Patent ID: 7802106

Claim:
A method for ensuring the integrity of a plurality of computer software programs carried out by means of at least one encryption/decryption module, the plurality of computer software programs being transmitted, by means of a transmitter, to a decoder which is equipped with the at least one encryption/decryption module by means of a long-distance information transmission network, the transmitter performing the steps comprising: a) a step ( 40 ) for encrypting information signals transmitted to the decoder, b) a step ( 50 ) for transmitting, to the at least one encryption/decryption module of the decoder, a message containing the information required for the decoder to decrypt the information signals transmitted at step a), and c) a step ( 42 , 100 ) for transmitting the plurality of computer software programs to the at least one encryption/decryption module of the decoder, the decoder carrying out: d) a step ( 74 ) for decrypting the information signals transmitted by the transmitter during step a) using the information provided for this purpose in the message transmitted during step b), e) a step for constructing a single identifier for the plurality of computer software programs to be transmitted during step c) based on information relating to each of the computer software programs of the plurality of computer software programs and in that the at least one encryption/decryption module carries out the same operation as that carried out during step e) in order to reconstruct a unique identifier corresponding to that constructed during step e) upon the plurality of computer software programs received by the decoder being identical to that transmitted by the transmitter, wherein, the transmitter inserts (at 52 , 124 ) in the message transmitted during step b) an additional item of information which allows the at least one encryption/decryption module to verify that it has effectively received each computer software program transmitted at step c), the at least one encryption/decryption module verifies (at 60 ), based on the additional information inserted by the transmitter in the message transmitted during step b), whether it has effectively received each computer software program of the plurality of computer software programs transmitted during step c), and upon each software program of the plurality of computer software programs having not been received, the at least one encryption/decryption module prevents step d) (at 68 ).