OA12034A - Mechanism of pairing between a receiver and a security module. - Google Patents

Abstract

The invention concerns a system for controlling data transmission between a receiver and a security module, in particular for a pay television system, wherein the transmitted data are encrypted and decrypted by means of an encryption key, stored in the receiver and in the security module.

Description

12 0 34 -1 -

MECHANISM OF MATCHING

BETWEEN A RECEIVER AND A SECURITY MODULE

TECHNICAL AREA

The invention relates to an information transfer control system between a receiver and a security module, especially for a pay-TV system, and a method for controlling the transfer of scrambled information.

BACKGROUND OF THE INVENTION

A pay-TV descrambling system is composed of a receiver and a security module. This module can be detachable or fixed. The receiver's mission is to unravel the signals received. The main purpose of the security module is to check the operation verifying the descrambling authorization and providing, if necessary, the information necessary for the operation of the descrambling module, for example by providing descrambling vectors called "controlword".

Existing systems use receivers that interrogate their security modules, and these respond by providing the necessary information for descrambling. At a given time, for the same program broadcast, all the security modules answer the same information. Since the information flowing between the security module and the receiver is of low speed (of the order of 20 to 30Oct / sec), fraudsters can use this information for public dissemination, for example via the Internet.

Such a system is illustrated in the document "DVD ConditionalAccess" written by David Cutts in the journal "Electronics & CommunicationEngineering Journal" of February 1997. It is described a standardized system

DUPLICATA -2- 12 0 3 4 for unscrambling video and audio streams from several service providers. The security module, called CA (conditional access) is responsible for delivering the CW control words. This module may incidentally use a smart card for the descrambling function. Once the information is unscrambled in the CA module, the control words CW are returned to the decoder to obtain the information in the clear.

In an earlier publication entitled "Conditional AccessBroadcasting: Datacare 2, an Over-Air Enabled System for General Purpose Data Channels," published August 1, 1988 in the BBCResearch and Development Report No. 10, there is described an independent module (Conditional Access Module) in charge of receiving and decoding the information necessary for descrambling. This module manages the keys specific to the system and delivers the control words indispensable for descrambling video broadcasts. In this type of module, once the controlwords are decrypted, they are sent in clear to the unit in charge of the scrubbing. . The problem then arises of making a receiver and a security module interdependent so that: the given security module can only be used in the receiver for which said security module has been provided; the information flow exchanged between the security module and the receiver is unique. This uniqueness prevents the public broadcast of this stream from allowing other receivers to work without the security module provided for this purpose.

SUMMARY OF THE INVENTION

The solution proposed for the problems mentioned above uses at least one encryption key specific to the receiver. This (or these) key (s) is (are) called the matching key. At least one of the keys is different for each receiver. This (or these) key (s) is (are) installed

DUPLICATE -3- 12 0 3 4 in the non-volatile memory of the receiver, either to the manufacture of said receiver or to a subsequent step. The receiver does not provide the outside world with any means of access to this (or these) key (s).

One possible way to program this key in the security module is to use the central information system that manages the receiver park and can drown in the flow of the video transmission of information for the programming of this key in the nonvolatile and secret memory security modules. The formatting of this procedure is of course kept secret.

When a transfer of sensitive information and / or necessary to the operation of the system of the security module to the receiver (typically "control words", but other information can be transferred as well), the security module encrypts this information to the with one or more unique pairing keys, common to only the receiver / security module. The encryption method is some but known to the security module, and the receiver knows the corresponding decryption method. Once received by the receiver, this information is then decrypted by the said receiver using the known decryption method and the pairing key stored in its non-volatile memory. The said information is then enlightened and usable by the said receiver. The invention thus proposes an information transmission control system between a receiver and a security module, especiallyfor a pay-TV system, where the transmitted information is encrypted and decrypted by means of at least one unique encryption key, stored on the one hand in the receiver, and on the other hand in the security module. The invention also relates to a scrambled information scrambling system and a pay-TV system having a transmission control system.

On the other hand, the invention relates to a method for controlling transmission of information between a receiver and a security module, particularly for a pay-TV system, characterized in that it stores at least one unique encryption key, on the one hand in the receiver, and on the other hand in the security module, and that encrypts and decrypts the information transmitted between the receiver and the security module by means of at least one said unique encryption key.

