Cryptography – Video cryptography – Video electric signal modification
Reexamination Certificate
1999-02-19
2001-10-23
Peeso, Thomas R. (Department: 2132)
Cryptography
Video cryptography
Video electric signal modification
C380S211000, C713S169000, C713S168000
Reexamination Certificate
active
06307939
ABSTRACT:
DESCRIPTION
1. Technical Domain
The purpose of this invention is a process and equipment for assigning a complementary conditional access to a television program already in conditional access.
New television systems are accompanied by the use of several conditional access systems. The term “television” is taken in a broad sense including radio broadcast or data broadcast programs. Throughout the rest of this document, a “television system” will be used to refer to technical aspects of the television signal; coding modes for images, sound and data, service descriptions, detailed signal syntax, modulation parameters, etc. A “conditional access system” will be used to denote the set of functions affecting a television signal to express its marketing modes; scrambling methods, functions and syntax of messages related to program marketing modes, etc.
The use of these digital techniques to build up a television signal, either in full (as in standard MPEG2/DVB) or in part (as in the D2-MAC/Packet multiplex packet*****), provides considerable flexibility in the choice of a conditional access system. In particular, it is now possible to make several conditional access signals coexist in the same signal, and this is even one of the important functions to be included when defining a new television system.
This need arises because the conditional access system is of overriding importance for an operator in his program marketing choices, since this type of system must allow him to express his marketing strategy (subscription, pay per view, etc.) and is accompanied with a complete technical environment (commercial user management, electronic program guide, installed terminals, etc.) guaranteeing him control over exclusiveness of his clientele. Similarly, a signal that becomes a multi-service signal naturally also becomes a multi-conditional access system.
The most widespread application of conditional access to a television system concerns the assignment of a conditional access signal to each service transported in a signal. This process is already implicitly used in single-service analog systems (DISCRET, SYSTER, VIDEOCRYPT, CRYPTOVISION systems, etc., in NTSC, PAL or SECAM) and is being generalized to digital multi-service systems; in the MPEG2/DVB standard, this process is called MULTICRYPT. Although it does enable independence of operators responsible for different services within the same signal, it becomes restrictive for users who need several decoders, or several multiple conditional access modules that are plugged into a more general terminal when required, if he wants to access several programs; thus, the MPEG2/DVB standard has defined a common scrambling algorithm and has defined and detailed the concept of a common conditional access interface for the terminals.
A process such as MULTICRYPT is applied at the same time as a television signal encoding function combining an encoder, multiplexer, a scrambler, and means of insertion of conditional access data.
FIG. 1
attached illustrates this process. It diagrammatically shows an operator A supplying a service composed of components
1
and marketing it according to methods
1
, and an operator B supplying a service composed of components
2
and marketing it by means of methods
2
. Marketing of these components is applied in equipment
10
, which is an encoder/scrambler/multiplexer. Blocks
12
and
14
diagrammatically show programs
1
and
2
with their conditional access conditions specific to operators A and B. The resulting television signal is of the MULTICRYPT type.
This embodiment may also be carried out or extended by a transcontrol function that modifies the conditional access level to a previously formed signal. This is illustrated in attached FIG.
2
. The television signal composed of programs
1
and
2
with their conditional access systems A and B respectively shown diagrammatically by blocks
12
and
14
, is input into a transcontroller
20
controlled by an operator C. This circuit deletes the access conditions A and B to programs
1
and
2
respectively, and replaces them by new access conditions C. The result is two new programs with a conditional access system C, shown diagrammatically by blocks
22
and
24
respectively.
Examples of a transcontroller are described in documents EP-A-0 461 029 and EP-A-0 666 694.
Another process may be used, which enables various commercial populations (in other words different terminals) access to the same program, provided that the various operators concerned have reached an agreement on how to share this service. This process is already used in D2-MAC/Packet and is called SIMULCRYPT in the MPEG2/DVB system, and it consists of associating several different conditional access systems with the same program, each of these systems being under the responsibility of an operator and allowing each operator to define his own marketing policy for the same program. Although strictly speaking this term relates to application of this process to MPEG2/DVB, this association of several conditional access systems to a single program will be referred to as “SIMULCRYPT” in this document for simplification purposes, regardless of the target supporting television system.
A process such as SIMULCRYPT is usually applied at the same time as the television signal encoding function. The purpose of this invention is a process and equipment for assigning data describing marketing through a second conditional access system, for a program that is already marketed through a first conditional access system. This equipment will be called “SIMULCRYPTEUR” throughout the rest of this document, with reference to the SIMULCRYPT process defined in the MPEG2/DVB standard, but it can be adapted to different television systems and different conditional access systems.
2. State of Prior Art
In a television signal, a program associated with a conditional access system makes use of several entities:
components: this refers to information flows representing images, sound, teletext data, etc.; all these components make up the technical aspect of the program and materialize the audiovisual contents themselves; components may be scrambled independently of each other;
access entitlement control message service: this includes all messages usually called ECM messages (Entitlement Control Messages); these messages are composed of data expressing routine marketing conditions for the service to which they are associated and called “access conditions”; consequently, they usually operate in real time due to their synchronization with the current program, particularly in pay per view; data for these messages are permanently compared with entitlements acquired by the terminal user, a positive comparison triggering access to the program by unscrambling the selected components; the ECM messages also transport parameters (or parameter references) which particularize the operation of scrambling and unscrambling algorithms; these parameters are commonly referred to as the CW (Control Word);
the access entitlement management message service: this is a set of messages commonly called EMM “Entitlement Management Messages”; these messages are composed of data managing entitlements acquired by the user; they are used mainly for registration of entitlements purchased by the user (subscriptions, credit units, etc.) on his terminal (or the associated security processor); apart from the fact that an entitlement has to be effectively registered before the need for this entitlement appears (comparison with ECM), these messages do not require fine synchronization with the program since the EMM/program link is more logical than operational;
links between components and access conditions: each component of a program may be marketed according to specific methods, or may be even broadcast without being encoded; similarly, several components may be marketed in the same way, in other words may share the same access conditions; since these links between components/access conditions are not defined in advance and are left to the judgment of the program
France Telecom
Jack Todd
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Peeso Thomas R.
LandOfFree
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