WO2000057261A1

WO2000057261A1 - Secure portable digital data handling medium, and security method using such a data handling medium

Info

Publication number: WO2000057261A1
Application number: PCT/FR2000/000638
Authority: WO
Inventors: Maurice Milgram
Original assignee: Dixet
Priority date: 1999-03-19
Filing date: 2000-03-16
Publication date: 2000-09-28
Also published as: EP1163563A1; FR2791153A1; CA2367014A1; AU3299000A; CN1347523A; JP2002540498A; BR0009169A; FR2791153B1; MXPA01009454A; ZA200107729B; KR20020006686A

Abstract

The invention concerns a secure portable digital data handling medium comprising a receiver interface (10) adapted to receive input data coming from a user electronic device by detecting the movements imposed on the data handling medium by the user device; an output interface (11) adapted to transmit output data on the basis of the received input data; and a central electronic unit (7) connected to the receiver and transmitter interfaces and adapted to determine the output data on the basis of the input data and to cause said output data to be transmitted.

Description

Secure portable digital data carrier, and method of securing using such a data carrier.

The present invention relates to secure portable digital data carriers, and to security methods using such data carriers.

More particularly, the invention relates to a secure portable medium for digital data readable by a user electronic device comprising at least one input interface, this data medium being intended to undergo at least one predetermined movement imposed by the user electronic device during reading said data medium, said data medium comprising an electronic security device which comprises: a reception interface adapted to receive input information from the user electronic device, a transmission interface adapted for send output information as a function of the input information received, this output information corresponding (directly or indirectly) to a security code intended to be communicated to the input interface of the user electronic device, - and a electronic central unit connected to the reception interfaces and transmission and adapted to determine the output information according to the input information and to transmit said output information by the transmission interface. Document US-A-5 652 838 describes an example of such a secure portable digital data medium, in this case constituted by an optical disc. The interface input is constituted by optical sensors adapted to detect the reading laser beam from a computer using the optical disc, which laser beam is controlled so that its sequence of passage on the optical sensors corresponds to a certain entry code . The output interface of the optical disc consists of a screen which displays an exit code according to the entry code received from the computer. The user must remove the optical disc from his reader in order to read the exit code, after which said user types this code on the keyboard of his computer, which authorizes the use of the optical disc by the computer. This protects against illegal copies of the optical disc.

These arrangements have the disadvantage of obliging to direct the reading beam towards the optical sensors of the data medium, which leads to placing the optical sensors in the data storage area of the data medium, hence constraints as to the arrangement of the data in said data storage area and the capacity limitations of said data storage area.

The object of the present invention is in particular to avoid these drawbacks.

