Method of determining illegal use of processing device of security system

FIELD: radio engineering, communication.

SUBSTANCE: invention relates to means of detecting illegal use of a processing device of a security system, used to descramble various media data distributed over multiple corresponding channels. The method includes counting new messages ECMj,c, received by the processing device of the security systems for channels, other than channel i, after the last received message ECMi,p; verifying that the message ECMi,c was received during said time interval by verifying that the number of new messages ECMj,c, received for channels other than i, reaches or exceeds a given threshold greater than two; increasing the counter Kchi by the given value each time when after verification a message ECMi,c is received during a given time interval, immediately after a message ECMi,p, otherwise the counter Kchi is reset to the initial value; detecting illegal use once the counter Kchi reaches said threshold.

EFFECT: reducing the probability of illegal use of a processing device.

10 cl, 3 dwg

 

Prior art

The invention relates to a method of determining the illegal use of device processing system of security used for diskriminirovaniya various multimedia data distributed on various appropriate channels. Also this invention relates to a processing device of a security system, and media for implementing this method.

There are known methods adapted to determine the illegal use. These methods include:

- with the help of an electronic device processing system security accept the ESM message (Message access control), denoted by ECMi,twhat you are doing to diskriminirovaniya a temporal sequence of frames with one key scrambled channel i, each message ECMi,tcontains at least one cryptogram of the control word CWi,tallowing descrambling period CPi,twith one key channel i, where i identifies the channel, and the index t is a sequence number or sequence number,

- each time using a processing device of the security system to accept a new message ECMi,ccheck that the ECM messagei,ctaken during a specified time interval, CL�blowing directly at your previous message ECM i,padopted this processing device of the security system for channel i, where the indices C and p are two specific values of the sequence number t,

The term "time interval immediately following the previous message ECMi,p"indicate the time interval of given duration, which begins directly after the reception of the message ECMi,p.

The term "multimedia data" refers to audio and/or visual data to be displayed in a form that is directly perceived by a person. Usually multimedia data correspond to the sequence of images that form a film, television program or advertisement. Multimedia data can also be interactive data, such as a game.

The level of technology

Known methods of simultaneous broadcasting of multiple multimedia data. To do this, each media item transmit data on its own channel. The channel used for transmitting multimedia data, also referred to as "station". The channel typically corresponds to a television station. This allows the user by changing channels to select only the media data that he wants to view.

To ensure the security of multimedia data and providing certain services.�Vij, such as, for example, payment of subscriptions, multimedia data are transmitted in scrambled form, and not in an open or unencrypted. In this description, the channel is called "scrambled" when scrambled multimedia data transmitted through this channel. More specifically, each multimedia data is divided into a sequence of frames with one key. During one period with one key access to scrambled multimedia data remain unchanged. In particular, during one period with one key multimedia data is scrambled with the same control word. In General, in different periods with the same key is used in different control words. Moreover, a control word, in General, is characteristic of the multimedia data. Thus, if in the given example N multimedia data simultaneously transmitting the N channels, there are N different control words, each of which is used for scrambling one program from the multimedia data.

Here the terms "scramble/descrambling" are considered synonyms. Similarly, the terms "encrypt/decrypt" are considered synonyms.

Open or unencrypted multimedia data correspond to the multimedia data before scrambling. These data can be directly understood people� without reference to the operations of diskriminirovaniya and without the imposition of conditions to see that data.

Control words needed to diskriminirovaniya multimedia data synchronously transmit multimedia data. For example, the control words needed to diskriminirovaniya t-th period with one key, take with each terminal at time t-1-th period with one key. To this end, for example, control words combine with scrambled multimedia data.

To ensure safe transmission of control words these words are transmitted to the terminal station in the form of cryptograms contained in the ECM messages (Messages access control).

Here the term "business" refers to information, which by itself is not enough to restore the control word in the clear. Thus, if the interrupt transfer control word, one knowledge of the cryptogram of the control word does not allow to recover the control word, which can be describiremos multimedia data. To restore public control word, the control word is directly used to diskriminirovaniya multimedia data, it must be combined with secret information. For example, the control word cryptogram obtained by encrypting the open control word using a cryptographic key. In this case, the secret info�information is a cryptographic key, which is used to decrypt this cryptogram. The cryptogram of the control word may also be a reference to a control word stored in the table, containing a large number of possible control words. In this case, the secret information is a table linking open control word to each link.

Secret information must be stored in a safe place. This purpose has already been proposed to store the secret information in the processing devices of the security system, such as a card with a microprocessor, which are directly connected to each terminal station.

Transmission of multimedia data through a variety of channels can be coordinated in time. For example, the time of broadcasting multimedia data is set so as to correspond to the broadcasting times specified in a pre-defined program guide. Thus, each terminal station on a given channel takes the same multimedia data at the same time. They say that multimedia data flows are "live" or "linearized" threads, because the user does not control the date of grant.

In this context, have been developed attack for the purpose of providing users with the possibility to diskriminirovaniya multimedia data, for which they have no time�esenich rights.

