Method and system for marking and identifying data.

p0001The invention relates to a method and a marking system and digitized information identification for its identification and its protection. With the development of digital technologies in the production and exchange of information, sound information or video, for example, the problem of identification, origin and therefore the legality of the exchange and use of this information has appeared so similar to that of computer software field.

p0002Indeed, unlike analog image productions, such as a film or video recording, which involve every copy from an original, or even a copy of itself, the introduction of degradations the information carrier, and finally the information itself, which allow identification of the copy compared to an original, digital techniques introduce substantially no degradation of the support or information, and make this makes almost impossible the identification of the copy by comparison, very small degradations introduced because of the reproduction is inherent to the support and the actually used technique. For example, an image stored on a data carrier, such as a flexible disk or a hard drive, undergoes during a duplicating any degradation, while a DVR usually introduces some defects due to the recording technique employee.

p0003Currently several techniques are applied to ensure the identification data such as scanned image data, these techniques based primarily on the development of a visible signature directly by keying a text or a distinctive sign or <u>logo</u> in the above image data. Regarding the moving image data such as television pictures, the coding standards specify techniques for inserting auxiliary data, component identification data, besides the useful video lines. As examples may be mentioned olefins standards by CEEFAX DIDON or services. Relatively digitized still images, no storage standard is established. The image is simply a computer file, provided useful digital video data formed of information words and structured according to the digital acquisition and restitution device. In this case, the conventional techniques for protection of computer files, such as entry of identification messages in reserved areas of the recording medium, may be used.

p0004above labeling techniques, national conventional inlay techniques can meet the needs of supply of non-altered images can ultimately ensure effective protection, the identification message may be deleted by a crop in for images, for example. In addition, ancillary data television systems are not protected against erasure or rewriting copy the video images directly to the video output source can not be effectively controlled.

p0005More recently, a method for marking and identification of digital information has been described by WO-A-89 08915. In its principle, this process consists in performing, in codewords digitally, the remplacemement of at least some significant bit by a corresponding bit of information to be encoded. In particular, this replacement can be performed on words, discrete coded information sequences, or on a continuous bit stream for example. However, this document merely states the corresponding general principles.

p0006Another similar method has been described by the European patent application EP 0205 200 in respect of digital audio type information, wherein the added coded information is introduced at the level of the least significant bits in words of fixed order . The number of bits of these words in which the additional information is added is detemine depending on the value of the word, that is to say the amplitude of the signal represented by these vis-a-vis a word arbitrary value corresponding to a threshold value.

p0007Such a technique appears to have to be reserved for the type of digital audio signal.

p0008The method of the present invention aims to overcome the above drawbacks to provide robust protection against unauthorized use of digital information, such as still images or movies, for example.

p0009An object of the present invention is a digital information marking method in which the data constituting the identification message can not be destroyed without a corresponding destruction of the thus marked information.

p0010Another object of the present invention, however, a digital information marking method in which the data constituting the identification message, although qu'indissociables of the actual digital information, are transparent thereto.

p0011Another object of the present invention is also a digital information labeling method in which the identification data can be used to prohibit the use of unauthorized copies of that information, lawful or unlawful character of such copies may be discriminated from data constituting the identification message.

p0012The digitized information marking process, this information being scanned in the form of successive information words formed by a plurality of bits, these words being formed in a sequential arragement to form the digital information according to the present invention is noteworthy in that it consists in associating the information words transparent coded identification data with respect to the scanned information.

p0013The method of the invention is applicable to the protection against the illegal use of digital information such as sound information and / or video.

p0014In particular the method of the present invention is particularly well suited to providing robust protection by identifying, following a marking, fixed scanned images, natural or synthetic, or pictures or television programs transmitted or recorded following a digital coding.

p0015The method of the present invention is also particularly advantageous in that it may allow the definition of descrimination protocols of legality or illegality of copies of digital information protected in accordance with the method of the invention, for the prohibition of the use of such copies, in case the illegality of the latter has been established.

