WO1989012890A1

WO1989012890A1 - Process and device for the numeric recording of data, a protected data recording substrate and a device for reading data recorded on such a substrate

Info

Publication number: WO1989012890A1
Application number: PCT/FR1989/000313
Authority: WO
Inventors: Michel-Jean Dupre
Original assignee: Dupre Michel Jean
Priority date: 1988-06-20
Filing date: 1989-06-19
Publication date: 1989-12-28
Also published as: FR2633086B1; FR2633086A1

Abstract

This numeric data recording substrate, comprising a fixed casing (75) and means for storing the data to be recorded contained within said casing, is remarkable in that it also comprises a micro-circuit (16) providing protection against the unauthorised duplication of the data intended to be contained in the storage means, said micro-circuit's being incorporated in said fixed casing (75) and comprising means (17) for the additional storage and/or processing of data which may be used by reading devices, the data to be recorded in said means of storage and means (78) associated with the protective micro-circuit (1, 6) designed to ensure to connection of said micro-circuit into the circuit of a reading device for said recording substrate.

Description

Method and apparatus for digital data recording, protected data recording medium and apparatus for reading data recorded on such a medium.

The present invention relates to analog or digital data recording media such as optical or magnetic discs, magnetic tapes or the like and relates more particularly to the protection of such recording media against their illicit use or reproduction.

The ever increasing proliferation of data recordings on magnetic media, in particular of sounds and images on the one hand and of sets of instructions such as computer programs on the other hand, as well as the technical progress made in the means of reproduction of the recordings incites the users to use or to reproduce the recordings which they need in defiance of the rights of their authors.

Certain techniques for the digital recording of sound on optical media such as compact discs and the pressing techniques used to ensure their duplication make their illicit reproduction practically impossible by the general public.

On the other hand, the technique of digital recording of audio signals on magnetic cassette which should become generalized in the very near future could see its commercial development disturbed by the risks of piracy already widely practiced in the matter of analog recordings on magnetic cassettes both audio and video. In the field of computers, the very rapid development of personal computers has shown the economic importance of the problem of software piracy.

Many processes have been implemented point to fight software piracy.

There is legal protection for software, the subject of which falls within the scope of copyright law both in France and in many foreign countries, particularly in the United States of America. However, if this legal protection begins to be dissuasive for organized piracy on a commercial scale, it is much less effective against private piracy for which the cost of prosecution would, in most cases be greater than the compensation for the damage suffered than one can hope to get.

A number of technical means have therefore been developed to prohibit the illegal reproduction of programs recorded on floppy disks, particularly in the case of microcomputer systems.

The simplest and most common means of protection against duplication consists in structuring the operating system which manages duplicates of files so that the instructions of copy are inoperative when they have for object a protected software or a floppy disk whole.

This process is very effective in discouraging non-computer users but does not withstand the copying attempts of a knowledgeable computer specialist or the special duplication programs commonly found on the market.

In particular, the operating system being in most cases present on the floppy disk itself, a bit-by-bit copying of the floppy disk provides a usable copy of the software.

Another solution is to include in the computer system, generally at the level of its ROM memory, an identification code and provide it with software comprising a routine responsible for verifying this identification code and which prohibits the execution of the software in the event of different identification codes.

This process does not resist any more to the informed computer specialists who can identify the verification routine and modify it to make it inoperative. Furthermore, such a solution complicates the software marketing process and makes updates, always inevitable, almost impossible.

A process fairly close to the previous one, but more flexible in terms of maintenance consists in using an identification code or a password provided to the user when purchasing his software and which is requested by a routine verification included in the software and capable of prohibiting its progress in the event of an incorrect password.

In this case again, it is possible for a computer specialist to short-circuit the verification routine. In addition, if this process can provide protection against a large-scale marketing of pirated software, nothing prevents the holder from providing copies to his relatives by indicating the password.

It is also possible to modify the recording formatting. The development of formatting techniques in software for recording media which replaced formatting by circuitry has made it possible to use protection methods based on a modification of the format. According to this process, all or part of the software is recorded on a disc in a format different from the standard format and which can therefore only be read by a special operating system which does not allow any copying.

Protection is not, however, absolute since it is always possible to make a mechanical copy of the floppy disk, which reproduces exactly the original format, but it is more dissuasive than the protection methods mentioned above.

However, its complexity of implementation limits its use to mass-market software used on microcomputers, also of large distribution. The "Prolok" protection system developed in 1984 by the American company Vault Corporation gives another solution to the problem of protection against piracy by associating a hardware element with the software protection provided by the processes mentioned above.

Each floppy disk, manufactured according to a specific process, has a fault zone materialized in the magnetic substrate of the floppy disk. The position of this fault on the floppy disk makes it possible to define a software encryption algorithm.

A specific, unencrypted operating system determines the position of the fault and can therefore decrypt the software.

Although particularly effective, this process has been circumvented either by hardware processes (duplication of the defect) or by software processes.

Another combined hardware / software solution is the dongle protection process. This process, developed in particular by the company Microphar in France, uses a module or "dongle" pluggable on one of the standard outputs of a microcomputer. This electronic module made up of a few components molded in a resin which prevents any access to its internal structure, constitutes an electronic key having a clean, secret code.

The programs protected by a "dongle" include a routine which checks the presence of the "dongle" determines its identification code and prohibits the continuation of the program if the identification is not satisfactory.

Although very effective, this process remains very cumbersome and impractical for the user if he has to change programs often.

It is also relatively expensive and can always be bypassed by the intervention of a programmer inhibiting the operation of the protection routine.

Another protection routine recently developed is called "Killer".

When trying to fold illegally, the "Killer" routine incorporated in the operating system does not prevent duplication. It is therefore not, at this stage, perceptible by the pirate. On the other hand, it detects with the greatest possible reliability any attempt at copying and intervenes, either immediately or subsequently to destroy the program itself and / or its copy, or to modify the program and / or its copy so that, when for future use, this program destroys or inflicts severe damage to the user's own files or to other programs. Protection is therefore not provided directly, but indirectly for fear of reprisals.

"Killer" systems, because of their psychological action, are particularly dissuasive, and since they only manifest their presence at the moment when they have inflicted reprisals, they are difficult to detect and therefore to bypass . However, they have the disadvantage of creating risks on the files and the programs which are the property of the user, which poses a certain number of legal problems, but also risks creating for the user disproportionate damage with the damage. suffered by the designer and cause a refusal reaction on the part of users, for software protected by this process.

The memory card is an effective means of software protection, thanks to the protection enjoyed by the data stored there as well as its operating autonomy.

At the start of the program, a verification routine generates a random number which is transmitted to the memory card.

This card includes a microprocessor which codes this number according to a secret algorithm which is specific to the protected program, which allows the routine to authenticate the memory card and therefore to authorize or prohibit the running of the program.

As in most other methods, the weak point of this method is the authentication routine which can always, at least in theory, be inhibited by a programmer familiar with the system.

It also has the disadvantage of requiring a memory card reader which is not, for the time being, a usual peripheral of microcomputer systems.

In addition to the problem of protection against unlawful duplication of software, a similar problem arises for documents saved on microcomputer media.

Indeed, the explosion of microcomputing and the availability of recording media of very large capacity (writable or rewritable digital optical discs) or very low costs (magnetic diskettes), gradually leads to the development of document distribution (texts, encyclopedias, directories, graphics, fonts, etc.) in the form of digital recordings. The refinement of these technologies should also lead to the dissemination in computerized form of spoken information (speech generators), music (control by microcomputers of sophisticated synthesizers), animated graphics, advertising documents, etc.

Given the very wide dissemination of the means enabling them to be exploited, the problem of illegal duplication arises for all of these documents. These documents are generally coded according to a system ensuring a strong compression of information (ASC II coding for example for alphanumeric documents) and the formatting of the data inside these documents is generally kept confidential, which implies the use of the software which was used to create the document to exploit it or modify it.

However, such measures only provide superficial and insufficient protection against the duplication of documents, the creation costs of which are often considerable.

The invention aims to improve the recording technique by creating a recording medium, the reading of which can only be carried out by authorized persons and the copying of which is made practically impossible at least without a notable loss of the quality of the recording. 'recording.

