Method for protecting a digital rights file description

1. Method of protecting a file containing a file containing data stored digitally in a memory of a terminal, the terminal having a processor and a right processing module, a right check module, a security processor, a multimedia reader and a non-secure memory area for storing at least one data file comprising a plurality of right descriptions D i (i=1 . . . N, where N is an integer number), each right D i defining use by a terminal of at least one resource and/or digital content among a plurality of resources and/or digital contents RC j (j=1 . . . M, where M is an integer number), and with each description of a given right D i comprising, an identifier of said right D i an identifier of each resource and/or content RC, the use of which is defined by said right D i conditions for use of said resources and/or said contents by the terminal, the method comprising the following steps:

storing, by the terminal processor, said rights descriptions in the terminal;

generating, by the terminal processor, a data structure (Id_RC j ,Id_D i ) for each resource and/or content RC, which comprises the identifier of said resource and/or said content;

defining, by the terminal processor, the use of said content RCj by the identifier of each right Di;

generating, by the terminal processor, each (Id_RC j , Id_D i ) data structure;

transferring, by the terminal processor, each (Id_RC j , Id_D i ) data structure generated into a secure memory area in said terminal;

calculating, by the terminal processor, a cryptographic digest Cnd_D i of each description of a right D i ;

associating, by the terminal processor, an identifier Id_D i of the right D i with the identifier of the cryptographic digest Cnd_D i that generates a pair (Id_D i , Cnd D i );

associating, by the terminal processor, an identifier of at least one right D m with the identifier id RC k of said resource and/or content RC k in the secure memory area;

transferring, by the terminal processor, the generated pair (Id_D i , Cnd D i ) into said secure memory area;

transferring, by the terminal processor, a digest Cndc D m into in the secure memory area;

verifying, by the terminal processor, that the identifier of at least one right D m is associated with the identifier Id RC k of said resource and/or content RC k in the secure memory area;

verifying, by the terminal processor, that the description of the right D m corresponds to a requested use of the resource and/or content RC k ;

recalculating, using the security module a cryptographic digest Cndc_D m of the right D m stored in the terminal;

comparing, by the terminal processor, the recalculated digest Cndc_D m with the digest Cndc_D m preciously transferred in the secure memory area; and

descrambling, by the terminal processor, the resource and/or the content for which the recalculated cryptographic digest Cndc_D m is identical to the digest Cnd_D m memorized in the secure memory area.

2. Method according to claim 1 , in which said secure memory area is part of the memory in said terminal.

3. Method according to claim 1 , in which said secure memory area is part of a memory of a removable smart card.

4. Method according to claim 1 further characterized by performing a preliminary check phase that establishing that:

the identifier of at least one right D m is associated with the identifier id RC k of said resource and/or content RC k in the secure memory area, and

the description of the right D m corresponds to the requested use with the check phase also comprising the steps of recalculating a cryptographic digest Cndc_D m of the right D m stored in the terminal and comparing the digest Cndc_D m obtained with the digest Cnd_D m of the right D m previously transferred in the secure memory area.

5. Method according to claim 1 , in which the resource RC j is a computer function of the terminal.

6. Method according to claim 1 , in which the resource RC j is a peripheral device connected to the terminal.

7. Method according to claim 1 , in which the resource RC j is an unencrypted audiovisual or multimedia program.

8. Method according to claim 1 , in which the digital content RC j is an audiovisual or multimedia program encrypted by a secret key stored securely in the terminal.

9. Method according to claim 4 ,further characterized in that the digital content RC j is encrypted by a secret key stored securely in the terminal; and

determining, by the terminal processor, that the check phase establishes that the identifier of a right D m is associated with the identifier to said content RC k in the secure memory area, and the description of the right D m corresponds to the requested used; and

wherein the method is further characterized by authorizing use of the secret key when the recalculated cryptographic digest Cndc D m is identical to the digest Cnd D m memorized in that secure memory area, and the description of the right D m corresponds to the requested use.

10. Method according to claim 8 , further characterized in that the digital content RC j is encrypted by a secret key stored securely in the terminal.

11. Method according to claim 10 , further characterized by the step of authorizing access to the file when the identifier Id_D m of a right D m is associated with the identifier Id_RC k of said content RC K in the secure memory area, and the description of the right D m corresponds to the requested use.

