diff --git a/src/security/validator-config.cpp b/src/security/validator-config.cpp
index b23a47c..a0a35d8 100644
--- a/src/security/validator-config.cpp
+++ b/src/security/validator-config.cpp
@@ -252,6 +252,7 @@
       if (static_cast<bool>(idCert))
         {
           BOOST_ASSERT(idCert->getName().size() >= 1);
+          m_staticContainer.add(idCert);
           m_anchors[idCert->getName().getPrefix(-1)] = idCert;
         }
       else
@@ -278,6 +279,7 @@
       if (static_cast<bool>(idCert))
         {
           BOOST_ASSERT(idCert->getName().size() >= 1);
+          m_staticContainer.add(idCert);
           m_anchors[idCert->getName().getPrefix(-1)] = idCert;
         }
       else
@@ -285,6 +287,57 @@
 
       return;
     }
+  else if (boost::iequals(type, "dir"))
+    {
+      if (propertyIt == configSection.end() || !boost::iequals(propertyIt->first, "dir"))
+        throw Error("Expect <trust-anchor.dir>!");
+
+      std::string dirString(propertyIt->second.data());
+      propertyIt++;
+
+      if (propertyIt != configSection.end())
+        {
+          if (boost::iequals(propertyIt->first, "refresh"))
+            {
+              using namespace boost::filesystem;
+
+              time::nanoseconds refresh = getRefreshPeriod(propertyIt->second.data());
+              propertyIt++;
+
+              if (propertyIt != configSection.end())
+                throw Error("Expect the end of trust-anchor!");
+
+              path dirPath = absolute(dirString, path(filename).parent_path());
+
+              m_dynamicContainers.push_back(DynamicTrustAnchorContainer(dirPath, true, refresh));
+
+              m_dynamicContainers.rbegin()->setLastRefresh(time::system_clock::now() - refresh);
+
+              return;
+            }
+          else
+            throw Error("Expect <trust-anchor.refresh>!");
+        }
+      else
+        {
+          using namespace boost::filesystem;
+
+          path dirPath = absolute(dirString, path(filename).parent_path());
+
+          directory_iterator end;
+
+          for (directory_iterator it(dirPath); it != end; it++)
+            {
+              shared_ptr<IdentityCertificate> idCert =
+                io::load<IdentityCertificate>(it->path().string());
+
+              if (static_cast<bool>(idCert))
+                m_staticContainer.add(idCert);
+            }
+
+          return;
+        }
+    }
   else if (boost::iequals(type, "any"))
     {
       m_shouldValidate = false;
@@ -293,6 +346,84 @@
     throw Error("Unsupported trust-anchor.type: " + type);
 }
 