It therefore relates to a method of digital recording of data on a recording medium comprising means for storing the data to be recorded contained in a fixed envelope, characterized in that it consists in incorporating into said envelope additional means of storage and / or processing of data forming part of a microcircuit provided with means of connection with an apparatus for reading the data contained in said storage means, to be recorded in said storage means, data drawn from the data to be recorded but unusable directly by the reading means and to record in the additional data storage means, capable of making usable, by the reading means, the data stored in said storage means. The subject of the invention is also a digital data recording medium comprising a fixed envelope and means for storing the data to be recorded contained in said envelope, characterized in that it also comprises a microcircuit of protection against illicit duplication data intended to be contained in the storage means, said micro-circuit being incorporated into said fixed envelope and comprising additional storage and / or processing means of data capable of making it usable by reading means, the data intended for be recorded in said storage means and means associated with the protection micro-circuit and intended to ensure the connection of said micro-circuit in the circuit of an apparatus for reading means of said recording medium.

The invention will be better understood with the aid of the description which follows, given solely by way of example and made with reference to the appended drawings, in which: FIG. 1 is a block diagram of conventional equipment d 'digital audio recording on magnetic tape; Fig.2 is a block diagram of a conventional apparatus for reading a recording made with the equipment of Fig.1; Fig.3 is a block diagram of an audio-digital recording equipment on magnetic tape according to the invention; - Fig. 4 is a block diagram of an apparatus for reading a recording produced with the equipment of FIG. 3; Fig. 5 is a block diagram of a transcoder using a wire-to-wire interconnection matrix fitted to a recording medium according to the invention; Fig.6 is a block diagram of a transcoder with ROM memory; Fig.7 is a block diagram of a micro-transcoder using a PROM memory; Fig.8 is a block diagram of a transcoder usable for recording using a RAM memory; Fig.9 is a perspective view of a magnetic cassette equipped with the protective means according to the invention; Fig.10 is an elevational view of a bar fitted to the cassette of Fig.9 and carrying the data protection means recorded on the magnetic tape contained in the cassette;

- Fig.11 is a partial sectional view on a larger scale of the bar, along line II-II of Fig.10; Fig.12 is a partial plan view showing the location of the electrical contacts in a cassette reading and recording apparatus shown in Fig.9 to 11; Fig.13 is a block diagram of a conventional magnetic computer / floppy drive assembly; Fig.14 is a block diagram of a computer / magnetic floppy drive assembly equipped with means of protection against duplication or illegal use according to the invention; - Fig.15 is a block diagram of an example of micro-circuit structure for protected magnetic disk according to the invention;

- Fig.16 is a diagram showing the organization of the memory means of the circuit of Fig.15; Fig.17 is a flowchart for priming the circuit of Fig.15;

- Fig.18 shows the structure of the data blocks on reception; Fig. 19 is a block diagram of a read / write unit for a conventional floppy disk; Fig.20 is a block diagram of a read / write unit for a protected floppy disk according to the invention;

- Fig.21 is a plan view of a magnetic diskette protected according to the invention; Fig.22 is a partial plan view showing the location of contacts of a floppy drive, intended to cooperate with the contacts of the micro-circuit equipping it; Fig.23 is a sectional view of a floppy drive showing the insertion and ejection mechanism in the high position; - Fig.24 is a view similar to that of Fig.23 showing in detail the contact between the micro-circuit fitted to the diskette and the corresponding contacts provided on the reader;

- Fig.25 is a partial view from below of a floppy disk provided with a protection micro-circuit according to the invention; Fig.26 is a section along line 26-26 of Fig.25; and Fig. 27 is a partial top view of the diskette in Fig. 25.

Typical digital audio recording equipment is shown in Fig. 1.

It comprises a left channel and a right channel each comprising a circuit 1,2 for sampling the analog signals applied to its input.

The outputs of the sampling circuits 1,2 are connected respectively to analog-digital coding circuits 3.4 whose outputs are in turn connected to a parallel / serial conversion circuit 5 common to the two channels.

The parallel-to-serial sampling and conversion circuits are synchronized by a common clock 6.

The output of the parallel-series conversion circuit 5 is connected to a modulator 7, the output of which is intended to be connected to a recording head, not shown. An apparatus for reading an unprotected recording produced with the apparatus of Fig. 1 is shown in Fig. 2.

It comprises a demodulator 8 whose input is connected to the output of a read head not shown.

The output of the demodulator is connected to the input of a circuit 9 for detecting synchronization and parallel-series conversion of the signals received from the read head and demodulated. Circuit 9 has two outputs defining two channels and a clock output.

To the outputs defining the two channels are connected digital / analog converters 10, 11 synchronized by the clock signal emitted by the circuit 9.

The outputs of the converters 10, 11 are respectively connected to amplifiers 12, 13, the outputs of which constitute the left and right outputs of the reading device, respectively.

The recording equipment according to the invention is shown in Fig.3.

The components of this equipment which are identical to those of conventional equipment of the Fig. 1 are designated by the same reference numbers.

The equipment according to the invention differs from the conventional equipment in that a transcoding circuit 14 is inserted between the outputs of the analog-digital coding circuits 3,4 and the input of the parallel-series conversion circuit 5 and the transcoding circuit 14 is also connected to the output of the clock 6 and transmits the clock signal to the parallel-series conversion circuit 5 which also ensures the incorporation of the synchronization signal into the transcoded signal to be recorded.

The recording playback device according to the invention is shown in Fig.4. The components of this device are identical to. those of the conventional reading device described with reference to FIG. 2 are designated by the same reference numbers.

The reading device according to the invention differs from the conventional reading device in that at the output of the demodulator 8 is connected a circuit 15 for detecting synchronization signals which includes an output connected to a first input of a micro-circuit 16 which, as will be seen hereinafter, is mounted on an envelope of the recording medium such as the cassette of a magnetic tape or the envelope of a floppy disk.

This micro-circuit 16 comprises a circuit 17 for transcoding and series-parallel conversion whose input is connected to the output of the synchronization detector 15 as well as two circuits 18, 19 digital-analog converters connected to two corresponding outputs of circuit 17 transcoding and serial-parallel conversion. The outputs of the converter circuits 18, 19 are respectively connected to the amplifiers 12 and 13, the outputs of which constitute the outputs of the two channels of the reading device. The micro-circuit 16 is connected in the circuit of the reading device by means of suitable electrical contacts carried by the envelope of the recording medium and which cooperate with corresponding electrical contacts provided in the reading device.

The arrangement of these contacts will be described later.

Fig. 5 shows an example of a very simple transcoder by wire-to-wire interconnection matrix.

This transcoder which can constitute the microcircuit 16 intended to be mounted on the casing of a cassette containing a magnetic recording tape and to be interposed in the reading device shown in FIG. 4 comprises a shift register 20, intended to convert the serial information which it receives from the demodulation circuit 8 (FIG. 4) on its input 20a, into parallel information. The outputs of the shift register 20 are connected to the inputs of a wire-to-wire interconnection matrix 21 intended, given its organization, to restore the digital signals it receives to their appropriate order so that the message they form be intelligible again. The outputs of the interconnection matrix 21 are connected in groups to a digital analog converter 22, 23 whose outputs are connected via the micro-circuit contacts to the corresponding amplifiers of the two output channels of the reading device. . The transcoder represented in FIG. 5 further comprises a clock terminal 24 intended to be connected to the shift register 20 and to the digital-analog converter 22,23, a supply terminal 25, a ground terminal 26 and two output terminals 27, 28 of digital-analog converters, all of these terminals being intended to be connected to the circuit of the reading device shown in FIG. 4, in a manner which will be described later. Fig. 6 shows another example of a transcoder which can be incorporated into a cassette containing a recording tape according to the invention.

This transcoder comprises a shift register 29, intended to convert the serial data which it receives on its input 30 into parallel data. This register is connected to a memory address register 31, the outputs of which are in turn connected to a ROM memory 32 which in the present example is a 256 × 8 bit memory. The outputs of memory 32 are connected to a memory input / output register 33, the outputs of which are in turn connected four by four to two digital-analog converters 34.35 intended to deliver on their outputs 36.37 analog signals corresponding to the two channels of the reading device.

