diff --git a/src/security/certificate-cache.hpp b/src/security/certificate-cache.hpp
index 8f2c068..c22de67 100644
--- a/src/security/certificate-cache.hpp
+++ b/src/security/certificate-cache.hpp
@@ -33,6 +33,18 @@
 
   virtual shared_ptr<const IdentityCertificate>
   getCertificate(const Name& certificateNameWithoutVersion) = 0;
+
+  virtual void
+  reset() = 0;
+
+  virtual size_t
+  getSize() = 0;
+
+  bool
+  isEmpty()
+  {
+    return (getSize() == 0);
+  }
 };
 
 } // namespace ndn