The Colossus Rebuild Project in
the National Museum of Computing

The Cipher Event.

Here you can find a new Virtual Colossus Mk 2 which you can use to find the wheel start positions on the intercepted SZ42 text.

If you are not sure of the algorithms and methods of attack go here first and read all about it. Note you need to use the original Virtual Colossus for these examples.

You can download colosmk2.zip to your hard disc, or just run it from here on the web. There are problems in loading a text file into an Html page. This has been solved in new virtual Colossus by having a text area in a frame in the header. The text file can be copied from Notepad and pasted into this text area.

The file to be deciphered or enciphered needs to be loaded into a Notepad window. (Notepad is in the Windows directory). First check that the text file has been terminated by ****. If it hasn't add this in and save it. Now click onto the Notepad window and "select all" under Edit in the top line of the window. Now click on "copy" under Edit. This copies your text into the Clipboard and it can now be "past"ed into the text Area in virtual Colossus header.

Start Colossus . Scroll down the header, data, window until the row of wheel start position boxes appear. Going slightly further on reveals the top of the large text Area box. Click on the very top left hand corner of this box and then click on "Past" under Edit in the top line of the Colossus window. This will copy the saved text from the Clipboard into the text Area.

Go back up to the top of the header data window and come down to the row of wheel start position boxes. Click on the left hand box, K1, enter its start postion and then use tab to proceed to the next wheel start, K2. When all 12 starts have been entered click on "pattern" drop down list and select the pattern to be used. This will be plugged up on the main window. Then click on the "cipher" drop down list and select "textin". The wheel starts will be plugged up on the main window.

Now you need to operate colossus. Run Colossus Mk2 .

Tony Sale, Leader, the Colossus Rebuild Project and Trustee/Director of the National Museum of Computing