This transcoder comprises, like the transcoder of FIG. 5, a clock input 38, a power supply terminal 39, and a ground terminal 40 intended to be connected as, moreover, the input terminal 30 and the terminals 36,37, to the reading device when inserting into it a cassette equipped with this transcoder.

The transcoders described with reference to Fig. 6 and 5 compo rten of its lg orithm s and transcoding s keys made during the manufacture of the microcircuit. They are identical for the same series of recordings, which leads to limited protection security insofar as the transcoding key cannot be modified at will.

The transcoder micro-circuit represented in FIG. 7 overcomes the drawback of the transcoders described with reference to FIGS. 5 and 6. This transcoder includes, like the transcoder of FIG. 6, a shift register 41 whose input 42 is intended to receive serial data and whose outputs on which are intended to appear parallel data are connected to a memory address register 43. The outputs of the register memory address 43 are connected to the inputs of a 256 x 8 bit PROM memory 44, the outputs of which are connected to a memory input / output register 45. The outputs of the input / output register 45 are connected four by four to digital-analog converters 46 and 47, the outputs 48, 49 of which are intended to deliver analog signals corresponding to the two channels of the reading device. The outputs of the memory input / output register 45 are also connected to a shift register 50 making it possible to program the PROM 44 in order to modify the transcoding key at will during recording.

The micro-circuit which has just been described further comprises a clock input 51, a power input 52, a ground terminal 53, an input terminal 54 of the shift register 50 and a terminal 55 connected to PROM memory 44 by means of a fuse 56 and intended to prohibit any modifications to the transcoding key of this memory by application of an overcurrent. In this transcoder, the transcoding key is recorded in the PROM memory 44 using the contact 42 input of the shift register 41 and the contact 54 input of the shift register 50. The recording of the transcoding key is performed just before or immediately after the actual registration.

The transcoder shown in Fig. 8 is a transcoder for use in the recording equipment shown in Fig. 3. It essentially comprises a RAM memory 60 to which is connected on the one hand a memory address register 61 and on the other hand a memory input / output register 62. Parallel buses 63 connected to the address register of memory 61, are intended for loading the RAM memory by the addresses or values to be coded and the parallel buses 64 connected to the inputs of the input / output register 62 are intended for loading into the memory data that is to say values transcoded.

The inputs of the memory address register 61 are also connected, in groups of four in the present example, to the corresponding outputs of the analog-digital encoders 3 and 4 of the recording equipment of FIG. 3. The outputs 67 of the memory input / output register 62 are connected to the serial parallel conversion circuits 5 of the same circuit shown in FIG. 2. The transcoder of FIG. 8 further comprises a clock terminal 68, a power supply terminal 69, a ground terminal 70 and a terminal 71 connected to the RAM memory 60 to temporarily freeze in it the transcoding key. loaded into memory by buses 63 and 64.

During the actual registration, the words, in four bits in the present example, coming from the two analog-digital converters 3,4 (Fig.3) are placed at the rate of the clock 6 whose signals are applied to the input 68 of the circuit of Fig. 8, respectively on the four least significant and most significant bits, of the address buses 65 and 66. The memory 60 in the reading position therefore restores on the bus 67, transcoded values.

Taking into account the operation of the transcoder of Fig.8, the recording equipment shown in Fig.2 operates as follows. The two analog signals of the right and left channels are sampled in the sampling circuits 1 and 2, then coded in digital form by the analog-digital converters 3 and 4. Before incorporation of the words of synchronization and conversion p-arallèle series, each word (or preferably the two words together) is transcoded by circuit 14. In the present example, associated with the operation of the transcoder of FIG. 8, a simple transcoding is used. Assuming that each channel has 4 bits, the two channels together constitute an eight-bit word, which can take all the values from 0 to 255. For each value of the input word, the transcoder 14 matches another word of eight bits. Of course, it is necessary that there is a two-to-one correspondence between the input and output codes for decoding to be possible. It is of course possible to use much more sophisticated transcoding means such as for example means using transcoding by using a series of pseudo-random numbers or else transcoding means in which an ope Transcoding ration depends on the previous code (s).

After transcoding, the different digital words are grouped together in a serial digital message obtained using the serial parallel conversion circuit 5, synchronization words being introduced into the serial message by the signals coming from the clock 6. This message is then modulated by the modulator 7 and applied to the recording head not shown.

When reading this signal on a device without a circuit capable of restoring the initial values of the words before transcoding, the output signals are totally modified and generally produce an absolutely distorted sound signal analogous to a noise.

The reading apparatus shown in Fig. 4 operates as follows. A cassette is placed in the reading device in which the micro-circuit 16 is incorporated, comprising the transcoding circuit 7 and the digital-analog converters 18 and 19. The transcoding circuit 17 has previously received the same transcoding key as that which was used in the transcoding circuit 14 of the recording equipment.

The signal detected by the read head not shown, is demodulated by the demodulator 8, then processed by the synchronization detection circuit which separates the signal proper from the clock signal. It is then applied to the transcoding circuit 17 which simultaneously transforms the serial signal from the read head into a parallel signal thanks to the passage of the serial signal in a parallel serial shift register such as the register 20, 29 or 41 of one of the transcoder circuits of Fig. 5,6,7. At the output of the parallel serial transcoding and conversion circuit 17, the signals are applied to the digital-analog converters 18, 19 which are also part of the micro-circuit 16 secured to the cassette containing the recording tape and the resulting analog signals are applied to the corresponding amplifiers 12, 13 which form part of the reading equipment and which are connected to the micro-circuit 16 secured to the cassette by suitable contacts which will be described later. The digital-analog converters 18, 19 of the micro-circuit 16 shown in Fig. 4 correspond to the digital-analog converters 22, 23, 34, 35 and 46, 47 of the transcoders shown in Fig. 5, 6 and 7. If the algorithm and the transcoding keys produced by the micro-circuit 16 correspond well to those used during the recording, the sequences of 4-bit words applied to the input of the digital-analog converters 18, 19 are indeed the same which existed at the recording, and the analog output signals of the micro-circuit 16 therefore perfectly restore the original analog signals.

In all the examples which have just been described, it has been assumed, for simplicity, that the analog-digital coding was 4 bits.

The method remains of course the same if the coding is carried out on a larger number of bits. In fact, the transmissions between the microcircuit 14 or 16 and the recording or recording device reading takes place in serial mode, the number of bits on which the coding is done only affects the internal complexity of the micro-circuit and not the number of connection contacts between the micro-circuit and the reading devices or registration. However, it is the number of these connection contacts which, as will be seen later, must be reduced to a minimum.

The means which have just been described with reference to FIGS. 3 to 8 provide protection against duplication of documents.

Indeed, although it is always possible to directly copy the signals recorded on a magnetic tape, on another magnetic cassette, these signals can only reproduce the original sound if the cassette on which one wishes to ensure duplication, is equipped with the adequate micro-circuit and that this micro-circuit is programmed so that the decoding key and the algorithm that it performs correspond well to those used for recording.

Even if the fraudulent candidate has cassettes fitted with blank micro-circuits, he should know the key and the transcoding algorithm. However, the micro-circuits are designed in such a way that these elements cannot be accessible from outside the micro-circuit and are therefore not therefore reproducible.

In addition, the fraudulent candidate can also reproduce the sound of his protected audio-digital magnetic cassette on an appropriate playback device, then record this sound again on a new unprotected cassette. However in this case, if the new recording is made in analog form, the signal loses the intrinsic qualities to digital recording (high dynamic range, noise immunity).

If the new recording is made in digital form, which implies professional equipment, which is not within the reach of the general public, analog-digital recoding introduces additional noise and distortions significantly reducing the quality of the new copy.

Figs. 9 to 12 show a practical example of a magnetic cassette protected according to the invention and the corresponding reading device.

FIG. 9 is a perspective view of a magnetic cassette, the casing 75 of the standard type having on its edge 76 opposite the window for access to the magnetic strip, a bar 77 fixed to the cassette, for example by bonding and comprising both a micro-circuit such as the micro-circuit 16 of FIG. 4 and contacts 78 for connection to the reading device.