To this end, according to the invention, a secure portable medium of digital data of the kind in question is characterized in that the reception interface of said data medium comprises a movement sensor adapted to detect the movements of the data medium. , the central unit of the data medium being adapted to determine the input information as a function of the detection of movements of the data medium over time. In preferred embodiments of the data carrier according to the invention, it is optionally possible to have recourse to one and / or the other of the following arrangements: the central unit is adapted to determine the information of entry in function of the detection and or the absence of detection of movement of the data medium over time; the data medium is intended to undergo several predetermined movements imposed by the electronic user device when reading said data medium, the central unit of the data medium being adapted to determine the input information according to the detections of said several predetermined movements of the data medium over time (these arrangements could if necessary be used independently of the arrangements described above, and in particular independently of the creation of the transmission interface in the form of a acoustic transducer); - the motion sensor is an acceleration sensor; the data carrier is intended to be rotated at least at a predetermined speed by the user electronic device when it is read, the motion sensor being a radial acceleration sensor adapted to detect the rotation of the data carrier at said at least one predetermined speed; the movement sensor is a current micro-generator which is adapted to generate an electric current when the data medium is in motion and which at least partially supplies the security device with electrical energy; the central unit is adapted to deactivate when the movement sensor detects a movement of said data medium which does not correspond to certain predetermined criteria corresponding to normal use; the central unit is adapted to deactivate when the movement sensor detects continuous movement for at least a predetermined duration; the transmission interface comprises an acoustic transducer which transmits the output information in the form of an acoustic signal (this arrangement could if necessary be used independently of the aforementioned input interface comprising a motion sensor); the central unit of the data carrier is adapted to cause the acoustic signal to be emitted by the transducer in the form of a series of sound signals of variable durations separated from each other by periods of silence of predetermined duration, the information of output being coded by the variation of the duration of the different sound signals; the central unit of the data carrier is adapted to cause the acoustic signal to be emitted by the transducer in the form of several trains of sound signals each comprising several elementary sound signals of constant duration, the number of elementary sound signals of each train of sound signals being between 1 and an integer n at least equal to 2, the sound signal trains being separated from each other by periods of silence at least equal to a predetermined duration, and the output information being coded by the number of elementary sound signals of each train of sound signals; the transducer is an electronic buzzer which emits an acoustic signal having a constant emission frequency spectrum; the transducer is a loudspeaker associated with voice synthesis means, the central unit of the data carrier being adapted to cause the loudspeaker to transmit an audible message understandable by a human operator and containing the output information; the data medium is an optical disc. It will be noted that, as a variant of the above-mentioned input interface comprising a motion sensor, one and / or the other of the following arrangements could be used where appropriate: the data medium is readable by a electromagnetic beam (in particular light beam) which locally heats said data medium when it is read, the reception interface comprising at least one thermoelectric element which has at least one electrical characteristic variable as a function of its temperature, this thermoelectric element being connected (directly or indirectly) to the central unit of the data carrier, and the data unit being adapted to detect the passage of the electromagnetic beam on the thermoelectric element as a function of variations in said electrical characteristic and to determine the information of entry into function of the detection of these passages over time (these provisions could e if necessary be used independently of the arrangements described above, and in particular independently of the implementation the transmission interface in the form of an acoustic transducer); the thermoelectric element is adapted to generate an electrical voltage when it is heated by the electromagnetic beam, this electrical voltage constituting said electrical characteristic; the thermoelectric element is based on PZT. Furthermore, the subject of the invention is also a method of securing using a data medium as defined above, comprising the steps consisting in: having the data medium read in a reader belonging to a user electronic device which comprises a input interface, - have the input information transmitted by the electronic user device to the reception interface of the data medium, have the output information determined by the central unit of the data medium, according to the information d input, send the output information in the form of an acoustic signal by the transducer of the data medium, communicate to the electronic user device the security code corresponding to the output information, via the input interface of said user electronic device, according to the security code received by the electronic device u user, authorize or not a certain mode of operation of said user electronic device. In preferred embodiments of the method according to the invention, it is possible optionally to have recourse to one and / or the other of the following arrangements: the acoustic signal containing the output information is listened to by a human operator, who operator determines the security code as a function of the signal listened to and communicates this security code to the user electronic device via its input interface; - the acoustic signal containing the output information is received directly by the input interface of the user electronic device; the acoustic signal containing the output information is transmitted to a remote control station which determines the security code as a function of said acoustic signal and whether or not transmits this security code to the input interface of the user electronic device.

In addition, the subject of the invention is also a method using a data medium as defined above, method in which coded data is exchanged between a remote central station and the central unit of the data medium, by the intermediary of the reception and reception interfaces of said data carrier. It is thus possible to identify the user as a function of the coded data exchanged between the remote central station and the central unit of the data carrier, to secure a remote operation, for example a remote payment operation. The invention also relates to a method using a secure data medium as defined above, method in which the electronic device for security has in memory a value unit account, and the central unit of said security device is adapted to vary said value unit account as a function of coded data received and transmitted by the central unit via reception and transmission interfaces.

The invention also relates to a method using a secure data medium as defined above, method in which the electronic security device has in memory at least one counter of usage units, and the central unit of said security device is adapted to vary said counter as a function of the movements of the data medium detected by the movement sensor. Advantageously, the counter of usage units can be read by an external reader, by means of a communication interface belonging to said security device.

