Method for access control to scrambled digital data

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SCREENED DIGITAL DATA ACCESS CONTROL PROCESS

DESCRIPTION

TECHNICAL AREA

The invention lies in the field of distribution of pre-scrambled digital data.

More specifically, the invention relates to a method of controlling access to scrambled digital data distributed to at least one user equipment and with which is associated an access control message comprising a plurality of conditional access criteria.

STATE OF THE PRIOR ART

Access control systems and methods have acquired increasing importance in recent years to meet the need for security of audiovisual programs or digital information broadcast by satellites, cable networks or terrestrial wireless networks, transmitted via the Internet or distributed as recordings on digital media such as for example DVDs (for Digital Video Disc in English).

A conditional access system addresses conditions that must be met by receiving equipment with respect to a business strategy of the service provider or DVD distributor.

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In the field of the distribution of audiovisual programs, the access control criteria used in the methods of the prior art generally relate to commercial conditions concerning the mode of distribution (subscription, reference to a session, pay-TV, etc. impulse purchase of programs ...) and possibly to additional conditions relating either to functional modes (preview, moral level, ...) or to the management of target terminals according to geographic or socio-cultural criteria for example.

A major drawback of these methods stems from the fact that when an access condition is associated with digital data, its verification is carried out only at the level of the receiving equipment item without autonomous confirmation.

Thus, in the case where the access condition relates to a reference to a geographical area of ​​use of the receiving equipment, there is no link between this reference and the effective geographical position of the user equipment. It is simply assumed that there is a high probability that the equipment will be used in the referenced geographic area. According to this principle, it is not certain that a user of a device for which access is prohibited in an area referenced in the access conditions can use this device to have access to data outside this area in s. the extent that the methods of the prior art do not provide for the possibility of verifying the position of the user equipment. Likewise, if the condition

SP 23860 / HM access relates to the user's membership of a group referenced in the access conditions, it is not possible to verify that this equipment is not used by a user who does not belong to to this group.

Moreover, in the field of satellite broadcasts, the footprint of the satellite beam does not precisely follow the border of a target area, therefore, it is difficult to manage access to programs by equipment located in locations. bordering areas in which access is prohibited.

The aim of the invention is to resolve the drawbacks described above.

DISCLOSURE OF THE INVENTION

The invention recommends a method for controlling access to scrambled digital data with which is associated an access control message comprising a geographical access condition and a plurality of other conditional access criteria, and which are distributed to a plurality of user equipments over the air, by cable, or by satellite broadcasting. This data can also be stored on digital media before being distributed to users.

The method according to the invention comprises the following steps:

a - define a plurality of geographical areas and identify each area by a geographical reference,

SP 23860 / HM b - associate with the access control message at least one reference of a geographical area defined in step a), c - calculate the real geographical position of the user equipment by means of an external positioner and transmit this position to said equipment, d - determine the zone or zones in which the user equipment is actually located from the real position calculated in step c), e - managing access to the data as a function of the access conditions of the user equipment in the zone or zones determined in step d).

By using the real geographical position calculated from location data determined outside the user equipment, as a parameter for verifying the access condition, the method according to the invention makes it possible to prevent a fraudulent modification of this position.

Preferably, to manage scrambled data in a given area, access to is assigned to each geographical area a priority level of access right to the distributed data and, either a mandatory presence condition of

The user equipment in the zone considered, that is to say a condition of compulsory absence of the user equipment of the zone considered.

Thus, if by virtue of its calculated real geographical position, exclusively in the user equipment there is an area with which is associated a

SP 23860 / HM presence condition mandatory, and if all the criteria of the access control message are verified, then data access is allowed in this actual position.

And, if, by virtue of its real geographical position, the user equipment is located exclusively in an area with which is associated a mandatory absence condition, then access to the data is prohibited in this real position.

Finally, if, by virtue of its real geographical position, the user equipment is in a region common to a group comprising at least one zone with which is associated a mandatory presence condition and at least one zone with which is associated a condition of compulsory absence, then the right of access to the data is managed according to the respective priority levels assigned to each zone of said group.

