Read The Code Book recently. Entertaining read. Simon Singh does a good job of explaining things very lucidly. But I am somewhat skeptical with regard to the future of cryptanalysis (quantum computing). Seems to belong to the realm of sci-fi. Quantum cryptography -- using polarised photons for transmitting messages -- has already been demonstrated to be feasible; it's only the cryptanalysis-using-quantum-computers part that I have issues with.

Interesting tit-bit from the book:

...young lovers in Victorian England were often forbidden from publicly expressing their affection, and could not even communicate by letter in case their parents intercepted and read the contents. This resulted in lovers sending encrypted messages to each other via the personal columns of newspapers. ...On one occasion, Wheatstone deciphered a note in The Times from an Oxford student, suggesting to his true love that they elope. A few days later, Wheatstone inserted his own message, encrypted in the same cipher, advising the couple against this rebellious and rash action. Shortly afterwards there appeared a third message, this time unencrypted and from the lady in question: 'Dear Charlie, Write no more. Our cipher is discovered.'