Other characteristics and advantages of the invention will appear during the following description of several of its embodiments, given by way of nonlimiting examples, with reference to the accompanying drawings. In the drawings: FIG. 1 is a schematic view of a microcomputer capable of using an optical disc according to the invention, comprising an electronic security circuit, FIG. 2 is a block diagram of the electronic circuit for securing the optical disc of FIG. 1, in a first embodiment of the invention, Figures 3 and 4 are views similar to Figure 2, respectively for second and third embodiments of the invention, and Figure 5 is a schematic view of a thermoelectric element usable in the embodiment of Figure 4.

In the different figures, the same references designate identical or similar elements.

FIG. 1 represents a microcomputer 1 comprising a screen 1a, a keyboard 1b and a reader 2 for digital optical discs (CD-ROM, DVD, etc.) or other digital data carriers.

The object of the invention is in particular to secure the use of the optical disc 3, or of any other similar digital data medium usable by the microcomputer or by another electronic device, in particular in order to prevent illegal copies of this optical disc (or other data medium).

To this end, the optical disc 3 (or other similar data carrier) comprises, preferably outside of its data storage area 4 and advantageously in its central part 5 devoid of data, an electronic security circuit β.

This electronic security circuit, which is shown in FIG. 2, is integrated in the resin matrix of the optical disc and comprises: an electronic central unit 7 such as a microcontroller or microprocessor associated with a memory 8 which may be internal to said microcontroller or microprocessor (one can use for example the microcontroller P8 E5032 marketed by PHILIPS SEMICONDUCTORS, a division of the company ROYAL PHILIPS ELECTRONICS, Eindhoven, NETHERLANDS, or the AT89SC microcontroller marketed by the company ATMEL CORPORATION, 2325 Orchard Park ay, San José, CA 95131, USA), a source of electrical energy 9 such as a miniaturized battery (for example, a marketed battery under the TMF® brand by the company BOLDER TECHNOLOGIES

CORPORATION, 4403 Table Mountain Drive, Golden, Colorado

(CO) 80403, USA), which supplies the electronic circuit β, a motion sensor 10 such as an acceleration sensor, suitable for detecting for example an orthoradial (tangential) acceleration of the optical disc or preferably a corresponding radial acceleration at the speed of rotation of the optical disc 3 when it is read in the reader 2 of the microcomputer (this sensor 10 is used to transmit information from the microcomputer to the optical disc 3, and advantageously to also control the sleep and waking up the central unit 7 as a function of the use of the optical disk 3), and an acoustic transducer, preferably piezoelectric, such as a loudspeaker or an electronic buzzer 11 ("buzzer") controlled by the central unit 7 and emitting for example sound signals having a constant frequency spectrum. The acceleration sensor 10 could for example be a microsensor (which may have for example a surface of 2 mm by 2 mm) obtained by micromachining on silicon, such as the 2g and 50g sensors produced by the Electronics Laboratory, of Technology and Instrumentation (LETI) of CEA (ATOMIC ENERGY COMMISSION), FRANCE. The device which has just been described makes it possible to implement a security method which makes it possible for example to verify the presence of the original optical disk 3 corresponding to a certain application (program, database, etc.) during installation. initial of this application on the microcomputer 1.

To this end, during the execution by the microcomputer 1 of the installation program of the application in question, this program generates input information such as a first random code, which is transmitted by the microcomputer 1 to the optical disc 3.

In the example considered here, this input information can be coded in the form of a sequence of starts and stops of the optical disc player 2, the coding of the input information can be obtained in particular by varying the duration of the on and / or off periods of the disc.

For example, this sequence of steps and stops can start with a predetermined fixed sequence of steps and stops which announces to the central unit 7 the transmission of a message containing the input information and which allows this central unit to synchronize with a predetermined time screen, each period of which contains an information bit. After this predetermined fixed sequence of steps and stops, the sequence of steps and stops contains the input information, the input information bit of each period of the time frame being worth for example 1 when the disc is in motion and 0 when stopped. The starts and stops of the reader 2 are detected by the sensor 10, which transmits the on / off information to the central unit 7. This central unit recognizes the predetermined sequence of starts / stops at the start of the coded sequence containing the first random code, and determines output information as a function of the input information: this output information can be presented for example under the form of a second pseudo-random code generated as a function of an encoding key contained in the memory 8 of the central unit.

