diff --git a/src/challenge-module.hpp b/src/challenge-module.hpp
index 80670f4..4cc5fa9 100644
--- a/src/challenge-module.hpp
+++ b/src/challenge-module.hpp
@@ -66,7 +66,7 @@
 
   // For CA
   virtual void
-  handleChallengeRequest(const JsonSection& params, CertificateRequest& request) = 0;
+  handleChallengeRequest(const Block& params, CertificateRequest& request) = 0;
 
   // For Client
   virtual JsonSection
@@ -75,6 +75,9 @@
   virtual JsonSection
   genChallengeRequestJson(int status, const std::string& challengeStatus, const JsonSection& params) = 0;
 
+  virtual Block
+  genChallengeRequestTLV(int status, const std::string& challengeStatus, const JsonSection& params) = 0;
+
   // helpers
   static std::string
   generateSecretCode();