better secmod

src/api.ml

@@ -3,6 +3,7 @@
    normalized JSON-object
      for signature of ExchangeKeysResponse.exetensions field
    option: correct use opt_mem or Jsont.option
+   properly combine jsont for "interface DenomGroupRsa extends DenomGroupCommon"
    better types:
      - payto_uri
      - uri
@@ -922,6 +923,19 @@ module SignKey = struct
     master_sig: ExchangeSigningKeyValidity.t;
   }
 
+  (* TODO rm one of them *)
+  let of_signkey
+      Signkey.
+        {
+          pub;
+          stamp_start;
+          stamp_expire;
+          stamp_end;
+          master_sig;
+          revoked_sig= _;
+        } =
+    { key= pub; stamp_start; stamp_expire; stamp_end; master_sig }
+
   let jsont =
     let make key stamp_start stamp_expire stamp_end master_sig =
       { key; stamp_start; stamp_expire; stamp_end; master_sig }