Using Colossus with Russian teleprinter traffic | Virtual Talk

This lecture was delivered by TNMoC Volunteers Jerry McCarthy & Peter Hoath

Peter gives an introduction to the Lorenz SZ40/42 machine and the principles behind Bill Tutte’s 1 + 2 attack linking it to the linguistic structure of the German language and how it interacts with the 5 unit teleprinter code. Peter then explains the basics of the Tutte algorithm which allows crucial machine settings to be derived simply from a long enough encrypted message.

Jerry then mentions that although "Colossus" was created to assist in the breaking of German teleprinter traffic encrypted using the Lorenz SZ40/SZ42 machine, there is a story concerning the fate of the Colossi at the end of WWII, that two Colossi were sent to GCHQ to help with breaking Russian teleprinter traffic encrypted with captured SZ4n machines.

This talk consequently explores the possibility that Colossus could have been used for that purpose, assuming the use of the SZ40/42 as the encryption methodology.

Recorded online on 28th February 2024.