BG64137B1 - Mechanism for matching a receiver with a security module - Google Patents

Abstract

The invention concerns a system for controlling data transmission between a receiver (A) and a security module (C), in particular for a pay television system wherein the transmitted data (1) are encrypted and decrypted by means of an encryption key (K), stored in the receiver on one side , and in the security module (C), on the other side. 20 claims, 3 figures

Description

Technical field

The invention relates to a system for controlling the transmission of information between one receiver and one security module, especially for a pay-TV system, as well as a method for controlling the transmission of scrambled information (adding by modulation 2 to a digital signal of a pseudorandom digital sequences with a large repetition period).

BACKGROUND OF THE INVENTION

The pay-per-view television system consists of one receiver and one security module. This module can be replaceable or fixed. The purpose of the receiver is to descramble the received signals. The main purpose of the security module is to control the action by checking the descrambled permission and by providing, as required, the information necessary for the operation of the descrambling module, for example by providing descrambling vectors, also called control words.

Existing systems use receivers that query their security modules and respond to them by providing the information needed to descramble. At any given time for the same broadcast, all security modules respond with the same information. Because information passes between the security module and the low-speed receiver (from about 20 to 30 bit / s), fraudsters can use this information to distribute it publicly, openly, for example via the Internet.

Such a system is described in the document "DVD Conditional Access", written by David Cutts in the description "Electronics & Communication Engineering Journal" of February 1997. A standardized system for non-scrambled audio and video streams coming from different service providers is described. The security module, called CA (Conditional Access), has the task of delivering CW control words. This module may additionally use a smart card (SM) for the descrambling function. After the information is descrambled into the CA module, the CW control words are returned to the decoder to receive non-encoded information.

The prior art publication "Conditional Access Broadcasting: Datacare 2, an Over-Air Enabled System for General Purpose Data Channels", published August 1, 1988 in BBC Airways Research and Development Report No. 10, describes an independent module ( conditional access module) responsible for receiving and decrypting the information required to descramble. This module controls the key assigned to the system and supplies the control words needed to descramble the video distribution. In this type of module, once the control words are declassified, they are transmitted unencrypted to the device loaded with descrambling.

Then there is the problem of how to make the receiver and the protection module dependent on each other so that:

- a security module can only be used in the receiver for which that security module is intended;

- the information flow exchanged between the security module and the receiver is unique and unique. This uniqueness prevents the stream from flowing publicly, preventing other receivers from operating without the security module provided for the purpose.

SUMMARY OF THE INVENTION

The proposed solution uses at least one receiver-specific encryption key. This (or these) key (s) is (are) called a matching key. At least one of the keys is different for each receiver. This (or these) key (s) is / are / are / are installed in a memory that can withstand interruptions (predictable, accidental) to the receiver during its making or in a subsequent step. The receiver does not provide a means of access to this (or these) key (s) to the outside world.

One possible means of programming this key in the security module is to use a central information system that manages a group of receivers and which can insert, into the video stream, information about programming the key in the secret memory that withstands interruptions of the security modules. The formation of this procedure is kept secret.

When transmitting classified information and / or information required for the operation of the system from the security module to the receiver (normally control words, but other information may also be transmitted), the security module encodes that information using one or more special matching keys common to a pair of receiver / security module. Any encoding method may be used provided the security module knows it and the receiver knows the appropriate decryption method. Once the information has been received by the receiver, it is then decoded by the receiver using the known decoding method and a matching key built into its interruptible memory. This information is then unencrypted and can be used by this receiver.

The invention therefore provides a system for controlling the transmission of information between one receiver and one security module, in particular for a pay-TV television system in which the transmitted information is encoded and decoded by at least one special key located one side of the receiver. and on the other hand - in the security module.

The invention also relates to a scrambled information descrambling system and a pay-TV system comprising a transmission control system.

The invention also relates to a method for controlling the transmission of information between one receiver and one security module, especially for a pay-TV television system, characterized in that at least one special matching key is located on one side in the receiver and on the other side, in the security module, and that the information transmitted between the receiver and the security module is encoded and decoded by at least one dedicated encryption key.

