Method and system for confidentially processing information registered on a portable carrier recording track with optical reading.

The present invention generally relates to improvements to portable media such as maps, and more particularly to a method and system for processing confidential information stored on a machine readable recording track of a portable media .

to magnetic recording strip cards are well known and widely used in many applications, especially consumer. These cards, however, have limited opportunities because they can not handle themselves the information they passively support.

To increase the possibilities of these cards, we turned to the technique of integrated circuits including in the cards processing circuits, including a microprocessor to process information internally and to ensure exchange of information with an apparatus operation which the card is temporarily coupled. Such a map is described in particular in French Patent No. 2,337,381 of the applicant. The card also includes a ROM of the ROM type or PROM which stores or prerecorded information to process and programs that drive the microprocessor. Generally, this memory replaces the magnetic strip, but the co-existence of these two types of memory is entirely possible.

A microprocessor card has two important advantages. The first advantage is the possibility of internal processing by the CPU and the second benefit is an increase in the storage capacity offered by the ROM compared to a memory constituted by a piece of tape.

The development of cards, including credit cards, required the confidentiality of certain information to counter the fraud. This problem is solved in microprocessor cards, particularly in the French Patent No. 2,401,459 of the applicant where a ROM contains at least an area inaccessible from outside read / write, only the microprocessor having access to this area containing confidential or secret information.

Given the cost of microcircuits, the ability ROMs used is limited. In addition, we must not forget that an important part of this memory is used to store en- most current information specific applications envisaged programs, which limits the memory available for the current management.

To increase low-cost storage capacity of a card, it was made use of optical recording media. If the evidence storage capacity is greatly increased, the information recorded on optical tracks are readable at any time from the outside, that is to say they can not keep any confidential vis-à -vis any person in possession of the card. Such a card is particularly described in US Patent No. 4,360,728.

The invention aims to overcome this drawback by considering an optical stripe card to increase storage capacity and microprocessor to treat confidentially all or only part of the information to be written on the optical track. in that the track is a magneto-optical track (13) in perpendicular recording.

9. Support tool according to claim 7 or 8, characterized in that the memory (12) contains at least one secret encryption key (KC) and decryption stored in a region (12A1) of the inaccessible memory from the outside.

10. portable medium according to one of Claims 7 to 9, characterized in that it also includes a magnetic stripe (14).

11. A system for processing information on an optical readable record track (13) of a portable medium (1) such as a card of the type comprising a treatment device (2) which is temporarily coupled to the support ( l), characterized in that the carrier (1) comprises at least one electronic memory (12) including at least one memory area (12A1) is inaccessible from the outside and in which is recorded at least a key encryption / decryption secret (KC), processing circuitry (11) such as a microprocessor with said key to encrypt the information to be written on the optical track (13) and to decrypt with said key information recorded on the optical track (13), and in that the processing device (2) comprises at least one optical device for reading information stored on the optical track (13), an information writing device (23) on the optical track (13) and a device transfer information (22) between the optical track (13) and the processing circuits (11) of the support (1).

12. The system of claim 11, characterized in that the writing device (23) is an optical laser device.

13. The system of claim 11, characterized in that the optically readable track (13) is a magneto-optical track.

14. The system of claim 11 or 13, characterized in that the writing device (23) is a magnetic device by laser.

15. The system of claim 11 or 13, characterized in that the writing device (23) is a magnetic device with perpendicular recording.

The device (22) is connected:<ul><li>- The keyboard (21) by a connection (b20), and</li><li>- The write / read devices (23, 24) and the display unit (25) by a bus (b21).</li></ul>

The card (1) is temporarily coupled to the terminal (2) by an interface (C) for example series as described in the French patent application No. 2483713 of the Applicant. This interface (C) is connected to the microprocessor (11) by a link (bll) and the device (22) by a connection (b22).

The terminal (2) can be connected to another terminal (not shown) by a transmission line (L) vector.

Under the name "terminal" shall mean generally any apparatus that is capable of processing data, transfer data and perform write / read operations in any medium such as a magnetic carrier , optics, paper ....

Let the information or data (D) to write on the optical path (13) of the card (1). These data (D), for example in plain, entered the keyboard (21) or reached by the transmission line (L).

These data are received in the transfer device (22) having a function of routing in the card (1) for temporary storage in the memory area (12B) of the memory (12) of the card (1 ). It is possible, depending on the applications envisaged, that these data (D) are pretreated with the transfer device (22).

