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1021 Jul 2014 - 16:15ThomasMisaAttached file NIST-on-economic-impact-DES_report01-2.pdf 
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Data Encryption Standard (DES)

The Data Encryption Standard (DES) is a 56-bit encryption algorithm that was developed by IBM and adopted by the National Bureau of Standards (NBS) for commercial use in the 1977. Walter Tuchman and Carl Meyer were the primary developers of the algorithm, though there was a larger team that worked on its implementation. During the adoption process there was a great deal of debate over the involvement of the National Security Agency (NSA) in DES development as well as concerns over whether 56 bits were enough to ensure security.(1)

Initially, the goal of the DES project was to develop an encryption system for Automated Teller Machines for Lloyd's Bank. While DES was still in development, however, the NBS published a request for proposals for a national standard for commercial cryptography. The NBS selected DES and asked that Tuchman and his team talk to the NSA in order to make sure that they were complying with laws barring the sale of weapons to foreign countries (this included codes). NSA officers explained that parts of the DES algorithms duplicated some of the NSA's own work, and so some of the mathematics would have to remain classified and unpublished. Tuchman and Meyer agreed not to publish parts of the algorithm, which raised objections from the academic community, including Martin Hellman, when the NBS held a seminar to discuss DES before officially making it a standard. Hellman and others objected to the confidentiality of DES as it prevented them from knowing if a mathematical "trapdoor" that bypassed the security algorithm had been included in the algorithm. They also argued that 56 bits was too few to ensure adequate security (Hellman calculated that it would cost $10,000 in hardware and computing time to break the encryption). A series of articles in major newspapers about the DES expressed concerns over collusion between IBM and the intelligence community and what that might mean for privacy. Tuchman argued against the allegations, and pointed out that the Senate Oversight Committee for the intelligence agencies investigated and found these charges to be false. As far as the trapdoor fears went, Tuchman later wrote that not only was there no trapdoor, but that he did not even understand how one could make a trapdoor in the encryption algorithms. As for the 56-bit key issue, Tuchman and Meyer examined exhaustion attacks from commercial computer and determined that no commercial attack would be feasible. This perhaps was a difference in opinion over the standards of commercial cryptography, as Tuchman also argued that commercial cryptography did not need to be held to as high a standard as military cryptography.(2)(3)


1 , 2 : Walter Tuchman, "A Brief History of the Data Encryption Standard" in Dorothy E. Denning and Peter J. Denning, eds., Internet Besieged: Countering Cyberspace Scofflaws, ACM Press New York (1998), 275-280

3 : Martin Hellman, OH 375. Oral history interview by Jeffrey R. Yost, 22 November 2004, Palo Alto, California. Charles Babbage Institute, University of Minnesota, Minneapolis.

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Topic revision: r4 - 07 Mar 2014 - 10:22:15 - norqu036
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