Descrambling a scrambled television signal using a cable box for authentication

• US 6,742,182 B1
• Filed: 01/24/2000
• Issued: 05/25/2004
• Est. Priority Date: 01/24/2000
• Status: Expired due to Term

• Current Assignee: Rovi Technologies Corporation (Adeia Inc.)
• Original Assignee: WebTV Networks Inc. (Microsoft Corporation)
• Inventors: Perlman, Stephen G.
• Primary Examiner(s): Kostak, Victor R.
• Assistant Examiner(s): VU, NGOC K
• Application Number:
  US09/490,427
• Time in Patent Office: 1,583 Days
• Field of Search: 380/200-203, 380/210, 725/25, 725/27-31, 725/139-141, 725/151-153, 725/131-133, 725/119, 725/120, 348/552
• US Class Current: 725/25
• CPC Class Codes: H04N 21/4383 Accessing a communication channel
• CPC Class Codes: H04N 21/4384 involving operations to reduce the access time, e.g. fast-tuning for reducing channel switching latency
• CPC Class Codes: H04N 21/4405 involving video stream decryption
• CPC Class Codes: H04N 21/44231 Monitoring of peripheral device or external card, e.g. to detect processing problems in a handheld device or the failure of an external recording device configuring of peripheral devices in general G06F9/4411; reporting information sensed by appliance or service execution status of appliance services in a home automation network H04L12/2823; monitoring the status of connected device in data switched networks H04L43/0817
• CPC Class Codes: H04N 21/4516 involving client characteristics, e.g. Set-Top-Box type, software version or amount of memory available
• CPC Class Codes: H04N 21/454 Content or additional data filtering, e.g. blocking advertisements
• CPC Class Codes: H04N 21/4623 Processing of entitlement messages, e.g. ECM [Entitlement Control Message] or EMM [Entitlement Management Message] arrangements for conditional access to broadcast information or to broadcast-related services H04H60/14
• CPC Class Codes: H04N 7/163 by receiver means only

Abstract

Methods, apparatus and computer program products for authenticating the right of a user to descramble and view scrambled television channels are provided. The set top box can use newer and faster technology to tune and descramble television channels and the right of the user to descramble those channels is authenticated by periodically examining all the television channels output by a cable box. If the cable box descrambles a particular channel, the right of the user to descramble that channel has been authenticated or verified and the set top box is enabled to descramble the same channel. As an additional security feature, the time base of the television channel output by the cable box can be compared to the time base of the same channel tuned and descrambled with the set top box. If the time bases match, then the right of the user to descramble and view that particular channel is authenticated. Once the right of the viewer to descramble a particular channel is authenticated, the channel is tuned and descrambled using the newer technology of the set top box. In this manner, the set top box can descramble and tune scrambled television channels without compromising the rights of the company supplying the scrambled television signal.

Claims

1. A set top box for descrambling a scrambled signal comprising:

means for receiving a scrambled signal;

means for monitoring an output signal of a cable box that corresponds with the scrambled signal;

means for authenticating a right of a user to descramble the scrambled signal based at least in part on whether the output signal of the cable box is scrambled or not scrambled;

a tuner for tuning the scrambled signal; and

a descrambler that is capable of descrambling the scrambled signal if the right of the user to descramble the scrambled signal is authenticated and that is capable of refraining from descrambling the scrambled signal if the right of the user to descramble the scrambled signal is not authenticated.

2. A set top box as defined in claim 1, wherein the means for receiving the scrambled signal comprises a multiplexor.

3. A set top box as defined in claim 2, wherein the multiplexor is capable of being connected to both the output signal of a cable box and the scrambled signal.

4. A set top box as in claim 1, wherein the means for authenticating further comprises a time base detector for measuring the synchronization of a time base of the scrambled signal with a time base of the output signal.

5. A set top box as defined in claim 4, wherein the time base of the scrambled signal and the time base of the output signal is the vertical blanking interval.

