diff -r 23d2adc5489e -r b50f8cc8c08e src/Pure/System/isabelle_system.ML
--- a/src/Pure/System/isabelle_system.ML	Mon Apr 12 22:45:38 2021 +0200
+++ b/src/Pure/System/isabelle_system.ML	Mon Apr 12 22:57:39 2021 +0200
@@ -121,6 +121,12 @@
 fun download_file url path = File.write path (download url);
 
 
+(* base64 *)
+
+val decode_base64 = Scala.function1 "decode_base64";
+val encode_base64 = Scala.function1 "encode_base64";
+
+
 (* Isabelle distribution identification *)
 
 fun isabelle_id () = Scala.function1 "isabelle_id" "";