Method for reading a service card

0001The present invention relates to a method for reading service information in a video-communication receiver provided with receiving means and deciphering encrypted signals to the receiver by a transmitter television, said means comprising in particular a microprocessor associated with a RAM and a memory Still containing instructions and a deciphering module to decrypt said encrypted signals, method which is introduced into the receiver in a fashion Service, encrypted information.

0002It also relates to a video-communication receiver, comprising means for receiving and deciphering encrypted signals to the receiver by a transmitter television, said means comprising in particular a microprocessor associated with a RAM and a memory Still containing instructions and a deciphering module to decrypt said encrypted signals.

0003It finally relates to a microprocessor card, intended a receiver according to the invention.

0004A television system with image descrambling is known from patent application WO 93/07715 (Thomson). According to this, a specific smart card is used by an installer to perform automatically, in a receiver, the update the allocation of television channels according to the site of reception.

0005Such an update of a receiver may concern receiving frequencies but also data of subscription of the user authentication. Thereby, it is useful for the service information, or at least some of them, to be encrypted, to be free from ill will. It is therefore necessary, in principle, using a deciphering module that delivers plaintext data from service information encrypted on the basis of a secret code and / or instructions decryption supplied thereto. Instructions deciphering may also be she same encrypted.

0006An object of the invention is to simplify the production a system capable of receiving and decrypting such service information.

0007To this end, to decrypt said information, one uses the deciphering module of the receiver itself, that is to say, a receiver is provided with means for deciphering the service information by its own module decryption.

0008Thus a specific decryption module becomes useless.

0009In a particular embodiment, the encrypted service information is loaded into a RAM of the receiver, and then shaped by the microprocessor before being treated by the module deciphering the receiver, that is to say, a receiver is provided with means for loading service information encrypted in RAM, and put them under a form which simulates signals transmitted to the receiver by a transmitter before treating them by means of its module deciphering.

0010In another embodiment, the information Figures are carried by a data stream that simulates signals transmitted to the receiver by a television transmitter, that is to say that this stream is organized into packets of same format as that of such signals.

0011Thus the information may be transmitted directly at the receiver decryption module.

0012Alternatively, is used as support for information entered in the receiver, a map of Microprocessor service placed in a card reader receptor, that is to say, a receiver equipped with a reader microprocessor card, is provided with means for reading a service card placed in the reader said.

0013According to another variant, is used to introduce information in the receiver, a connector for connection with the exterior, carried by the receiver, that is to say the latter is provided with means for receiving information encrypted service via this connector.

0014A service card advantageously produces a stream of encrypted data which simulates signals transmitted to the receiver by a transmitter, that is to say that it is organized in packages of the same format as that of such signals.

0015These aspects of the invention and other aspects More detailed emerge more clearly through following description of an embodiment constituting a non-limiting example.

0016The single figure shows schematically a receiver video-communication, equipped with a card reader microprocessor.

0017The video-communication receiver represented by the figure comprises a unit for receiving satellite 1-6 and a all cable reception 7-11.

0018The satellite receiving assembly is constituted by a parabolic antenna 1 and a receiver 2, followed by a intermediate frequency amplifier 3. At this point the signal is modulated by a known method, said QPSK. The intermediate frequency signal is converted into values digital in an analog-digital converter 4, then it is demodulated by the demodulator 5 of QPSK. Finally, some errors in the signal are corrected by an error corrector 6 ( "Forward Error Correction"), based on the fact that the signal includes redundancy bits according to a known coding scheme.

0019The cable receiver assembly is constituted from a signal input, by a 7 followed by a tuner transposer 8. At this point the signal is modulated according to a known method, said 64 QAM. The frequency signal intermediate is converted to digital values ​​in an analog-digital converter 9, and is then demodulated by demodulator 10 type 64 QAM. Finally, some errors in the signal are corrected in a corrector Error 11, of the same type as the corrector 6.

0020At this level, the demodulated signal is called MPEG-2 TS (For "MPEG-2 Transport Stream"): it is a signal of a capacity of about 36 megabits, with up to twenty program with data and sound which, if appropriate, are scrambled.

0021A set of satellite reception and a set of cable reception are present here together, although they be made, often in two separate devices. A Switch 12 allows here to select the satellite signal or that of the cable. The signal is then descrambled in a descrambling module 13 connected via a bus 27, a reader 23 of smart card 17, said smart card, and a microprocessor 15.

