Methods for providing conditional access information to decoders in a packet-based multiplexed communications system

• US 5,420,866 A
• Filed: 03/29/1994
• Issued: 05/30/1995
• Est. Priority Date: 03/29/1994
• Status: Expired due to Term

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Scientific-Atlanta Incorporated (Cisco Systems, Inc.)
• Inventors: Wasilewski, Anthony J.
• Primary Examiner(s): MARCELO, MELVIN C
• Application Number:
  US08/219,648
• Time in Patent Office: 427 Days
• Field of Search: 370/60, 370/94.1, 370/110.1, 348/460, 348/465, 348/474, 380/10, 380/20, 380/21, 380/42, 380/43, 380/47
• US Class Current: 370/426
• CPC Class Codes: H04H 60/15 on receiving information
• CPC Class Codes: H04H 60/19 on transmission of information
• CPC Class Codes: H04N 21/2347 involving video stream encryption
• CPC Class Codes: H04N 21/235 Processing of additional data, e.g. scrambling of additional data or processing content descriptors
• CPC Class Codes: H04N 21/23614 Multiplexing of additional data and video streams arrangements for simultaneous broadcast of plural pieces of information H04H20/28
• CPC Class Codes: H04N 21/2362 Generation or processing of Service Information [SI]
• CPC Class Codes: H04N 21/2365 Multiplexing of several video streams
• CPC Class Codes: H04N 21/26606 for generating or managing entitlement messages, e.g. Entitlement Control Message [ECM] or Entitlement Management Message [EMM] arrangements for conditional access to broadcast information or to broadcast-related services H04H60/14
• CPC Class Codes: H04N 21/4345 Extraction or processing of SI, e.g. extracting service information from an MPEG stream
• CPC Class Codes: H04N 21/4347 Demultiplexing of several video streams
• CPC Class Codes: H04N 21/4348 Demultiplexing of additional data and video streams
• CPC Class Codes: H04N 21/435 Processing of additional data, e.g. decrypting of additional data, reconstructing software from modules extracted from the transport stream
• 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 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 7/20 Adaptations for transmission via a GHz frequency band, e.g. via satellite

Abstract

In a packet-based multiplexed communications system, a method of providing different sets of conditional access information to a remote location comprises the steps of: (a) for each different set of conditional access information, inserting the set of conditional access information into a respective sequence of transport packets and assigning a unique packet ID to the transport packet of that sequence; (b) generating a table that specifies, for each of the different sets of conditional access information, the packet ID of the transport packets that carry that set of conditional access information; and (c) transmitting the table and the transport packets that carry each of the different sets of conditional access information to the remote location along with other information bearing transport packets. A decoder at the remote location can employ the transmitted table to identify and extract the transport packets that carry a selected one of the sets of conditional access information.

Claims

1. In a packet-based multiplexed communications system wherein a plurality of different elementary streams are each segmented and inserted into respective transport packets that are then multiplexed to form a single transport stream for transmission to a remote location, and wherein the elementary streams are separately and uniquely encrypted prior to transmission, and wherein encryption related information specific to each elementary stream is generated and must be provided to the remote location for decryption purposes, and further wherein different combinations of elementary streams define a plurality of different programs, a method of providing the encryption related information for each elementary stream to the remote location comprising the steps of:

a) for each elementary stream, inserting the encryption related information for that elementary stream into a respective sequence of transport packets;

b) generating, as part of a program map table that specifies, for each of said different programs, which of said elementary streams comprise said each program, a table that specifies, for each elementary stream of each program, which of the transport packets generated in step (a) carry the encryption related information for that elementary stream; and

c) transmitting the program map table and the transport packets that carry the encryption related information for each elementary stream to the remote location as part of the transport stream along with the transport packets that carry the encrypted data of each elementary stream,

whereby a decoder at the remote location can access the program map table to identify which elementary streams comprise a program selected by a user at that location, as well as to identify which transport packets transmitted in step (c) carry the encryption related information for the elementary streams of the selected program.

2. The method recited in claim 1 wherein step (a) further comprises, for each elementary stream, assigning a unique packet ID to the encryption related information for that elementary stream and inserting the assigned packet ID is a header section of each transport packet that carries a portion of the encryption related information for that elementary stream.

3. The method recited in claim 2 wherein said table specifies, for each elementary stream, the packet ID of the transport packets that carry the encryption related information for that elementary stream.