p0016A more detailed description of the process object of the present invention will be given hereinafter with reference to the drawings in which:<ul><li>1a shows, illustratively, the different steps for the implementation of the object of the present invention, according to a first embodiment not limitative and,</li><li>1b shows a particular implementation detail of a further step according to an advantageous variant of the embodiment of Figure 1a;</li><li>2a shows, also in an illustrative manner, the steps for the implementation of the method of the present invention in a second non-limiting embodiment;</li><li>2b shows a detail of realization and implementation of the above-mentioned embodiment, as shown in Figure 2a;</li><li>Figure 3 shows another alternative embodiment of the method of the invention wherein the variations shown in Figure 1a and 2a are somehow associated to form a process according to the object of the present invention, this other variant of realization is likely to present a character greater likelihood of identification messages of concealment and, ultimately, better protection;</li><li>4 shows an embodiment of a marking system and digitized information identification enabling the implementation of the method according to the invention,</li><li>5a and 5b show an alternative embodiment of the system according to the invention as shown in Figure 4, specifically adapted to the prohibition of copies of second generation of digital video tapes, television programs, for example.</li></ul>

p0017A more detailed description of the method for marking and identification of digital information according to the object of the present invention will now be given in connection with FIG 1a.

p0018According to the method of the present invention, it applies to digital information in the form of successive words Rated M_i where i is the order of the word during the recording or reading the aforementioned digital information on the corresponding carrier, which information is thus constituted by a set of bits, words M_i being organized in a sequential arrangement.

p0019According to the method of the invention, it consists of associating the words info M_i transparent coded identification data relating to the aforementioned digital information.

p0020Generally it will be considered words M_i constituted by N bits, the number N may according to an exemplary non-limiting embodiment, for example equal to 8 and the information words being thus formed in byte.

p0021Of particular note, as shown in Figure 1a, the words M_i may for example be represented by a hexadecimal coding, a set of N M words_i, With i varying from 1 to N, being represented on the line <u>at</u> of Figure 1a supra. The representation of the coding of words corresponding to the hexadecimal encoding, as mentioned previously, the first number is the value of the higher-order quartet binary coded and the second digit in the sense of writing or reading the words , also corresponds to the binary coded value of the lower order quartet, as has been shown in Figure 1a. For the embodiment of Figure 1a, in particular on line<u>at</u> thereof, the word M_i is the hexadecimal value 81. It will be understood of course that the eight words represented at line <u>at</u> of Figure 1a are in fact eight successive words recorded on the information carrier, the words being encoded as described above.

p0022As was also shown in Figure 1a and one example where the information words M_i are encoded on eight bits, according to a first implementation variant of the object of the invention, the of the above digital information identification data is associated with specific encoding of one of the least significant bits of a plurality of information words M_iThese words are so constructed as carriers words identification data.

p0023Of course, and according to an advantageous aspect of the method of the invention, as shown in particular in Figure 1a, the plurality of information words M_i Identification data carriers is a multiple of the number N of bits of the code words constituting the identification data.

p0024The data constituted by the identification words are constituted by one or more strings of alphanumeric characters, for example.

p0025In accordance with the embodiment of Figure 1a, the identification data are associated with specific encoding of one of the least significant bits on a plurality of information words M_i A determined to address_i in sequential arrangement.

p0026As was shown in particular in Figure 1a, as one example, the addresses Ai are uniformly distributed in the sequential arrangement such that the N information words M_i are successive, the specific coding of one of the least significant bits then intervening on each data word adjacent M_i.

p0027Of course info M words of addresses_i on which the specific coding is performed may advantageously be evenly distributed in sequential arrangement in a given law of periodicity. The law of periodicity can be set so as to provide the identical addresses gaps between the information words M_i encoded to thereby constitute carriers words of identification data, or different address ranges divided according to a given periodic law.

p0028Furthermore, and particularly preferably in a preferred embodiment of the method of the invention, the address information words M_i encoded to form identification data carriers words may instead be distributed randomly or pseudo-randomly in the sequential arrangement.

p0029Note of course that such a randomized or pseudo-random addresses the above makes it more difficult fraudulent identification information information words M_i Identification data carriers.

