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Software-efficient pseudorandom function and the use thereof for encryption

  • US 5,454,039 A
  • Filed: 12/06/1993
  • Issued: 09/26/1995
  • Est. Priority Date: 12/06/1993
  • Status: Expired due to Term
First Claim
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1. A method for transforming a table of pseudorandom numbers into a pseudorandom bit string useful for data encryption, the table being precomputed from a key, comprising the steps of:

  • (a) using an index and a set of values from the table of pseudorandom numbers to generate initial values for a set of registers;

    (b) mixing at least some of the register values by taking a current value of a register and replacing the current value with a function of the current value and a value retrieved from the table;

    (c) concatenating into the pseudorandom bit string a function of the register values as modified in step (b); and

    (d) repeating steps (b)-(c) a predetermined number of times until the pseudorandom bit string reaches a desired length.

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