Interactive video distribution systems – Access control or blocking – With encryption or scrambling of video signal
Reexamination Certificate
1998-10-28
2002-11-26
Faile, Andrew (Department: 2611)
Interactive video distribution systems
Access control or blocking
With encryption or scrambling of video signal
C725S025000, C380S210000, C380S240000
Reexamination Certificate
active
06487720
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a digital broadcast signal receiving apparatus for receiving a digital broadcast signal including both watch-unable digital broadcast information indicating a television program and broadcast-watching enabling information, which enables a user to watch the television program, from a sender, converting the watch-unable digital broadcast information into watch-enabled digital broadcast information indicating the television program and outputting the watch-enabled digital broadcast information. Also, the present invention relates to a digital information recording and reproducing apparatus in which the watch-unable digital broadcast information of the digital broadcast signal transmitted from the sender is converted into the watch-enabled digital broadcast information and the watch-enabled digital broadcast information is reproduced.
2. Description of the Related Art
2.1. Previously Proposed Art
Data, information and keys generally included in a digital broadcast signal are described with reference to
FIGS. 1 and 2
.
FIG. 1
is a block diagram of a digital broadcast sending system from which a multiplexed digital broadcast signal including both pieces of digital broadcast information indicating television programs and broadcast-watching enabling information is transmitted to a plurality of receivers in the form of a transport stream according to a Moving Picture Experts Group 2 (MPEG 2).
As shown in
FIG. 1
, a digital broadcast sending system
100
of a sender comprises:
a plurality of signal processing units
101
a
,
101
b
, ------, arranged in parallel to each other, for respectively producing digital broadcast information including audio/video data of a television program;
an enciphering unit
121
for enciphering a work key Kw used to encipher attribute information of the television programs and enciphering contract information of each receiver (or viewer); and
a multiplexing unit
122
for performing the time-division multiplexing for the pieces of digital broadcast information produced in the signal processing units
101
a
,
101
b
, ------, the work key Kw and the contract information enciphered in the enciphering unit
121
, an electronic program guide (EPG) prepared in a broadcast scheduler (not shown) and specific information added by the sender and outputting packets of multiplexed digital broadcast signal.
In each signal processing unit
101
of this digital broadcast sending system
100
, video/audio data of a television program P
1
, P
2
, ------, or Pk are compressed in compression units
102
according to a compression format of the MPEG 2, the compressed video/audio data of the television program P
1
are divided into a series of packetized elementary stream (PES) packets in a PES packet unit
103
. Also, character data indicating characters to be displayed in a teletext broadcasting is divided into another series of PES packets in the PES packet unit
103
, and the time-division multiplexing is performed for the PES packets.
Thereafter, because the sender desires that the television programs P
1
, P
2
, ------, and Pk are watched by a plurality of limited viewers who contract with the sender to watch television programs transmitted by the sender, information of the PES packets is scrambled in a scrambling unit
104
by using a scramble key Ks.
Thereafter, as shown in
FIG. 2
, each scrambled PES packet is divided into a plurality of transport stream (TS) packets in a TS packet unit
105
. Each TS packet has a data length of 188 bytes and is composed of a TS packet header of 4 bytes and an adaptation field and/or a payload of 184 bytes, and each scrambled PES packet is inserted into regions of the payloads of the TS packets. Each television program inserted into the TS packets is identified by a packet identification PID written in the TS packet header of each TS packet.
Also, the scramble key Ks and attribute information of the television program P
1
, P
2
, ------, or Pk are enciphered according to a work key Kw in an enciphering unit
106
to produce an entitlement control message ECM, and the entitlement control message ECM is divided into a plurality of TS packets in the TS packet unit
105
. The entitlement control message ECM indicates information common to all receivers, and an example of the message ECM is shown in FIG.
3
.
In the enciphering unit
121
, the work key Kw and contract information of each receiver are enciphered to produce an entitlement management message EMM, and the entitlement management message EMM is divided into a plurality of TS packets. The message EMM is identified by a prescribed packet identifier arranged in each TS packet header. The entitlement management message EMM indicates individual information corresponding to each receiver, and an example of the message EMM is shown in FIG.
4
.
Thereafter, the time-division multiplexing is performed in the multiplexing unit
122
for the pieces of digital broadcast information arranged in the TS packets in the signal processing units
110
a
,
101
b
, ------, and
101
k
and the entitlement management message EMM arranged in the TS packets, and the time-division multiplexed TS packets are output from the system
100
to a digital information recording and reproducing apparatus of each receiver as TS packets of a multiplexed digital broadcast signal.
In addition to the entitlement management message EMM, the sender can send an electronic program guide (EPG) prepared in a broadcast scheduler (not shown) and specific information added by the sender with the TS packets of the multiplexed digital broadcast signal. In this case, the electronic program guide and the specific information added by the sender are inserted into a series of TS packets defined by the sender. For example, in cases where the sender desires to change an algorithm of an enciphering method to a new algorithm and to send television programs enciphered according to the new algorithm to a group of limited receivers, control software installed in a receiving apparatus of each limited receiver is rewritten to new control software according to the specific information added by the sender to decipher the enciphered television programs received by the limited receiver according to the new control software. In this case, because the entitlement management message EMM and the specific information added by the sender are correctly processed in receiving apparatuses of a plurality of limited receivers, a group of limited receivers can watch television programs sent by the sender. Therefore, the entitlement management message EMM and the specific information added by the sender are called “broadcast-watching enabling information” in this specification.
Because updated broadcast-watching enabling information included in the packets of the multiplexed digital broadcast signal is intermittently sent to a group of limited receivers who formally contract with a television program sender, the broadcast-watching enabling information can be used by the group of limited receivers. Therefore, in cases where a contract of a receiver with a sender is, for example, canceled because the receiver does not pay the sender for a charge, updated broadcast-watching enabling information included in the packets of the multiplexed digital broadcast signal is not sent to the receiver any more. In this case, because the updated broadcast-watching enabling information is required to correctly decipher television programs transmitted from the sender, the receiver cannot watch any television program.
Also, even though a receiver formally contract with a sender, in cases where particular updated broadcast-watching enabling information transmitted from the sender cannot be received by the receiver because of a stoppage of electric power supplied to a receiver's apparatus, the receiver cannot watch any television program transmitted from the sender. In this case, the receiver informs the sender that the receiver cannot watch any television program transmitted from the
Anderson Kill & Olick
Brown Reuben M.
Faile Andrew
Lieberstein Eugene
Meller Michael N.
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