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Method and apparatus for uniquely encrypting a plurality of services at a transmission site

  • US 5,381,481 A
  • Filed: 08/04/1993
  • Issued: 01/10/1995
  • Est. Priority Date: 08/04/1993
  • Status: Expired due to Term
First Claim
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1. In a communications system wherein a plurality of services are to be transmitted from a transmission site to a reception site, a method for uniquely encrypting each service at the transmission site comprising the steps of:

  • a) generating a unique spreading function for each service to be transmitted, wherein each unique spreading function comprises a unique N-bit quantity;

    b) generating a random quantity;

    c) for each service, (i) convolving the random quantity with the spreading function generated for that service in step (a) to produce a unique encryption seed for that service, and (ii) encrypting at least a portion of that service in accordance with an encryption algorithm upon the encryption algorithm being keyed with the unique encryption seed; and

    d) transmitting the random quantity to the reception site along with said encrypted portions of each service, but not transmitting the unique encryption seeds produced for each service in step (c)(i).

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