This solution according to the invention answers the problems posed. Indeed: - a security module inserted in a receiver other than the one with which said security module has been paired will provide this other receiver a flow of sensitive information and / or necessary to the operation of the encrypted system with a key not corresponding to that used to decipher it. The result is then unusable; a flow of information that is sensitive and / or necessary for the operation of the system from a security module can not be distributed to several receivers. Only the matched receiver with the map providing this flow of sensitive and / or necessary information is able to decipher the said stream successfully.

The system may include a matching check mechanism. The central information system can register a personal number to the receiver in the security module paired with the receiver, for example generated randomly by the latter, or simply use its serial number. A means is offered to the receiver to freely check this personal number entered in the security module and compare it to that stored in its non-volatile memory.

This mechanism has the advantage of not using clean data. The result of an encryption followed by decryption by a clifferent usually provides a pseudo-random result. If the result is not recognized as false and this result is used as is, it

DUPLICATA 12 0 3 4 -5- may result in damage to the receiver or devices connected to it.

Some types of receivers have a detachable detachment module. This module supports a number of operations including the descrambling operation of the received signals. The transfer of sensitive information then takes place between the detachable security module and this detachable descrambling module. The encryption mechanism of the communication described above between a receiver and a security module is then reported as such between the detachable security module and the detachable descrambling module.

In the same way, the pairing mechanism described above between the security module and the receiver is then transferred as such between the detachable security module and the detachable descrambling module.

A descrambled signal transfer then takes place between the detachable descrambling module and the receiver. The communication encryption mechanism as well as the pairing mechanism described above between the security module and the receiver is then reported as such between the receiver and the detachable descrambling module.

The functions performed by the detachable descrambling module and the detachable security module can be performed by a single module called a descrambling and detachable security module. The pairing mechanism previously described is then reported as such between the detachable descrambling and security module and the receiver.

In all the cases described above, the pairing key (s) may be used to encrypt a flow of sensitive data and / or necessary to the operation of the system in the opposite direction, by respectively interregulating: receiver and detachable security module; - detachable descrambling module and security module

DUPLICATE -6 12 0 34 detachable; receiver and detachable descrambling module; receiver and descrambling and detachable security module.

In all cases where a pairing key is unique to a device (receiver or detachable module), the same principles apply to the use of one or more matching key (s) group of devices.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1 illustrates a configuration implementing a receiver and a detachable security module.

Figure 2 illustrates a configuration implementing a receiver, a detachable descrambling module and a detachable security module.

Figure 3 illustrates a configuration implementing a receiver and a detachable descrambling and security module.

DETAILED DESCRIPTION

Receiver A of Figure 1 receives a video-scrambled information stream 1 from a source such as a satellite or cable receiver. This flow, of the order of several megabits per second, is formatted in the receiver A and then transmitted to a control unit B which is responsible for scrambling and managing the access authorization to the scrambled video information. For this purpose, this control unit B interrogates the detachable security module C (channel 3) which responds to it by a flow of sensitive data and / or necessary for the operation of the control unit B (channel 4). These exchanges are at low rates and can be easily handled by the microprocessors of smart cards available on the market. According to the invention, the detachable security module C comprises at least one key

DUPLICATE -7- 1 2 0 3 4 encryption K in a non-volatile memory by means of which the data sensitive and / or necessary for the operation of the control unit B (channel 4) to the receiver A are encrypted. This key K is unique Receiver A and enrolled in the detachable security module C, making the flow of information 4 unique to this set. The public dissemination of this information 4 will no longer be of any use to other receivers because for the latter, not being in possession of the same key K, the flow of information is perfectly incomprehensible. By means of the information 4, the control unit B can find the unscrambled video signal 2, the latter being processed and then transmitted in a standard form (PAL, SECAM, NTSC) to the video monitor.

A variant of the invention implements an encryption of the information 3 sent to the detachable security module Csoit by the same key K, or by a different key J, unique and specific to the set formed by the receiver A and the module C. Thus, any attempt to find the K key of the flow of information 4 extended much more difficult. . FIG. 2 illustrates a variant using a detachable D-blocking module integrating the control unit B. In this case, the video-filtered stream 1 is shaped by the receiver A and routed to the detachable descrambling module D. The operating mode described for Figure 1 between the receiver A and the detachable security module C is applied to the dialogue between the detachable descrambling module D and the detachable security module C. The key K is written in a secret part of the detachable descrambling module D in place and Thus, the information provided by the detachable security module C to the detachable descrambling module D is encrypted and thus without values for another detachable descrambling module D.

