Digital Fortress

Digital Fortress is a techno-thriller by the American writer Dan Brown, published in 1998 by St Martin's Press and the first of his novels.

The story is set in 1996, when the National Security Agency's code-breaking supercomputer, TRANSLTR, encounters a cipher it cannot crack: a programme named Digital Fortress, written by a former agency employee, Ensei Tankado, who had come to believe that the agency had no business reading the private messages of the people it is meant to protect. Tankado's arrangement is that the algorithm will be released to the world if anything happens to him, and when he dies the agency's head cryptographer, Susan Fletcher, is called in with very little time to work out who now holds it. Her search runs alongside the question of what the man who wrote the programme wanted and why he attached those terms to it, and the novel's subject is surveillance, secrecy and the point at which the two begin to look like each other.

Brown went on to write the novels about Robert Langdon, and this first book sets out the interest in codes and institutions that runs through them.