As shown in more detail in Fig. 10, the bar 77 consists of a double-sided printed circuit with metallized holes 79, the part facing outwards of the cassette comprises eight contacts 78 intended to ensure the connection with the contact correspondent of the reading device. The lower part of the printed circuit of the wafer 77 has eight tracks 80 each connected by a metallized hole 79 at the corresponding contact 78 of the upper part. As can be seen better in Fig. 11, the eight tracks each end with a contact area 81 used to connect them to a corresponding pad of the chip 83 forming the integrated micro-circuit 16 by means of a wire. or 82. The clean micro-circuit ment said constituted by the chip 83 is glued to the center of the underside of the bar 77 and encapsulated by a drop of resin 84. A thick plastic film 85 bonded to the underside of the bar 77 ensures the flatness of the together, the electrical insulation and the mechanical protection of the conductive tracks 80.

Fig.12 shows the location of the electrical contacts on the reading device intended to receive a cassette 75 of the type described with reference to Figs 9 to 11.

We can see in this figure, a housing 86 intended to receive the cassette 75 and into which open the drive pins 87, 88 of the reels of the cassette as well as the means 89 for applying the strip against the read head 90. In the bottom of the housing 86 are provided two contact strips 91 and 92 fixed to the housing of the device by elastic tabs 93 and each carrying electrical contacts 94, 95 intended to cooperate with the contacts 78 of the strip 77 during the introduction of the cassette 75 into the housing 86.

Contacts 94 and 95 are appropriately connected to the rest of the circuit shown in Fig. 4 of the reading device.

In the embodiment described with reference to Figs. 4 and 12, the reading device according to the invention is adapted to receive only cassettes provided with a protective micro-circuit. However, it is easily understood that the reading device can be designed to receive both protected cassettes according to the invention or conventional unprotected cassettes.

To do this, the device reading comprises between the demodulator 8 and the amplifiers 12. 13 a first channel comprising components of the circuit of FIG. 2 and a second channel in parallel on the first comprising the synchronization detector 15 and the contacts for connection to the micro-circuit 16 of Fig.4 and a switch allowing to pass either on the first reading channel of unprotected cassettes or on the second reading channel of protected cassettes. In the description which follows, we will focus on the application of the present invention to protection against duplication of information and in particular of computer programs recorded on magnetic floppy disks. Fig. 13 is a block diagram of a computer / magnetic floppy drive assembly without protection against duplication or illegal use.

We see in this figure, a floppy drive 95 connected to a microcomputer 96 by a coupler 97 which manages the transfer of orders and data between the microcomputer and the reader.

In the reader 95, the magnetic interface circuits 98 ensure the processing and transmission of the data to and from the read / write head 99 which, itself, inscribes and re-reads the information on the magnetic tracks 100 in a floppy disk 101. This therefore contains only one type of information which is that stored on these tracks.

The microcomputer 96 is also associated with a microprocessor 102, a memory 103 and other couplers 104, all connected to a bus 105 for connection with peripheral members associated with computer / floppy drive.

Fig.14 is a block diagram of the same computer / magnetic floppy drive assembly, but is intended to operate with a protected floppy disk according to the invention. The diagram in FIG. 14 is similar to FIG. 13, so that the components of the computer / floppy drive common to the two embodiments have the same reference numbers. The arrangement of FIG. 14 differs from that of FIG. 13 in that its floppy disk reader-recorder 95 comprises a circuit 106 of micro-circuit interface connected to the coupler 97 associated with the microcomputer 96 and to the magnetic interface 98 of the reader / writer 95.

The micro-circuit interface circuit 106 is connected to micro-circuit contacts 107 intended to cooperate with a protective micro-circuit 108 carried by the casing of the floppy disk 101 and including contacts which allow during the introduction of the diskette recording medium into the diskette drive, the connection of the microcircuit 108 to the micro-circuit interface 106 intended to provide the link between the micro-circuit 108 of the diskette and the microcomputer 96 which drives the player.

The diskette 101 therefore contains two types of information this time.

Those which are stored on the magnetic tracks 100 and which are accessible and modifiable by any appropriate software of the microcomputer 96. Those which are contained in the micro-circuit 108 and which are accessible and modifiable only within limits defined by the structure even from micro-circuit.

It is this duality between these two types of information as well as the limitations on the accessibility of the information contained in the micro-circuit 108 which makes it possible to ensure protection against duplication of software or documents recorded on the floppy disk 101.

Fig.15 shows an example of micro-circuit structure for protected magnetic diskette. The structure of the micro-circuit represented in this figure, is in fact that of an integrated microcomputer, communicating with the outside only by a serial input / output interface, itself managed by a program residing in the micro-circuit read-only memory.

The micro-circuit comprises a microprocessor 109 which can be very simple taking into account the operations which it will have to carry out and the fact that it will have to manage only one input / output circuit. Its speed is generally not critical. A conventional eight or sixteen bit microprocessor such as that of type 28 from ZILOG, 6801 from MOTOROLA or 8086 from INTEL is perfectly suitable.

The micro-circuit also includes a ROM 110 which can be very small, for example 256 bytes if it contains only the microprocessor cold start micro-program when the micro-circuit is powered up. A larger size, preferably from 1 to 4 Kbytes, makes it possible to incorporate subroutines in the memory which reduce the size of the program residing in other means of memorizing the micro-circuit which will now be described.

This also includes a PROM memory 111 writable once, not erasable, the size of which can preferably be between 1 Kbyte and 8 Kbytes. Depending on the case, we can also use for this memory or for a part of this memory an EE PROM technology, also permanent in the event of a power cut, but which can be modified by writing instructions. The ROM 110 and PROM 111 memories are associated with a volatile write / read RAM memory 112, the size of which is preferably between 4 and 16 kbytes.

The microprocessor 109 and the memories 110 to 112 are interconnected by an address bus 113, a data bus 114 and a control bus 115.

To these three buses 113, 114 and 115 is connected an input / output interface circuit 116 which provides serial / parallel conversion to input and parallel / serial conversion to output as well as the exchange of the associated clock signals. .

The choice of a serial transmission in preference to a parallel transmission is fundamental because it makes it possible to limit the number of contacts of the microcircuit 108 (Fig. 14) and therefore considerably simplify the practical realization thereof as well as that of the corresponding contacts in the floppy drive 95.

The transmission can be either of the synchronous type, or of the asynchronous type with a preference for the first mode because of its speed and its similarity with the mode of transfer of information located on the magnetic tracks. The micro-circuit finally comprises service circuits, not shown, such as a supply circuit or the like.

The input / output interface circuit includes a clock input 117, a data input 118, a reception request input 119, a transmission request input 120, a power input 121, a ground terminal 122, a data output 123 and a signal ready for transmission output 124.

The operation of the micro-circuit shown in FIG. 15 will now be described with reference to FIGS. 16 and 17.

Fig. 16 shows the organization of the memory of the micro-circuit of FIG. 15.

As indicated above, the memory is broken down into three areas:

The ROM memory area 110, the content of which is fixed during the manufacture of the micro-circuit and cannot be modified thereafter. This area contains the bootstrap program;

The PROM 111 memory area which is empty during construction but in which it is possible to write but not to erase. In this example, this area contains an interpreter program.

The contents of ROM and PROM areas 110 and 111 are retained when the micro-circuit is switched off. The RAM memory area 112 which is also empty during construction but whose content can be written, erased or modified when the micro-circuit is energized. The contents of this area are not retained when the micro-circuit is switched off.

The flowchart of the cold start program contained in the ROM 110 area is therefore fixed during construction. It is shown in FIG. 17.

This program starts at power up of the micro-circuit, that is to say during the introduction of the floppy disk 101 into its reader 95 (FIG. 14). This start-up takes place during phase 125 of the organization chart. The initialization of the various organs of the micro-circuit is ensured during phase 126 and, during phase 127, there is put on hold in the reception position.