4. In a packet-based multiplexed communications system in which a plurality of different elementary streams are each segmented and inserted into respective transport packets that are then multiplexed to form a single transport stream for transmission to a plurality of different remote locations, each remote location employing a decoder, each decoder operating in accordance with one of a plurality of different conditional access systems, wherein different sets of conditional access information specific to each of the different conditional access systems must be provided to the remote locations, a method of providing the different sets of conditional access information to the remote locations comprising the steps of:

a) for each of said conditional access systems;

i) inserting a set of conditional access information specific to that conditional access system into a respective sequence of transport packets;

ii) assigning a unique packet ID to the set of conditional access information and inserting the unique packet ID in a header section of each transport packet in the respective sequence;

b) generating a conditional access table that specifies, for each of said different conditional access systems, the packet ID of the transport packets that carry the set of conditional access information specific to that conditional access system; and

c) transmitting the conditional access table and the transport packets that carry each of the different sets of conditional access information to the remote location along with the transport packets that carry the different elementary streams,

whereby a decoder at a remote location, which operates in accordance with one of said different conditional access systems, can employ the transmitted conditional access table to identify and extract the transport packets that carry the set of conditional access information specific to the conditional access system upon which that decoder operates.

5. The method recited in claim 4 wherein each of said different sets of conditional access information comprises a plurality of Entitlement Management Messages unique to a particular one of said different conditional access systems.

6. The method recited in claim 4 further comprising the steps of:

i) assigning a unique conditional access system identifier (CA_-- System_-- ID) to each of the conditional access systems in operation within the communications system; and

ii) providing each decoder in the communications system with the CA_-- System_-- ID of the conditional access system in accordance with which that decoder operates.

7. The method recited in claim 6 wherein said conditional access table comprises a plurality of entries, one entry for each conditional access system in operation within the communications system, each entry of the conditional access table comprising a first identifier that specifies the CA_-- System_-- ID of the conditional access system to which the entry pertains, and a second identifier that specifies the packet ID of the transport packets that carry conditional access information specific to the conditional access system identified by the CA_-- System_-- ID of that entry.

8. In a packet-based multiplexed communications system wherein a plurality of different elementary streams are each segmented and inserted into respective transport packets that are assigned a unique packet ID and then multiplexed to form a single transport stream for transmission to a remote location, different combinations of said elementary streams defining a plurality of different programs, and wherein the elementary streams are separately and uniquely encrypted prior to transmission and, for each elementary stream, encryption related information necessary for decrypting that elementary stream is inserted into a respective sequence of transport packets also being assigned a unique packet ID, and further wherein a program map table is transmitted in the transport stream that specifies, for each of said different programs, the packet IDs of the transport packets that carry each of the elementary streams that comprise said each program, said program map table further specifying, for each elementary stream of each program, the packet ID of the transport packets that carry the encryption related information for that elementary stream, a method of accessing a selected program for output at a remote location comprising the steps of:

a) receiving the transport stream at the remote location and retrieving the program map table from the received transport stream;

b) identifying from the program map table the packet IDs of the transport packets that carry the elementary streams of the selected program, and also identifying from the program map table the packet IDs of the transport packets that carry the encryption related information necessary for decrypting each elementary stream of the selected program;

c) extracting from the received transport stream the transport packets having the packet IDs identified in step (b) in order to retrieve and decrypt the elementary streams of the selected program for output at the remote location.

9. In a packet-based multiplexed communications system in which a plurality of transport packets are multiplexed to form a single transport stream for transmission to a plurality of different remote locations, each remote location employing a decoder and each decoder operating in accordance with one of a plurality of different conditional access systems, each conditional access system having a unique identifier (CA_-- System_-- ID) associated therewith and each decoder being provided with the CA_-- System_-- ID of the conditional access system in accordance with which it operates, and wherein, for each conditional access system, conditional access information specific to that conditional access system is transmitted to each remote location in a respective sequence of transport packets having a unique packet ID, and further wherein a conditional access table is transmitted in the transport stream that specifies, for each conditional access system operating in the communications system, the packet ID of the transport packets that carry the conditional access information specific to that conditional access system, a method of retrieving at a decoder the conditional access information specific to the conditional access system in accordance with which the decoder operates, said method comprising the steps of:

a) receiving the transport stream at the remote location;

b) accessing the conditional access table transmitted in the transport stream with the CA_-- System_-- ID provided to the decoder to identify the packet ID of the transport packets that carry conditional access information specific to the conditional access system of that decoder; and

c) extracting from the transport stream the transport packets having the packet ID identified in step (b) in order to obtain the conditional access information specific to the conditional access system of the decoder.