+time::nanoseconds
+ValidatorConfig::getRefreshPeriod(std::string inputString)
+{
+  char unit = inputString[inputString.size() - 1];
+  std::string refreshString = inputString.substr(0, inputString.size() - 1);
+
+  uint32_t number;
+
+  try
+    {
+      number = boost::lexical_cast<uint32_t>(refreshString);
+    }
+  catch (boost::bad_lexical_cast&)
+    {
+      throw Error("Bad number: " + refreshString);
+    }
+
+  if (number == 0)
+    return getDefaultRefreshPeriod();
+
+  switch (unit)
+    {
+    case 'h':
+      return time::duration_cast<time::nanoseconds>(time::hours(number));
+    case 'm':
+      return time::duration_cast<time::nanoseconds>(time::minutes(number));
+    case 's':
+      return time::duration_cast<time::nanoseconds>(time::seconds(number));
+    default:
+      throw Error(std::string("Wrong time unit: ") + unit);
+    }
+}
+
+void
+ValidatorConfig::refreshAnchors()
+{
+  time::system_clock::TimePoint now = time::system_clock::now();
+
+  bool isRefreshed = false;
+
+  for (DynamicContainers::iterator cIt = m_dynamicContainers.begin();
+       cIt != m_dynamicContainers.end(); cIt++)
+    {
+      if (cIt->getLastRefresh() + cIt->getRefreshPeriod() < now)
+        {
+          isRefreshed = true;
+          cIt->refresh();
+          cIt->setLastRefresh(now);
+        }
+      else
+        break;
+    }
+
+  if (isRefreshed)
+    {
+      m_anchors.clear();
+
+      for (CertificateList::const_iterator it = m_staticContainer.getAll().begin();
+           it != m_staticContainer.getAll().end(); it++)
+        {
+          m_anchors[(*it)->getName().getPrefix(-1)] = (*it);
+        }
+
+      for (DynamicContainers::iterator cIt = m_dynamicContainers.begin();
+           cIt != m_dynamicContainers.end(); cIt++)
+        {
+          const CertificateList& certList = cIt->getAll();
+
+          for (CertificateList::const_iterator it = certList.begin();
+               it != certList.end(); it++)
+            {
+              m_anchors[(*it)->getName().getPrefix(-1)] = (*it);
+            }
+        }
+      m_dynamicContainers.sort(ValidatorConfig::compareDynamicContainer);
+    }
+}
+
 void
 ValidatorConfig::checkPolicy(const Data& data,
                              int nSteps,
@@ -303,10 +434,6 @@
   if (!m_shouldValidate)
     return onValidated(data.shared_from_this());
 
-  if (m_stepLimit == nSteps)
-    return onValidationFailed(data.shared_from_this(),
-                              "Maximum steps of validation reached");
-
   bool isMatched = false;
   int8_t checkResult = -1;
 
@@ -342,10 +469,6 @@
   if (!m_shouldValidate)
     return onValidated(interest.shared_from_this());
 
-  if (m_stepLimit == nSteps)
-    return onValidationFailed(interest.shared_from_this(),
-                              "Maximum steps of validation reached");
-
   bool isMatched = false;
   int8_t checkResult = -1;
 
@@ -375,5 +498,35 @@
     }
 }
 
+void
+ValidatorConfig::DynamicTrustAnchorContainer::refresh()
+{
+  using namespace boost::filesystem;
+
+  m_certificates.clear();
+
+  if (m_isDir)
+    {
+      directory_iterator end;
+
+      for (directory_iterator it(m_path); it != end; it++)
+        {
+          shared_ptr<IdentityCertificate> idCert =
+            io::load<IdentityCertificate>(it->path().string());
+
+          if (static_cast<bool>(idCert))
+            m_certificates.push_back(idCert);
+        }
+    }
+  else
+    {
+      shared_ptr<IdentityCertificate> idCert =
+        io::load<IdentityCertificate>(m_path.string());
+
+      if (static_cast<bool>(idCert))
+        m_certificates.push_back(idCert);
+    }
+}
+
 
 } // namespace ndn
diff --git a/src/security/validator-config.hpp b/src/security/validator-config.hpp
index 6759ee1..a55797a 100644
--- a/src/security/validator-config.hpp
+++ b/src/security/validator-config.hpp
@@ -33,6 +33,7 @@
 
 class ValidatorConfig : public Validator
 {
+
 public:
   class Error : public Validator::Error
   {
@@ -122,12 +123,95 @@
   onConfigTrustAnchor(const security::conf::ConfigSection& section,
                       const std::string& filename);
 