This solution according to the invention solves the problem because:

- a security module plugged into a receiver other than the one for which this security module has been tuned will provide the other receiver with a stream of confidential information and / or information necessary for the operation of the key-encoded system, which does not match the one used to decode it. Therefore, the result is unusable;

- the flow of confidential information and / or information required for the operation of the system coming from one security module cannot be distributed to several receivers. Only the receiver, coordinated with the card providing this stream of confidential and / or necessary information, is able to successfully decode the stream.

The system may contain a mechanism for verifying the reconciliation procedure. The central information system may record a number personally for the receiver in the security module in agreement with the receiver, for example, a number randomly generated by the latter, or may simply use its serial number. A means accessible to the receiver serves to freely check the personal number recorded in the security module and to compare it with that stored in its memory, which withstands interruptions.

The mechanism has the advantage of not using incorrect data. The result of encoding, followed by decoding through a different key, is usually a pseudorandom result. If the result is not recognized as false and if used as it is, the receiver or its associated device may be damaged.

Some types of receivers have a removable descrambling module. This module is responsible for (determines) a certain number of operations, among which is the operation to descramble the received signals. Confidential information is then transmitted between the removable security module and the removable descrambler. The messages between the receiver and the security module according to the encoding mechanism described above are transmitted as between the replaceable security module and the replaceable descrambling module.

Similarly, the matching method described above between the security module and the receiver moves as it is between the replaceable security module and the replaceable descrambler module.

The descrambling signals are then transmitted between the removable descrambling module and the receiver. The message encoding mechanism, together with the matching mechanism described above, moves between the security module and the receiver as it is between the receiver and the replaceable descrambling module.

The functions provided by the removable descrambler module and the removable security module can be performed by a single module called a removable descrambler protection module. The matching mechanism described above then moves as it is between the removable descrambling module and the receiver.

In all the cases described above, the reconciliation key or keys may be used to encrypt the flow of confidential data and / or data required to operate the system in the opposite direction, by reversing accordingly:

- the receiver and the replaceable protection module;

- the replaceable descrambling module and the replaceable security module;

- the receiver and the removable descrambling module;

- the receiver and the replaceable descrambling-protection module.

In all cases where the matching key is specific to one element of the equipment (receiver or replaceable module), the same principles apply when using a matching key (or multiple matching keys) specific to one group or element of the equipment.

Description of the attached figures

Figure 1 illustrates a configuration that includes a single receiver and a removable security module.

Figure 2 illustrates a configuration that includes a single receiver, a replaceable descrambler module and a replaceable security module.

Figure 3 illustrates a configuration that includes a single receiver and a removable descrambling security module.

Examples of carrying out the invention

The receiver A of FIG. 1 receives a stream of scrambled video information 1 from a single source, such as a satellite receiver or cable. This stream, in the order of several megabits per second, is formed in receiver A and then transmitted to control device B, which is responsible for descrambling and managing the authorized access to the scrambled video information. In order to do this, control device B requests a periodically replaceable security module C (channel 3) that responds to the latter with a single stream of confidential data and / or data required for operation of control device B (channel 4). These exchanges of information are carried out at low speed and can be easily processed through the microprocessors of smart cards available on the market. According to the invention, the replaceable security module C comprises at least one interruptable key K in memory that encodes confidential data and / or data necessary for the operation of control device B (channel 4) with respect to receiver A. This key A is unique (specific) to receiver A and integrated into the replaceable security module C, making information stream 4 unique to this system. The public dissemination of this information 4 will no longer be used by other receivers, since in the latter case they do not have the same key K and the information flow is completely unavailable. Through information 4, control device B can detect the descrambled video signal 2, the latter to be processed and then transmitted in standard form (Pal, Sekam, NTSC) to the video monitor.

An embodiment of the invention uses encoding of the same type of information 3 transmitted to the replaceable security module C using the same key K or using a different key J that is unique and specific to the system formed by receiver A and the replaceable security module C Thus, any attempt to find the key K of information stream 4 is made much more difficult.

