change request id to be bytes

Change-Id: If980f23259a31acc59d17e3115a27320e94dcacb
diff --git a/src/detail/new-renew-revoke-encoder.hpp b/src/detail/new-renew-revoke-encoder.hpp
index 70e69aa..8b083d6 100644
--- a/src/detail/new-renew-revoke-encoder.hpp
+++ b/src/detail/new-renew-revoke-encoder.hpp
@@ -37,12 +37,13 @@
 
   static Block
   encodeDataContent(const std::string& ecdhKey, const std::string& salt,
-                             const CaState& request,
-                             const std::list<std::string>& challenges);
+                    const CaState& request,
+                    const std::list<std::string>& challenges);
+
   struct DecodedData {
     std::string ecdhKey;
     uint64_t salt;
-    std::string requestId;
+    RequestID requestId;
     Status requestStatus;
     std::list<std::string> challenges;
   };