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Security document and authentication scheme

  • US 6,209,923 B1
  • Filed: 04/14/1999
  • Issued: 04/03/2001
  • Est. Priority Date: 04/14/1999
  • Status: Active Grant
First Claim
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1. A security document wherein said covert trigger elements and said security image elements are constructed of shapes having substantially identical geometry.

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