<td>In</td><td>a</td><td>first</td><td>variant</td><td>of</td><td>production,</td>

<td colspan="4">a geographical area is defined by</td><td>the</td><td>contact information</td>

<td>geographical</td><td>his</td><td>contour.</td><td></td><td></td><td></td>

<td>In</td><td>a</td><td>second</td><td>variant</td><td>of</td><td>production,</td>

<td colspan="4">a geographical area is defined by</td><td>the</td><td>contact information</td>

<td>geographical</td><td>her</td><td>position</td><td colspan="2">and by the</td><td>scription of</td>

<td>its outline.</td><td></td><td></td><td></td><td></td><td></td>

<td>To</td><td></td><td>to avoid</td><td>all</td><td></td><td>modification</td>

<td>fraudulent</td><td>the</td><td>position</td><td>real</td><td>of</td><td>The equipment</td>

<td>user,</td><td>the</td><td colspan="2">positioner</td><td colspan="2">external is</td>

<td colspan="2">functionally</td><td colspan="2">independent of</td><td>this</td><td>equipment</td>

user.

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This external positioner can be of the GPS type or any device implementing the radio location technique for example.

In a preferred embodiment of the invention, the user equipment comprises a terminal and a security processor and the scrambled digital data represents at least one audiovisual program broadcast or distributed on a recording medium. In this case, the access control message is transmitted in an ECM (for Entitlement Control Message), and the definition of the geographical areas can be transmitted to the user equipment in EMM (for Entitlement Management Message). , in English) in encrypted form, or stored in the user equipment in encrypted form.

The access control message can also be recorded in encrypted form on the recording medium or pre-loaded in the user equipment.

The invention is implemented in a system for controlling access to scrambled digital data distributed to at least one user equipment and with which is associated an access control message comprising a plurality of conditional access criteria.

This system includes:

a - means for defining a plurality of geographical areas and means for identifying each area defined by a geographical reference,

SP 23860 / HM b - means for associating with the access control message at least one reference of a defined geographical area, c - an external positioner for calculating the real geographical position of the user equipment and for transmitting this position to said equipment, d - means for determining the zone or zones in which the user equipment is actually located from the actual position

<td>calculated</td><td>through</td><td>the positioner</td><td>external, and</td><td></td><td></td>

<td></td><td>e</td><td>means</td><td>to manage</td><td>Access</td><td>to the</td>

<td>data</td><td>in</td><td>function of</td><td>conditions</td><td>access</td><td>of</td>

<td colspan="2">The equipment</td><td colspan="2">user in the area</td><td>where the</td><td>areas</td>

determined in the previous step.

The receiving equipment according to the invention comprises:

- a first module intended to determine the geographical areas in which the user equipment is actually located as a function of its real geographical position calculated by an external positioner,

a second module intended to check whether access to the data in the areas in which the user equipment is actually located is authorized or prohibited.

Preferably, the user equipment comprises a decoder and a security processor.

In a first embodiment of the invention, the first module and the second module are arranged in the decoder.

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In a second embodiment, the first module is arranged in the terminal · decoder and the second module is arranged in the security processor.

In a third embodiment, the first module and the second module are arranged in the security processor.

The digital decoder according to the invention comprises software intended to determine the geographical areas in which the

The user equipment according to the real geographical position of this equipment calculated by an external positioner, and to check if the access to the data in the zones in which is actually located

User equipment is permitted or prohibited.

The invention also relates to a computer program comprising software modules capable of implementing the steps of the method of the invention and a computer program product comprising software modules stored on a medium readable by a computer in order to implement. implement this process.

In the case where the user equipment consists of a decoder and a security processor, the latter can take the form of a smart card comprising at least one software module for controlling access to digital data.

The implementation of the method by means of this equipment supposes that the data is distributed in a plurality of predefined geographical areas to which references and levels are assigned.

SP 23860 / HM with specific priority of access rights, and each zone is assigned either a condition of mandatory presence of the user equipment in the zone considered or a condition of mandatory absence of the user equipment of the zone considered .