It then becomes apparent that the information transmitted to the receiver Aconstitutes in a stream of unscrambled video information 6 and which can be

DUPLICATE -8 1 2 0 3 4 easily exploitable, for illicit copies for example. In a variant of the invention, the stream 6 is encrypted in the unreliable deblocking module D before being transmitted to the receiver A for decryption by the decryption unit E '. This operation is carried out by a key K 'owned only by the receiver set A and the unreliable debrising module D. As a result, the information flow 6 has no longer any significance and can only be understood by the receiver A having of the same key K '.

In the scrambled video stream 1, the receiver A can add thereto control information to the unreliable debrouillage module D. In order to prevent this information from being public and opening a door to the understanding of the encryption mechanism, this information is encrypted by the encryption unit E to obtain a scrambled video stream 6 containing encrypted control information.

FIG. 3 illustrates a variant of the invention where the detachable security module is integrated in a descrambling module and detachable security F. This module has the function of descrambling and managing the authorization of the video signals received by the receiver A. According to the In the invention, this module comprises a unique encryption key, own receiver A and registered in this descrambling security module F. In this way, the unscrambled video stream 6 is encrypted key field and transmitted in this form to the receiver A. This Ci, thanks to the decryption unit E ', and using the same unique key, to find the clear video signal.

By analogy with the operation described in FIG. 2, the control information contained in the scrambled video stream 1 may be encrypted by means of a single encryption key by the unit E before transmission to the detaching security and descrambling module F .

DUPLICATE -9- 12 0 3 4

In all the examples described in FIGS. 1 to 3, the control of the pairing can take place. In the case of Figure 1, the receiverA registers a personal number, for example its serial number, in the detachable security module C. Thus, the receiver can at any time, verify that the detachable security module C is the one that he is destined. In the context of the example illustrated in FIG. 2, the control can be done on two levels: a first level between the detachable D and the detachable security module C; and a second level between the detachable descrambling module D and the receiver A. This second level is particularly important if the descrambled information 6 is encrypted towards the receiver A.

In the solution of FIG. 3, the control of the pairings is carried out between the receiver A and the unscrambling and security module F.

In a particular form of the invention, the receiver A is an MPEG undecoder using "control words" (for necessary information) for the unscrambling of the video signal. These "controlwords" are provided by the detachable security module C. This module, for example a smart card, includes a nonvolatile memory for their storage.

In a particular embodiment of the invention, the detachable detachment module D is a PCMCIA type card including an MPEG undecoder (control unit B).

In a particular form of the invention, the detaching and detaching security module F is implemented in the form of an intelligent smart card integrating an MPEG decoder and a security module C '.

In a particular form of the invention, the unique decryption key K is common to a receiver group. This possibility is

For example, in a school with several receivers, to which the same security module will be applied depending on the needs. In the same way, several detachable security modules include the same encryption key so that they can be placed in any of the receivers in the group. In this case, the pairing control is done on a number which is no longer specific to a receiver but to a receiver group. A combination can be realized with a number composed of two parts, one qualifying the group, the other qualifying the receiver. The uniqueness of the personal number is respected, the matching matching test then being done more than on the group part of this number.

DUPLICATE

Claims (20)

