With great rigor and a huge documentation work the author tells the story, often secret, changes secret codes, conspiracies and men who worked, mostly in the shade, or to code or to decode messages of sometimes paramount. Finally published in pocket, this book reads in one night (unless the effort is made to use the algorithms described, which is also exciting and accessible to everyone). A must for every scientist and every historian ... Note the excellent "Fermat's Last Theorem" by the same author.