When a message arrives from the floppy drive 95, the content of this message is placed in the RAM memory area during phase 128. Then, the program is connected to an address calculated as the difference between the first address of the RAM 112 and the content of the first address of the PROM 111. This operation takes place during phase 129. This set of operations allows:

First, to operate the micro-circuit under the control of a program transmitted from the outside. The initial content of the PROM 111 memory being zero. The connection address at the output of the cold start program is the first address of the RAM 112 memory.

This program transmitted from the outside ensures, in the present example, the loading of an "interpreter program" into the PROM memory 111 during the recording.

Secondly, when the "interpreter program" has been loaded into the PROM 111 memory, it makes it possible to operate the micro-circuit under the control of this "interpreter program".

In fact, since the initial content of the PROM memory 111 is no longer zero, the connection address at the output of the cold start program corresponds to an address determined in the PROM memory 111. This "interpreter program" represented at

Fig. 18, interprets alo rsprograms cha rg e s in RAM memory 112 but, like any interpreter, it can be structured so as to prohibit any attempt by programs transmitted from outside the micro-circuit to read or modify the content of certain memory areas. This program therefore ensures its own inviolability. Such programs are well known to those skilled in the art and do not pose any particular problems with their design or their development.

In Fig. 19 shows the structure of a conventional floppy disk unit and an associated controller.

In the present description, the term "floppy drive" is used in abbreviation of the term floppy drive / recorder. It will however be understood that the equipment available on the market almost always has both functions.

The reader comprises four main members: one or more read and record heads 130 and the associated interface circuits 131; a main motor 132 which rotates the diskette. thus causing the heads 130 to run circular tracks thereon; a stepper motor 133 moving the heads! 130 parallel to the floppy disk and therefore making it possible to pass from one track to another;

- An index detector 134 which makes it possible to determine the position of a head 130 relative to the different sectors making up a track.

The main motor 132 is associated with a control circuit 135, with the stepping motor is associated a circuit 136 for positioning the read / write heads and with the index detector 134 is associated a sector detection means 137 constituted either by a circuit or by software. All of the components which have just been described constitute the diskette unit 138 proper. To this unit is associated a floppy controller 139 which comprises an interface circuit 140 for controlling the floppy controller which receives orders from a microcomputer not shown to which the floppy disk drive is connected, and which consequently adjusts the speeds of the main motor 132, the position of the head or heads 130 and the detection of the position of the index. The control interface 140 is associated with a DMA interface circuit 141 which, when a head 130 is adequately positioned both with respect to a track on the floppy disk and with respect to a sector, ensures the transfer of a block of data between the head and the computer memory.

In Fig. 20, there is shown the structure of a diskette unit protected according to the invention and of the associated controller.

The components of this diskette drive which are identical to those of the drive described with reference to FIG. 19 have the same reference numbers.

The reader comprises, like that shown in FIG. 19, four main organs, namely read and record heads 130, a main motor 132, a stepper motor 133 and an index detector 134. In addition, the controller 135 of the main motor is also part of the reader. .

To these components is also added a cir micro-circuit interface circuit 106 which is connected on the one hand to micro-circuit contacts 107 intended to ensure the connection to the floppy disk drive of the micro-circuit shown in FIG. 15 and incorporated into the envelope of the floppy disk 101. the interface circuit 106 being further connected to the interface circuit for read / write heads 131, by means of sector detection 137 and to circuit 136 for positioning the heads read / write. The operation of the protected floppy drive according to the invention is based on the following principle.

Seen from the programmer's point of view, the microcircuit 108 incorporated into the envelope of the floppy disk and described with reference to FIG. 15 appears as a particular track on the floppy disk.

A 8.89 cm (3 1/2 inch) single-sided, double-density magnetic diskette usually has eighty tracks numbered 0 to 79. It is circuit 136 for positioning the heads which ensures the positioning in function requests from microcomputer 96 (Fig. 14).

In the protected floppy disk drive, this circuit is modified to detect track requests other than tracks 0 to 79 and, when such a case is detected, it informs the micro-circuit interface 106.

This circuit interprets this signal as a request for transfer of information between the microcomputer 96 and the microcircuit 108 of FIG. 14 which is described in detail with reference to FIG. 15.

In addition, the head positioning circuit 136 checks, by its links with the read head interface circuit 131, whether it is a write (transfer to micro-circuit 108) or read (transfer from micro-circuit 108) request.

It sends a transmission request to the micro-circuit 108. It waits for the response from the microcircuit 108 indicating that it is ready to transmit or receive. It simulates, by its links with the sector detection circuit 137, the positioning of the head above the sector requested by the microcomputer 96 and thus causes the initialization of the data transfer by the DMA 141.

It ensures, by its links with the read / write head interface 131, the transfer of data not between the tracks of the floppy disk and the memory of the computer but between the micro-circuit 108 incorporated in the envelope of this and the microcomputer 96.

In this way, there is total transparency of the device for the programmer who can address the micro-circuit 108 like any other track on the floppy disk.

The arrangement which has just been described makes it possible to achieve double compatibility.

A typical floppy drive can read unprotected information to run unprotected software stored on the floppy disk.

A protected floppy disk drive can read all of the information and run any software stored on an unprotected floppy disk. Fig. 21 shows a practical embodiment of a protected floppy disk according to the invention. This diskette comprises an outer casing 150, of plastic material, in the thickness of which is embedded a micro-circuit 108 of the type described. with reference to Figs. 14 and 15. This micro-circuit includes contacts 151 for connection with the contacts 107 of the diskette unit 138 shown in FIG. 20. The incorporation of the micro-circuit 108 into the thickness of the envelope 150 of the floppy disk is carried out according to methods well known by the manufacturers of memory cards. The micro-circuit 108 is located in the center of the base of the diskette and the contacts 151 thereof are located on the rear face of the diskette.

FIG. 22 diagrammatically shows the practical embodiment of the protected floppy drive according to the invention compatible with the floppy disk described with reference to FIG. 21. The reader comprises inter alia a read head 130, a stepping motor 133 and a housing 152 for the floppy disk. At its end opposite to the read head, the housing 152 includes contacts 107 intended for the connection of the reader to the micro-circuit 108 incorporated in the envelope of the floppy disk 150. The connection contacts 107 are fixed on the base of the reader opposite the position that will take the contacts 151 of the micro-circuit 108 when the floppy disk is inserted into the device. In Figs. 23 and 24, there is shown in more detail and on a larger scale the organs of the floppy disk drive of FIG. 22 allowing the implementation of the invention.

The floppy drive shown in FIG. 23 comprises a housing 154 provided with a base 155 against the underside of which is disposed a printed circuit 156 on which are placed the electronic components of the floppy drive described with reference to FIG. 20. PCB 156 is connected by conductors 157 to a device 158 for interconnecting the printed circuit with the micro-circuit 108 carried by the envelope of the floppy disk, the device 158 forming part of a contactor 159 which carries on its upper face contacts 107 of connection of the printed circuit 156 with the micro-circuit 108 of the floppy disk 150.

In Fig. 23, the floppy disk 150 is shown, disposed in a floppy disk ejection mechanism 161 and located in the high position relative to the reader base, so that the contacts 107 of the reader and the contacts 151 of the printed circuit 108 are disconnected. .

Such an arrangement allows, as shown in FIG. 24, to take advantage of the lowering movement which the disk 150 undergoes on the part of the insertion and ejection device 161 when the disk arrives at the end of the travel of the introduction movement, and of the vertical elasticity of this system insertion, to ensure the connection between the two series of contacts 151 and 107.

This arrangement also allows very short connections between the contacts of the reader and the printed circuit 156 which groups together all of the electronic circuits of the reader and which is fixed under the base 155. It also eliminates any risk of hindering the movements of the parts mobile mechanics of the player due to the existence of these connections.

The protective micro-circuit 108 is incorporated into the envelope of a floppy disk in a manner which will be described with reference to FIGS. 25 to 27.

The chip constituting the micro-circuit 108 is fixed to the rear face of a printed circuit on flexible film for example or polyester 170 which has on its front face copper tracks 151 constituting the connection contacts of the micro-circuit. Reserves 167 formed in the film allow the passage of the gold wires 168 which provide the connection, the studs of the chip and the contacts 151.

