src/Pure/General/bytes.scala

--- a/src/Pure/General/bytes.scala	Mon May 07 22:48:24 2018 +0200
+++ b/src/Pure/General/bytes.scala	Mon May 07 23:08:22 2018 +0200
@@ -56,6 +56,12 @@
     new Bytes(a, 0, n)
   }
 
+  def base64(s: String): Bytes =
+  {
+    val a = Base64.getDecoder.decode(s)
+    new Bytes(a, 0, a.length)
+  }
+
 
   /* read */