Then, the central processing unit transmits the output information in the form of an acoustic signal by the transducer 11, preferably without removing the disc 3 from its reader 2.

This acoustic signal can comprise several trains of sound signals (for example 3 to 6 trains of sound signals) each comprising several elementary sound signals close together (separated from each other for example by a duration of 0.2 s) and of constant duration. The number of elementary sound signals of each sound signal train is between 1 and a predetermined integer n at least equal to 2 and for example equal to 4. The sound signal trains can be separated from each other by periods of silence at least equal to a predetermined duration (for example, these periods of silence can all be equal to approximately 2 s). The output information is thus coded by the number of elementary sound signals of each train of sound signals.

The acoustic signal containing the output information is listened to by a human operator, which operator thus determines the aforementioned second code in the form of a series of digits each of between 1 and n, corresponding respectively to the numbers of sound signals. res of the various trains of elementary sound signals successively emitted by the disc 3.

Then said operator communicates to the microcomputer 1 a security code as a function of said second code (in practice confused with said second code), for example by means of the keyboard lb. These operations are preferably guided by one or more messages displayed on the screen la of the microcomputer.

If the security code received is properly linked to the first code mentioned above by a predetermined relationship, the microcomputer 1 then authorizes the installation program to run; otherwise, it prohibits the normal running of this program.

This control of the smooth running of the installation program can also be obtained in particular: by encryption of the data contained in the optical disc 3, the decryption of this data can only be carried out by the microcomputer with a key decryption which is a function of the security code mentioned above and of the first code mentioned above, or by including in the installation program or in a program contained in the optical disk 3 and intended to be copied in the memory of the microcomputer, a connection to a programming address which can only be determined according to the aforementioned security code and the first aforementioned code.

The same principles can be used to control not only the installation, but the use of the computer application considered, by obliging the user to insert the optical disc 3 in the reader at least when launching said application. In this case, it will be noted that it is also possible to control the terms of use of this computer application as a function of data included in the memory 8 of the central unit of the optical disk 3, and to provide that the unit central 7 returns the second code mentioned above only if the required conditions of use are met.

By way of example, we can thus provide: a maximum number of uses or a maximum duration of use of the computer application, or even a date from which the computer application no longer works except to buy a disc optics 3, or a limitation of the program or data modules accessible to the user (in the latter case, the above-mentioned security process must be repeated each time the user wants to access a new program module or data).

It will be noted that the acoustic signal emitted by the transducer 11 could be coded otherwise than in the manner described above, and in particular: by causing this acoustic signal to be emitted in the form of a series of sound signals of variable durations separated from each other. others by periods of silence of predetermined duration, the output information being coded by the variation of the duration of the various sound signals; or by modulating the frequency of the sound signal emitted (in this case, the frequency spectrum of the transducer 11 must not be constant, this transducer being able to take the form of a piezoelectric speaker). As a variant, it would also be possible to provide for the acoustic signal emitted by the transducer 11 to be received directly by the microcomputer 1, in particular by means of an external microphone 12 which is connected to an internal sound card of the microphone -computer and which is approached from reader 2 by the user at the appropriate time, according to the indications given on the screen of the microcomputer. Taking into account the weak directivity of the emission of the sound signal by the transducer 11, this sound signal diffuses very widely, including outside the microcomputer case: it is therefore easily picked up by the microphone 12 .

According to another variant, the acoustic signal emitted by the transducer 11 is transmitted to a remote control station 13: via the aforementioned microphone 12 and a modem 14 belonging to the microcomputer 1 and connected to the remote control station 13 via the switched telephone network, - or via the user telephoning the control station 13.

In the latter case, the remote control station 13 determines the security code as a function of said acoustic signal and transmits this security code to the microcomputer 1 via the modem 14 (or else the security code is given by telephone to the user, who then types it on the keyboard 1b of the microcomputer). Optionally, the remote control station 13 may have to not transmit this security code to the microcomputer 1, for example if the use of the computer application in question is subject to a subscription which has not been paid. According to another variant, represented in FIG. 3, the acoustic transducer can be a loudspeaker 16 associated with a speech synthesis circuit 15 itself controlled by the central unit 7: in this case, the loudspeaker 16 emits an audible message understandable by the user and containing the exit information which corresponds to the security code. Optionally, the voice synthesis circuit 15 can be integrated into the central unit 7, constituted for example by a microprocessor of the TSP50C0x / lx type sold by the company TEXAS INSTRUMENTS, Dallas, USA.