p0030Of course, for information words and / or word identification data encoded on N bits, the value of each bit of a word identification data to be encoded is set in the order of succession information words M_i encoded by specific coding, the value 2^N-1 to 2⁰. In fact each information word M_iFor a plurality N of these words is associated with a corresponding weight value of the weight of the coding bits of an identification data word considered in the direction of the information sequence M_i supra.

p0031A more specific example of encoding N information words M_i, More particularly of eight of these words will be given in connection with the lines b, c, d of FIG 1a. Although in Figure 1a said information words M_i subject to coding to form words holders of identification data are represented successive course be understood that these words can succeed in any manner, the information words M_i being successively identified by their address Ai in sequential arrangement. The information words M_i and above belong to the original media sources and thus are selected by their address.

p0032According to the method of the invention, as represented at line <u>b</u> of Figure 1a, to the least significant bit, for example each word M_i Information is assigned a value of zero to thereby make a unification value at the lowest level of the bit of the word in question. We notice that on the line<u>b</u> of Figure 1a all information words M_i and in particular the zero bit of the lower order quartet coding for the latter to zero.

p0033On the line <u>c</u> of Figure 1a, there is shown one word of identification data to be encoded. This word is naturally encoded on N bits and in the embodiment of Figure 1a on eight bits. This word or byte, by way of example, corresponds to C alphanumeric character whose hexadecimal encoding ASCII representation is given by the value 43. On the line<u>c</u> of 1a was therefore represented the alphanumeric character corresponding C, binary coded, bit order 1 to N i corresponding course, in order of decreasing weight of these, in successive order information words M_i previously selected.

p0034Finally, according to the process object of the present invention, as represented in line <u>d</u> of 1a, at the least significant bit data words M_i identified is assigned respectively, in the order of their registration, the value of the corresponding bit of the information data word to be encoded, the alphanumeric character C in the example shown in Figure 1a. Such allocation allows to form words info M_i Identification data carriers. Of course it will be understood that the aforesaid allocation is performed by a logical addition operation (operation OR between the least significant bit of the lower quartet information word M_i shown for example at line <u>b</u> of Figure 1 and the corresponding bit of the identification data word to be encoded, or the alpha-numeric character represented on line C <u>c</u> of 1a above).

p0035It is understood of course that in order to encode a word identification data comprising for example three alphanumeric characters to form an identification message, each character of the message of the aforementioned identificaion being transposed on a series of eight words of information M_i, It is necessary for example to carry out the operations described above in conjunction with Figure 1 of 24 information words M_i Scanned information data marking and protection.

p0036Of course, the method of the invention may advantageously comprise, before the step of assigning to the least significant bit of each of the N or 8 words identified information, a control step that is to prevent the appearance of reserved codes such as, for example, or FF OO code in hexadecimal encoding, reserved for the identification of auxiliary data and reference sequences of digital television in rhythm.

p0037For this purpose, control of the step may include comparing bit by bit the value of bits of a fictitious identification word data carrier such as a word formed by the most significant bit of the corresponding word to be encoded and by bit heavier than the carrier information word M_i the aforementioned reserved code words or neighbor codewords such as 01 FE respectively for example.

p0038In case of positive response to the above test, the previous step of selecting the information word M_i for this word is considered canceled for example to perform a new stage of selection in relation to an information word M_i Ai address k + higher order in sequential arrangement to identify a word substitution information bits associated with greater weight corresponding to encode bits are different from the reserved code or code above neighbor. Such control step is then used to guard the encoding of reserved code words or code neighbor mentioned above.

p0039Of particular note is that in the process object of the present invention as shown in Figures 1a and 1b, the identification data are recorded by changing a level of quatification representative information words of digital information. The impact of the insertion of the words or bytes constituting the identification message under the subject of the invention, especially when it is applied to a standard television image is imperceptible on the image since the course bit information words M_i thus modified are the bits of the lowest weight. The impact of such integration on the actually returned signal could be encrypted to 0.4% of the amplitude before filtering it. In addition, the insertion of the identification data areas can be selected outside the scope of the useful analog image, digital active line being wider than the analog active line.

