Lorenz ciphers and the Colossus

1. Introducing the Lorenz cipher machine, and how Bletchley Park broke it.

2. The proposal for high-speed machine codebreaking methods, leading to the Heath Robinson and the Colossus.

3. The rebirth of the Colossus as described by its rebuilder.

4. The slow evolution from a Mk 1 to a Mk 2 Colossus.

Now you can also read about the rebuild of Heath Robinson.

You can now see more of the Colossus Reconstruction. Continue to Walk Around Colossus.

You can also use an interactive Virtual Colossus.
You will need to print this PDF file of instructions before you run it.

These pages may not be suitable for use with a Macintosh and there may be other browser-dependent features which are not yet optimised. Tony Sale will welcome your comments.

You should also see the original 1945 document, The Newmanry History, which was released from secrecy in 2000. It details the methods by which the Lorenz cipher was broken.

Tony Sale has now made available HTML and PDF editions of this crucial document.

This page was originally created by the late Tony Sale the original curator of the Bletchley Park Museum and is currently being hosted by Rich Sale and Partners.