초록 ▼

An encryption arrangement for multiple encryption of television programs. A system according to embodiments of the present invention multiple encrypts only a portion of the data required for full presentation of a television program to permit coexistence of multiple conditional access encryption sys

An encryption arrangement for multiple encryption of television programs. A system according to embodiments of the present invention multiple encrypts only a portion of the data required for full presentation of a television program to permit coexistence of multiple conditional access encryption systems associated with multiple manufacturer's set-top boxes within a single system. In one embodiment, only audio data are encrypted leaving video in the clear. By only encrypting a portion of the program, dramatically less bandwidth is consumed than the alternative of multiple encryption of all program data, thus permitting a larger number of programs to be carried over the same bandwidth while permitting coexistence of multiple conditional access systems in a single cable television system.

대표청구항 ▼

What is claimed is: 1. A method of encrypting a digital television signal, comprising: encrypting data representing an audio portion of the television signal according to a first encryption method to produce a first encrypted audio portion and encrypting a duplicate of the data representing the aud

What is claimed is: 1. A method of encrypting a digital television signal, comprising: encrypting data representing an audio portion of the television signal according to a first encryption method to produce a first encrypted audio portion and encrypting a duplicate of the data representing the audio portion according to a second encryption method to produce a second encrypted audio portion; combining an unencrypted video portion of the television signal with the first and second encrypted audio portions to produce the encrypted digital television signal; and transmitting the encrypted digital television signal comprising the unencrypted video portion and the encrypted first and second audio portions. 2. The method according to claim 1, wherein the encrypting comprises encrypting packets identified as audio packets. 3. The method according to claim 2, wherein the digital television signal complies with an MPEG standard, and wherein the audio packets are identified for encryption by a packet identifier (PID). 4. The method according to claim 2, wherein the digital television signal complies with a digital satellite service (DSS) transport standard, and wherein the audio packets are identified for encryption by a service channel identifier (SCID). 5. The method according to claim 2, wherein audio packets encrypted according to the first encryption method are assigned a first packet identifier and audio packets encrypted according to the second encryption method are assigned a second packet identifier. 6. The method according to claim 5, wherein the first packet identifier and the second packet identifier are referenced as primary elementary packet identifiers (PIDs) in a program map table (PMT). 7. The method according to claim 5, wherein the first packet identifier is referenced as a primary elementary packet identifier (PID) in a program map table (PMT) and the second packet identifier is referenced as a secondary elementary packet identifier (PID) in the program map table (PMT). 8. The method according to claim 5, wherein the first encrypted audio portion and the second encrypted audio portion are distributed over one of a terrestrial broadcast system, a satellite system and a cable system. 9. The method according to claim 8, further comprising distributing system information to provide locating information used to locate the first and second encrypted audio portions. 10. The method according to claim 9, further comprising combining encrypted system information with the video portion and first and second encrypted audio portions. 11. An electronic storage medium storing instructions which, when executed on a programmed processor, carry out the method of encrypting a television signal according to claim 1. 12. An encrypted television signal stored in electronic transmission readable-medium encrypted by the method according to claim 1. 13. A method of multiple encrypting a digital television signal, comprising: encrypting data representing an audio portion of the television signal according to a first encryption method to produce a first encrypted audio portion; encrypting a duplicate of the data representing the audio portion of the television signal according to a second encryption method to produce a second encrypted audio portion; combining the first encrypted audio portion and the second encrypted audio portion with an unencrypted video portion of the television signal to produce a multiple partially encrypted digital television signal; and transmitting the multiple partially encrypted digital television signal comprising the unencrypted video portion and the first and second encrypted audio portions. 14. The method according to claim 13, wherein the multiple encrypting comprises encrypting packets identified as audio packets. 15. The method according to claim 14, wherein the digital television signal complies with an MPEG standard, and wherein the audio packets are identified for multiple encryption by a packet identifier (PID). 16. The method according to claim 13, further comprising distributing the multiple partially encrypted television signal over one of a cable system, a terrestrial broadcast system and a satellite system. 