6. A set top box as defined in claim 1, further comprising a computer-readable medium having stored thereon channel authorization information generated by the means for monitoring an output signal of a cable box to authenticate the right of a user to descramble the scrambled signal, the channel authorization information being used by the set top box to selectively enable or disable the descrambler.

7. A set top box as defined in claim 6, wherein the channel authorization information is stored persistently on the computer-readable medium.

8. In a system having a cable box and a set top box, a method for selectively descrambling a scrambled channel at the set top box based on the right of a viewer to receive the scrambled channel in descrambled form, comprising the steps of:

determining whether the cable box is capable of descrambling a scrambled channel;

receiving the scrambled channel at the set top box;

if the cable box has been capable of descrambling the scrambled channel, then descrambling the scrambled channel with the set top box; and

if the cable box has not been capable of descrambling the scrambled channel, then refraining from descrambling the scrambled channel with the set top box.

9. A method as defined in claim 8, further comprising the steps of:

determining whether the cable box is capable of descrambling each of one or more other scrambled channels;

receiving one of the one or more other scrambled channels at the set top box;

if the cable box has been capable of descrambling said one of the one or more other scrambled channels, then descrambling said one of the one or more other channels with the set top box; and

if the cable box has not been capable of descrambling said one of the one or more other scrambled channels, then refraining from descrambling said one of the one or more other scrambled channels with the set top box.

10. A method as defined in claim 8, wherein the step of determining whether the cable box is capable of descrambling the scrambled chancel comprises the steps of:

using the set top box, causing the cable box to tune to the scrambled channel; and

using the set top box, monitoring an output signal from the cable box to determine whether the output signal is descrambled.

11. A method as defined in claim 8, wherein the scrambled channel is included in a scrambled signal that further comprises a plurality of other scrambled channels.

12. A method as defined in claim 11, further comprising the step of examining an output signal of the cable box for each scrambled channel in the scrambled signal to determine if the output signal is scrambled or descrambled.

13. A method as defined in claim 8, further comprising the step of tuning to the scrambled channel at the set top box.

14. A method as defined in claim 8, further comprising the step of allowing a viewer to view the scrambled channel in descrambled form.

15. A method as defined in claim 8, wherein each step or determining whether the cable box is capable of descrambling a scrambled channel is repeated periodically.

16. A method as defined in claim 8, wherein the step of determining whether the cable box is capable of descrambling a scrambled channel is repeated daily.

17. A method as defined in claim 8, further comprising the steps of:

storing a descrambling algorithm at the set top box; and

receiving an upgrade of the descrambling algorithm, wherein the upgrade is used in the step of descrambling the scrambled channel.

18. A method as defined in claim 8, further comprising the steps of:

identifying a scrambling technique that has been used to scramble the scrambled channel; and

receiving a descrambling algorithm compatible with the scrambling technique from a remote source, the descrambling algorithm being used in the step of descrambling the scrambled channel.

19. A computer program product comprising one or more computer-readable media having computer-executable instructions for implementing the method recited in claim 8.

20. In a system having a cable box and a set top box, a method for determining whether a user has a right to view a scrambled channel in descrambled form, the method comprising the steps of:

receiving the scrambled channel at the set top box without the scrambled channel passing through the cable box;

detecting a first time base of the scrambled channel at the set top box;

receiving a channel to be tested at the set top box, the channel to be tested purportedly being the scrambled channel that has been descrambled at the cable box;

detecting a second time base of the channel to be tested at the set top box;

comparing the first time base with the second time base;

concluding that the user has the right to view the scrambled channel in descrambled form if the first time base matches the second time base; and

concluding that the user does not have the right to view the scrambled channel in descrambled form if the first time base does not match the second time base.

21. A method as defined in claim 20, wherein the step of detecting the first time base further comprises the steps of:

tuning the set top box to the scrambled channel; and

measuring a vertical blanking interval of the scrambled channel.

22. A method as defined in claim 20, wherein the step of detecting the second time base further comprises the steps of:

tuning the cable box to the channel to be tested; and

measuring a vertical blanking interval of the channel to be tested.

