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Shvoong Home>Books>Mystery & Thrillers>Digital Fortress Review

Digital Fortress

Book Review   by:Eva215     Original Author: Eva215
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Susan Fletcher, a brilliant mathematician and head of the National Security Agency''s (NSA''s) cryptography division, finds herself faced with an unbreakable code named "Digital Fortress", which is resistant to brute-force attacks by the NSA''s 3 million processor supercomputer dubbed "TRANSLTR". The code is written by Japanese cryptographer Ensei Tankado, a fired employee of the NSA, who is displeased with the agency''s intrusion into people''s privacy. Tankado auctions the algorithm on his website, threatening that his accomplice "North Dakota" will release the algorithm for free if he dies. Tankado is found dead in Seville, Spain. Fletcher, along with her fiancé, David Becker, a skilled linguist with eidetic memory, must find a solution to stop the spread of the code. Real life scenarios The book is loosely based around the recent history of cryptography. In 1976 the Data Encryption Standard (DES) was approved with a 56-bit key rather than the 64-bit key originally proposed. It was widely reckoned that the National Security Agency had pushed through this reduction in security on the assumption that it could crack codes before anyone else. In fact the DES was first publicly broken in 1997, 96 days after the first of the DES Challenges. In 1998, the same year as Digital Fortress was published, the Electronic Frontier Foundation (featured in the book) built a piece of hardware costing less than $250,000 called the EFF DES cracker which broke it in 56 hours. The brute force search used by TRANSLTR takes twice as long for each extra bit added to the key (if this is done sensibly), so the reaction of the industry has understandably been to lengthen the key. The Advanced Encryption Standard established in 2001 uses 128, 192 or 256 bits, which take at least 1021 times as long to solve by this technique.
Unbreakable codes are not new to the industry. The One-time pad, invented in 1917 and used by the Russians for many years, was proved to be unbreakable by Claude Shannon in 1949, when used correctly. However it is inconvenient and expensive to use in practice and its use is generally limited to government and military agencies. Public-key cryptography does not generally use fixed length keys and is not susceptible to the computer described in Digital Fortress although it is not unbreakable and may be broken in the future using quantum computing techniques. Code solution The code that appears in the end of the book 128-10-93-85-10-128-98-112-6-6-25-126-39-1-68-78 is decrypted by looking at the first letter of the chapter for each number. For example, chapter 128 starts ''When Susan awoke''. The resulting text is WECGEWHYAAIORTNU Decryption is performed using a columnar transposition cipher, termed a "Caesar Square" cipher in the book (this is unrelated to the Caesar cipher). The letters are arranged into a square: W E C G E W H Y A A I O R T N U and read from the top down. WEAREWATCHINGYOU Add spaces and you get the plaintext, "We are watching you" a reference to the NSA''s monitoring systems.
Published: December 13, 2007   
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