The single film is bonded by its rear face to one of the halves 150a of the envelope 150 in which a window 165 is made, allowing the housing of the chip 108 and the gold wires 168. A force of resin 166 makes it possible to protect the chip 108 and the gold wires 168 and ensure the filling of the window 165. When there is a protected floppy disk according to the invention and a floppy disk drive intended to receive it, of the type described with reference to Figs. 14 and 15 to 24, the protection of software against duplication attempts is carried out as follows.

The software includes a main part which is executed by the microprocessor 102 of the microcomputer 96 as well as a certain number of subroutines which are executed by the interpreter and the microprocessor 109 (Fig. 15) located in the microcircuit 108 incorporated in the floppy disk.

The operation of the interpreter residing in the PROM 111 memory of the micro-circuit (Fig. 15) is not known to the user of the software and cannot be discovered by the latter because the interpreter has been designed, as indicated in the description of the micro-circuit made with reference to FIG. 15, so as to ensure its own inviolability. The subroutine program executed by the interpreter of the microcircuit incorporated in the floppy disk and the data on which this subroutine acts are transmitted by the microcomputer 96 (Fig. 14) to the microcircuit 108 in the form of an information block.

The result of the execution of the subroutines is retransmitted from the micro-circuit 108 to the microcomputer 96 also in the form of a data block.

These subroutine programs are stored on the magnetic tracks of the floppy disk 101 (Fig. 14). If necessary, they can be presented in an encrypted form, the interpreter then carrying out the de-encryption before the execution of the subroutines using, if several different encryption keys have been used to encrypt the different subroutines, a key which is part of the data block transmitted from the microcomputer 96 to the microcircuit 108.

It will be borne in mind that the exchanges of data blocks between the microcomputer 96 and the microcircuit 108 is carried out, in the present example, as a simple write or read operation on a track of diskette 101.

We will now describe a simple example of implementing the protection of software recorded on a protected floppy disk according to the invention.

Although this example is generally difficult to use due to the slowing down that it requires, it makes it possible to clearly understand the operation of the protection according to the invention.

In its unprotected version, software frequently executes a subroutine which adds two operands located in memory. In its protected version, this routine is replaced by a routine which:

- places an FFFF code at a given address,

- places the first operand at the following address,

- places the second operand at the next word,

- writes the block thus formed on track n ^· 80 of the floppy disk 101 (Fig. 14), reads a block on track n ^· 80 of the floppy disk,

- places the first word of this block at the address provided for the result of the addition.

In view of the above, we realize that if a person, even a computer specialist, disassembles the program, it will be extremely difficult, even in this simple example, to understand what the program worked and what is the utility of this subroutine.

Even in this simple example, there is therefore protection against software piracy attempts by analyzing its logical structure.

The interpreter located in the micro-circuit 108 carries out the following operations:

- waiting for a transmission request from the microcomputer 96,

- reception of the message and writing of it in the RAM memory 112 of the micro-circuit 108 (FIG. 15), reading of the first address of the RAM memory 112. If the content of this address is FFFF,

- reading of the content of address n ^· 2,

- reading of the content of address n ^· 1, - addition - writing the result to address n ^· 1, - waiting for a request for transmission to the microcomputer 96,

- transmission to the microcomputer 96,

- waiting for a new transmission request from the microcomputer 96.

If the content is different from FFFF,

- connection to an endless loop. During the recording of the software on the floppy disk, the floppy disk is initially a new floppy disk provided with a micro-circuit 108 whose memory area PROM 111 is empty.

The computer which manages the recording of the floppy disk transmits to the micro-circuit 108 (FIG. 14) a block which comprises;

- a program allowing the microprocessor 109 (Fig. 15) of the micro-circuit to record the interpreter in the PROM memory 111, - the following of the instructions constituting the interpreter but in which the comparison code FFFF has been replaced by a other code determined randomly.

The computer then records the following instructions from the software on the floppy disk, but also replacing the FFFF code in the addition routine with the same code as that used for the interpreter.

We therefore see, in this example, that any copy of a copy of the software onto a floppy disk other than the one on which it was originally recorded will only be executable:

- if the micro-circuit 108 of this diskette has in its PROM memory 111 the same interpreter as that for which the software was written, - and if there is also a correspondence between the codes defining, for the interpreter and for the main program, the addition operation. If these codes are tried at random, this second condition has a probability which decreases exponentially with the length of the code.

Some examples of concrete applications of the software protection method according to the invention are given below. The subroutine executed by the interpreter contained in the micro-circuit 108 of the floppy disk is limited to the comparison between a code read on one of the magnetic tracks of the floppy disk 101 and a code located in the PROM area 111 of the micro-circuit of this diskette.

If there is no identity, the interpreter connects to an endless loop, thus blocking the following transfer requests and consequently the operation of the software. In a calculation program or in spreadsheet-type software, the library of mathematical functions can be executed by the interpreter of micro-circuit 108 when each function is triggered by a particular code different from one recording to another of the software or when this library of mathematical functions is stored on the floppy disk 101 in an encrypted form and transferred on each call to the micro-circuit 108 of this floppy disk, the interpreter of which then firstly decrypt and then execute the function requested.

In word processing software with spell checking, the dictionary can be saved in encrypted form on the floppy disk 101 and transferred to the RAM memory 112 of the micro-circuit 108 of the floppy disk.

The interpreter contained in this micro-circuit then has the function of encrypting the word whose verification is requested according to the same encryption algorithm, of researching the encrypted values, of retransmitting to the computer either a good result response or bad is a decrypted list of neighboring spelling words. Such a subroutine, although generally long, can be executed by the microprocessor 109 of the micro-circuit 108 in masked time while the microprocessor 102 (FIG. 14) of the microcomputer will perform other tasks. In this case, the protection is accompanied by an increase in the overall speed of execution of the software.

The means of protecting data recorded on recording media such as magnetic tapes or floppy disks which have just been described have the following advantages over the means used to date.

They offer almost total security, They do not impose specific conditions of use, They do not significantly influence the costs of software design and duplication.

The security of protection against illicit duplication of software results from four factors: - Simple copying of the software onto a floppy disk not fitted with a micro-circuit according to the invention or whose micro-circuit is programmed differently cannot be executed because the information on the diskette itself is incomplete your. In fact, the subroutines executed by the interpreter contained in the micro-circuit 108 cannot be executed.

Attempts to reconstruct the interpreter located in the micro-circuit 108 associated with the floppy disk come up against the self-inviolability ensured by such an interpreter and the possibility of varying this interpreter from one recording to another either at the level of its structure, or at the level of its configuration.

The substitution of subroutines performing functions determined by subroutines appearing at the level of the executable code recorded on the floppy disk, like a write / read operation on floppy disk makes the a posteriori structural analysis of the software extremely delicate, all the more so that according to the content of the transferred block, the subroutine which the interpreter contained in the micro-circuit of the floppy disk will execute will correspond to completely different algorithms.

The possibility of encrypting subroutines recorded on diskette, of having them decrypted by the interpreter of the micro-circuit which will ensure their execution further increases the efficiency of the system because of all the possibilities offered by encryption.

The recording protection method according to the invention is completely transparent to the user who uses the floppy disk in exactly the same way, whether conventional or not.

As noted above, there is dual compatibility, since conventional floppy disks that cannot be used on protected floppy disk drives and protected floppy disks can be used on conventional floppy drives.

The arrangement which has just been described allows the user to save as many backup copies as he wishes, even using conventional floppy disks.

Finally, subject to ensuring their protection by the use of the same interpreter contained in the micro-circuit of the floppy disk, several different programs can be run on a hard disk, but protected against illicit copying by the necessity of the presence of one of the original protected floppy disks in a floppy drive connected to the system.

Given a possible standardization of the micro-circuit 108 incorporated in the floppy disk, it can be produced in very large series.

The techniques for incorporating such micro-circuits for memory cards are already used in large series and therefore transposable to protected floppy disks.

With regard to the costs of recording the software on their original floppy disks, the programming of the micro-circuits is an operation controlled by the same computer as that which records the program on the floppy disk and the time of which execution is weaker or of the same order of magnitude as that of the recording operation. Under these conditions, the additional cost of protection according to the invention should not exceed 1 to 2% of the selling price of software.

