The Italian physicist Guglielmo Marconi invented a powerful form of telecommunication, which made the need for secure encryption even more pressing. Marconi's invention tantalised the military, who viewed it with a mixture of desire and tr…

The problem of the key revolves around the fact that applying it one way will scramble the message, and applying it in reverse unscrambles the message. Unscrambling a message is almost as easy as scrambling it. However, experience tells us…