diff --git a/api/api.proto b/api/api.proto
index ce4477a081c..e621379da94 100644
--- a/api/api.proto
+++ b/api/api.proto
@@ -310,6 +310,16 @@ service Wallet {
       }
     };
   }
+  //Warning: do not invoke this interface provided by others.
+  rpc GetTransactionSign (TransactionSign) returns (Transaction) {
+    option (google.api.http) = {
+      post: "/wallet/gettransactionsign"
+      body: "*"
+      additional_bindings {
+        get: "/wallet/gettransactionsign"
+      }
+    };
+  };
 };
 
 
diff --git a/core/Tron.proto b/core/Tron.proto
index 87c83105eec..e804da178ea 100644
--- a/core/Tron.proto
+++ b/core/Tron.proto
@@ -194,6 +194,11 @@ message Transactions {
   repeated Transaction transactions = 1;
 }
 
+message TransactionSign {
+  Transaction transaction = 1;
+  bytes privateKey = 2;
+}
+
 message BlockHeader {
   message raw {
     int64 timestamp = 1;