diff --git a/protos/message.proto b/protos/message.proto
index faa5059..21bee3c 100644
--- a/protos/message.proto
+++ b/protos/message.proto
@@ -329,6 +329,7 @@ message CursorPosition {
 message Hash {
   string salt = 1;
   string challenge = 2;
+  bool support_controlling_salt = 3;
 }
 
 enum ClipboardFormat {