validate(data,
+                          bind(&Logic::onSyncDataValidated, this, _1),
+                          bind(&Logic::onSyncDataValidationFailed, this, _1));
+  else
+    onSyncDataValidated(data.shared_from_this());
   _LOG_DEBUG_ID("<< Logic::onSyncData");
 }
 
@@ -544,7 +554,11 @@
   shared_ptr<Data> syncReply = make_shared<Data>(name);
   syncReply->setContent(state.wireEncode());
   syncReply->setFreshnessPeriod(m_syncReplyFreshness);
-  m_keyChain.sign(*syncReply);
+
+  if (m_signingId.empty())
+    m_keyChain.sign(*syncReply);
+  else
+    m_keyChain.signByIdentity(*syncReply, m_signingId);
 
   m_face.put(*syncReply);
 
diff --git a/src/logic.hpp b/src/logic.hpp
index cd5cd29..acca168 100644
--- a/src/logic.hpp
+++ b/src/logic.hpp
@@ -32,6 +32,7 @@
 #include <ndn-cxx/face.hpp>
 #include <ndn-cxx/util/scheduler.hpp>
 #include <ndn-cxx/security/key-chain.hpp>
+#include <ndn-cxx/security/validator.hpp>
 
 #include "interest-table.hpp"
 #include "diff-state-container.hpp"
@@ -84,6 +85,7 @@
    * @param syncPrefix The prefix of the sync group
    * @param userPrefix The prefix of the user who owns the session
    * @param onUpdate The callback function to handle state updates
+   * @param validator The validator for packet validation
    * @param resetTimer The timer to periodically send Reset Interest
    * @param syncReplyFreshness The FreshnessPeriod of sync reply
    * @param resetInterestLifetime The lifetime of sync interest
@@ -94,6 +96,8 @@
         const Name& syncPrefix,
         const Name& userPrefix,
         const UpdateCallback& onUpdate,
+        const Name& signingId = DEFAULT_NAME,
+        ndn::shared_ptr<ndn::Validator> validator = DEFAULT_VALIDATOR,
         const time::steady_clock::Duration& resetTimer = DEFAULT_RESET_TIMER,
         const time::steady_clock::Duration& cancelResetTimer = DEFAULT_CANCEL_RESET_TIMER,
         const time::milliseconds& resetInterestLifetime = DEFAULT_RESET_INTEREST_LIFETIME,
@@ -326,6 +330,10 @@
   void
   printDigest(ndn::ConstBufferPtr digest);
 
+public:
+  static const ndn::Name DEFAULT_NAME;
+  static const ndn::shared_ptr<ndn::Validator> DEFAULT_VALIDATOR;
+
 private:
 
   static const ndn::ConstBufferPtr EMPTY_DIGEST;
@@ -373,8 +381,10 @@
   /// @brief FreshnessPeriod of SyncReply
   time::milliseconds m_syncReplyFreshness;
 
-  // Others
+  // Security
+  ndn::Name m_signingId;
   ndn::KeyChain m_keyChain;
+  ndn::shared_ptr<ndn::Validator> m_validator;
 
 #ifdef _DEBUG
   int m_instanceId;
diff --git a/src/socket.cpp b/src/socket.cpp
index 55296ab..45c6890 100644
--- a/src/socket.cpp
+++ b/src/socket.cpp
@@ -30,16 +30,20 @@
 
 namespace chronosync {
 
+const ndn::Name Socket::DEFAULT_NAME;
+const ndn::shared_ptr<ndn::Validator> Socket::DEFAULT_VALIDATOR;
+
 Socket::Socket(const Name& syncPrefix,
                const Name& userPrefix,
                ndn::Face& face,
-               const UpdateCallback& updateCallback)
+               const UpdateCallback& updateCallback,
+               const Name& signingId,
+               ndn::shared_ptr<ndn::Validator> validator)
   : m_userPrefix(userPrefix)
   , m_face(face)
-  , m_logic(face,
-            syncPrefix,
-            userPrefix,
-            updateCallback)
+  , m_logic(face, syncPrefix, userPrefix, updateCallback)
+  , m_signingId(signingId)
+  , m_validator(validator)
 {
 }
 
@@ -62,7 +66,10 @@
   dataName.append(m_logic.getSessionName()).appendNumber(newSeq);
   data->setName(dataName);
 
-  m_keyChain.sign(*data);
+  if (m_signingId.empty())
+    m_keyChain.sign(*data);
+  else
+    m_keyChain.signByIdentity(*data, m_signingId);
 
   m_face.put(*data);
 
@@ -116,8 +123,11 @@
                const ndn::OnDataValidationFailed& onFailed)
 {
   _LOG_DEBUG("Socket::onData");
-  // Placeholder for validator
-  onValidated(data.shared_from_this());
+
+  if (static_cast<bool>(m_validator))
+    m_validator->validate(data, onValidated, onFailed);
+  else
+    onValidated(data.shared_from_this());
 }
 
 void
diff --git a/src/socket.hpp b/src/socket.hpp
index 11dc684..c01fb05 100644
--- a/src/socket.hpp
+++ b/src/socket.hpp
@@ -26,7 +26,6 @@
 #define CHRONOSYNC_SOCKET_HPP
 
 #include <ndn-cxx/face.hpp>
-#include <ndn-cxx/security/validation-request.hpp>
 
 #include "logic.hpp"
 
@@ -61,7 +60,9 @@
   Socket(const Name& syncPrefix,
          const Name& userPrefix,
          ndn::Face& face,
-         const UpdateCallback& updateCallback);
+         const UpdateCallback& updateCallback,
+         const Name& signingId = DEFAULT_NAME,
+         ndn::shared_ptr<ndn::Validator> validator = DEFAULT_VALIDATOR);
 
   /**
    * @brief Publish a data packet in the session and trigger synchronization updates
@@ -143,6 +144,10 @@
   onDataValidationFailed(const shared_ptr<const Data>& data,
                          const std::string& failureInfo);
 
+public:
+  static const ndn::Name DEFAULT_NAME;
+  static const ndn::shared_ptr<ndn::Validator> DEFAULT_VALIDATOR;
+
 private:
 
   Name m_userPrefix;
@@ -150,7 +155,9 @@
 
   Logic m_logic;
 
+  ndn::Name m_signingId;
   ndn::KeyChain m_keyChain;
+  ndn::shared_ptr<ndn::Validator> m_validator;
 };
 
 } // namespace chronosync