Digital Fortress - Real Life Scenarios

Real Life Scenarios

The book is loosely based around 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 believed 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 and by 1999 the record was under 24 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 (i.e. 270) to solve by this technique.

Unbreakable codes are not new to the industry. The one-time pad, invented in 1917 and used for the cold-war era Moscow-Washington hotline, was proved to be unconditionally secure by Claude Shannon in 1949 when properly implemented. However it is inconvenient to use in practice and is limited mainly to military and governments.