According to another variant, the motion sensor 10 could communicate to the central unit 7 a measurement of the speed of rotation of the optical disc, for example by means of an analog / digital converter (not shown), and the reader. optical discs 2 would be controlled by the microcomputer 1 to successively rotate the disc at several different speeds to encode the input information. It is thus possible to transmit said input information in the form of a multivalent signal with more than two values, for example a quadrivalent signal if the reader 2 can selectively * stop the disc 3 or rotate it at three different speeds: in this particular case, the transmission rate of the input information is doubled compared to the coding of said input information in the form of a simple sequence of on / off.

Furthermore, to further increase the security of the optical disc 3, the central unit 7 is preferably adapted to deactivate in particular: when the movement sensor 10 detects a movement of the disc 3 which does not correspond to certain predetermined criteria corresponding to normal use, and in particular when the motion sensor detects continuous movement for at least a predetermined period (which may reveal an attempt to "hack" the optical disc), and when it receives an order deactivation of the microcomputer 1, for example when the latter has received several successive erroneous codes in place of the security code corresponding to the output information from the central unit 7.

According to yet another variant, the acceleration sensor 10 could be constituted by a current microgenerator capable of generating an electric current under the effect of the rotation of the optical disc. This current sensor, associated with an electronic energy storage circuit comprising for example a capacitor, could then replace the battery 9, or at least supply part of the electrical energy consumed by the electronic circuit 6. It will be noted moreover that the transmission of the input information from the microcomputer 1 to the optical disc 3 can be carried out by another means than a sequence of starts and stops of the reader 2. In this case, it is nevertheless possible to keep the sensor movement 10 in circuit 6, to control the sleeps and awakenings of the central unit 7, as shown in FIG. 4.

This transmission of information can be done for example by controlling the laser beam for reading the optical disc 2 so that it passes over one or more light sensors connected to the central unit 7, as was already known in the art. prior. As a variant, as shown in FIG. 4, the phenomenon of local heating of the optical disc 3 when it is scanned by the reading laser beam can be used: in this case, instead of using light sensors, uses one or more thermoelectric elements 17 which are connected to the central unit 7 each via an analog / digital converter 18 or another adaptation circuit, and which have at least one electrical characteristic which varies according to of their temperature.

The central unit 7 can thus detect the passages of the reading beam on the thermoelectric element 17 as a function of the variations of said electrical characteristic and determine the input information as a function of the detection of these passages over time.

The thermoelectric element 17 can in particular be based on PZT (zirconium titanate - lead) and be adapted to generate an electrical voltage (by piezoelectric effect in the case of PZT) when it is heated by the beam of reading, this electrical voltage constituting said electrical characteristic detected by the central unit 7.

For example, as shown in FIG. 5, the element 17 can be in the form of a parallelepiped of PZT 19 having a thickness e of a few microns in the direction of the thickness of the optical disc and a surface of the order from 1 to a few μm ² in the plane parallel to the faces of the optical disc, this parallelepiped being surrounded by two electrodes 20 connected to the above-mentioned circuit 18. Despite the brevity of the illumination of the element 17 during the passage of the reading laser beam (of on the order of 1 μs), the light energy then collected by the element 17 is sufficient to generate a voltage of a few volts between the electrodes 20.

Compared with the light sensors of the prior art, this embodiment has the advantage of requiring less precision in positioning the reading laser beam relative to the thermoelectric element 17: indeed, even if the laser beam of reading does not pass exactly on the thermoelectric element 17, but slightly beside it, the passage of said laser beam nevertheless causes heating which is detected by the thermoelectric element 17.

It will also be noted that one or other of the above-mentioned reception interfaces could be used with a transmission interface other than an acoustic interface, for example an optical interface.