12. Method according to claim 10 further characterized by the step of

determining, by the terminal processor, that the recalculated cryptographic digest Cndc D m is identical to the digest Cnd D m in the secure memory area;

based on determining, by the terminal processor that the recalculated cryptographic digest Cndc D m is identical to the digest Cnd D m in the secure memory area, authorizing access to the file.

13. Method according to claim 8 , in which said secret key is encrypted by a second key stored in the secure memory area.

14. Method according to claim 8 , in which said secret key is stored unencrypted in the secure memory area.

15. Method according to claim 14 , in which said secure memory area is part of the memory in said computer in the terminal.

16. Method according to claim 14 , in which said secure memory area is in a removable smart card.

17. Multimedia terminal that contains a right processing module, a right check module, a security processor, a multimedia reader and a non-secure memory area ( 4 ) that stores at least one data file containing a plurality of rights descriptions Di(i=1 . . . N) each defining the use of at least one resource and/or digital content among a plurality of resources and/or digital contents RC j (j=1 . . . M), each description of a given right D i comprising an identifier of said right D i , an identifier of each resource and/or content RC j for which use is defined by said right D i , and conditions for use of said resources and/or said contents, a secure memory area and a rights processing module and including:

a terminal processor;

memory containing stored instructions, when executed by the terminal processor cause the terminal processor to perform the steps of:

storing said rights descriptions in the terminal;

generating a data structure (Id_RC j , Id_D i ), for each resource and/or content RC, which comprises the identifies of said resource and/or said content;

defining the use of said content RCj by the identifier of each right Di;

generating each (id_RC j , Id —D i ) structure;

transferring each generated (Id_RC j , Id_D i ) structure into a secure memory area in said terminal;

calculating a cryptographic digest Cnd D i of each description of a right D i ;

associating an identifier Id_D i of th right D i with the identifier of the cryptographic digest Cnd_D i to generate a pair (Id_D i , Cnd_D i );

associating an identifier of at least one right D m with the identifier Id RC k of said resource and/or content RC k in the secure memory area;

transferring the generate pair (Id_D i , Cnd_D i ) in said secure memory area;

transferring a digest Cndc_D m into in the secure memory area;

verifying that the identifier of at least one right D m is associated with the identifier Id RC k of said resource and/or content RC k in the secure memory area;

verifying that the description of the right D m corresponds to a requested use of the resource and/or content RC k ;

recalculating, using the security module a cryptographic digest Cndc_D m of the right D m stored in the terminal;

comparing the recalculated digest Cndc_D m with the digest Cndc_D m previously transferred in the secure memory area; and

descrambling the resource and/or the content for which the recalculated

cryptographic digest Cndc_D m is identical to the digest Cnd_D m memorized in the secure memory area.

18. Terminal according to claim 17 , characterized in that said terminal includes a security processor and said secure memory area is stored in the security processor.

19. Terminal according to claim 17 , characterized in that said security processor is a removable smart card.

20. Terminal according to claim 17 , characterized in that said terminal consists of a mobile telephone.

21. Method according to claim 8 , further characterized by the step of:

determining, by the terminal processor, that the check phase establishes that the identifier of a right D m is associated with the identifier of said content RC k in the secure memory area, and that the description of the right D m corresponds to the requested used;

based on the determination that the the check phase establishes that the identifier of a right D m is associated with the identifier of said content RC k in the secure memory area, and that the description of the right D m corresponds to the requested use, authorizing use of the secret key.

22. Method according to claim 8 , further characterized by the step of:

determining that the cryptographic digest Cndc_D m is recalculated and determined to be identical to the digest Cnd_D m in the secure memory area, and the description of the right D m corresponds to the request use;

based on the determination that the cryptographic digest Cndc_D m is recalculated and determined to be identical to the digest Cnd_D m in the secure memory area, and the description of the right D m corresponds to the requested use, authorizing use of the secret key.

23. Method according to claim 7 ,further characterized by the step of

determining that the identifier Id_D m of a right D m is associated with the identifier Id_RC k of said content RC k in the secure memory area, and the description of the right D m corresponds to the requested use;

based on the determination that the identifier Id_D m of a right D m is associated with the identifier Id_RC k of said content RC k in the secure memory area, and the description of the right D m corresponds to the requested use, authorizing access to the file.

24. Method according to claim 7 , characterized by the step of authorizing access to the file when the cryptographic digest Cndc_D m is recalculated and determined to be identical to the digest Cndc_D m in the secure memory area, and the description of the right D m corresponds to the requested use.

25. Terminal according to claim 19 , characterized in that the terminal consists of a mobile telephone.