Today's Radio 4 Computing Britain programme (which aired at 13:45, Thursday September the 17th) was entitled "Connected Thinking" and described part of Donald Davies' career, ranging from his early work with Alan Turing through to his invention of packet switching, and its effect on data (and thus multimedia) communications.  What the programme did not mention at all was that following his work on packet switching his interests moved into cryptology and cryptography.  He worked in this area towards the end of his Civil Service career at the National Physical Laboratory and then carried on as an independent consultant.  The security of pay television systems was one of the areas he worked in (another was banking security).  One aspect where he made a major contribution to digital television was in the development and specification of the DVB Common Scrambling Algorithm.  As is now widely known, this comprises two elements, a block cipher and a stream cipher, and Donald designed the block cipher.  So as well as ending by saying how all modern communications are based on Donald's work on packet switching, the BBC programme should have mentioned that all DVB encrypted digital television transmissions are also based on his work.  Despite this omission the programme is well worth listening to.