change request id to be bytes

Change-Id: If980f23259a31acc59d17e3115a27320e94dcacb
diff --git a/src/ca-module.hpp b/src/ca-module.hpp
index d29f49b..22c53fc 100644
--- a/src/ca-module.hpp
+++ b/src/ca-module.hpp
@@ -70,7 +70,7 @@
   void
   onRegisterFailed(const std::string& reason);
 
-  CaState
+  std::unique_ptr<CaState>
   getCertificateRequest(const Interest& request);
 
   security::Certificate