The German ENIGMA encryption system was considered uncrackable, and indeed would have been so had it been correctly implemented. However, slapdash operation by the German forces, by sending some messages in the clear and the use of obvious codewords like HITLER or BERLIN, opened a loophole that the British scientists at Bletchley Park, under the mathematical genius Alan Turing, were able to exploit, with the result that the Allies often knew about German military operations before the intended recipients at the front.

The system is just as secure today. Although superseded by electronic systems, and the use of data scrambling and systems such as PGP, an Enigma-encoded message will be as secure as the others - and of course is not limited to on-line communications!

To download the software to encrypt and decrypt Enigma, click here.

For brief instructions on how to use the software, click here.

For more information about different versions of Enigma and other encryption systems, (and the author of this programme), click here.

To learn about Bletchley Park and how you can see what went on there, follow one of the links listed here.

Click here for the Yahoo mailing list.