Title of Invention

METHOD AND DEVICE FOR PROTECTING DIGITAL DATA STORED IN A MEMORY

Abstract The invention concerns a method for protecting digital data stored in a memory (4) and previously encrypted with an encryption key. The inventive method is characterized in that said encryption key is dynamically defined on the basis of at least one operating parameter intrinsic to said smart card.
Full Text



CLAIMS
1. Method for protecting digital data stored in a memory (4) of a chip card and previously encrypted using a ciphering key, characterised in that said ciphering key is dynamically defined as a function of at least an operating parameter intrinsic to said chip card.
2. Method according to claim 1, characterised in that said encrypted digital data are digital keys for cryptographic coding of EMM and ECM messages.

3. Method according to claim 1 or 2, characterised in that said operating parameter intrinsic to the chip card is generated by a function generator integrated in the chip card.
4. Method according to claim 1, characterised in that said operating parameter is intrinsic to the memory of the chip card.
5. Method according to claim 4, characterised in that it comprises the following steps :
• during the phase of writing data into the memory
(4),
a- deriving an analogue signal from an analogue voltage (18) for writing in the memory (4),
b- converting this signal into a digital sequence S,
c- ciphering the data to be stored by means of said digital sequence S,
d- storing the ciphered data into the memory (4),
• and during a later phase of reading the stored
data,
- re-computing the ciphering key defined in the steps a and b of the phase of writing and
- decrypting the data by means of the re-computed key.

6. Method according to claim 5, characterised in that the analogue writing voltage (18) is provided by a charge pump (12).
7. Device for protecting digital data stored in a memory (4) of a chip card and previously encrypted using a ciphering key, characterised in that it comprises a computing module (10) to define the key for ciphering said data as a function of at least an operating parameter intrinsic to said chip card.
8. Device according to claim 1, characterised in that said digital data are digital keys for cryptographic coding of EMM and ECM messages.

9. Device according to claim 7, characterised in that said operating parameter intrinsic to the chip card is generated by a function generator integrated in the chip card.
10. Device according to claim 9, characterised in that said operating parameter is intrinsic to the memory of the chip card.
11. Device according to claim 10, characterised in that said ciphering key is computed from an analogue voltage (18) for writing of data into the memory of the chip card.
12. Device according to claim 11, characterised in that said analogue writing voltage is provided by a charge pump.
13. Device according to claims 7 and 11, characterised in that the computing module (10) extracts an analogue signal from said voltage (18) and converts this analoge signal into a digital sequence to form the ciphering key.

14. Device according to claim 13, characterized in that the computing module (10) comprises an analogue/digital converter (14).
15♦ Access control card comprising a central unit for data processing, at least a memory for storing data, a module (6) for ciphering said digital data and a module for computing (10) of at least one key for ciphering said data, characterised in that said computing module (10) comprises means to define the ciphering key as a function of at least an operating parameter intrinsic to said memory (4) , and means to dynamically re-compute said ciphering key at each reading of the stored data.
16- Access control card according to claim 15, characterised in that the analogue voltage is provided by a voltage generator independent from the charge pump.
17. Access control card according to claim 15, characterised in that the computing module (10) is functionally independent from the central unit (2) in order that the computing of the ciphering key is not supervised by the central processing unit (2) .
18- Chip card according to claim 17, characterised in that the computing module (10) comprises a charge pump (12) to provide an analogue voltage (18) for writing data into the chip card, an analogue-digital converter (14) to convert an analogue signal extracted from said analogue voltage (18) into a digital sequence S forming the ciphering key.
19. Chip card according to claim 18, characterised in that the computing module (10) comprises an analogue function generator to provide an analogue voltage, an analogue-digital converter (14) to convert said analogue voltage into a digital sequence (S) forming the ciphering key.

20. Chip card according to claim 19, characterised in that it comprises a digital circuit independent of the central unit (2) to generate the digital sequence (S) .
21. Chip card according to claim 15, characterised in that the cipheri -J--■»---!- "-) ^g a logic circuit,
22. Chip card according to one of the claims 15 to 21, characterised in that the memory (4) is of the EEPROM type.
23- Chip card according to claim 22, characterised in that the memory (4) is of the flash type-

with reference to the accompanying drawings. 25. A chip card substantially as herein described with reference to the accompanying drawings.


Documents:

2245-CHENP-2004 AMANDED CLAIMS 25-03-2010.pdf

2245-CHENP-2004 AMANDED PAGES OF SPECIFICATION 25-03-2010.pdf

2245-CHENP-2004 CORRESPONDENCE OTHERS 25-03-2010.pdf

2245-CHENP-2004 FORM-1 25-03-2010.pdf

2245-CHENP-2004 FORM-3 25-03-2010.pdf

2245-CHENP-2004 OTHER PATENT DOCUMENT 25-03-2010.pdf

2245-CHENP-2004 POWER OF ATTORNEY 25-03-2010.pdf

2245-CHENP-2004 EXAMINATION REPORT REPLY RECIEVED 28-08-2009.pdf

2245-CHENP-2004 PCT SEARCH REPORT 28-08-2009.pdf

2245-chenp-2004 power of attorney 30-04-2010.pdf

2245-chenp-2004-claims.pdf

2245-chenp-2004-correspondnece-others.pdf

2245-chenp-2004-correspondnece-po.pdf

2245-chenp-2004-description(complete).pdf

2245-chenp-2004-drawings.pdf

2245-chenp-2004-form 1.pdf

2245-chenp-2004-form 26.pdf

2245-chenp-2004-form 3.pdf

2245-chenp-2004-form 5.pdf

2245-chenp-2004-pct.pdf


Patent Number 244193
Indian Patent Application Number 2245/CHENP/2004
PG Journal Number 48/2010
Publication Date 26-Nov-2010
Grant Date 23-Nov-2010
Date of Filing 06-Oct-2004
Name of Patentee NAGRA THOMSON LICENSING
Applicant Address 46 QUAY ALPHONSE LE GALLO-92110 BOULOGUNE BILLAMCOURT FRANCE
Inventors:
# Inventor's Name Inventor's Address
1 DAUVOIS, JEAN-LUC 19, RUE EUGENE MANUEL, F-75116 PARIS, FRANCE ; FRENCH
PCT International Classification Number G06F1/00
PCT International Application Number PCT/FR03/01024
PCT International Filing date 2003-04-02
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 02/04321 2002-04-08 France