Thomas Jericho

I like numbers, because with numbers, truth and beauty are the same thing.

Every day, our Typex machines have to be set the same way the Germans set their Enigmas. And figuring out the settings is the hard part. That's where the code breakers come in.

She'd need a crib. Let's say this tombstone was in code. If I knew more or less who's buried here, I'd have a pretty good idea what the code meant. You try to work out the settings and then type the coded message into the Enigma machine. If the message comes out nonsense, the settings are wrong. If it comes out "Mary Jane Hawkins," you've broken Enigma for that day.

The problem? The problem is the machine has a hundred and fifty million, million, million ways of doing it, according to how you set these three rotors, and how you connect these plugs. Press the same key any number of times, it'll always come out different.

No. No, no, no, this is the one we can break. Shark is enciphered on a special Enigma machine with a fourth rotor, designed especially for U-Boats - which gives it about four thousand million, *billion* starting positions. And, uh, we've never seen one.