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Scalable key agile cryptography

  • US 5,796,836 A
  • Filed: 08/29/1995
  • Issued: 08/18/1998
  • Est. Priority Date: 04/17/1995
  • Status: Expired due to Term
First Claim
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1. A method of encrypting a plurality M of plain text blocks, the method comprising the steps of:

  • providing a plurality N of memory locations, where M>

    N and N>

    1;

    storing precomputed pseudorandom vectors in each of the plurality of memory locations; and

    encrypting the ith plain text block, wherein M>

    i>

    N and wherein the step of encrypting the ith plain text block comprises the steps;

    a) performing a first function CT(i)=f(PT(i),PV(i-N)), where CT(i) is the ith cipher text block, PT(i) is the plain text block for iteration i, PV(i-N) is the pseudorandom vector calculated during iteration i-N and the first function, f( ), is a first encryption algorithm;

    b) calculating a new pseudorandom vector, wherein the step of calculating a new pseudorandom vector comprises the step of performing a second function PV(i)=g(PV(i-N))!g( ) on PV(i-N) to calculate PV(i), where PV(i) is the pseudorandom vector calculated during iteration i, PV(i-N) is the pseudorandom vector calculated during iteration i-N and the second function, g( ), is a second encryption algorithm; and

    c) storing the new pseudorandom vector in one of the N memory locations.

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