One of these attacks is known as "cardsharing". This attack is a legitimate receiving processing unit of the security system to obtain the access rights needed to diskriminirovaniya multiple channels. Next is "lawful" processing device of the security system put in "pirate" server that accepts the ECM messages from a large number of pirated satellite terminal stations. Thus, when pirate satellite terminal station wants to illegally descrambling transmitted multimedia data, it accepts these multimedia data and transmits the corresponding ECM messages on a pirate server. Pirate server ECM transmits these messages to the lawful processing device of the security system. In response to legitimate the processing device of the security system decrypts the control words contained in the ECM messages, and sends these control words in the clear ago on a pirate server. Next pirate server sends the decrypted or open control words on pirate satellite final station, which is then descrambled desired multimedia data.

In this attack the processing device of the security system used in the usual way except that it processes the ECM messages from a large number of satellite end mill�rd, while legitimate when you use it processes the ECM messages only from Terminus. To detect this type of attack has already proposed the following:

- calculate the changes in channels that occur within a specified period of time (see patent application EP 1575293),

- count the number of different channels, descrambling the processing device of the security system during a given period of time (see patent application EP 1447976), and

- count the number of ECM messages received by the processing device of the security system during a given period of time (see patent application WO 2008049882).

In all of these detection methods exploit the fact that the attack by cardsharing leads to:

- excessively large number of channel changes (toggles), and/or

- excessively large quantity of the received ECM message.

Detection of this attack allows you to set the response.

Also there is another attack called "sharing control words", which is also used to legitimate the processing device of the security system with the aim of diskriminirovaniya one or more channels. In this attack the legitimate processing device of the security system is inserted into the server control words. This server adopt�et multimedia data and extracts the ECM messages. The extracted ECM message is passed to the lawful processing device of the security system, which then decrypts the cryptogram of the control word and sends back to the server thus decrypted control words. The server then transmits or distributes these control words on a large number of pirated satellite terminal stations, thus enabling them illegal to descrambling multimedia data. For example, in this attack pirate satellite terminal station just signed to open stream control words generated by the server and corresponding to the channel that they want to descrambling.

This last attack is different from the attacks of cardsharing what pirate satellite terminal stations do not need to send the server the ESM message channel that they want to descrambling. Therefore, when this attack is much less than the number of ECM messages processed by the processing device of the security system, compared with the attack of cardsharing. However, if this attack is the same processing device of the security system used to process the ECM messages of different channels, this attack can still be detected by the above detection methods corresponding to the prior art.

In the last time attack ka�daringa or attack with sharing control words have been modified for the purpose of obstruction detection. The modification consists in the use of not one legitimate processing device of the security system, and to use lawful processing devices of the security system in the amount equal to the amount descrambling channels. Then each lawful processing device of the security system to allocate the corresponding channel, i.e. it is used solely to process the ECM messages only this channel or a very limited number of channels. The rest of the attack similar to that which was described above. This means that the processing device of the security system no longer perceives the change channel or switch, making ineffective the known methods of detection.

Disclosure of the invention

The invention is aimed at overcoming this drawback and proposed a new method for detecting illegal use of device processing system security.

Therefore, the purpose of the invention is to provide a method, comprising stages on which:

- increase the counter Kchiby a predetermined amount whenever, after verification, the message ECMi,ctaken in a predetermined time interval immediately following the message ECMi,pand, otherwise reset the counter Kchiin the source value�,

- detect the illegal use, once the counter Kchireaches a predetermined threshold.

The above-mentioned method can detect attacks cardsharing attack or sharing control words provided that each card is allocated a limited number of channels Really in this case, the processing device of the security system processes the ECM messages to the same channel for a very long periods of time. It is a long no switch is used here to detect the illegal use of device processing system security. More specifically, it is the prolonged absence of the switch causes the counter Kchireaches a predetermined threshold that triggers the detection of the illegal use.

In addition the stability of the detection method from the point of view of a hidden switch can be adjusted by setting the duration of the time interval.

Embodiments of this method may have one or more of the following:

- each received message ECMi,talso includes a section of historical data, allowing to identify immediately preceding the ECM messagei,t-1or directly following message ECMi,t+1and the method includes PR�tested, the ECM messagei,cwith made within this time interval by verifying that the new received message ECMi,cis the message, following directly behind the ECM messagei,p, or message, the immediate previous message ECMi,pbased on the mentioned part of the chronological data contained in the ECM messagei,cor ECM messagei,p;

- this method includes checking that the message ECMi,ctaken within this time interval, by verifying that the difference between the labels TScand TSptime contained respectively in the messages ECMi,cand ECMi,pthat is less than the preset time interval ΔT, the larger is double the time interval between the timestamp of the following directly after the other messages ECMi,tand ECMi,t+1;

the method includes the stages on which:

- measure the time interval ΔVc pbetween the moments of reception of messages ECMi,cand ECMi,pand

