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Systems for fingerprinting digital data

  • US 7,158,655 B2
  • Filed: 12/22/2004
  • Issued: 01/02/2007
  • Est. Priority Date: 10/28/1999
  • Status: Expired due to Fees
First Claim
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1. A system for detecting a fingerprinting word comprising:

  • means for receiving a protected object that has embedded therein a fingerprinting word that contains a plurality of spread spectrum chips that are arranged in individual blocks that define individual spread sequences; and

    means for processing the protected object sufficient to identify an entity that is associated with the fingerprinting word, said entity comprising a potential colluder, wherein said means for processing comprises;

    means for calculating a weight for each block; and

    means for restricting the weights of certain blocks to a predetermined value,wherein said means for calculating comprises means for determining the weight of a block of an original spread sequence block value in accordance with the following equation;


    Let x∈

    {1, −

    1} and y∈

    {0, 1, −

    1};

    f(y, x)=1 if x is not equal to y and y is not equal to 0,0 Otherwise.Let X=(x1, . . . , xd), where xi

    {1, −

    1} and Y=(y1, . . ., yd), where yi

    {1, −

    1, 0}. The weight of Y relative to X is w(Y, X)—

    which is the sum from i=1 to d of f(yi, xi), where “

    d”

    is the number of chips in each block.

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