diff --git a/src/protocol-detail/challenge.hpp b/src/protocol-detail/challenge.hpp
index aafcd42..8078237 100644
--- a/src/protocol-detail/challenge.hpp
+++ b/src/protocol-detail/challenge.hpp
@@ -30,6 +30,17 @@
 public:
   static Block
   encodeDataPayload(const RequestState& request);
+
+  struct DecodedData{
+      Status status;
+      std::string challengeStatus;
+      size_t remainingTries;
+      time::seconds remainingTime;
+      optional<Name> issuedCertName;
+  };
+
+  static DecodedData
+  decodeDataPayload(const Block& data);
 };
 
 }  // namespace ndncert