- check that the ECM messagei,ctaken within this time interval by checking whether the measured interval ΔVc pless than or equal to the specified interval ΔT, which is more than double the time interval ΔVt,t+1that can be measured between the moments of reception directly following�directly after each other messages ECM i,tand ECMi,t+1;

the method includes the stages on which:

- count new messages ECMj,cadopted by this processing device of the security system for channels that differ from channel i, after the last received message ECMi,pand

- check that the message ECMi,ctaken within this time interval, by checking that the number of new messages ECMj,ctaken for channels that differ from channel i, reaches or exceeds a predetermined threshold, greater than two;

- the method comprises a stage on which: selects the counter Kchi, the value of which increases, among X tellers Kchj, wherein X is an integer greater than or equal to 2, depending on the ID channel i is contained in the ECM messagei,c;

the method includes the stages on which:

- count the channels associated with the meter Kchiwhose value has reached or surpassed their respective defined thresholds,

- compare the number of Z counters Kchiwhose value has reached or surpassed their respective defined thresholds, with a specified limit of P, equal to the maximum number of channels that can be simultaneously descramblers using a processing device of a security system, and

- if the number of Z achieved�t or exceeds the limit value P, automatically launch a strong counter-measures, and otherwise running other weaker counter-measures;

- in response to the detection of the illicit use method includes stages, at which: automatically trigger countermeasures that prevent diskriminirovaniya channel i and displays a message asking the user to perform a specific action for the recovery of diskriminirovaniya channel i;

- specified a particular action is a channel change.

These embodiments of the invention additionally have the following advantages:

- comparing the difference between the timestamps or time intervals ΔVc pat intervals of ΔT prevents reset counter Kchiby simply manikopoulos operations from channel i to the other channel that can easily interfere with detection described here,

- counting the number of ECM messages received between the ECM messagei,pand the message ECMi,cand further comparison of this amount with a certain threshold also prevents the breakdown of a method of detection using a simple manikopoulos move from channel i to the other channel;

- select counter Kchithat will increase, depending on the channel ID i allows real�to use the above-mentioned method, even when the processing device of the security system is adapted for the reception of the ECM messages for simultaneous diskriminirovaniya different channels;

- count the number of counters Kchithat have reached or exceeded their specified thresholds, and compare this quantity with the limit P simultaneously descrambling channels allows to reliably detect the illegal use;

- diskriminirovaniya block by displaying messages on the screen, asking the user to take a particular action that hinders the implementation of the attacks cardsharing attacks or sharing control words while limiting negative consequences for the user in case of a false detection of the illicit use;

request the user to change channels to restore diskriminirovaniya this channel allows you to simply restore it diskriminirovaniya in the case of a false detection of the illicit use while the difficulty of implementation attacks cardsharing or sharing control words.

The purpose of the present invention is to propose an information carrier containing commands to implement the above method, when these teams performs electronic computer.

Finally, the goal of every�retenu, to offer an electronic device processing system of security for the end station, which is used to diskriminirovaniya various multimedia data distributed on various appropriate channels, the processing device is able to do the following:

- take the ECM messages (Messages access control), denoted by ECMi,tand used to diskriminirovaniya a temporal sequence of frames with one key for scrambled channel i, each message ECMi,tcontains at least one cryptogram of the control word CWi,tallowing descrambling period CPi,twith one key for channel i, where the index i identifies the channel, and the index t is a sequence number,

- whenever the received ECM messagei,ccheck that the ECM messagei,ctaken in a predetermined time interval immediately following the previous message ECMi,ptaken using this device for handling security for the channel i, where the indices C and p are two specific values of the sequence number t,

- increase the counter Kchiby a predetermined amount whenever, after verification, the message ECMi,ctaken during a given time interval is directly next�responsible for the ECM message i,pand otherwise, reset the counter Kchiin the initial value,

- to detect the illegal use, once the counter Kchireaches a certain preset threshold.

Brief description of the drawings

The invention will be better understood from the following description, given merely as non-exclusive invention of example and with references to the accompanying drawings, in which:

Fig.1 - view, schematically showing a system for transmitting and receiving scrambled multimedia data;

Fig.2 - view, schematically showing a table used in the system of Fig.1; and

Fig.3 is view showing a block diagram of a method of encryption and decryption of multimedia data, in which using the system of Fig.1 detect unlawful use of device processing system security.

In these drawings the same reference position used to denote the same elements.

The implementation of the invention

Below in the description is not described in detail the characteristics and functions well known to specialists in this field. Moreover, the terminology is the terminology for systems of conditional access to multimedia data. For further information on this terminology, the reader may be obtained from the following document:

- "Functional�I model of conditional access systems". An overview of the European broadcasting Union (EBU), EBU Technical issues, Brussels, BE, n. 266, 21 December 1995.

Fig.1 shows a system 2 adapted for transmitting and receiving scrambled multimedia data. Sent multimedia data are linearized multimedia data. For example, every multimedia data correspond to the sequence of an audiovisual program, such as a television show or movie.

