signature: Add ValidityPeriod into SignatureInfo

Change-Id: I02571a4876e2f0ccd8cc088ecc6477d20dd701cb
Refs: #2868
diff --git a/src/signature-info.hpp b/src/signature-info.hpp
index a88b759..4ee8e64 100644
--- a/src/signature-info.hpp
+++ b/src/signature-info.hpp
@@ -24,6 +24,7 @@
 
 #include "encoding/tlv.hpp"
 #include "key-locator.hpp"
+#include "security/validity-period.hpp"
 #include <list>
 
 namespace ndn {
@@ -90,6 +91,18 @@
   const KeyLocator&
   getKeyLocator() const;
 
+  /// @brief Set ValidityPeriod
+  void
+  setValidityPeriod(const security::ValidityPeriod& validityPeriod);
+
+  /// @brief Unset ValidityPeriod
+  void
+  unsetValidityPeriod();
+
+  /// @brief Get ValidityPeriod
+  security::ValidityPeriod
+  getValidityPeriod() const;
+
   /// @brief Append signature type specific tlv block
   void
   appendTypeSpecificTlv(const Block& block);