gm2-libs-iso/SimpleCipher

DEFINITION MODULE SimpleCipher ;

(*
    Description: provides a simple Caesar cipher layer which
                 can be attached to any channel device.  This,
                 pedagogical, module is designed to show how
                 it is possible to add further layers underneath
                 the channel devices.
*)

FROM IOChan IMPORT ChanId ;

(*
   InsertCipherLayer - inserts a caesar cipher below channel, cid.
                       The encryption, key, is specified.
*)

InsertCipherLayer
PROCEDURE InsertCipherLayer (cid: ChanId; key: INTEGER) ;

(*
   RemoveCipherLayer - removes a Caesar cipher below channel, cid.
*)

RemoveCipherLayer
PROCEDURE RemoveCipherLayer (cid: ChanId) ;

END SimpleCipher.