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Verification of the source of program information in a conditional access system

  • US 6,105,134 A
  • Filed: 07/31/1998
  • Issued: 08/15/2000
  • Est. Priority Date: 04/03/1995
  • Status: Expired due to Term
First Claim
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1. A method, in a cable television system comprising a programming source and a set top terminal, of verifying said programming source at said set top terminal, the method comprising the steps ofat said programming source,providing said programming information, a control word, and a shared secret as inputs to a secure hash function;

  • using at least a portion of an output from said secure hash function as a source authentication;

    encrypting said control word to generate an encrypted control word; and

    transmitting said source authentication, said programming information, and said encrypted control word; and

    at said receiver,receiving said source authentication, said programming information, and said encrypted control word;

    decrypting said encrypted control word to recover therefrom said control word;

    providing said programming information, said control word, and said shared secret as inputs into said secure hash function;

    using at least a portion of an output from said secure hash function as a receiver authentication; and

    comparing said source authentication with said receiver authentication, the programming information and the control word being authentic when said source authentication and said receiver authentication are the same.

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