Patent ID: 8374340
Filing Date: 2013-02-12
Classification: H04L

Abstract:
1. A method for secure transmission of a file fragmentable into a plurality of fragments, where a processor performs the method in which: (a) a global encipherment key is fixed initially; (b) the fragmentable file is enciphered as a function of said global key to form a first encrypted file; (c) the global key is enciphered by the processor using an asymmetric encipherment algorithm to obtain an enciphered global key; (d) values representative of the enciphered global key are inserted among the fragments of said encrypted file to form a second encrypted file; and (e) said second encrypted file is transmitted, wherein, in step (b), for a succession of fragments: (b1) each current fragment is assigned a dynamic encryption key determined on the basis of a combination involving a group of previously encrypted fragments, wherein a linear combination is applied to the values of the previously encrypted fragments by the processor, the linear combination expressed by: where: (b2) the value of the current fragment is allocated a value which is dependent on its initial value and on said dynamic key.