Unformatted text preview: eyer, Bill Notz, Lynn Smith, Walt Tuchman, and Bryant Tuckerman. The algorithm, although complicated, was straightforward. It used only simple logical operations on small groups of bits and could be implemented fairly efficiently in hardware. The NBS requested the NSA’s help in evaluating the algorithm’s security and determining its suitability as a federal standard. IBM had already filed for a patent [514], but was willing to make its intellectual property available to others for manufacture, implementation, and use. Eventually, the NBS worked out the terms of agreement with IBM and received a nonexclusive, royaltyfree license to make, use, and sell equipment that implemented the algorithm. Finally, in the March 17, 1975 Federal Register, the NBS published both the details of the algorithm and IBM’s statement granting a nonexclusive, royaltyfree license for the algorithm, and requested comment [536]. Another notice, in the August 1, 1975 Federal Register, again requested comments from agencies and the general public. And there were comments [721,497,1120]. Many were wary of the NSA’s “invisible hand” in the development of the algorithm. They were afraid that the NSA had modified the algorithm to install a trapdoor. They complained that the NSA reduced the key size from the original 128bits to 56bits (see Section 13.1). They complained about the inner workings of the algorithm. Much of NSA’s reasoning became clear in the early 1990s, but in the 1970s this seemed mysterious and worrisome. In 1976, the NBS held two workshops to evaluate the proposed standard. The first workshop discussed the mathematics of the algorithm and the possibility of a trapdoor [1139]. The second workshop discussed the possibility of increasing the algorithm’s key length [229]. The algorithm’s designers, evaluators, implementors, vendors, users, and critics were invited. From all reports, the workshops were lively [1118]. Despite criticism, the Data Encryption Standard was adopted as a federal standard on November 23, 1976 [229] and authorized for use on a...
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This note was uploaded on 10/18/2010 for the course MATH CS 301 taught by Professor Aliulger during the Fall '10 term at Koç University.
 Fall '10
 ALIULGER
 Cryptography

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