Open the multimedia data to generate one or more sources 4 and transferred to the device 6 broadcast. Device 6 simultaneously transmits multimedia data towards the many receiving end stations on the network 8 information transfer. Transmitted multimedia data is synchronized in time with each other, for example, to meet the specified program.

The network 8 is typically a network of information transmission over long distances, such as the Internet or satellite network, is a network or broadcast of any type, such as a network used for transmission of digital terrestrial television (DTTV).

To simplify Fig.1 shows only three receiving end station 10-12.

The device 6 comprises a device 16 encoding, which compresses multimedia data that it receives. The encoding device 16 about�creating digital multimedia data. For example, the encoding device operates in accordance with the standard MPEG-2 (expert Group on cinematography - 2) or standard UIT-T N.

Compressed multimedia data is sent to the input device 22 of scrambling. The device 22 performs scrambling scrambling each compressed multimedia data, to impose conditions to see that data, such as the purchase users receiving end stations access rights. Scrambled multimedia data display device 24 the output of which is connected to the input of the unit 26 of Association.

The device 22 performs scrambling scrambling each compressed multimedia data using the control word CWi,tthat generator 32 keys provides the 22 scrambling, and the system 28 conditional access. The system 28 is better known as CAS (conditional access system). The index i represents the identifier of the channel on which to transmit the scrambled multimedia data and the index t is an identifier of the period with one key, which was carried out by scrambling using this control word. Below in the description of the period with one key, which is the end station scrambling at the present time is t-1 period with one key.

Usually, this scrambling corresponds to �tenderto, such as DVB-CSA (digital video broadcasting - common scrambling algorithm), ISMA Cryp (Internet Streaming Media Alliance Cryp), SRTP (secure data transfer Protocol in real time), AES (advanced encryption standard), etc.

For each channel i, the system 28 generates the ECM messages (Messages access control), denoted by ECMi,tand containing at least the cryptogram CW*j,tcontrol word CWj,tdeveloped by the generator 32 and used by the device 22 scrambling for scrambling the t-th period with one key. These messages and the scrambled multimedia data combined with the help of the device 26 of the Association, wherein said data respectively provided by the system 28 conditional access device and 22 of scrambling, and then passed to the network 8.

The system also inserts 28 in each ECM message:

- the identifier of the first channel;

- the cryptogram CW*i,tand CW*j,t+1control words CWi,tand CWi,t+1that allow you to descrambling t-th and t+1 periods with one key, which follow directly behind the channel i;

tags TStand TSt+1time that identify the moments in which you want to play t-th and t+1-th phase with one key;

- SA conditions of access that are tailored to them compared with the access rights obtained by�isovaline; and

- cryptographic redundancy MAC or signature, which is used to check the integrity of the ECM messages.

Below in the description of the ECM message containing a pair of control words CWi,t/CWi,t+1, denote by ECMi,twhile

the index i identifies the channel; and

the index t is a serial number identifying the temporal position of this ECM message relative to other ECM messages sent to diskriminirovaniya channel i.

Here, the index t also identifies the period CPi,twith one key, which can be descramblers using the control word CWi,tcontained in the ECM messagei,t. The index t is unique for each period CPi,twith one key.

Timestamp defined in relation to the ultimate source, regardless of the transmission of multimedia data and the channel on which to transmit multimedia data.

The same ID i put in all the ECM messagei,tcontaining the cryptogram CW*i,twhat you are doing to diskriminirovaniya multimedia data transferred through one channel. For illustration here scrambling and combining multimedia data Protocol-compliant DVB-Simulcrypt (ETSI TS 103197). In this case, the ID i corresponds to a unique pair of "channel ID/thread ID", through whic�'s send all requests for the development of the ECM messages for this channel.

Each message ECMi,tcontains a pair of cryptograms CW*i,t/CW*i,t+1with the control words. After decrypting this pair of cryptograms CW*i,t/CW*i,t+1lets get a few CWi,t/CWi,t+1control words. Cryptogram CW*i,t+1contained in the ECM messagei,there is used as part of historical data to identify the message ECMi,t+1following directly after the message ECMi,t. Indeed, for example, after decryption of these cryptograms CW*i,tand CW*i,t+1, control word CWi,t+1can be compared with the first pair of control words control word contained in the ECM messagei,t+1. If there is a match, then it means that the ECM messagei,t+1is the actual message immediately follows message ECMi,t. It is also possible to compare the control words CWi,tcontained in the ECM messagei,t, with the second control word of the pair of control words contained in the ECM messagei,t+1. If there is a match, then it means that the ecm messagei,t-1is the actual message that is immediately before the ECM messagei,t.

For example, the end station 10-12 same here and described in detail only the terminal station 10.

Here end mill�July 10 will describe in a particular case, when she is able to simultaneously descrambling two different channel i, j. For this end station 10 contains two lines 60 and 62 diskriminirovaniya used for simultaneous diskriminirovaniya respectively of the channels i, j. For example, a line 60 descrambler channel i in order to display the result on the device 84 display, at the same time parallel to the line 62 descrambler channel j for the purpose of recording using the device 64 records.