p0040According to a variant of the control procedure described above in conjunction with Figure 1b, the tranformation of the original information words M_i in modified words identical to reserved words such as OO and FF in hexadecimal encoding is unlikely, it is also possible, if the information word M_i after encoding the obtained identification data is OO, advantageously to replace it for example by the word O2 and if on the contrary the information word obtained after encoding is FF it may then advantageously be replaced by FD.

p0041Indeed, with this judicious choice of encoding information words M_i after encoding identification data, the gap between the information words M_i before and after encoding concerns only the least significant bit of the words M_i.

p0042Another embodiment of the method of the present invention will now be described with Figures 2a and 2b.

p0043In this new embodiment, the identification data are not registered, the information words M_i then being kept unchanged, but the composition of the words constituting the identification data is referenced in the information words M_i component useful original scanned data or optionally partially altered.

p0044Similarly as in the embodiment described above, the composition of the words forming the identification data or identification message is defined for example by a series of alphanumeric characters of ASCII, these characters are encoded as previously mentioned on N bits and for example, as will be described without limitation in connection with figures 2a and 2b, for coding on eight bits.

p0045Under the new embodiment of the method of the invention, the identification data associated with the form of at least one word to encode the information words M_i by operations consisting successively to locate in the successive information words of all component bits of digital information a bit having the value of the specified bit of the word to be coded, that is to say character constitutive alphanumeric identification of the message and to associate with the bit and spotted the weight corresponding to the word bit of weight to encode up a bit spotted the word to be coded. The address of the information word M_i thus identified, and the identified bit thereof, is then stored on the digital information carrier.

p0046The aforementioned operations are then successively repeated for successive bits of the word to be coded, that is to say the constituent character of the identification message, to constitute an identification of the digital information file. Of course, the identification of the digital information file can be stored in a stored information identification zone provided on the support of digitized information, or any other separate support thereof.

p0047A more detailed description of the method of the invention in its second embodiment will be given in conjunction with Figures 2a and 2b in the specific case of digital information comprised of a digital television image, for example.

p0048Figure 2a shows as an example the identification of an alpha-numeric character "C" constituting an identification message to be encoded. This alphanumeric character C as mentioned previously is represented by the ASCII code 43 in hexadecimal code. Figure 2a shows the alpha-numerical character constituting the aforementioned identification word to be coded representation in binary code to represent the set of bits thereof.

p0049Advantageously, the corresponding bits of the identification word to be coded supra are marked on the successive lines of the image, which are shown in Figure 2a and numbered from an image scan line <u>not</u> to n + 7 for example.

p0050Preferably, the corresponding bits of the identification word to be coded, the alpha-numeric character C are spotted on the aforementioned lines of the image between the columns of a determined order, p and q of the image. According to the embodiment not limitative of Figure 2a, the columns<u>p</u> and <u>q</u> correspond to the columns 5 and 19 of the image in the line scanning direction thereof.

p0051According to another advantageous feature of the method of the invention in the second embodiment described herein, the corresponding bits of the identification code word, such as alphanumeric character C, for example, are marked on the bit 2¹ information words M_i.

p0052The corresponding address Ai information words M_i thus identified are then defined as shown in Figure 2a in relative addressing with respect to the reference grid consisting of lines <u>not</u> and higher order and order columns <u>p</u> and <u>q</u> cited above. The address coding Ai relative addressing information words M_i is advantageously carried out in hexadecimal code. Figure 2a shows the successive information words M₁ on the line<u>not</u>, M₂ on line n + 1 and M_i on line n + 3 and following example highlighted by **. The corresponding address in hexadecimal code of the identified information word is postponed as well in Figure 2a for each line considered.

p0053In Figure 2b, and in particular non-limiting case given only as an example where the information words and word identification coding such as alphanumeric character C are encoded on eight bits is shown successively the order of the information word considered, the weight of the corresponding bit of the identification code word, the lower the quartet word infomation M_i, The corresponding bit of the identification code word being spotted on the bit 2¹, word identification, the alphanumeric character C and address of each bit and spotted. Note, however, as represented at line n + 7 of Figure 2a or Figure 2b, if bit to identify, and thus to be coded, is not provided in the column line interval above a specific code address can be used, the F code in hexadecimal code example. The specific address is symbolically represented by the code itself encircled, and corresponds to the complement of bit values ​​of the line in either 0 or 1.