Figure 2 shows an embodiment that utilizes a removable descrambling module D that includes a control device B. In this case, the scrambling video stream 1 is formed by receiver A and transmitted to the removable descrambling module D. The method of operation described in the case of FIG. 1 between receiver A and replaceable security module C, this time is applicable to the exchange of information between replaceable descrambler D and replaceable security module C. The key K is embedded in the secret part of replaceable descrambler D, instead of receiver A. Thus the information provided by the removable security module C to the removable descrambling module D is encoded and therefore has no value for another removable descrambler module D.

Thus, it can be seen that the information transmitted to receiver A consists of a stream of descrambled video information 6 that can be readily used immediately, for example for prohibited copies. In one embodiment of the invention, the flow 6 is encoded in the removable descrambler D before being sent to receiver A for descrambling via the decoder E '. This operation is performed using a key K 'that is specific only to receiver A / the system of replaceable descrambling module D. Accordingly, information stream 6 is no longer meaningful and can only be understood by receiver A, which has the same key K'. .

Receiver A may add to the scrambled video stream 1 control information intended for the removable descrambling module D. To protect this information from the public and to understand the encoding mechanism, this information is encoded by the encoder E in order to a scrambled video stream 6 containing encoded control information was obtained.

Figure 3 illustrates one embodiment of the invention wherein the replaceable security module C 'is incorporated into the replaceable descrambling-protection module F. The function of this module is to descramble and control the authorization of the video signals received from receiver A. According to the invention, this module includes only encoder key specific to receiver A and embedded in this removable descrambling-protection module F. Similarly, the descrambling video stream 6 is encoded by this key and sent in this form to receiver A. The latter by e the encoder E 'and by using the same single key will be able to detect the unencrypted video signal.

By analogy with the operation described with reference to FIG. 2, the control information contained in the scrambled video stream 1 may be encoded by a single encryption key through the device E before it is sent to the removable descrambling-security module F.

In all the examples described with reference to FIG. 1 to 3, the matching can be checked. In the case of FIG. 1, the receiver writes the personal number, such as the serial number, to the replaceable security module C. Thus, the receiver can check at any time whether the replaceable security module C is really the one intended for it. In the context of the example illustrated in FIG. 2, the verification can be done on two levels, namely, firstly, the level between the removable descrambling module D and the removable security module C and the second level between the removable descrambling module D and receiver A. This second level is especially important if the unscrambled information 6, supplied to receiver A is encoded.

In the embodiment shown in FIG. 3 solution, the matching is verified between receiver A and the replaceable descrambling-protection module F.

In one embodiment of the invention, receiver A is an MPEG decoder that uses control words (information required to descramble the signal) in order to descramble the video signal. These control words are provided by the removable security module C. This module, such as a smart card, contains interruptible memory for storing them.

In another embodiment of the invention, the replaceable descrambling module D is a PCMCIA card (chip) that includes an MPEG decoder (control device B).

In another embodiment of the invention, the replaceable descrambling-protection module F is made in the form of a smart card that includes one MPEG decoder and one security module C '.

In another embodiment of the invention, the only coding key K is common to one group of receivers. This possibility is an advantage, for example, in a school that has several receivers to which the same removable security module is applied, depending on the requirements. Similarly, several interchangeable security modules contain the same encryption key to be able to be inserted into each of the receivers in the group. In this case, the matching check is performed on a number that is no longer specific to one receiver but to a group of receivers. The combination can be obtained by a number consisting of two parts, one part defining the group and the other the receiver. The uniqueness of the personal number is respected, respected, and the same form of concordance test is performed on more elements than only on the part of the group corresponding to that number.

Claims (20)