For example, these lines 60 and 62 are identical and further detail will be described only line 60.

Line 60 comprises a device 70 receiving the transmitted multimedia data. This device 70 connected to the reception input device 72 of the separation that passes from one side of the multimedia data to the device 74 diskriminirovaniya, on the other hand sends the ECM the ECM messagei,tand EMM (a message to the rights management) on the device 76 processing.

The device 74 diskriminirovaniya by diskriminirovaniya scrambled multimedia data using the control word transmitted by the device 76 processing. Diskriminirovaniya multimedia data is transmitted to the device 80 decoding, which decodes them. Diskriminirovaniya multimedia data is transmitted to the device 80 decoding, which decodes them. Expanded or decoded multimedia d�record is passed to the graphics card 82, which handles the display of the multimedia data block 84 display, equipped with a screen 86.

Unit 84 displays on the display screen 86 multimedia data in the clear.

The device 76 processing handles sensitive information such as cryptographic keys. In order to preserve the confidentiality of this information, the device 76 treatments done as far as possible resistant to possible attacks by computer hackers. Therefore, it is more robust to these attacks compared to the other components of the terminal station 10. For example, for this purpose, the device 76 processing is a card with a microprocessor.

In this embodiment, the device 76 of the processing is common to lines 60 and 62.

For example, the device 76 of the processing performed with the aid of a programmable electronic computer or calculator 77, is able to execute commands recorded on the media. For this purpose, the device 76 of the handle is connected to a memory 78 that contains the commands necessary for performing the method of Fig.3.

The memory 78 also contains the following:

- the local table 79 for the analysis of change channels or switch channels,

- the original value of Y for counters Kchi,

- the number X whose value specifies the maximum number of CAD�fishing, which can be monitored simultaneously

- the limit R channels that can be simultaneously descrambling using the same processing device 76,

- the time interval ΔT, and

- threshold Δ corresponding to the number of ECM messages.

Usually the values of X, P, ΔT, Δ and Y, or installed on all occasions at the enterprise in the manufacture of the processing device 76, or may be installed after the start of operation of the processing device 76 to the terminal station 10 by using a specific EMM messages sent from the device 6.

Fig.2 schematically shows an example of the structure of the table 79. This table contains five columns and X rows. Three small points contained in each column, means that this table 79 presents all of the data.

These columns respectively contain (from the first to the fifth column):

- the identifier of the monitored channel,

- the value of the counter Kchi,

- the value of the counter Kecmi,

- the value of the previous control word LCWiadopted in channel i device 76 processing, and

- the value of the mark LTSitime contained in the previous message ECMi,pthat made for channel i.

Below in this description the value of "p" and "C" index of t correspond to the order numbers respectively the previous and the new ECM message accepted for one�th the same channel i.

Below will be described the operation of the system 2 with reference to the method of Fig.3.

Initially, in step 120, the device 6 simultaneously transmits several different multimedia data through a variety of channels. For each channel period t with one key and the next period t+1 with one key scrambler using control words, respectively, CWi,tand CWi,t+1. Messages ECMi,tand ECMi,t+1containing the cryptogram CW*i,tand CW*i,t+1control words CWi,tand CWi,t+1combine with the transmitted multimedia data. This Association allows you to transfer control words synchronously with the transmission of multimedia data. Here cryptogram CW*i,tand CW*i,t+1transmitted to the terminal station during the period t-1 with one key, prior to the period t with one key.

Usually each message ECMi,trepeat several times during the same period with one key. For example, messages ECMi,trepeat each time interval of 0.1 seconds to 0.5 seconds. The duration of the period with one key more than 5 seconds and preferably is from 5 seconds to 10 minutes. Here the duration of the period with one key is 10 seconds.

Scrambled multimedia data are essentially at the same time on each con�station: 10-12. Therefore, subsequent steps are performed essentially in parallel with each of these end stations. They are described in the specific case of the terminal station 10.

Similarly, the same operations performed in parallel by lines 60 and 62. Here they are described only in the specific case of line 60.

During stage 122 scrambled multimedia data and messages ECMi,ttaken with the help of the device 70 of admission.

Next, in step 124 in the device 72, the separation of the extracted scrambled multimedia data corresponding to the channel i, diskriminirovaniya which currently asks the user. In step 124 in the device 72 division also retrieve only messages ECMi,tassociated with channel i. The device 72 separation transmit the extracted multimedia data to the device 74 diskriminirovaniya. The extracted message ECMi,tfor its part passed to the device 76 processing. This message ECMi,tis a new ECM message accepted for channel i, and therefore denote it using ECMi,c.

In step 126 in the device 76 treatment compare SA conditions of access contained in the ECM messagei,c, access rights, pre-recorded in the memory 78.

If the user's access rights do not meet the conditions of the SA access, then in step 128, the device 76 of the processing is prohibited�t descrambling channel i using the end station 10. For example, for this purpose, the device 76 treatment is not transmitting to the device 74 diskriminirovaniya control word.