In addition to ensuring the protection of software against illegal duplication, the protected diskettes according to the invention make it possible to control or limit the use which is made of the software such as the show the examples below.

The start of the interpreter program located in the PROM area 111 of the memory of the micro-circuit 108 (FIGS. 14 and 15) comprises a sequence of instructions, activated when the micro-circuit 108 is energized, that is to say say during the introduction of the diskette into the reader, these instructions verifying the identity of a password requested from the user by the main program with a secret word contained in a special area of the PROM 111 memory. If there is identity, the interpreter is activated and normally ensures the execution of the subroutines that the computer subcontracts to him, until the power to the micro-circuit 108 is cut. If there is no identity, the interpreter connects to an endless loop thus preventing the execution of the program.

More complex structures can be imagined allowing the repetition of the password request, a limited number of times or the modification of this password, when a first password recognition has taken place.

The arrangement which has just been described can also ensure the restriction of use of software to a given copy of computer. The start of the interpreter program located in the PROM area 111 of the micor-circuit memory includes a sequence of instructions activated when the micro-circuit 108 is energized, therefore when the floppy disk is inserted into the reader, which verifies the identity of a code read by the main program, for example in a read-only memory of the main computer, with the content of a corresponding code recorded in the PROM memory 111 of the micro-circuit 108. If there is an identity, the interpreter is activated and normally ensures the execution of the subroutines that the computer subcontracts to him, until the power to the micro-circuit is cut. If there is no equality, the interpreter connects to an endless loop thus preventing the execution of the program. The modification of the code can be done under the control of a password allowing to assign a copy of the software to a specific copy of the main computer. The copy of the software is no longer transportable.

Thanks to the arrangement of the invention, it is also possible to limit the number of uses of software. We use a specific area of memory

PROM 111 of micro-circuit 108 (Figs. 14 and 15) which initially only includes 0s.

Each time the micro-circuit 108 is powered up, a subroutine of the interpreter contained in the micro-circuit checks the number of bits in this PROM zone which are at 1. If all the bits are at 1, the interpreter plugs into an endless loop. Otherwise, this subroutine sets 1 bit more from the PROM area 111 and then activates the interpreter in normal operation. This method therefore limits the number of times that the software can be used to the number of bits contained in the specific area of the PROM 111 memory.

The protection against duplication of documents can be achieved as follows.

The use of protected diskettes according to the invention and of the readers associated with these diskettes makes it possible to prohibit the duplication of documents recorded on these diskettes provided that: - these documents are saved in a format which represents a certain compression of information compared to the format in which the information will be used; - the use of these documents does not require computer processing in compressed form.

A simple example illustrates these conditions. Text encoded in ASCII with which a font is associated represents a significant compression of information compared to the display of this same text with the same font on a computer screen.

If the only use of this text is to display it as it is on the screen, it does not require processing in its compressed form. On the other hand, if it is intended to be used by word processing software, it requires computer processing in compressed form.

Under these conditions, protection against unlawful duplication of such documents is based on: the encrypted storage of the compressed version of the document on the magnetic tracks of the floppy disk, the use of the micro-circuit 108 and its interpreter to decrypt the information then to convert it into its uncompressed form, this uncompressed form being that which will be retransmitted towards the main computer which will ensure its exploitation. The protection against duplication of documents can be applied for example to the recording of text. A text is first converted into ASCII code, code which is itself encrypted for example by a series of reversals of ASCII codes. The font (s) used for this text as well that any formatting instructions are also encrypted.

The result of this encryption is then saved on the protected floppy disk. At the time of this recording, an interpreter is loaded into the microcircuit 108 associated with the floppy disk, as indicated above.

This interpreter performs the following operations: - reception of a data block from the main computer, decryption of the data according to the reverse algorithm to that used during encryption,

- from the ASCII coding of the text, the fonts and formatting instructions, reconstruction in the RAM 112 of the microcircuit, of the screen image corresponding to the text, transfer of a data block containing this screen image to the computer with only the task of transferring this data block to its screen memory area.

This process can also be applied to texts used by speech generation software, to musical documents exploited by sound synthesis software, to graphic documents animated or not using software for generating shapes or synthetic images and others.

The security of protection against illegal duplication of documents results from three factors:

- encryption of the compressed form of the document, which ensures its protection against direct use by an appropriate program;

- the use of the associated micro-circuit 108 the recording disk whose algorithm is non-violable to ensure decryption; the use of the micro-circuit 108 to ensure the transformation of the compressed form of the document into its uncompressed form.

The computer to which the protected floppy disk drive is connected therefore only has access to either the encrypted compressed form which it cannot use because it is encrypted, or to the decompressed decrypted form which it cannot use or record on another medium due to the memory capacity or excessive recording capacity required which would make such recording inconvenient and economically unacceptable.

Claims

CLAIMS 1. Method for digital recording of data on a recording medium comprising means for storing the data to be recorded contained in a fixed envelope, characterized in that it consists in incorporating into said envelope (75; 150) means additional storage and / or data processing (16; 108) forming part of a micro-circuit provided with connection means (78,79,80; 151,168) with an apparatus for reading the data contained in said storage means , to record in said storage means, data drawn from the data to be recorded but which cannot be used directly by the reading means and to record in the additional storage means (16; 108) data capable of making it usable by the reading means , the data stored in said storage means.

2. Method according to claim 1, characterized in that the additional means (16; 108) of storage and / or of data processing carry out by themselves the operations making the data stored in the storage means, usable by the means of reading, and prohibit any access to the additional data which they contain.

3. Method according to one of claims 1 and 2, of digital recording of data on a recording medium contained in a fixed envelope, characterized in that it consists in transcoding the data to be recorded on said medium, using the using an appropriate code or encryption algorithm to make them unusable directly by a reading device, to record the transcoded data on the recording medium contained in the fixed envelope (75; 150) and to record in the additional storage means (16; 108) of said micro-circuit the code or the decryption algorithm corresponding to that using which the data recorded on the medium have been transcoded.

4. Method according to one of claims 1 and 2, digital recording of data on a recording medium contained in a fixed envelope, characterized in that it consists in storing a first part of the data to be recorded, on said medium and storing in the additional storage means (108) of said micro-circuit a second part of the data to be recorded, access to said second part of the data making said first part of the data exploitable by a reading device.

5. Method according to one of claims 1 to 4, characterized in that said recording medium is a magnetic tape or floppy disk or an optical disc.

6. Method according to one of claims 3 to 5, characterized in that the operation of transcoding the data to be recorded on said medium using an appropriate encryption code and the operation of recording in the means additional storage (16; 108) of said micro-circuit of the decryption code, are carried out simultaneously or successively.