+  time::nanoseconds
+  getRefreshPeriod(std::string refreshString);
+
+  inline time::nanoseconds
+  getDefaultRefreshPeriod();
+
+  void
+  refreshAnchors();
+
+
 private:
+
+  class TrustAnchorContainer
+  {
+  public:
+    TrustAnchorContainer()
+    {
+    }
+
+    const std::list<shared_ptr<IdentityCertificate> >&
+    getAll() const
+    {
+      return m_certificates;
+    }
+
+    void
+    add(shared_ptr<IdentityCertificate> certificate)
+    {
+      m_certificates.push_back(certificate);
+    }
+
+  protected:
+    std::list<shared_ptr<IdentityCertificate> > m_certificates;
+  };
+
+  class DynamicTrustAnchorContainer : public TrustAnchorContainer
+  {
+  public:
+    DynamicTrustAnchorContainer(const boost::filesystem::path& path, bool isDir,
+                                time::nanoseconds refreshPeriod)
+      : m_path(path)
+      , m_isDir(isDir)
+      , m_refreshPeriod(refreshPeriod)
+    {
+    }
+
+    void
+    setLastRefresh(const time::system_clock::TimePoint& lastRefresh)
+    {
+      m_lastRefresh = lastRefresh;
+    }
+
+    const time::system_clock::TimePoint&
+    getLastRefresh() const
+    {
+      return m_lastRefresh;
+    }
+
+    const time::nanoseconds&
+    getRefreshPeriod() const
+    {
+      return m_refreshPeriod;
+    }
+
+    void
+    refresh();
+
+  private:
+    boost::filesystem::path m_path;
+    bool m_isDir;
+
+    time::system_clock::TimePoint m_lastRefresh;
+    time::nanoseconds m_refreshPeriod;
+  };
+
   typedef security::conf::Rule<Interest> InterestRule;
   typedef security::conf::Rule<Data>     DataRule;
   typedef std::vector<shared_ptr<InterestRule> > InterestRuleList;
   typedef std::vector<shared_ptr<DataRule> >     DataRuleList;
   typedef std::map<Name, shared_ptr<IdentityCertificate> > AnchorList;
+  typedef std::list<DynamicTrustAnchorContainer> DynamicContainers; // sorted by m_lastRefresh
+  typedef std::list<shared_ptr<IdentityCertificate> > CertificateList;
+
+  static inline bool
+  compareDynamicContainer(const DynamicTrustAnchorContainer& containerA,
+                          const DynamicTrustAnchorContainer& containerB)
+  {
+    return (containerA.getLastRefresh() < containerB.getLastRefresh());
+  }
 
   /**
    * @brief gives whether validation should be preformed
@@ -141,7 +225,11 @@
 
   InterestRuleList m_interestRules;
   DataRuleList m_dataRules;
+
   AnchorList m_anchors;
+  TrustAnchorContainer m_staticContainer;
+  DynamicContainers m_dynamicContainers;
+
 };
 
 inline void
@@ -150,7 +238,12 @@
   m_certificateCache->reset();
   m_interestRules.clear();
   m_dataRules.clear();
+
   m_anchors.clear();
+
+  m_staticContainer = TrustAnchorContainer();
+
+  m_dynamicContainers.clear();
 }
 
 inline bool
@@ -191,6 +284,8 @@
 
       shared_ptr<const Certificate> trustedCert;
 
+      refreshAnchors();
+
       AnchorList::const_iterator it = m_anchors.find(keyLocatorName);
       if (m_anchors.end() == it)
         trustedCert = m_certificateCache->getCertificate(keyLocatorName);
@@ -207,6 +302,10 @@
         }
       else
         {
+          if (m_stepLimit == nSteps)
+            return onValidationFailed(packet.shared_from_this(),
+                                      "Maximum steps of validation reached");
+
           OnDataValidated onCertValidated =
             bind(&ValidatorConfig::onCertValidated<Packet, OnValidated, OnFailed>,
                  this, _1, packet.shared_from_this(), onValidated, onValidationFailed);
@@ -270,6 +369,12 @@
   onValidationFailed(packet, failureInfo);
 }
 
+inline time::nanoseconds
+ValidatorConfig::getDefaultRefreshPeriod()
+{
+  return time::duration_cast<time::nanoseconds>(time::seconds(3600));
+}
+
 } // namespace ndn
 
 #endif // NDN_SECURITY_VALIDATOR_CONFIG_HPP