Scrambled Digital Data Item

• US 20090028331A1
• Filed: 05/03/2007
• Published: 01/29/2009
• Est. Priority Date: 05/04/2006
• Status: Active Grant

• Current Assignee: Synamedia Limited
• Original Assignee: NDS Limited (Cisco Systems, Inc.)
• Inventors: Millar, Keith, Harvey, Colin
• Granted Patent: US 9,338,405 B2
• Time in Patent Office: Days
• US Class Current: 380/255
• CPC Class Codes: H04N 21/2662 Controlling the complexity of the video stream, e.g. by scaling the resolution or bitrate of the video stream based on the client capabilities
• 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 21/4623 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 21/6125 involving transmission via Internet transmission by internet of broadcast information H04H60/82
• CPC Class Codes: H04N 21/64322 IP
• CPC Class Codes: H04N 7/1675 Providing digital key or authorisation information for generation or regeneration of the scrambling sequence pseudo-random number generators in general G06F7/58
• CPC Class Codes: H04N 7/17318 Direct or substantially direct transmission and handling of requests

Abstract

A method of decrypting a scrambled digital data item at a client is disclosed, the method including: receiving actual control messages at the client, wherein each actual control message includes control word generating information for generating a control word associated with the actual control message; storing the actual control messages at the client; receiving the scrambled digital data item at the client independently of the actual control messages, wherein the scrambled digital data item includes a plurality of segments of scrambled digital data, each segment of scrambled digital data being associated with one of the actual control messages and being scrambled with the control word associated with the one of the actual control messages, and wherein the scrambled digital data item further includes a plurality of reference control messages, each segment of scrambled digital data comprising one of the reference control messages, each of the reference control messages including a control message reference value identifying the actual control message associated with the segment of scrambled digital data; and decrypting the scrambled digital data item using the plurality of actual control messages.

Claims

1-35. -35. (canceled)

36. :

A method of decrypting a scrambled digital data item at a client, said method comprising;

receiving actual control messages at said client, wherein each actual control message comprises control word generating information for generating a control word associated with the actual control message;

storing said actual control messages at said client;

receiving said scrambled digital data item at said client independently of said actual control messages, wherein said scrambled digital data item comprises a plurality of segments of scrambled digital data, each segment of scrambled digital data being associated with one of said actual control messages and being scrambled with the control word associated with said one of said actual control messages, and wherein said scrambled digital data item further comprises a plurality of reference control messages, each segment of scrambled digital data comprising one of said reference control messages, each of said reference control messages comprising a control message reference value identifying the actual control message associated with the segment of scrambled digital data; and

decrypting said scrambled digital data item using said plurality of actual control messages without storing said scrambled digital data item at said client.

37. :

A method according to claim 36, Wherein said actual control messages are received via a multicast.

38. :

A method according to claim 36, wherein said actual control messages are received via a broadcast television network.

39. :

A method according claim 36, wherein said scrambled digital data item is received via a multicast.

40. :

A method according to claim 36, wherein said scrambled digital data item is received via a broadcast television network.

41. :

A method according to claim 36, wherein receiving said scrambled digital data item comprises receiving a portion of said scrambled digital data item.

42. :

A method according to claim 41, said method further comprising;

stopping the receiving of said portion of said scrambled digital data item whilst continuing to receive actual control messages associated with a subsequent portion of said scrambled digital data item;

receiving, via a unicast, said subsequent portion of said scrambled digital data item; and

decrypting said subsequent portion of said scrambled digital data item using said actual control messages.

43. :

A method according to claim 41, said method further comprising;

stopping the receiving of said portion of said scrambled digital data item whilst continuing to receive actual control messages associated with a subsequent portion of said scrambled digital data item;

receiving, via a unicast, actual control messages associated with a previous portion of said scrambled digital data item;

receiving, via a unicast, said previous portion of said scrambled digital data item; and

decrypting said previous portion of said scrambled digital data item using said actual control messages received via said unicast.

44. :

A method according to claim 42, wherein a command from said client causes the stopping of receiving of said portion of said scrambled digital data item.

45. :

A method according to claim 42, wherein a command from said client causes said receiving, via a unicast, of said subsequent portion of said scrambled digital data item.

46. :

A method according to claim 43, wherein a command from said client causes said receiving, via a unicast, of said previous portion of said scrambled digital data item.

47. :

A method according to claim 36, wherein said scrambled digital data item is received via a unicast.

48. :

A method according to claim 47, wherein all actual control messages associated with said scrambled digital data item are received in a single control message file.

49. :

A method according to claim 36, wherein said actual control messages are received via a multicast in advance of said scrambled digital data item, and wherein said scrambled digital data item is received via a unicast.

50. :

A method of decrypting a scrambled digital data item at a client, said method comprising;

receiving a first portion of said scrambled digital data item at said client via a broadcast as a broadcast scrambled digital data item, said broadcast scrambled digital data item comprising a plurality of broadcast control messages, each broadcast control message comprising broadcast control word generating information for generating a broadcast control word associated with the broadcast control message, said broadcast scrambled digital data item also comprising a plurality of segments of broadcast scrambled digital data, each segment of said broadcast scrambled digital data being associated with one of said plurality of broadcast control messages and being scrambled using the broadcast control word associated with said one of said broadcast control messages;

decrypting said first portion of said scrambled digital data item using said plurality of broadcast control messages without storing said first portion of said scrambled digital data item at said client;

stopping the receiving of said broadcast scrambled digital data item;

receiving actual control messages at said client, wherein each actual control message comprises control word generating information for generating a control word associated with the actual control message;

storing said actual control messages at said client;

receiving a further portion of said scrambled digital data item at said client, wherein said further portion of said scrambled digital data item comprises a plurality of segments of scrambled digital data, each segment of scrambled digital data being associated with one of said actual control messages and being scrambled with the control word associated with said one of said actual control messages, and wherein said further portion of said scrambled digital data item further comprises a plurality of reference control messages, each segment of scrambled digital data comprising one of said reference control messages, each of said reference control messages comprising a control message reference value identifying the actual control message associated with the segment of scrambled digital data; and

decrypting said further portion of said scrambled digital data item using said plurality of actual control messages without storing said further portion of said scrambled digital data item at said client.

51. :

A method according to claim 50, wherein a command from said client causes the stopping of receiving of said broadcast scrambled digital data item.