p0054The address of the bit thus identified is incorporated file for reconstructing identification.

p0055An essential advantage of the embodiment of the inventive object method, as described in FIG 2a and 2b, is the fact that the identification of the picture or scanned data component so it can be performed in the absence of modification of it or, at least, given a minimum of modification for example.

p0056Of course, the method of the invention can also be implemented by combining the first and second embodiments described above.

p0057In this case, as shown in Figure 3, the identification data is associated with the words of digitized information of the source or origin information support, identification of word bits or alphanumeric character being conducted in accordance with second mode aforementioned embodiment, as shown in Figure 3, similarly to that of Figure 2a and 2b for the information words one of the lines such as line <u>not</u>, In particular the information words M_i located at addresses Ai O 7 thereof being encoded according to steps <u>at</u>, <u>b</u>, <u>c</u>, <u>d</u> as shown according to the first embodiment illustrated in Figure 1a and 1b.

p0058The introduction of the above encoding at some information words M_i as shown in Figure 3 or alteration on the above words prior to the formation of the identification file by storing the addresses according to the second embodiment described above ultimately allows particularize the scanned data, for example image TV and marked. The identification and attached to the above image allows to remove uncertainties resulting from the identification of the original image for other users.

p0059The method of the invention, particularly in the embodiment as shown in Figure 3, ensures a high degree of security marking of digital information including the redundancy of information available and the difficulty of decoding those -ci for unauthorized third parties.

p0060of course be understood that the object of the invention can be used for protection against illegal copying of digital television programs. In such a case, the information words can advantageously be located in portions of the digital video multiplex format capable of being recorded by digital television recorders.

p0061In a television program whose final copy is made on magnetic tape to digital recording, the method of the invention can of course be used. In such cases it is sufficient to select some special pictures of that program to apply to them the process of the invention.

p0062One of the characteristics of digital video recorders for digital television images is including the introduction of impairments on digital signals, these impairments are related to playback recording techniques such as device failure tapes, contact fault between magnetic read-write heads and magnetic tapes.

p0063To minimize these shortcomings, digital television recorders implement error correction techniques and concealment of errors, these techniques have been the subject of Recommendation 657 of the CCIR (Consultative Committee for International Radio-communications).

p0064The reading process and subsequent copies of the digitized information that can implement error concealment techniques may degrade the credentials registered in accordance with the method of the invention. It is useful to repeat several times the record of these credentials, M Information words_i in which will be associated the identification information being chosen so that playback concealment probability of all these words is small. A selection criterion such words may for example consist in the use of words corresponding to samples spatially neighbors in the image luminance, and the use of words stored on the magnetic strip to the less critical areas.

p0065A description of a system of marking and identification of digital information for implementing the digital television pictures of the method of the invention described above will now be given in conjunction with Figures 4 and 5a, 5b.

p0066By convention, will denote the information source information unmarked and marked the information source information to which the identification data were combined accordance with the method of the invention described above. The identification of the scanned information is then made by restitution from the information marked with identification data.

p0067As has been shown in Figure 4, the system according to the invention comprises an input port PE noticed a signal noted SIs support the information source or signal noted SIm Information Support marked and an output port PS noted the marked information carrier signal.

p0068The object of the invention system also comprises a circuit 1 extractor of a synchronization signal from the source labeled or information carrier signal. By way of non-limiting example, when the scanned information is constituted by information words M_i a television picture for example, the synchronization signal comprises in conventional manner a byte sync signal, a horizontal sync signal and a frame synchronization signal. All of these signals will not be described since it corresponds to the synchronization signals of the two types 525/60 or 625/50 standards. These synchronization signals are available throughout the system as shown in Figure 4 from a conventional synchronization bus not shown in the aforementioned figure.

p0069As is also noted in Figure 4, the system comprises a circuit 2 for controlling the marking or identification of digital information.

p0070A 3-bit multiplexer circuit is further provided, said circuit being interconnected with the PE input port. It thus receives the SIs carrier signal source of information or support information SIm signal marked. The multiplexer circuit 3 is connected to the circuit 2 control via a first 4 and a second 5 specialized circuits.

