Digital Fortress

Digital Fortress is a book by Dan Brown.

Plot Overview

Spoiler warning: Plot or ending details follow.

Susan Fletcher, a brilliant mathematician, head of NSA's cryptography division, finds herself faced with an unbreakable code, resistant even to brute-force attacks by a 3,000,000 (3 million what?) processor supercomputer. Along with her fiancé, a skilled linguist with eidetic memory, she must find a solution to stop the spreading of the code.

Code Solution

The code that appears in the end of the book

is decrypted by looking at the bold letter on the page decided by the number. For example, the bold letter on page 128 is "W". The resulting text is

The decryption is much like that of a scytale cypher. Write every fourth letter and skip used letters.

Add spaces and you get the clear text.

a reference to the NSA's monitoring systems.

Links