If access rights are consistent with the terms of the SA access, then in step 132 in the device 76 processing of decrypting the cryptogram CW*i,cand CW*i,c+1with working key, stored in the memory 78. Usually this working key update once a month.

Next, in step 134 in the device 76 treatment reduce the counter Nb-ECM to the preset value. For example, the set value is 1.

In step 136 to the processing device checks whether the counter Nb-ECM predetermined threshold S0. For example, here the value of the threshold S00.

If the response is positive, the operation moves to step 138 to store table 79 in non-volatile memory device 76 processing. In addition, in step 138 the processing device will reset the counter Nb-ECM in the original value of Vsave. For example, the value of Vsaveequal to 200.

In the event of a power failure or reset of the processing device 76 to 79 table is re-loaded values in this table are recorded in the nonvolatile memory. Thus, a power failure or reset device 76 processing makes it impossible to re-establish portions of the data contained in table 79, equal to their initial values.

After step 138, or directly after step 136, the EU�and the count value Nb-ECM has not reached the threshold S 0in the device 76 of the processing in step 140 increases to the preset value counter Kecmiwhose values are recorded in table 79. For example, the set value is 1.

In step 142 to the processing device checks whether the channel for which you received the message ECMi,ctracked by the channel. The monitored channel is the channel identifier i which is contained in the first column of the table 79. To this end, in the processing device extracts the identifier i from the channel contained in the received ECM messagei,cand then compare this ID i ID contained in the first column of the table 79.

If none of the identifiers contained in table 79, does not match the ID i, then in step 143 in the device 76 processing searches in this table, the rows being at least one of the following conditions:

1)TSi-LTSi>ΔT or

2) Kecmi>Δ.

If one of the rows of the table 79 satisfies one of the conditions 1) or 2), it means that the device 76 treatment had not received a single ESM message for a long period of time for a channel corresponding to that row. Consequently, the device 76 treatment is no longer used for diskriminirovaniya of a channel corresponding to that row. In step 144 this line of Svoboda�t for use in tracking channel i. To this end the cells of this row are filled as follows:

- ID i write in the first column,

- the value of the counter Kchirelieve, that is, its value becomes equal to Y,

- the value of the counter Kchirelieve, that is, its value becomes equal to 0

- control word CWi,c+1write to equal the previous accepted the control word LCWi,

- mark TSitime is equal to the previous record with the adopted LTS labelitime.

At the end of stage 144, the implementation of the method returns to step 122 in order to process new received ECM message.

If the channel i already trace, in the device 76 of the processing selects the corresponding row in the table 79 and move on to step 150, in which checks that the message ECMi,ctaken within a time interval FT immediately following the previous message ECMi,padopted for this channel (i. The length of time FT greater than or equal to the duration of the period with one key. Here the length of time FT is equal to the maximum duration of DCPperiod with one key, duration, interval and duration ΔT ΔE*DCP/P.

Here the phase of 150 start with operation 152 in which the device 76 processing checks whether the message ECMi,cimmediately before�previous message ECM i,p.With this purpose, compare the last received control word, LCWiwhose value is recorded in the fourth column of the table 79, with control word CWi,ccontained in the ECM messagei,c.

If control words LCWiand CWi,cequal, the device 76 of the processing goes directly to step 153. In step 153, the counter Kchiincrease by a predetermined amount equal to, for example, 1. At this stage in table 79 the values of the control word LCWiand labels LTSimodify so that they become respectively equal to the values of the control word CWi,c+1and TSc. Finally, only the value of the counter Kecmireset to the original value of 0.

If control words LCWiand CWi,cdifferent, then at operation 154 the difference between the label TSctime contained in the ECM messagei,cand mark LTSitime contained in table 79, compared with the interval ΔT. If the difference is less than the interval ΔT, the message ECMi,ctaken in FT interval and the device 76 of the processing goes directly to step 153.

Otherwise, skip to operation 156, during which compare the value of the counter Kecmiassociated with channel i, in table 79, the threshold ΔE. If the counter Kecmiless than threshold ΔE, in the range of FT made novaezealandiae ECM i,c. Therefore, continue the implementation of the method in step 153. The number of messages ECMj,cprocessed by the device 76 processing for other channels, shows the time elapsed since the reception of the message ECMi,p.

If the answer is believe that the ECM messagei,cwas not taken in the interval FT. This means that the device 76 processing not one used to diskriminirovaniya channel i. Next, perform step 158. In step 158 counters Kchiand Kecm, reset to their original values. More specifically, restore counter values Kchiand Kecmiare, respectively, Y and zero. In addition, ATPA 158 control word CW+1 are inserted in the table 79 as of the last received control word LCWi. The LTS valueitake is equal to the timestamp TSc.*

Thus, operations 154 and 156 prevent the reset counter Kchicaused by hidden or fast by changing the channel or switching. Hidden changing the channel is short mathiaparanam movement to the other channel. It manikopoulos movement is quite short, so as not to cause interruption of diskriminirovaniya channel i, which makes it difficult to view this channel. When operations 154 and 156 do not exercise, it's a hidden change systematically resets the counter Kchithat can be�ü used as a hindrance to the implementation of the method of detection of the illicit use of the above-described processing device 76.