Confidential or secret information is prerecorded in the secret memory area (12A1) of the card (1). This information comprises for example by:<ul><li>- An encryption key (KC),</li><li>- An encryption algorithm stored as a program (P) to encrypt data from the key (KC)</li><li>- A secret code (S) unknown to the cardholder, and</li><li>- An identification code (IN) (PIN-NUMBER in English) known to the card holder.</li></ul>

The data (D) stored in the memory area (12B) of the card (1) is encrypted following the execution of the program (P) by the microprocessor (11). This program (P) performs data encryption (D) from the encryption key (KC). The data (D), once encrypted, are transmitted by the transfer device (22) of the terminal (2), the write / read device (23) whose function is to record on the optical track (13) of the card (1) in a per se known manner by conventional techniques.

These encrypted data stored on the optical path (13) are readable by any suitable device, but they remain unusable the moment we do not know the key that allowed to encrypt data.

These data will be even more unusable the key (KC) encryption is not accessible from the outside as recorded in the protected area (12A1) of memory (12) of the card (1).

Conversely, the encrypted data stored on the optical path (13) can be read by the device (23). The read data are then again transmitted in the card (1) to be decrypted by the processing circuits (11) using a decryption key for example identical to the encryption key (KC). Once the data decrypted by the card (1), they are broadcast clear to the terminal (2) for exploitation. This operation may be a display on the unit (25) or a transmission to another terminal via the transmission line (L).

As stated earlier, it is already known a writing device / laser optical reading according to patent No. 4 360 728. The material constituting the optical track must be temperature sensitive reflector for writing and for reading.

The invention provides a variant which consists in using a magneto-optical track consisting for example garnet (Fe-TR) (SI: rare earth such as Fe-GB, Fe-TB).

These magneto-optical tracks are scanned and they essentially differ from the slopes optical writing by a magnetic writing or by laser or by a conventional magnetic method.

The laser writing mode is a mode of thermo-magnetic writing of using the thermal effect due to the impact of a laser electromagnetic radiation beam on the magnetic material constituting the electro-optical track. This radiation is such that the surface of the magneto-optical track on which focused the laser beam undergoes heating such that the temperature of the magnetic layer at this point becomes higher than the Curie temperature of the magnetic material, temperature at which it loses its magnetization. If this place is subjected to a magnetic field whose direction is opposite to the magnetization in the magnetic layer on cooling of the magnetic material (the beam is removed), the magnetic material will then take a magnetization direction opposite to magnetization of the remainder of the magnetic layer.

Another mode of usable magnetic writing can be perpendicular to the record type.

Under these conditions, the write / read device (23) can be:<ul><li>- An optical scanning device and optical laser writing,</li><li>- An optical reading device for laser and conventional magnetic writing, including perpendicular recording, or</li><li>- An optical reading device and magnetic writing laser.</li></ul>

Finally, it should be noted that the reading mode information recorded on a magneto-optical layer based on the principle of interaction of polarized light with the magnetic state of the layer interaction which results in the rotation of the vector field power in the plane perpendicular to the direction of propagation of the laser beam.

This detection is done either by "Kerr effect", using a reflection phenomenon, or by "Faraday effect" where the laser beam passes through the magneto-optical layer). Advantageously, to improve the reading, one may use the combination of the two above effects. It is not necessary to further describe these well-known effects of skill in the art.

Of course, encryption algorithms will be more or less sophisticated depending on the degree of security desired and the decryption key is not necessarily identical to the encryption key as in the case of public key algorithms.

The secret nature of the encryption algorithm is based on the type of the chosen algorithm, so it can be stored in the memory area (12A3) accessible from the outside especially in the case of a key algorithm where only the public decryption key must remain secret.

It is important that encryption is done inside the card and not in the terminal where it is not possible -.de ensure one hundred percent of the secret information such as encryption / decryption key. According to the invention, the terminal that should be accessible to the public is completely trivialized since it contains in itself no infor confidential training.

Finally, in a simplified embodiment of the invention, the encryption / decryption key may simply be constituted by the secret (S). In a more complex embodiment, the encryption algorithm may consider an encryption key (KC) different secret or not secret (S) and an additional secret key (SI) prerecorded in the memory area (12A2) . This key (SI) is only accessible by the microprocessor only if an identification code (IN) type on the keyboard (21) of the terminal (2) is identical to the identification code (IN) prerecorded in the memory area (12A1) of the card (1).