Method and device to guarantee the integrity and authenticity of a set of data

Abstract

Method and a device for guaranteeing the integrity and authenticity of data transmitted between a management center and one or several receiver units, wherein each receiver unit comprises a decoder (IRD) and a security unit (SC) and means for communicating (NET, REC) with the management center. The method consists in calculating a check information (Hx) representative of the result of a unidirectional and collision-free function, performed on all or part of the transmitted data and in transmitting the result to the management center for verification. The center will be able to inform the decoder concerning the authenticity of the data through return channels or through the main channel.

1 - 26 . (canceled)  
   
   
       27 - 42 . (canceled)  
   
   
       43 . A method to check the integrity and the authenticity of a set of data (M 1  to Mn) memorized inside a data storage unit connected with a security unit (SC) including the following steps: 
 transmission from the storage unit to the security unit (SC) of the control data (R 1 ) including ciphered reference check information k 1 (Hy) representative of the result of a mono-directional and collision-free function, carried out on all or only a part of the data (M 1  to Mn);    calculation of check information (Hx) which is representative of the result of a mono-directional and collision-free function, carried out on all or only a part of the data (M 1  to Mn);    comparison of the calculated value (Hx) with the deciphered reference value (Hy) by the security unit (SC) and transfer of the management data (R 2 ) including the result of the comparison to the storage unit.    
   
   
       44 . A method according to  claim 43 , characterized by the fact that the calculation is carried out by the storage unit, with the result of the calculation (Hx) being transmitted to the security unit (SC).  
   
   
       45 . A method according to  claim 43 , characterized by the fact that the calculation is carried out by the security unit (SC), with the data (M 1  to Mn) being transmitted from the storage unit to the security unit (SC).  
   
   
       46 . A method according to claims  44  or  45 , characterized by the fact that the control data (R 1 ) includes a utilization describer (D) for the data (M 1  to Mn), and if the result of the comparison is positive, sends the utilization describer (D) back to the storage unit in a deciphered form, to process the data (M 1  to Mn) by the storage unit according to the guidelines contained in the describer (D).  
   
   
       47 . A method according to  claim 43 , characterized by the fact that the control data (R 1 ) includes a certificate that certifies the broadcaster of the data (M 1  to Mn).  
   
   
       48 . A method according to  claim 43 , characterized by the fact that it consists of calculating periodically, or when requested, the values (Hx) representative of the result of a so-called mono-directional and collision-free function, carried out on all or only a part of the data (M 1  to Mm), with the security unit (SC) comparing the result (Hx) with the reference value (Hy).  
   
   
       49 . A method according to  claim 43 , characterized by the fact that it consists of: 
 storing the data (M 1  to Mn) in a ciphered form;    transmitting to the security unit (SC) in the control data (R 1 ) of a deciphering key (k 3 ) for the data (M 1  to Mn).    if the result of the comparison Hx=Hy is positive, deciphering of the data (M 1  to Mn) with the use of the cipher-key (k 3 ).    
   
   
       50 . A method according to  claim 49 , characterized by the fact that the deciphering operation of the data (M 1  to Mn) is carried out by the storage unit, the deciphering key (k 3 ) being transmitted by the security unit (SC).  
   
   
       51 . A method according to  claim 49  characterized by the fact that the deciphering operation of the data (M 1  to Mn) is carried out by the security unit (SC), the data (M 1  to Mn) being transmitted from the storage unit to the security unit (SC).  
   
   
       52 . A method according to  claim 49  characterized by the fact that it includes, inside the control data (R 1 ), a utilization describer (D) for the data (M 1  to Mn), to decipher the control data (R 1 ) and transmit the describer (D) to the storage unit if the result of the comparison is positive, to process the data (M 1  to Mn) by the storage unit according to the guidelines contained in the describer (D).