Digital Fortress

Digital Fortress

First edition cover
Author	Dan Brown
Country	United States United Kingdom
Language	English
Genre	Mystery Techno-thriller
Publisher	St. Martin's Press Transworld (United Kingdom)
Publication date	1998
Media type	Print (hardback, paperback), audiobook
ISBN	(first edition hardcover)
OCLC	55045760

Digital Fortress is a techno-thriller novel written by American author Dan Brown and published in 1998 by St. Martin's Press. The book explores the theme of government surveillance of electronically stored information on the private lives of citizens, and the possible civil liberties and ethical implications of using such technology.

When the United States National Security Agency's code-breaking supercomputer TRANSLTR encounters a new and complex code—Digital Fortress—that it cannot break, Commander Trevor Strathmore calls in head cryptographer Susan Fletcher to crack it. She discovers that it was written by Ensei Tankado, a former NSA employee who became displeased with the NSA's intrusion into people's private lives. If the NSA doesn't reveal TRANSLTR to the public, Tankado intends to auction the code's algorithm on his website and have his partner, "North Dakota", release it for free if he dies, essentially holding the NSA hostage. The agency is determined to stop Digital Fortress from becoming a threat to national security.

When Tankado does indeed die in Seville, of what appears to be a heart attack, Strathmore asks David Becker (Susan's fiancé) to travel to Seville and recover a ring that Tankado was wearing when he died. The ring is suspected to have the code that unlocks Digital Fortress. However, Becker soon discovers that Tankado gave the ring away just before his death. Each person he questions in the search for the ring is murdered by Hulohot, a mysterious deaf assassin.

Meanwhile, telephone calls between North Dakota and Tokugen Numataka (chairman of the Japanese computer company Numatech) reveal that North Dakota hired Hulohot to kill Tankado in order to gain access to the passcode on his ring and speed up the release of the algorithm. At the NSA, Fletcher's investigation leads her to believe that Greg Hale, a fellow NSA employee, is North Dakota. Phil Chartrukian, an NSA technician who is unaware of the Digital Fortress code breaking failure and believes Digital Fortress to be a virus, conducts his own investigation into whether Strathmore allowed Digital Fortress to bypass Gauntlet (NSA's virus/worm filter). However, Chartrukian is murdered by being pushed off the catwalk in the sub-levels of TRANSLTR by an unknown assailant. Since Hale and Strathmore were both in the sub-levels, Fletcher assumes that Hale is the killer; however, Hale claims that he witnessed Strathmore killing Chartrukian. Chartrukian's fall also damages TRANSLTR's cooling system.