17. The method according to claim 16, further comprising transmitting system information to provide locating information used to locate the first encrypted audio portion. 18. The method according to claim 17, further comprising encrypting the system information. 19. The method according to claim 13, further comprising partially encrypting the unencrypted video portion of the television signal. 20. An electronic storage medium storing instructions which, when executed on a programmed processor, carry out the method of encrypting a television signal according to claim 13. 21. A multiple encrypted television signal stored in electronic transmission readable-medium encrypted by the method according to claim 13. 22. A digital television receiver device, comprising: a receiver receiving a dual partially encrypted television signal, the dual partially encrypted television signal comprising audio packets containing audio data encrypted under a first encryption algorithm and duplicate audio packets containing a duplicate of the audio data encrypted under a second encryption algorithm; a decrypter that receives encrypted audio packets encrypted under the first encryption algorithm from the receiver and decrypts the encrypted audio packets; and a decoder that receives and decodes the decrypted audio packets, and that receives and decodes unencrypted video packets to produce a television signal as an output signal suitable for play on a television receiver. 23. The digital television receiver device according to claim 22, wherein the receiver further receives and discards audio packets encrypted under a second encryption algorithm. 24. A cable system headend, comprising: a first encryption system that encrypts data in audio packets using a first encryption algorithm; a second encryption system that encrypts data in duplicates of said audio packets using a second encryption algorithm; and means for distributing an output stream of packets representing a dual partially encrypted television program over a cable television system, the stream of packets comprising video packets or audio packets encrypted under the first encryption algorithm, and duplicates of said audio packets encrypted under the second encryption algorithm and system information packets. 25. The cable system headend according to claim 24, wherein the video packets are unencrypted. 26. The cable system headend according to claim 24, wherein the system information packets are unencrypted. 27. The cable system headend according to claim 24, wherein the video packets are partially encrypted. 28. The cable system headend according to claim 24, wherein the system information packets are encrypted. 29. A method of decoding a multiple partially encrypted television signal, comprising: receiving a television signal having a multiple encrypted audio portion and a clear video portion, wherein the multiple encrypted audio portion comprises a first encrypted audio portion having audio data encrypted under a first encryption method and a second encrypted duplicate audio portion having a duplicate of said audio data encrypted under a second encryption method; decrypting the first encrypted audio portion to produce a decrypted audio portion; and decoding the decrypted audio portion and the clear video portion to produce a decoded television signal as an output signal. 30. The method according to claim 29, wherein the decoded signal is suitable for play on a television set. 31. The method according to claim 29, wherein the first encrypted audio portion is identified by a first packet identifier (PID) associated with a first decryption algorithm used for decrypting the first encrypted audio portion and the second encrypted audio portion is identified by a second packet identifier (PID) associated with a second decryption algorithm used for decrypting the second encrypted audio portion. 32. The method according to claim 31, wherein the first PID is a secondary PID and wherein the second PID is a primary PID. 33. The method according to claim 31, wherein the first PID is a primary PID and wherein the second PID is a secondary PID. 34. The method according to claim 29, carried out in one of an integrated circuit and a programmable logic device. 35. The method according to claim 29, carried out in one of an application specific integrated circuit and a field programmable gate array. 36. The method according to claim 29, carried out in a television device. 37. The method according to claim 29, carried out in a television set-top box. 38. A method of decoding a partially encrypted television signal, comprising: receiving a television signal having a first encrypted audio portion, a second encrypted audio portion and a clear video portion, the first audio portion being identified by a first packet identifier (PID), and the second audio portion being identified by a second PID, the second audio portion comprising data that is a duplicate of data contained in the first audio portion when the first and second audio portions are unencrypted; discarding the second encrypted audio portion by PID filtering; decrypting the first encrypted audio portion to produce a decrypted audio portion; and decoding the decrypted audio portion and the clear video portion to produce a decoded output signal. 