An Enciphering Module for Multics

Abstract

Recently IBM Corporation has declassified an algorithm for encryption usable for computer-to-computer or computer-to-terminal communications. Their algorithm was implemented in a hardware device called Lucifer. A software implementation of Lucifer for Multics is described. A proof of the algorithm's reversibility for deciphering is provided. A special hand-coded (assembly language) version of Lucifer is described whose goal is to attain performance as close as possible to that of the hardward device. Performance measurements of this program are given. Questions addressed are: How complex is it to implement an algorithm in software designed primarily for digital hardware? Can such a program perform well enough for use in the I/O system of a large time-sharing system?