Finally, it should be noted that the security process authorized by the optical disc 3 or other data medium according to the invention is not limited to controlling the use of programs or data contained in the optical disc: on the contrary, this process security can be used for example to identify the user, in particular to allow remote payment operations to allow remote access to protected data, without the need to provide the microcomputer with a specific security device such as a memory card reader or the like.

In this case, when the microcomputer 1 has a microphone 12 and a modem 14, the security process begins with the entry of a secret code by the user on the keyboard 1b, then central station 13 aforementioned (or similar) exchange coded messages with the security circuit 7 of the optical disc, to check the consistency between the code entered by the user and a secret key contained in the memory 8 of the central unit 7, as is already known for memory payment cards.

One could also use a secure data carrier as described above as an electronic purse or the like. In this case, the electronic security device 6 may have in memory an account of value units (monetary units or the like), and the central unit 7 of said security device is then adapted to vary said account from value units as a function of coded data received and transmitted by the central unit 7 via the reception and transmission interfaces, for example to reload the account when the user redeems value units or on the contrary to debit the account according to purchases or other paid operations carried out by the user, for example on the Internet.

When the security device 6 is used to control or limit the use of the data medium, as already indicated above, or to establish a user profile, this electronic security device can have one or more in memory usage unit counters.

When it is desired to limit the use of the data medium, this counter can be representative for example of a duration of use or of a number of uses, and the central unit 7 of said security device can be adapted to increment or decrement said counter as a function of the movements of the data medium detected by the movement sensor 10. For example, the transmission interface of the security device stops transmitting the coded output information which normally allows the user device to operate the data medium when the central processing unit 7 has detected a predetermined number x of activations of the data medium, that is to say when the counter reaches x starting from 0 or when it reaches 0 starting from x.

When it is desired to establish a user profile, the use counter or counters can for example be incremented each time the data carrier makes certain movements or certain predetermined sequences of movements, representative of certain predetermined operations.

Advantageously, the counter of usage units can be read by an external reader 22 (EXT. DRV - FIG. 2), by means of a communication interface 21 such as an electronic tag (TAG) adapted to communicate with the interface 22 over the air and belonging to said security device 6. Such a reading of the usage counter may take place for example during the passage of the user in a store marketing the data medium. In this case, the data medium can advantageously be miniaturized, for example in the format of a credit card.

Claims

1. Portable secure digital data carrier readable by a user electronic device (1) comprising at least one input interface (1b, 12, 14), this data carrier being intended to undergo at least one predetermined movement imposed by the user electronic device (1) during the reading of said data medium, said data medium comprising an electronic security device (6) which comprises: a reception interface (10) adapted to receive input information from the user electronic device, a transmission interface (11; 15, 16) adapted to transmit output information according to the input information received, this output information corresponding to a security code intended to be communicated to the input interface (lb, 12, 14) of the user electronic device, - and an electronic central unit (7) connected to the reception (10) and send interfaces sion (11; 15, 16) and adapted to determine the output information according to the input information and to have said output information transmitted by the transmission interface, characterized in that the interface for receiving said medium comprises a motion sensor (10) adapted to detect the movements of the data medium, the central unit (7) of the data medium being adapted to determine the input information according to the detection of the movements of the data medium data over time.

2. Data medium according to claim 1, in which the central unit (7) is adapted to determine the input information as a function of the detection and or the absence of detection of movement of the data medium during the time.

3. Data medium according to claim 1, intended to undergo several predetermined movements imposed by the user electronic device (1) when reading said data medium, the central unit (7) of the data medium being adapted to determine the input information according to the detections of said several predetermined movements of the data medium over time.

4. Data medium according to any one of the preceding claims, in which the motion sensor is an acceleration sensor (10).

5. Data carrier according to claim 4, in which the data carrier is intended to be rotated at least at a predetermined speed by the user electronic device (1) during its reading, the motion sensor being a radial acceleration sensor (10) adapted to detect the rotation of the data carrier at said at least a predetermined speed.

6. Data medium according to any one of the preceding claims, in which the motion sensor (10) is a micro-current generator which is adapted to generate an electric current when the data medium (3) is in motion and which at least partially supplies the security device (6) with electrical energy.