39. The method according to claim 38, wherein the decoded signal is suitable for play on a television set. 40. The method according to claim 38, wherein the first PID is a secondary PID and wherein the second PID is a primary PID. 41. The method according to claim 38, wherein the first PID is a primary PID and wherein the second PID is a secondary PID. 42. The method according to claim 38, carried out in an integrated circuit. 43. The method according to claim 38, carried out in one of an application specific integrated circuit and a field programmable gate array. 44. The method according to claim 38, carried out in a television device. 45. The method according to claim 38, carried out in a television set-top box. 46. A method of encrypting a television signal, comprising: encrypting data representing a video portion of the television signal according to a first encryption method to produce a first encrypted video portion; encrypting a duplicate of the data representing said video portion according to a second encryption method to produce a second encrypted video portion; combining an unencrypted audio portion of the television signal with the first and second encrypted video portions; and transmitting the encrypted television signal comprising the first and second encrypted video portions and the unencrypted audio portion. 47. The method according to claim 46, wherein the television signal is a digital television signal, and wherein the encrypting comprises encrypting packets identified as video packets. 48. The method according to claim 47, wherein the digital television signal complies with an MPEG standard, and wherein the video packets are identified for encryption by a packet identifier (PID). 49. The method according to claim 47, wherein the digital television signal complies with a digital satellite service (DSS) transport standard, and wherein the video packets are identified for encryption by a service channel identifier (SCID). 50. The method according to claim 47, wherein video packets encrypted according to the first encryption method are assigned a first packet identifier and video packets encrypted according to the second encryption method are assigned a second packet identifier. 51. The method according to claim 50, wherein the first packet identifier and the second packet identifier are referenced as primary elementary packet identifiers (PIDs) in a program map table (PMT). 52. The method according to claim 50, wherein the first packet identifier is referenced as a primary elementary packet identifier (PID) in a program map table (PMT) and the second packet identifier is referenced as a secondary elementary packet identifier (PID) in the program map table (PMT). 53. The method according to claim 50, wherein the first encrypted audio portion and the second encrypted audio portion are distributed over one of a terrestrial broadcast system, a satellite system and a cable system. 54. The method according to claim 53, further comprising distributing system information to provide locating information used to locate the first and second encrypted video portions. 55. The method according to claim 54, further comprising combining encrypted system information with the audio portion and the first and second encrypted video portions. 56. An electronic storage medium storing instructions which, when executed on a programmed processor, carry out the method of encrypting a television signal according to claim 46. 57. An encrypted television signal stored in electronic transmission readable-medium encrypted by the method according to claim 46. 58. A method of multiple encrypting a television signal, comprising: encrypting data representing a video portion of the television signal according to a first encryption method to produce a first encrypted video portion; encrypting a duplicate of the data representing said video portion of the television signal according to a second encryption method to produce a second encrypted video portion; combining the first encrypted video portion and the second encrypted video portion with an unencrypted audio portion of the television signal to produce a multiple partially encrypted television signal; and transmitting the multiple partially encrypted television signal comprising the first and second encrypted video portions and the unencrypted audio portion. 59. The method according to claim 58, wherein the television signal is a digital television signal, and wherein the multiple encrypting comprises encrypting packets identified as video packets. 60. The method according to claim 59, wherein the digital television signal complies with an MPEG standard, and wherein the video packets are identified for multiple encryption by a packet identifier (PID). 61. The method according to claim 59, further comprising distributing the multiple partially encrypted television signal over one of a cable system, a terrestrial broadcast system and a satellite system. 62. The method according to claim 61, further comprising transmitting system information to provide locating information used to locate the first encrypted video portion. 63. The method according to claim 62, further comprising encrypting the system information. 64. The method according to claim 58, further comprising partially encrypting the unencrypted audio portion of the television signal. 65. An electronic storage medium storing instructions which, when executed on a programmed processor, carry out the method of encrypting a television signal according to claim 58. 66. A multiple encrypted television signal stored in electronic transmission-readable medium encrypted by the method according to claim 58.