p0071The first dedicated circuit 4 ensures the operation / stop control of the multiplexer circuit 3 depending on the nature of the information source or marked this EP input port.

p0072The second dedicated circuit 5 by against, possible to generate and deliver to the multiplexer circuit 3 a proxy bit in an information word M_i considered.

p0073In addition the system also includes a bit demultiplexer circuit 6 interconnected to the PE input port. The demultiplexer circuit 6 receives the source information the media signal or marked, SIS or SIM. The demultiplexer circuit 6 is further connected to the control circuit 2 via the first dedicated circuit 4, which ensures the stop control / operation of the circuit demultiplexer 6 according to the nature of the source or marked information.

p0074In addition this same circuit demultiplexer 6 is connected to the control circuit 2 via a third dedicated circuit 7 to ensure the extraction from an information word M_i, Of a significant bit of the identification data.

p0075It will thus be understood that the control circuit 2 allows from the synchronization signal to ensure a function of the nature of the scanned information, marked source information or information substitution respectively extracting a bit of the status word information M_i to generate or restore the identification data such as character C example described above.

p0076As can further be noted in Figure 4, the first dedicated circuit 4 has by way of nonlimiting example, a first activation circuit / inhibition and inhibition / activation of the multiplexer 3 respectively demultiplexer 6 and a circuit order 41 choosing the weight of the M bit data word_i on which the significant bit of identification data is substituted at the multiplexer 3, respectively extracted at the demultiplexer 6. It will be understood of course that according to an advantageous embodiment, the control circuits 40 and 41 may be constituted by a single circuit, which in accordance with instructions received from the control circuit 2 can for example deliver a coded instruction, 4 bits for example, to ensure both the activation / inhibition and inhibition functions / activation of the multiplexer and demultiplexer 3 6 and the choice of the weight of the M bit data word_i where the MSB is substituted or extract.

p0077In an embodiment of the object of the invention system, the input and output ports PE and PS consist of input ports and output digital video parallel interfaces as standard 4-2-2 8 data bits plus one clock signal. The source or strong information carrier signals are at TTL level, the floors conversions ECL / TTL and TTL / ECL not being shown in Figure 4. The multiplexers 3 demultiplexers 6 consist of demultiplexers digital multiplexers.

p0078Note further, as has been shown in Figure 4, the first dedicated circuit 4 includes a memory circuit addresses information words M_i. By way of nonlimiting example, when digital information is composed of a television picture, a sequencing system on the whole image requires a 64K byte storage capacity circuit which is used for storing Address 16 384 words of information M_i identified by row and column in the image of a pair of two two-byte words; while a sequencing restricted to one such line scanning requires knowledge of a corresponding line number, or 2 bytes. Of course the address storing circuit information words M_i is itself interconnected to the control circuit 2 and updated by the latter. Other solutions such as the use of a PROM type memory can be considered.

p0079As was further shown in Figure 4, the second specialized circuit 5 comprises a character memory denoted 50 interconnected to the control circuit 2. This is character memory for storing the characters or the constituent data or messages identification to be inserted into the digital information data such as the character C mentioned above. The character memory 50 is a RAM memory whose capacity is based on the size of the identification messages to insert.

p0080In the second five specialized circuit is also provided a circuit 51 of formatting characters which is interconnected to the character memory 50. The formatting circuit is intended to extract and format sequentially constituent character data stored in the memory 50.

p0081The second specialized circuit 5 lastly comprises a circuit 52 significant bits of generator, which is interconnected to the said formatter circuit and the first dedicated circuit 4. The bit generating circuit 52 may be constituted by a RAM memory organized in bits, each bit constituting a significant bit of the identification data to be inserted in one of the information words M_i can be read sequentially by the multiplexer circuit 3. Circuit It is further noted that the 51 character formatting takes into account the read-write access conflicts circuit 52 bit generator, the transfer instruction significant bits to the 52 bit generator circuit being generated by the control circuit 2 via the first dedicated circuit 4, in particular the circuits 40 and 41 for example.