Claims 1. A pay-TV reception system comprising one receiver (A) connected to a security means (C, D, F), wherein this receiver (A) receives descrambled information from the security means (C, D, F), characterized by with at least some of the information (4, 6) supplied by the security means (C, D, F) to the receiver (A) being encoded by a special encryption key. 2. A pay-TV reception system according to claim 1, characterized in that the special decoding key is common to a group of receivers. Pay-per-view television receiving system according to claim 1 or 2, characterized in that at least some of the information (3, 5) supplied by the security means (C, D, F) to the receiver (A) is encoded through a special encryption key. Pay-per-view television receiving system according to claims 1 to 3, characterized in that the receiver (A) includes a personal number that can be stored in the security means (C, D, F), where possible the receiver (A) to check at all times the identity of that personal number recorded in the safeguards (C, D, F). 5. A pay-per-view television system according to claim 4, characterized in that the personal number comprises one part specific to one group of receivers and one part specific to one receiver and that the uniformity of matching is checked in the part specific the group of receivers. 6. A pay-TV reception system according to claims 1 to 5, characterized in that the receiver (A) comprises one control device (B) and that the security means consist of a replaceable security module (C) in which it is stored confidential information (4) and / or information (4) necessary for the operation of the control unit (B). 7. A pay-TV reception system according to claims 1 to 5, characterized in that the security means comprise a removable descrambling protection module (F) comprising one control device (B) and one security device (C '), such as Devices are responsible for descrambling and allowing video information. 8. A pay-TV reception system comprising one receiver (A) connected to a security means (C, D, F), this receiver (A) receives the descrambled information from the security means, characterized in that these security means comprise one replaceable security module (C) and one replaceable descrambling module (D) that includes one control device (B) as at least some of the confidential information (4) and / or information (4) required for the operation of the control device (B) is encoded before being transmitted to the removable desk mapping module (D) via the replaceable security module (C) by means of a special encryption key. 9. A pay-TV reception system according to claim 8, characterized in that at least some of the information (3) transmitted by the replaceable descrambling module (D) to the security module (C) is encoded by a special encryption key. 10. A pay-TV reception system according to claim 8 or 9, characterized in that the removable descrambler module (D) includes a personal number that can be stored in the removable security module (C), whereby the removable descrambler is possible. module (D) to check at all times the identity of that personal number recorded in the replaceable security module (C). 11. A pay-as-you-go television system according to claim 10, characterized in that the personal number comprises one part specific to a group of replaceable descrambling modules (D) and one part specific to one replaceable descrambling module (D) and the uniformity of matching is checked in part specific to the group of replaceable descrambling modules (D). 12. The pay-per-view television system according to claims 9 to 11, characterized in that at least some of the information (5) transmitted by the receiver (A) to the removable descrambling module (D) is encoded by a special encryption key. 13. A pay-TV reception system according to claims 9 to 12, characterized in that at least part of the information (6) supplied by the removable descrambling module (D) to the receiver (A) is encoded by one special coding key. A television reception system according to any one of claims 12 and 13, characterized in that the receiver (A) includes a personal number that can be stored in the replaceable descrambling module (D), whereby it is possible for the receiver (A) to check at all times the identity of that personal number recorded in the replaceable descrambling module (D). 15. A method for controlling the transmission of information in a pay-per-view television system between one receiver (A) and security means (C, D, F), transmitting these security means to the receiver (A) for decoding video and audio signals, characterized in that at least one special encryption key is located on one side in the receiver (A) and on the other hand in the security means and that the information transmitted between the receiver (A) and the security means is encodes and decodes using at least one special encryption keys. A method according to claim 15, characterized in that a number, personal to the receiver (A), is stored in the security means during an initialization operation and that the receiver (A) can check at any time the uniformity of this a personal number recorded in the protective equipment. 17. A removable security module (C) for connection to a receiver (A) as part of a pay-TV reception system comprising at least one intermittent memory designed to store confidential data and / or data required for the operation of the descrambling system and transmission means with the receiver (A), characterized in that this replaceable security module (C) includes means for encoding the transmission and that this memory also includes at least one encoding key which affects the encoder n and the show. 18. Removable descrambling module (D) as part of a pay-TV receiving system comprising one control device (B), first transmission means (3, 4) with one replaceable security module (C), second transmission means ( 5, 6) with a single receiver (A) and one interruptable memory, characterized in that it comprises first coding means and that said memory comprises at least one coding key which influences the first coding means provided for coding the transmission of the first transmission means (3, 4). 19. A removable descrambling module (D) according to claim 18, characterized in that it comprises second encoders and that the memory contains at least one encoding key that acts on the second encoders provided for encoding the transmission of the second means for transmission (5, 6). 20. A descrambling receiver (A) for pay-TV, comprising means for transmission to the security means (C, D, F), as well as memory for interruptions, characterized in that it includes means for encoding / decoding transmission from and to the safeguards (C, D, F) and that this memory includes at least one encryption key that affects the encoding / decoding means of the transmission.