-11 - 12 0 3 4 CLAIMS A pay television receiving system comprising a receiver (A) connected to security means (C, D, F), the receiver (A) receiving descrambling information from the security means (C, D, F) ), characterized in that at least a part of the information (4, 6) transmitted from the security means (C, D, F) to the receiver (A) is encrypted by a single encryption key. 2. Pay-TV reception system according to claim 1, characterized in that the unique encryption key is common to a group of receivers. 3. Pay TV reception system according to claims 1 or 2, characterized in that at least a part of the information (3, 5) transmitted from the receiver (A) to the security means (C, D, F) are encrypted by a unique encryption key. 4. Pay-TV reception system according to claims 1 to 3, characterized in that the receiver (A) comprises a personal number which can be written in the security means (C, D, F), said receiver (A) being able to check at any time the conformity of this personal number inscribed in said security means (C, D, F). A pay television receiving system according to claim 4, characterized in that the personal number comprises a party specific to a group of receivers and a receiver-specific part, and that the verification of the conformity of the matching is carried out on the part of the receiver group. 6. A pay-TV reception system according to claims 1 to 5, characterized in that the receiver (A) comprises a control unit (B) and the security means are constituted by a detachable security module (C) in which the sensitive and / or necessary information (4) to the operation of the control unit (B) are stored. DUPLICATE -12- 12 0 3 4 Pay-TV reception system according to Claims 1 to 5, characterized in that the security means comprise a detachment and detachable security module (F) comprising a control unit (B) and a security unit (C '). responsible for the descrambling and authorization of the video information. 8. Pay TV reception system comprising a receiver (A) connected to security means (C, D, F), the receiver (A) receiving descrambling information from the security means (C, D, F) ), characterized in that these security means comprise a detachable security module (C) and a detachable detachment module (D) including a control unit (B), and in that at least part of the sensitive and / or necessary information (4) Operation of the control unit (B) is encrypted before being transmitted to the detachable descrambling module (D) by the detachable security module (C) by means of a single encryption key. 9. A pay-TV reception system according to claim 8, characterized in that at least a part of the information (3) transmitted from the detachable descrambling module (D) to the security module (C) is encrypted by an encryption key unique. A pay television receiving system according to claim 8 or 9, characterized in that the detachable descrambling module (D) comprises a personal number which can be written in the detachable security module (C), said detachable descrambling module ( D) can check at any time the compliance of this personal number entered in the detachable security module (C). The pay television receiving system according to claim 10, characterized in that the personal number has a part specific to a group of detachable descrambling modules (D) and a part suitable for a detachable descrambling module (D), and the Verification DUPLICATA -13- 12 0 3 4 of the conformity of the pairing is carried out on the own part of the group of detachable descrambling modules (D). Pay-TV reception system according to claims 9 to 11, characterized in that at least a part of the information (5) transmitted from the receiver (A) to the detachable descrambling module (D) is encrypted by a key of unique encryption. A pay television receiving system according to claims 9 to 12, characterized in that at least a part of the information (6) transmitted from the detachable descrambling module (D) to the receiver (A) is encrypted by a key of unique encryption. The pay television receiving system according to claims 12 to 13, characterized in that the receiver (A) comprises a personal number which can be written in the detachable descrambling module (D), said receiver (A) being able to check any moment the compliance of personal number registered in said detachable descrambling module (D). 15. A method of controlling transmission of information in a pay-TV reception system between a receiver (A) and security means (C, D, F), the latter sending to the receiver (A) information enabling the signal to be unraveled audio and video, characterized in that at least one unique encryption key is stored, on the one hand in the receiver (A), and on the other hand in the security means, and that the transmitted information is encrypted and decrypted between the receiver (A) and the security means by means of at least one of said single decryption keys. 16. Method according to claim 15, characterized in that a personal number to the receiver (A) is written in the security means during an initialization operation and the receiver (A) can check at any time the conformity of this number. personnel enrolled in said security means. DUPLICATE -14- 12 0 3 4 17. Detachable security module (C) intended to be connected to a receiver (A) as part of a pay television reception system, comprising at least one non-volatile memory for austocking the sensitive data and / or necessary for the operation of the descrambling means of transmission with the receiver (A), characterized in that this detachable security module (C) comprises means of encryption of the transmission, and that this memory also includes at least one encryption key acting on the encryption means of the transmission. 18. A detachable descrambling module (D) forming part of a pay television reception system, comprising a control unit (B), first transmission means (3, 4) with a detachable security module (C), second transmission means (5, 6) with a receiver (A), as well as a non-volatile memory, characterized in that it comprises first encryption means, and this memory includes at least one encryption key acting on the first means of encryption encryption for encrypting the transmission of the first transmission means (3,4). 19. Detachable descrambling module (D) according to claim 18, characterized in that it comprises second encryption means, etque this memory comprises at least one encryption key acting on the second encryption means for encrypting the transmission second means transmission (5, 6). 20. Receipt receiver for pay television (A) comprising means for transmission to security means (C, D, F), as well as a non-volatile memory, characterized in that it comprises means of encryption of the transmission of and to the security means (C, D, F) and that this memory comprises at least one encryption key acting on the encryption means of the transmission. DUPLICATE