23. A method as defined in claim 20, further comprising the steps of:

receiving a user request to tune to the scrambled channel and to descramble the scrambled channel;

if the first time base matches the second time base, descrambling the scrambled channel at the set top box; and

if the first time base does not match the second time base, refraining from descrambling the scrambled channel at the set top box.

24. A method as defined in claim 20, further comprising the step of repeating the steps of detecting the first time base and detecting the second time base.

25. A computer program product comprising one or more computer-readable media having computer-executable instructions for implementing the method recited in claim 20.

26. In a system having a cable box and a set top box, a method for descrambling a scrambled channel, the method comprising the steps of:

receiving the scrambled channel at the set top box;

receiving an output signal at the set top box, the output signal being received from the cable box;

determining whether a user has a right to receive the scrambled channel in descrambled form based at least in part on whether the output signal received from the cable box is scrambled or not scrambled;

if it is determined that the user has the right to receive the scrambled channel in descrambled form, then descrambling the scrambled channel with the set top box; and

if it is determined that the user does not have the right to receive the scrambled channel in descrambled form, then refraining from descrambling the scrambled channel.

27. A method as defined in claim 26, wherein the step of determining whether a user has a right to receive the scrambled channel in descrambled form further comprises the steps of:

determining if the output signal is scrambled;

if the output signal is in scrambled form, then determining that the user does not have the right to receive the scrambled channel in descrambled form; and

if the output signal is not in scrambled form;

detecting, with the set top box, a first time base of the scrambled channel;

detecting, with the set top box, a second time base of the output signal;

comparing the first time base to the second time base;

if the first and second time base match, then determining that the user has the right to receive the scrambled channel in descrambled form; and

if the first and second time base do not match, then determining that the user does not have the right to receive the scrambled channel in descrambled form.

28. A method as defined in claim 27, wherein the scrambled channel and the output channel are the same channel.

29. A method as defined in claim 26, wherein the step of determining whether the user has the right to receive the scrambled channel in descrambled form further comprises the steps of:

under control of the set top box, tuning the cable box to a plurality of scrambled channels, including said scrambled channel and other scrambled channels;

examining each channel tuned by the cable box with the set top box to determine which of the plurality of scrambled channels are descrambled by the cable box;

for each channel that is descrambled by the cable box;

determining that the user has the right to receive the particular scrambled channel in descrambled form; and

enabling the set top box to descramble the particular scrambled channel; and

for each channel that is not descrambled by the cable box;

determining that the user does not have the right to receive the particular scrambled channel in descrambled form; and

disabling the set top box from descrambling the particular channel.

30. A method as defined in claim 29, wherein the step of tuning the cable box to a plurality of scrambled channels further comprises the step of periodically causing the cable box to cycle through each of the plurality of scrambled channels.

31. A method as defined in claim 29, wherein the step of examining each channel tuned by the cable box is repeated periodically.

32. A computer program product comprising one or more computer-readable media having computer-executable instructions for implementing the method recited in claim 26.

33. A computer program product for implementing a method for descrambling a scrambled channel, the computer program product comprising:

a computer readable medium carrying computer-executable instructions for implementing the method wherein the computer-executable instructions comprise;

program code means for causing a cable box to output one or more channels;

program code means for examining whether each channel output by the cable box is scrambled or descrambled;

program code means for descrambling, with the set top box, each channel the cable box is capable of descrambling; and

program code means for refraining from descrambling each channel the cable box is not capable of descrambling.

34. A computer program product as defined in claim 33, wherein the computer-executable instructions further comprise program code means for periodically examining whether the one or more channels output by the cable box are scrambled or descrambled.

35. A computer program product as defined in claim 33, wherein the computer-executable instructions further comprise:

program code means for obtaining a first time base of the scrambled channel received at a set top box;

program code means for obtaining a second time base of the output channel of the cable box;

program code means for comparing the first time base with the second time base;

program code means for descrambling the scrambled channel at the set top box if the first and second time bases match; and

program code means for refraining from descrambling the scrambled channel at the set top box if the first and second time bases do not match.