At the end of phase 153 or 158, the processing device in step 160 counts the number of counters Kchiequal to 0, and write the result into the variable Z.

In step 162 the processing device is satisfied, is it fair that the variable Z is strictly greater than 0.

A positive response means discovered the illegal use of the treatment device 76. In this case, the device 76 processing is carried out step 164, in which it automatically launches counter-measures to combat this illegal use. Here the applied countermeasures chosen as a function of the variable z is Usually more than the value of the variable Z, the greater the force applied counter-measures, that is, they become more difficult for the user.

Examples of responses are listed below in order of increasing strength:

1) Suspend diskriminirovaniya channel or all channels within the set period, followed by automatic restart of diskriminirovaniya these channels after a specified period of time.

2) Suspend diskriminirovaniya this channel and simultaneously display a screen with a message asking the user to change channels before returning to the channel i that do for the purpose of re-authorization of diskriminirovaniya channel i. In �the case of diskriminirovaniya again be allowed only after as the user changed the channel i to another channel.

3) Suspend the processing of the ECM message, thereby preventing diskriminirovaniya channels as long as the device 76 treatment will not be reset, for example, by turning off power to the terminal station.

4) Prevent diskriminirovaniya channel or channels until such time as the value written to the nonvolatile memory device 76 treatment will not be reset by using EMM messages. Such countermeasures can force the user to communicate with the operator so that the operator sent the EMM message that allows you to unlock the device 76 processing.

5) Final blocking device 76 treatment completely prevents the use of this device processing.

Preferably, in step 164, the value of Z is compared with a limit of P that indicates the number of channels that can be simultaneously descramblers using the processing device 76. If the variable is strictly greater than the boundaries of the District, it certainly means that the device 76 processing used in an illegal manner. In this case, use a strong counter-measures, such as the steps 5) and 6) counter.

If the value of Z is zero or after step 164, the method returns to step 122 for the purpose milling�tki new ECM messages.

Here the initial value Y of the counter Kchi, the value of decrease and the threshold, which must be achieved to start the detection of the illegal use of the processing device 76, is selected so that this threshold was reached after at least three hours and preferably after at least 12 hours or three days without any change channels. For example, the value of Y is 432000.

The interval ΔT more than double the difference between the timestamps of two consecutive ECM messages. For example, the interval ΔT is equal to at least two minutes.

The threshold ΔE of at least more than two, and preferably three or more six.

Many other patterns are possible for practicing the invention. For example, different counters described here can be increased by a fixed amount instead of reducing them.

The magnitude of increase or decrease may be negative. Thus, in this description it is believed that the reduction of the counter coincides with the increase of the counter to a negative value.

Lines 60, 62 may be independent from each other, as described with reference to Fig.1, or they may use shared resources. Usually sharing common resources perform by temporarily combining their use. A shared resource may be a receiving device, the separation device or device�tvo of diskriminirovaniya.

Alternatively, the processing device of the security system or the end-station is equipped with clocks that measure the time interval between the moments of reception of messages ECMi,cand ECMi,p.Further, this interval is used instead of the difference between the labels TSi,cand TSi,p.In this embodiment, ΔT more than double the interval between two reception following directly after the other, the ECM messages.

One or two of operations 152, 154 and 156 may be omitted. In particular, can be omitted various stages described here, adapted to prevent counter reset Kchiin the case of a hidden channel change.

Also simultaneous diskriminirovaniya multiple channels by using the same processing device of the security system can be used in other contexts. For example in this context is a case where it is possible to simultaneously display multiple channels on one screen. This capability is known, for example, the term "picture in picture".

Countermeasures can be applied only to channels for which the counter Kchireached the threshold of detection of the illicit use. As an option each countermeasure is applied to all channels.

Finally, other possible mechanisms to verify that the message ECMi,cwhen�the poor in the interval, following directly behind the ECM messagei,p.For example, as a variant, each ECM message further comprises a sequence number indicating the position relative to other ECM messages sent to the same channel. In this case, the reception of the message ECMi,cin the interval FT verify, for example, by comparing the difference between sequence numbers of messages ECMi,cand ECMi,pwith a given threshold. In particular the sequence of messages ECMi,cand messages ECMi,pcheck the following: make sure that their respective sequence numbers actually follow each other. Thus, in this embodiment, each of the ECM message is not obliged to simultaneously contain both control words CWi,tand CWi,t+1.

In this embodiment, the sequence number is considered as a timestamp, as it represents some measure, from the point of view of the number of frames with one key, the number of frames with one key, which was a common time source for all channels.

Preferably, the duration of this time interval was strictly greater than the duration of the period with one key.

