The whole encryption business is extremely interesting - more so than I originally thought it would be. I suppose the stories which are described in some detail in the book add to the intrigue, such as that of the German Enigma encryption machine, and how it was cracked open by Marian Rejewski and Alan Turing.

Can you imagine how both of them must have felt when they each managed to break what was deemed by the Germans - and the French - to be unbreakable? The fear gripping the Polish (Rejewski) before the war started and that of the rest of Europe once it had must have been utterly unbelievable, and I don't think it's unreasonable to say that had Enigma not been rendered mostly useless by two great minds, the war might not have been won.

I've tried to imagine how I would have felt if I had been in their places, once I knew I had done something Great. I think I would know instantly that I could very well be changing the course of history rather profoundly. Then again, they didn't work entirely on their own, and in times of crisis there exists such a feeling of team bonding I'm sure I would have just been so happy that I would credit everyone the same, even in my own mind. So I'm not sure, I suppose.

Thinking about WW2 gives me that strange tingle down my spine that I usually get when someone points a sharp object at me, or, as a haphazard child, falling halfway through a deliberately concealed hole in a derelict building's first floor, only to save myself from being punctured by countless rusted nails below me at the last moment by spreading my arms, shouting a lot, being pulled out by two others, and thinking about what could have happened to me. I don't like fascist megalomaniacs trying to achieve world domination, and I don't like pointy objects. Because of this (the former specifically), any story of Allied victory during the war always fills me with some kind of relief. But hey, the encryption part is good too!

Mary Queen of Scots also dabbled in an early form of encryption (monoalphabetic substitution as a matter of fact, which we've all done as children I'm sure), and it was the weakness of her method which led to her being found guilty of treason.

I like one-time pad ciphers, which are utterly unbreakable, in theory. Even a quantum computer could not decipher a message encrypted this way. All it could do, so long as the key used to encipher the message is used _only_ once ever, would be to suggest every single possible coherent sentence of the same length as the encrypted text. This of course, is utterly useless.

What is also interesting, although not nearly as useful on its own, is steganography - the art of message concealment, as opposed to encryption. I like the method involving a hard-boiled egg, an ounce of alum, and a pint of vinegar. The alum/vinegar solution produces an ink which penetrates the porous shell, and leaves a visible message on the albumen's surface. On peeling the shell, the message can then be seen.