Long Key Variants of DES

  • Thomas A. Berson


The Federal Data Encryption Standard (DES) [1] is a block product cipher which converts 64-bit blocks of plaintext into 64-bit blocks of cipher text, or vice-versa, under the control of a 56-bit key. There has in the past been considerable controversy over the adequacy of DES key length [2,3,4]. Easily implemented modifications to the DES key schedule (KS) would allow the use of keys longer than 56 bits.


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  1. [1]
    Data Encryption Standard, FIPS PUB 46, U.S. Department of Commerce, National Bureau of Standards, (January, 1977).Google Scholar
  2. [2]
    W. Diffie and M.E. Hellman, “Exhaustive cryptanalysis of the NBS Data Encryption Standard,” Computer (10) pp.74–84 (June, 1977 ).Google Scholar
  3. [3]
    R. Morris, N.J.A. Sloane, and A. Wyner, “Assessment of the National Bureau of Standards proposed Federal Data Encryption Standard,” Crvptoloaia, (1) pp. 281–291 (July, 1977 ).Google Scholar
  4. [4]
    R. Sugarman, “On foiling computer crime,” IEEE Spectrum, (16), 7 (July, 1979 ).Google Scholar
  5. [5]
    D.W. Davies, “Some regular properties of the DES algorithm,” presented at CRYPTO ‘81, Santa Barbara, CA, (August, 1981 ).Google Scholar

Copyright information

© Springer Science+Business Media New York 1983

Authors and Affiliations

  • Thomas A. Berson
    • 1
  1. 1.Sytek, Inc.Mountain ViewUSA

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