1. Method of detection of the illicit use of processing devices of the security system used to diskriminirovaniya various multimedia data distributed by �skolkin the appropriate channels, containing phases in which:
with the help of an electronic device processing system security accept (122) of the ECM messages (messages access control), denoted as ECMi,tfor diskriminirovaniya a temporal sequence of frames with one key scrambled channel i, each message ECMi,tcontains at least one cryptogram of the control word CWi,tallowing descrambling period CPi,twith one key channel i, where i identifies the channel, and the index t is a sequence number,
each time you receive a new message ECMi,cusing the device for processing security checks (150) that the ECM messagei,ctaken in a predetermined time interval immediately following the previous message ECMi,ptaken by the processing device of the security system for channel i, where the indices C and p are two specific values of the sequence number t,
characterized in that the method includes stages, at which:
count (140, 153, 158) new messages ECMj,ctaken by the processing device of the security system for channels that differ from channel i, after the last received message ECMi,p
check (150) that the ECM messagei,ctaken during a specified time interval, by about�enables (156), the number of new messages ECMj,ctaken for channels that differ from channel i, reaches or exceeds the specified threshold, the larger of the two,
increase (153) counter Kchiby a predetermined amount whenever in the test phase, it is established that the ECM messagei,ctaken during a specified time interval immediately following the message ECMi,pand otherwise, reset the counter Kchiin the initial value,
find (162) illegal use when the counter reaches Kchia given threshold.

2. A method according to claim 1, wherein each received message ECMi,t also contains a portion of historical data, allowing to identify immediately preceding the ECM messagei,t-1or directly following message ECMi,t+1the method contains the stages on which: validate (150) that the ECM messagei,ctaken during a specified time interval, by checking (152) that the new received message ECMi,cis the message, following directly behind the ECM messagej por message, just prior to the ECM messagei,pbased on the mentioned part of the chronological data contained in the ECM messagei,cor ECM messagei,p.

3. A method according to claim 1, containing a stage, on which: validate(150), the ECM messagei,cmade within the specified interval by verifying that the difference between the labels TScand TSptime contained respectively in the message ECMi,c and ECMi,p, is less than a specified time interval ΔΤ, more than twice the time interval between the specified timestamps directly following each other messages ECMi,tand ECMi,t+1.

4. A method according to claim 1, comprising stages on which:
measure the time interval ΔVc pbetween the moments of reception of messages ECMi,cand ECMi,pand
check that the ECM messagei,ctaken during a specified time interval by checking whether the measured interval ΔVc pless than or equal to the specified time interval ΔΤ, more than twice the time interval ΔVt,t+1measured between the moments of reception following directly after the other messages ECMi,tand ECMi,t+1.

5. A method according to claim 1, containing a stage, on which: choose (150) counter Kchiwhose value increases from X possible counter Kchj, wherein X is an integer greater than or equal to 2, depending on the ID channel i is contained in the ECM messagei,c.

6. A method according to claim 5, comprising stages on which:
count (162) - related channels counter�Kch com iwhose value has reached or surpassed their respective defined thresholds,
compare (164) the quantity Ζ counter Kchiwhose value has reached or surpassed their respective defined thresholds, with a specified limit of P, equal to the maximum number of channels that can be simultaneously descramblers using a processing device of a security system, and
if the number Ζ reaches or exceeds the boundary limit R, automatically launch a strong counter-measures, and otherwise running other, weaker responses.

7. A method according to claim 1, containing a stage at which in response to the detection of the illicit use automatically trigger (164) countermeasures that prevent diskriminirovaniya channel i and displaying a message prompting the user to perform a specific action for the recovery of diskriminirovaniya channel i.

8. A method according to claim 7, wherein said specific action is changing the channel.

9. Media (78), characterized in that it comprises a command for performing the method according to any one of claims. 1-8, wherein said commands are executed by the electronic computer.

10. Device (76) processing of security for the end station, used to diskriminirovaniya various multimedia�'iynaya data disseminated through various appropriate channels, performed with the opportunity to:
take the ECM messages (messages access control), denoted as ECMi,tfor diskriminirovaniya a temporal sequence of frames with one key scrambled channel i, each message ECMi,tcontains at least one cryptogram of the control word CWi,tallowing descrambling period CPi,twith one key channel i, where the index i identifies the channel, and the index t is a sequence number,
each time you receive a new message ECMi,ccheck that the ECM messagei,ctaken in a predetermined time interval immediately following the previous message ECMi,ptaken using a processing device of a security system for channel i, where the indices C and p are two specific values of the sequence number t,
characterized in that also is capable of:
count (140, 153, 158) new messages ECMj,ctaken by the processing device of the security system for channels that differ from channel i, after the last received message ECMi,p
check (150) that the ECM messagei,ctaken during a specified time interval, by checking (156) that the number of new messages ECMj,ctaken of telekanalov, different from channel i, reaches or exceeds the specified threshold, the larger of the two,
to increase counter Kchiby a predetermined amount every time when the inspection reveals that the ECM messagei,ctaken during a specified time interval,
immediately following the message ECMi,pand otherwise, reset the counter Kchiin the initial value,
to detect the illegal use when the counter reaches Kchia given threshold.



 

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2 cl, 13 dwg

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