p0082The third dedicated circuit 7, as shown in Figure 4, substantially comprises elements of dual components of the second dedicated circuit 5.

p0083As shown in the aforementioned FIG 4, the third dedicated circuit comprises a first circuit 70 bit memory, the circuit being interconnected to the demultiplexer 6 and the first dedicated circuit 4. The first storage circuit 70 is constituted for example by a memory RAM type déstinée sequentially receiving the demultiplexer 6 the significant bit data words M_i successive holders of the identification data.

p0084A second circuit 71 for storing character is connected to the first circuit 70 bits of storage. This second memory circuit can store and format successive significant bits output by the bit storage circuit 70. The second circuit 71 ensures that the composition of messages in ASCII characters as the character C mentioned above.

p0085A third circuit 72 of strings of memory is provided. This circuit is interconnected to the second circuit 71 and the memory control circuit 2, it delivers the identification message consisting of the character string stored in the control circuit 2 for further processing. the second type of memory circuit will also be noted that allows taking into account the read access conflicts / write circuit 70 first bits of storage during the transfer, the transfer order is also generated by the control circuit 2 by means of circuits 40 and 41 of the first dedicated circuit 4. the third storage circuit 72 may then be constituted by a RAM memory organized in bytes to ensure storing strings aforementioned characters.

p0086The control circuit 2 has a function of managing reading and writing of memory circuits such as the memory circuit 42 of the first dedicated circuit 4, 52 of the second specialized circuit 5 and 72 of the third dedicated circuit 7. it also ensures management control instructions elements such as circuits 40, 41 of the first dedicated circuit 4, 51 of the second dedicated circuit 5 and 71 of the third dedicated circuit 7 allowing insertion and extraction identification messages in accordance with the method of the invention described above.

p0087For this purpose, the control circuit 2 comprises in particular a microprocessor. Which may each be constituted by a microprocessor 8 or 16 bits for example. The aforementioned microprocessor ensures the functioning of the system as described in Figure 4 in accordance with the timings mentioned above. In addition, the control circuit includes an input-output interfacing circuit 20 for introducing for example addresses Ai information words M_i on which the insertion or reading the significant bit of the identification data is performed, the composition of identification messages to insert or read the display of identification messages. Figure 4 shows the circuit 20 interfacing the form of a keyboard screen without limitation by way of example only. It is understood that the above-mentioned interface circuit may be formed by any insertion element of a corresponding address database or by an auxiliary computer for example. The interface circuit 20 also allows a user to determine the nature of digital information, source or marked this EP input port from a dedicated key for example.

p0088The method and the system of the invention appear particularly advantageous insofar as it is likely to be used to ensure the prohibition of employment of illegal copies of digital information, including images of television, as will be described later in the description.

p0089For this purpose it is necessary firstly to have saved credentials accordance with the method of the invention, identification information for which read concealment probability is low and secondly to record random or pseudo-random, or possibly permanently, control information, for example according to the first embodiment of the method of the invention, in which encoding information words M_i is performed, the words of the aforementioned information being chosen so that playback concealment probability of these words is important.

p0090The control information thus recorded are then affected by errors due to the commissioning of playing VCR concealment circuits when playing the first generation of digital information consisting of the original to be a first-generation copy . Re-recording of this band by direct copying is possible and leads to a second-generation copy. The prohibition of review of this second copy of second generation, can then be considered on the basis of detection of errors introduced due to the recording of the second generation copy, these errors are not attributable to the commissioning playback VCR concealment circuits. Discrimination between copies of first generation and second generation copies can thus be performed, reading of first-generation copies may well be only permitted, prohibiting the reading of second-generation copies that can be made ​​on detection of the first error on non-control information due to the implementation of concealment circuits corresponding playback VCR.

p0091A more detailed description of a system to protect against unauthorized copying of a digital recording tape from a VCR to a TV picture will be given in conjunction with Figures 5a and 5b.

