diff --git a/src/validator-invitation.hpp b/src/validator-invitation.hpp
new file mode 100644
index 0000000..c2a0e5a
--- /dev/null
+++ b/src/validator-invitation.hpp
@@ -0,0 +1,92 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil -*- */
+/*
+ * Copyright (c) 2013, Regents of the University of California
+ *                     Yingdi Yu
+ *
+ * BSD license, See the LICENSE file for more information
+ *
+ * Author: Yingdi Yu <yingdi@cs.ucla.edu>
+ */
+
+#ifndef CHRONOS_VALIDATOR_INVITATION_HPP
+#define CHRONOS_VALIDATOR_INVITATION_HPP
+
+#include "common.hpp"
+
+#include <ndn-cxx/security/validator.hpp>
+#include <ndn-cxx/security/certificate-cache.hpp>
+#include <ndn-cxx/security/sec-rule-relative.hpp>
+
+#include "endorse-certificate.hpp"
+
+namespace chronos {
+
+class ValidatorInvitation : public ndn::Validator
+{
+  typedef function<void(const std::string&)> OnValidationFailed;
+  typedef function<void()> OnValidated;
+
+public:
+  class Error : public ndn::Validator::Error
+  {
+  public:
+    Error(const std::string& what)
+      : ndn::Validator::Error(what)
+    {
+    }
+  };
+
+  static const shared_ptr<ndn::CertificateCache> DefaultCertificateCache;
+
+  ValidatorInvitation();
+
+  virtual
+  ~ValidatorInvitation()
+  {
+  }
+
+  void
+  addTrustAnchor(const Name& keyName, const ndn::PublicKey& key);
+
+  void
+  removeTrustAnchor(const Name& keyName);
+
+  void
+  cleanTrustAnchor();
+
+protected:
+  void
+  checkPolicy(const Data& data,
+              int stepCount,
+              const ndn::OnDataValidated& onValidated,
+              const ndn::OnDataValidationFailed& onValidationFailed,
+              std::vector<shared_ptr<ndn::ValidationRequest> >& nextSteps);
+
+  void
+  checkPolicy(const Interest& interest,
+              int stepCount,
+              const ndn::OnInterestValidated& onValidated,
+              const ndn::OnInterestValidationFailed& onValidationFailed,
+              std::vector<shared_ptr<ndn::ValidationRequest> >& nextSteps);
+
+private:
+  void
+  internalCheck(const uint8_t* buf, size_t size,
+                const Signature& sig,
+                const Name& keyLocatorName,
+                const Data& innerData,
+                const OnValidated& onValidated,
+                const OnValidationFailed& onValidationFailed);
+
+private:
+  typedef std::map<Name, ndn::PublicKey> TrustAnchors;
+
+  ndn::SecRuleRelative m_invitationReplyRule;
+  ndn::Regex m_invitationInterestRule;
+  ndn::Regex m_innerKeyRegex;
+  TrustAnchors m_trustAnchors;
+};
+
+} // namespace chronos
+
+#endif //CHRONOS_VALIDATOR_INVITATION_HPP