diff --git a/src/secmod_signkey.ml b/src/secmod_signkey.ml
index 8ca280fc..0e1bfb6b 100644
--- a/src/secmod_signkey.ml
+++ b/src/secmod_signkey.ml
@@ -1,7 +1,8 @@
 (* TODO
    - key rotation
    - how many signkey to use?
-     we just use 1 for now *)
+     we just use 1 for now
+   - does the secmod's key as metadata/expiration date? *)
 open Syntax
 
 type exchange_pub = Crypto.EddsaPublicKey.t