Method for protecting the audio/visual data across the NRSS interface
First Claim
Patent Images
1. A method for protecting the output audio/visual stream of a smart card comprises the steps of:
- (a) receiving a scrambled signal from a source external to said smart card;
(b) generating a descrambling key in response to said received signal;
(c) descrambling said received signal using said descrambling key to generate a descrambled signal;
(d) receiving data from said external source;
(e) generating a scrambling key in response to said received data;
(f) scrambling said descrambled signal using said scrambling key to generate a rescrambled signal; and
, (g) providing said rescrambled signal to said external source.
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Abstract
A system for enhancing the security of the interface between a consumer electronic device and a removable security device is provided by protecting the audio/visual (A/V) stream descrambled in the removable security device. The protection involves dynamically computing a shared key followed by the rescrambling of the A/V stream.
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Citations
19 Claims
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1. A method for protecting the output audio/visual stream of a smart card comprises the steps of:
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(a) receiving a scrambled signal from a source external to said smart card;
(b) generating a descrambling key in response to said received signal;
(c) descrambling said received signal using said descrambling key to generate a descrambled signal;
(d) receiving data from said external source;
(e) generating a scrambling key in response to said received data;
(f) scrambling said descrambled signal using said scrambling key to generate a rescrambled signal; and
,(g) providing said rescrambled signal to said external source. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
(a) generating a random sequence in response to said seed value; and
(b) generating said rescrambled signal by exclusive ORing said random sequence and said descrambled signal.
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4. The method of claim 3 wherein said received scrambled signal comprises video, audio and control packets and said seed value is generated, in said external source, in a unique manner in response to said video, audio and control packets.
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5. The method of claim 4 wherein said smart card verifies said seed value by comparing said seed value to a subsequent seed value generated in said unique manner in response to said video, audio and control packets.
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6. The method of claim 5 wherein said seed value is generated utilizing said hash of video, audio and control packets.
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7. The method of claim 5 wherein said seed value is generated by exclusive ORing said video, audio and control packets together.
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8. The method of claim 1 wherein said smart card has a card body having a plurality of terminals arranged on a surface of said card body in accordance with one of ISO 7816 and PCMCIA card standards.
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9. The method of claim 1 further comprising the step of generating, in said smart card, a first seed value, and wherein said received data is a second seed value.
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10. The method of claim 9 wherein the step of generating said scrambling key comprises generating said scrambling key in response to said first and second seed values.
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11. The method of claim 10 wherein said scrambling key comprises a seed value and wherein the step of scrambling said descrambled signal comprises the steps of:
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(a) generating a random sequence in response to said seed value; and
(b) generating said rescrambled signal by exclusive ORing said random sequence and said descrambled signal.
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12. The method of claim 11 wherein said received scrambled signal comprises video, audio and control packets and said first and second seed values are generated in a unique manner in response to said video, audio and control packets.
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13. The method of claim 10 wherein said first and second seed values are generated utilizing said hash of video, audio and control packets.
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14. The combination of claim 10 wherein said first and second seed values are generated by exclusive ORing said video, audio and control packets together.
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15. A system for managing access between a service provider and a host device having a smart card coupled thereto, said host device performing the steps of:
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(a) receiving a scrambled signal from said service provider;
(b) sending, to said smart card, a seed value generated in said host device and encrypted using a public key of said smart card;
(c) coupling said received signal to said smart card, said smart card having a means for access control processing, said access control processing means comprising means for generating a descrambling key in response to said received signal, means for descrambling said received signal using said descrambling key to generate a descrambled signal, means for decrypting said encrypted seed value using a private key of said smart card to provide said seed value, means for generating a random sequence in response to said seed value and means for scrambling said descrambled signal using said random sequence and said descrambled signal to generate a rescrambled signal; and
(d) receiving from said smart card said rescrambled signal. - View Dependent Claims (16, 17)
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18. A system for managing access between a service provider and a host device having a smart card coupled thereto, said host device performing the steps of:
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(a) receiving a scrambled signal from said service provider;
(b) sending, to said smart card, a second seed value;
(c) coupling said received signal to said smart card, said smart card having a means for access control processing, said access control processing means comprising means for generating a descrambling key in response to said received signal, means for descrambling said received signal using said descrambling key to generate a descrambled signal, means for generating a first seed value, means for generating a scrambling key in response to said first and second seed values, and means for scrambling said descrambled signal using said scrambling key to generate a rescrambled signal; and
(d) receiving from said smart card said rescrambled signal. - View Dependent Claims (19)
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Specification