0022The microprocessor 15 includes a ROM in which are listed basic instructions. It is associated with a random access memory 22 for instantaneous data, a so-called "flash" memory 30, for storing items programs that can be updated, as well as card reader 23, to a control keyboard and / or a remote control receiver, with a data display screen 25, and possibly a modem 24.

0023The descrambled signal is then subjected to the action a demultiplexer 16, connected to the microprocessor 15, demultiplexer which separates from each other the various programs of MPEG-2 TS signal, one of them being selected by means of a switch 26. The signal from this demultiplexer is still in digital form and requires to be converted into an analog signal for displaying an image on a screen and apply the sound to a loud speaker. This final transformation is performed on the one hand in a video decoder 19 which delivers a signal of known type, for example says 4-2-2, referred to as YUV and on the other hand in a sound decoder 18. These decoders are followed by processing circuits ( "post-processing") of its 20 and Video 21, connected by a connection 28 to standard circuits of sound and video receiver, if it is a TV, or an external TV, in the case wherein the receptor described herein is a housing decoder for be connected to a signal input of a conventional TV type PAL, SECAM or NTSC.

0024The card reader 23 to chip 17 serves, of course, read the map information needed to descrambling of television images, in a known manner. It is used also for introducing into the receiver service information, including software. For this, the card of the user, containing information personal, such as a distribution key, the characteristics of the subscription television service pay, etc., is replaced in the same drive, a service card containing update information, for example software elements, in encrypted form. Clearly, alternatively, this information could also be introduced into the receiver by means of a 32 connector, for example as the standard type IEEE 1284 for the introduction of information, this connector can be connected to a microcomputer of the kind known as "PC", or a device specially designed to adjust the receivers, or a bond, RS232 example, to a loading station data.

0025To decrypt the service information is used the descrambling module 13 of the receiver itself. Various means can be employed for this purpose:<ul><li>coming out of the card may be fed directly to the module descrambler 13 by 29 scheduled connection this effect between the card reader 23 and the Switch 12, which selects the connection 29 to connect to the module 13. The card microprocessor then produces a data stream which simulates signals transmitted to the receiver by a transmitter, that is to say it is held in packets of the same format as the MPEG-2 TS signal. A software adapted that the art can write on demand, is loaded into a course microprocessor memory for that information from the module 13 to be recognized as intended to update the software, and are operated as appropriate.</li><li>Information can also be transferred, in encrypted form, directly into memory 22, from drive 23 or connector 32, and then be brought, by the microprocessor 15 itself, in the form of packets of the same size the MPEG-2 TS signal, and then applied to unit 13. In this case, it is unnecessary for the smart card produces a stream simulating data signals transmitted to the receiver by a transmitter.</li></ul>

0026The information in the map may show layering a first layer contains the control word needed to decrypt; the word Control can be himself in encrypted form. A key, provided by the installer, used to decrypt the password control, which will be decrypted with the other information, constituting a second layer. The first layer may also contain various other information on the content of the second layer, and on the way to the decipher. It is always possible to achieve in some cases, the decryption of service information to the using decryption instructions are directly provided with the information of the first layer, that is to say that do not use the decryption module Receiver: while it is also indicated in the first layer. This may depend, for example, a choice made by the broadcaster of television programming that is involved in the provision of service information.

0027Thus, the mode of operation of the assembly is the following (it is assumed that the transfer is done through a smart card): the installer places the card in the receiver, it recognizes a card Service (known way), and then reads the first pack in the map, then dialogue with the installer to to obtain from him the key to decrypt it first packet; there may be further a signature in the card that allows to recognize that the key provided by the installer is valid without knowing to advance; such different encryption methods are known per se. In the case where the invention is in work, the obtained data is transmitted to the module 13, enabling it to decode the rest of the packets contained encrypted form in the map 17 (second layer). In Alternatively, a stand-alone microcontroller 31 may further be responsible for operations of reading and interpreting information of the first layer. If the information in the first layer indicates that information of the second layer are in a form which is intended to be processed by the descrambling module of the receiver, the standalone microcontroller 31 then passes control to main microprocessor 15 which will decrypt the rest of the information, that is to say the second layer.