In privacy and computer security, real information is too hard to find. Most people don 't know what's really going on, and many people who do know aren't telling.

This book was written to reveal a hidden truth. The standard way that the US Government recommends that we make information secure and private, the "Data Encryption Standard" or DES, does not actually make that information secure or private. The government knows fairly simple ways to reveal the hidden information (called "cracking" or "breaking" DES).

Many scientists and engineers have known or suspected this for years. The ones who know exactly what the government is doing have been unable to tell the public, fearing prosecution for revealing "classified" information. Those who are only guessing have been reluctant to publish their guesses, for fear that they have guessed wrong.

This book describes a machine which we actually built to crack DES. The machine exists, and its existence can easily be verified. You can buy one yourself, in the United States; or can build one yourself if you desire. The machine was designed and built in the private sector, so it is not classified. We have donated our design to the public domain, so it is not proprietary. There is no longer any question that it can be built or has been built. We have published its details so that other scientists and engineers can review, reproduce, and build on our work. There can be no more doubt. DES is not secure.



The first section of the book describes the Electronic Frontier Foundation's research project to build a machine to crack DES. The next section provides full technical details on the machine that we designed: for review, critique, exploration, and further evolution by the cryptographic research community. The final section includes several hard-to-find technical reports on brute force methods of cracking DES.

Technical description

Chapter 1, Overview, introduces our project and gives the basic architecture of the Electronic Frontier Foundation's DES-cracking machine.

Chapter 2, Design Specification, by Paul Kocher of Cryptography Research, provides specifications for the machine from a software author's point of view.

Chapter 3, Hardware Specification, by Advanced Wireless Technologies, provides specifications for the custom gate array chips, and the boards that carry them, from a hardware designer's point of view.

Technical design details

Chapter 4, Scanning the Source Code, explains how you can feed this book through an optical scanner and regenerate the exact source code needed to build the software and the specialized gate array chip that we designed.

Chapter 5, Software Source Code, contains a complete listing of the C-language software that runs on a PC and controls the DES-Cracker.

Chapter 6, Chip Source Code, contains a complete listing of the chip design language (VHDL) code that specifies how we designed the custom gate array chip.

Chapter 7, Chip Simulator Source Code, contains a complete listing of the C-language software that simulates the operation of the chip, for understanding how the chip works, and for generating test-vectors to make sure that the chips are properly fabricated.

Chapter 8, Hardware Board Schematics, provides schematic diagrams of the boards which provide power and a computer interface to the custom chips, as well as information on the layout of the boards and the backplanes that connect them.


Related Research Papers

Chapter 9, Breaking One Million DES Keys, by Yvo Desmedt, is a 1987 paper proposing an interesting design for a machine that could search for many DES keys simultaneously.

Chapter 10, Architectural considerations for cryptanalytic hardware, by Ian Goldberg and David Wagner, is a 1996 study that explores cracking DES and related ciphers by using field-programmable gate array chips.

Chapter 11, Efficient DES Key Search - An Update, by Michael J. Wiener, revises for 1998 the technology estimates from his seminal 1993 paper, which was the first to include full schematic diagrams of a custom chip designed to crack DES.

Chapter 12, About the Authors, describes the foundation and the companies which collaborated to build this project.