According to the invention, the software module integrated into the card comprises at least the following functions:

determine the zone or zones in which the user equipment is actually located

- manage the access to the data according to the access rights of the user equipment to the data in the determined zone or zones.

The software module integrated into the card can also include the following functions:

determining the actual geographic position where the user equipment is located based on geographic coordinates provided by an external positioner, determining the area or areas in which the user equipment is actually located from said actual position.

BRIEF DESCRIPTION OF THE DRAWINGS

Other characteristics and advantages of the invention will emerge from the description which follows, taken by way of non-limiting example, with reference to the appended figures in which:

FIG. 1 diagrammatically represents examples of definitions of zones according to the invention,

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FIG. 2 is a general block diagram illustrating the method according to the invention.

- Figure 3 shows a first embodiment of the invention,

- Figure 4 shows a second embodiment of the invention,

FIG. 5 represents a third embodiment of the invention.

DETAILED PRESENTATION OF PARTICULAR EMBODIMENTS

The invention will be described in the context of a particular application in which the scrambled digital data represents an audiovisual program broadcast in one or more geographical areas comprising a plurality of user equipments each provided with a decoder and a security processor. .

FIG. 1 schematically illustrates a zone 2 defined by the geographic coordinates of its contour, and zones 4 defined by the geographic coordinates of their respective positions and by the description of their respective contours.

Each of the zones 2 and 4 is identified by a reference consisting of a digital code associated with an access control message ECM transmitted in the digital stream representing the audiovisual program.

FIG. 2 schematically illustrates the steps of the method.

Before broadcasting, step 10 consists in associating with the data stream 12 to be broadcast the access control message 13 comprising in particular a geographical access criterion 14 referencing at least one of the

SP 23860 / HM numerical codes relating to predefined zones 2 and 4, and at least one access criterion of any other type 15.

On the reception side, step 16 consists in defining the real geographical coordinates of the receiving equipment item by a GPS device (for Global Positioning System in English) and in transmitting these coordinates to said equipment item. These coordinates are then used as input data of a software module which determines (step 18) in which or which of the predefined zones 2 and 4 the actual position of the user equipment is located. Another software module checks (step 20) whether one or more of the areas where the equipment is located are referenced in the access control message 13 in the geographic access criterion 14. Step 22 consists of checking whether the other criteria 15 contained in the access control message 13 are verified, and step 24 consists of authorizing or prohibiting access to the data stream 10 according to the combined results of steps 20 and 22.

This method is implemented in a system comprising a GPS positioner 23, user equipment comprising a decoder 24 and a security processor 26 (FIGS. 3 to 5).

In a first embodiment illustrated by FIG. 3, the GPS positioner 23 transmits (arrow 30) to the decoder 24 the real geographical position of the user equipment, the first module 32 of the latter determines a list of geographical areas in which is actually the user equipment, and the second

SP 23860 / HM module 34 compares said list with the references of the zones associated with the access control message provided by the security processor (arrow 36), said access control message being previously transmitted to the security processor 26 in a message ECM (38). The module 34 determines according to the result of the comparison whether access to said digital data is authorized or prohibited by taking into account the authorized or prohibited access associated with the other criteria contained in the access control message.

In a second embodiment, the GPS positioner 23 transmits (arrow 40) to the decoder 24 the real geographical position of the user equipment, the first module 42 of the latter determines a list of geographical areas in which the equipment is actually located. user and transmits (arrow 44) said list to the security processor 26. The second module 46 of the latter compares the content of said list with the references of the zones associated with the access control message to determine whether access to said digital data is authorized or prohibited, taking into account the other criteria contained in the message of. access control.

In a third embodiment, the GPS positioner 23 transmits (arrow 50) via the decoder 24 the real geographical position of the user equipment to the security processor 26, the first module 52 of the latter determines a list of geographical areas in which is actually the user equipment and the second

SP 23860 / HM module 54 of the latter compares said list with the references of the zones associated with the access control message to determine whether access to said digital data is authorized or prohibited taking into account the other criteria contained in the control message. access control.

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