7. Digital data recording medium comprising a fixed envelope (75; 150) and means for storing the data to be recorded contained in said envelope, characterized in that it further comprises a micro-circuit (16; 108) of protection against unlawful duplication of data intended to be contained in the storage means, said micro-circuit being incorporated into said fixed casing (75; 150) and comprising means (17: 110,111,112) for storage and / or additional processing of data capable of making it usable by reading means, the data intended to be recorded in said storage means and means (78,79,80; 151,168) associated with the protection micro-circuit (1 6; 108) and intended to ensure the connection of said micro-circuit in the circuit of a device of reading means of said recording medium. θ. Digital recording medium according to claim 7, characterized in that the micro-circuit (16; 83) comprises means (17) for transcoding the data recorded on said medium in order to make them usable by a reading device, as well as means (78,80,82) for connecting the micro-circuit (16; 83) in the circuit (8,15,12,13) of said reading device. 9. Digital recording medium according to claim 8, characterized in that the micro-circuit (16) further comprises analog-digital converter means (18,19) connected to the outputs of the transcoding means (17) and intended for be connected to corresponding amplifier means (12, 13) of the reading device when the micro-circuit (16) is inserted into the circuit thereof. 10. Digital recording medium according to one of claims 8 and 9, characterized in that said transcoding means consist of a wire-to-wire interconnection matrix (21) at the inputs of which is connected a shift register ( 20) series / parallel intended to receive on its input the data to be transcoded from the read head of the reading device and to the outputs of which analog digital converters (22, 23) are connected intended to be connected to the two output channels of the reading device, when inserting the micro-circuit into the circuit of said reading device. 11. digital recording medium according to one of claims 8 and 9, characterized in that said transcoding means consist of a ROM memory (32) containing an algorithm for transcoding the encrypted data recorded on the recording medium, a serial / parallel shift register (21) intended to receive at its input the data coming from the read head of the reading apparatus, said shift register being connected to the inputs of said ROM memory (32) by via a memory address register (32), the outputs of said memory being connected in groups to digital-analog converters (34,35) via a memory output input register ( 33). 12. Digital recording medium according to one of claims 8 and 9, characterized in that said transcoding means consist of a PROM memory (44) containing an algorithm for transcoding the encrypted data recorded on the recording medium, a serial / parallel shift register (41) intended to receive on its input the data coming from the read head of the reading apparatus, said shift register being constituted at the inputs of said PROM memory (44) by the via a memory address register (43), the outputs of said memory being connected in groups to analog-to-digital converters (46,47) via a memory output input register (45), a serial / parallel shift register (50) for programming the PROM memory (44) being further associated with the memory input-output register (45). 13. Digital recording medium according to claim 7, characterized in that said medium is intended to store a first part of the data to be recorded, while said additional storage means (108) are intended to store a second part of the data to be record, access to said second part of the data making said first part of the data usable by the reading device. 14. Digital recording medium according to claim 13, intended for recording a computer program, characterized in that said additional storage means consist of a ROM memory (110) for storage, a start-up program and the content of which is fixed during the manufacture of the micro-circuit (108), a PROM memory (111) which is empty during the construction of the micro-circuit (108) and intended to contain an interpreter program. the contents of said ROM (110) and PROM (111) memories being retained when the micro-circuit (108) is de-energized, a RAM memory (112) also empty during the construction of the micro-circuit (108) and intended for contain encrypted programs and data to be interpreted by the interpreter program stored in the PROM (111), said interpreter program being structured so as to prevent any attempts by _{an d} program transmitted from the outside of the micro-cir cooked (108) to read or modify the content of certain memory areas, a microprocessor (109) for managing said memories under the control of a microcomputer forming part of the reading apparatus and an input interface circuit / output (116), the memories (110,111,112), the microprocessor (109) and the input / output interface circuit (116) being interconnected by address, data and control buses (113,114,115) . 15. Digital recording medium according to any one of claims 7 to 14, characterized in that it is constituted by a magnetic cassette, the magnetic tape of which constitutes the actual recording medium and whose housing (75) of standard type carries on its edge (76) opposite the access window to the magnetic strip, a strip (77) fixed to the cassette and comprising a protective micro-circuit (16) and contacts (78) for connection to a reading device. 16. digital recording medium according to any one of claims 7 to 14, characterized in that it consists of a magnetic diskette which forms the actual recording medium and the envelope (150) of plastic carries a protective micro-circuit (108) embedded in the thickness of said envelope, said micro-circuit (108) comprising contacts (151) for connection with a reading device. 17. Digital recording medium according to claim 16, characterized in that the micro-circuit (108) is mounted in a window (165) formed in a half (150a) of the envelope (150) of the floppy disk and embedded in a coating resin (166) and in that a printed circuit (170) carrying pads contact (151) is fixed on the free surface of the envelope half (150a) over said window (165) and connected to the micro-circuit (108) by wires (168) embedded in the resin (156) micro-circuit coating. 18. Apparatus for digital recording of analog data on a recording medium intended for carrying out the method according to one of claims 1 to 3, 5 and 6 on a recording medium according to one of claims 7 to 12, said apparatus comprising means (1,2) for sampling analog signals intended to be applied to its input, means (3,4) for analog-digital coding of the signals sampled by the sampling means, means (5) for parallel / serial conversion of the output signals from the analog-digital coding means (3,4) and means (7) for modulating the output signals from the parallel / serial conversion means with a view to their application to a recording head, characterized in that a transcoding circuit (14) containing an encryption code is inserted between the analog-digital coding means (3,4) and the parallel / serial conversion means (5). 19. Digital recording apparatus according to claim 18, characterized in that said transcoding circuit comprises a RAM memory (60) intended to contain an encryption code of the data to be transcoded for the purpose of recording, and to which is connected d firstly a memory address register (61) and secondly a memory input / output register (62), parallel buses (63) connected to the memory address register (61) being intended for loading the RAM memory (60) by addresses or values in a coded sense and parallel buses (64) connected to the memory input / output register (62) being intended for loading into the RAM memory (60) transcoded.

20. Apparatus for reading data, recorded on a recording medium according to one of claims 7 to 15, comprising a read head, means (8) for demodulating the signals coming from the read head and means ( 12,13) amplifying the output of the reading device, characterized in that it further comprises contacts (94,95) for connection in the circuit of the reading device of the micro-circuit (16) incorporated in the fixed casing (75) of the recording medium, said micro-circuit comprising serial / parallel conversion means and means (18,19) of analog digital conversion necessary for the circuit of the reading apparatus as well as a transcoding circuit (17) intended to make the data read by the read head on the recording medium operable by the reading apparatus.

21. A data reading apparatus according to claim 20, intended for reading data recorded on a recording medium according to claim 15, constituted by a magnetic cassette, comprising a housing (86) intended to receive the cassette and in the bottom of which are provided contact strips (91, 92) fixed to the housing of the reading device by elastic tabs (93), said strips each carrying electrical contacts (94,95) for connection of the micro-circuit (16 ) carried by the cassette in the circuit of the reading device, said contacts (94,95) being intended for cooperate with the contacts (78) of the bar (77) carrying the micro-circuit (16) integral with the housing (75) of the magnetic cassette during the introduction of the latter into the housing (86). 22. Apparatus for reading data recorded on a recording medium according to one of claims 7, 13, 14 and 17, intended for reading magnetic floppy disks, said apparatus comprising at least one read-write head (99; 130), magnetic interface circuits (98) associated with said head, and intended to ensure the processing and transmission of data between a microcomputer (96) associated with the reading device and the read-write head (99), via a floppy coupler (97), characterized in that it further comprises a micro-circuit interface circuit (106) connected to the floppy coupler (97) and to the circuit magnetic interface (98) and micro-circuit contacts (107) intended to cooperate with the micro-circuit (108) for protecting the floppy disk carried by the envelope of the floppy disk (101), during the introduction of the diskette into said reading device.

23. A data reading apparatus according to claim 22, comprising a diskette unit (138) comprising a main motor (132), a stepping motor (133), an index detector (134), a circuit (135 ) for controlling the main motor, a circuit (136) for positioning the read / write head (130) and an index detection means (137) and a floppy disk controller (139) comprising an interface circuit ( 140) for controlling the diskette drive, with which is associated a DMA interface circuit (141) intended to ensure the transfer of data between the read / write head and the memory of a computer. with which the reading device is associated, characterized in that the micro-circuit interface circuit (106) is also connected to the read / write head interface circuit (131), to the circuit (136) for positioning of the read / write head and to the index detection circuit (137) of the diskette unit (138).

24. Data reading device according to one of claims 22 and 23, characterized in that the micro-circuit (108) is assimilated to an additional magnetic track of the floppy disk for the transfer of data between the computer and the microphone -circuit.

25. Data reading apparatus according to one of claims 22 to 24, comprising a housing (154) provided with a base (155), a housing (152) by a floppy disk and a mechanism (161) for ejecting floppy disk movable between a low insertion position of the floppy disk and a high ejection position of the latter, characterized in that the contacts (107) for connecting the reading device to the protective micro-circuit (108) of the floppy disk are part of a contactor (159) mounted in the base (155) of the reading device, the connection of said contacts (107) with the contacts (151) of the micro-circuits (108) being ensured by low position of the ejection mechanism (161).

26. Reading device according to claim 25, characterized in that said contactor (159) comprises a device (158) for interconnection with the micro-circuit (108) of the floppy disk, of a printed circuit (156) on which the electronic components of the reading device are placed, the printed circuit (156) being placed against the face of the base (155) opposite the floppy disk housing (151) and being connected by conductors (157) to the interconnection device (158).