diff --git a/src/prolog/lib/crypto.pl b/src/prolog/lib/crypto.pl
index 67fef071..cd7f93c5 100644
--- a/src/prolog/lib/crypto.pl
+++ b/src/prolog/lib/crypto.pl
@@ -10,6 +10,10 @@
 
    Especially for cryptographic applications, it as an advantage that
    using strings leaves little trace of what was processed in the system.
+
+   For predicates that accept an encoding/1 option to specify the encoding
+   of the input data, if encoding(octet) is used, then the input can also
+   be specified as a list of bytes, i.e., integers between 0 and 255.
 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
 
 :- module(crypto,