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Cryptographic method and apparatus for restricting access to transmitted programming content using program identifiers

  • US 6,373,948 B1
  • Filed: 08/15/1997
  • Issued: 04/16/2002
  • Est. Priority Date: 08/15/1997
  • Status: Expired due to Term
First Claim
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1. A method of transmitting a program having restricted access to an end-user, said method comprising the steps of:

  • assigning a program identifier to said program, said program identifier uniquely identifying said program for a duration of said program;

    defining a plurality of master keys;

    providing entitlement information to said end-user derived from said master keys;

    encrypting said program using a program key, said program key being a linear combination of said master keys and said program identifier determining which keys in said plurality of master keys are utilized to generate said program key; and

    transmitting said encrypted program together with said program identifier to said end-user, whereby said end-user can derive said program key from only said program identifier and said entitlement information.

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