7. Data carrier according to any one of the preceding claims, in which the central unit (7) is adapted to deactivate when the movement sensor (10) detects a movement of said data medium which does not correspond to certain predetermined criteria corresponding to normal use.

8. Data carrier according to claim 7, wherein the central unit (7) is adapted to deactivate when the motion sensor (10) detects a continuous movement for at least a predetermined duration.

9. Data medium according to any one of the preceding claims, in which the transmission interface comprises an acoustic transducer (11, 16) which transmits the output information in the form of an acoustic signal.

10. Data medium according to claim 9, in which the central unit (7) is adapted to cause the acoustic signal to be emitted by the transducer (11, 16) in the form of a series of sound signals of variable durations separated by each other by silence periods of predetermined duration, the output information being coded by the variation of the duration of the various sound signals.

11. Data medium according to claim 9, in which the central unit (7) is adapted to cause the acoustic signal to be emitted by the transducer (11, 16) in the form of several sound signal trains each comprising several elementary sound signals. of constant duration, the number of elementary sound signals of each train of sound signals being between 1 and an integer n at least equal to 2, the train of sound signals being separated from each other by periods of silence at least equal at a predetermined duration born, and the output information being coded by the number of elementary sound signals of each train of sound signals.

12. Data medium according to any one of claims 9 to 11, wherein the transducer is an electronic buzzer (11) which emits an acoustic signal having a constant emission frequency spectrum.

13. Data medium according to claim 9, in which the transducer is a loudspeaker (16) associated with voice synthesis means (15), the central unit (7) of the data medium being adapted to make emit a loud message through the loudspeaker understandable by a human operator and containing the output information.

14. Data medium according to any one of the preceding claims, constituting an optical disc.

15. Method for securing a data carrier (3) according to any one of claims 9 to 13, and comprising the steps consisting in: - reading the data carrier in a reader (2) belonging to an electronic device user (1) which comprises an input interface (1b, 12, 14), have the input information transmitted by the user electronic device (1) to the reception interface (10) of the data medium, have determined the output information by the central unit (7) of the data medium, as a function of the input information, causing the output information to be transmitted in the form of an acoustic signal by a transducer (11, 16) belonging to the medium of data, communicate to the user electronic device (1) the security code corresponding to the output information, via the input interface (lb, 12, 14) of said user electronic device, according to the code security received by the user electronic device (1), authorize or not a certain mode of operation of said user electronic device.

16. Securing method according to claim

15, in which the acoustic signal containing the output information is listened to by a human operator, which operator determines the security code as a function of the signal listened to and communicates this security code to the user electronic device via its interface d 'entry (lb).

17. The security method as claimed in claim 15, in which the acoustic signal containing the output information is received directly by the input interface (12) of the user electronic device.

18. A security method according to any one of claims 15 to 17, wherein the acoustic signal containing the output information is transmitted to a remote control station (13) which determines the security code based on said acoustic signal and transmits or not this security code at the input interface (14) of the user electronic device.

19. Use of a data medium according to any one of claims 1 to 14, in which coded data is exchanged between a remote central station (13) and the central unit (7) of the data medium. born, via the reception (10) and reception (11; 15, 16) interfaces of said data carrier.

20. Use according to claim 19, in which the user is identified as a function of the coded data exchanged between the remote central station (13) and the central unit (7) of the data medium, to secure a remote operation. .

21. Use according to claim 20, for securing a remote payment transaction.

22. Use of a secure data medium according to any one of claims 1 to 14, in which the electronic security device (6) has in memory an account of value units, and the central unit (7) said security device is adapted to vary said account of value units as a function of coded data received and transmitted by the central unit (7) via the reception (10) and transmission (11; 15.16).

23. Use of a secure data medium according to any one of claims l to 14, in which the electronic security device (6) has in memory at least one counter of use units, and the central unit (7) of said securing device is adapted to vary said counter as a function of the movements of the data medium detected by the movement sensor (10).

24. Use according to claim 23, in which the counter of usage units is read by an external reader (22), by means of a communication interface (21) belonging to said security device (6).