p0092Figure 5a shows a system according to the object of the present invention in which the already shown in Figure 4 elements bear the same references. In addition, the system comprises a circuit 8 for inclusion in a reserved area of ​​the support of digital information, the source information for example, a message or identification data. The aforementioned reserved area is separate from the support area of ​​information words M_i. The message registered in the reserved area is other than alpha-numeric message associated with encoding or by detection as previously described with the method of the invention or a part of it, the message and registered in the reserved zone being intended to constitute a version of reference or comparison with respect to the encoded identification message or part thereof.

p0093In addition, a reading circuit 9 of the message and registered in the reserved area is also expected to generate the reference version or comparison of the aforementioned message or identification data. As has been shown in Figure 5a the writing circuit includes a RAM type memory organized in bytes 82, a member 81 interconnected to the type of memory RAM 82 playing a role similar to the circuit 51 of the second circuit specialized 5 including formatting to ensure the identification data and the management of read-write access conflicts from memory 82 and a RAM organized in bytes type of memory playing a role analogous to the circuit 50 of the second dedicated circuit 5.

p0094Similarly, the reading circuit 9 includes dual elements noted 90,91,92 82,81,80 circuits of the write circuit 8. Thus, the circuit 90 is composed of a type of memory RAM, circuits 90 and 82 being formed in memory of bytes containing the identification data to be written or read in the reserved area. 8 and reading registration circuits 9 are connected firstly to the control circuit 2 and on the other hand respectively to the multiplexer 3 and the demultiplexer 6.

p0095In the case where the digital information consists of television pictures, the reserved area is preferably constituted by one or more video half-lines, identification messages being thus limited to 712 characters per half line video. The identification message is well developed ancillary data format registered with the aforementioned half-lines.

p0096Furthermore, as will be seen in Figure 5a, a circuit 10 ensures from the synchronization supplied by the circuit 1 signals the sequencing of addresses of the RAM memory byte write circuit 82 of registration 8 and reading the RAM type memory 90 bytes of read circuit 9. the circuit 10 cited above also ensures the control of the multiplexer and demultiplexer 3 6 from the instructions sent by the control circuit 2 function of 525/60 or 625/50 standard detected by the timing circuit 1.

p0097As was further shown in Figure 5b, the control circuit 2 also comprises a circuit 21 to ensure the comparison of the message or identification data, the encoded identification message at each word information M_i to form words identification data carrier information and version comparison of the message registered in the designated area described above. The comparison circuit 21 is interconnected and one hand on the type of RAM memory 92 of the read circuit 9, this memory containing the reference version of the identification message and also in memory of 72 characters of the third dedicated circuit 7 which contains the identification message obtained from the detection information words M_i Identification data carriers.

p0098In addition, the control circuit 2 also comprises a circuit 22 for controlling inhibition of the playback apparatus of digital information data such as a VCR in the case of television pictures, and a detection circuit 23 of the non-functioning registration error concealment circuits of the read / write device. This circuit 22 may also advantageously be constituted by the control CPU of the playback apparatus that is to say the VCR, programmed accordingly. The circuit 23 is also preferably incorporated into the reading apparatus. This circuit provides a no error concealment signal. The read inhibition occurs upon a negative response to an identity between the test message or control data, or a portion thereof, from the detection or identification of information words M_i holders of the control data and the version comparison of the message included in the reserved area of ​​the medium, the circuit 23 delivering the absence of error concealment signal, the differences between the control information and version reference is then attributable to the read-only copy of an illicit second generation.

p0099These identification or identification data encoded messages at the information words sucessifs M_i so are the control information, which recorded with quine errors are due to the commissioning of playing VCR concealment circuits during playback of a second-generation copy make it easy to distinguish the copies of copies of first generation and thus allow only read recent on detection of the first error of the control information not due to the implementation of video error concealment circuits.

p0100It is further noted that the system object of the invention as shown in Figure 5a has two referenced parts I and II defined in phantom. For general public use, only Part II, operating in reading information protected by the object of the present invention is to be incorporated into the read / write protected to prevent the user from use illicit copies. In this case, the interface circuit 20 may be replaced by an address information of the charging circuit of the data words M_i holders of the control information.

p0101We have thus described a digital information marking method particularly advantageous, especially in the field of consumer application, insofar as the object of the invention process allows the implementation of a protection system against the achievement and the use of illegal copies of digital video programs.