Method for protecting confidentiality of a file distributed and stored at a plurality of storage service providers

摘要

This method comprises the steps of: —choosing (1) a security parameter n,—segmenting (2) the file in n chunks S1, . . . , Sn, —randomly choosing (3) n² coefficients a_ij for i=1, . . . , n and j=1, . . . , n,—verifying (3) that the vectors a_i1, . . . , a_in, for i=1, . . . , n, are linearly independent, otherwise generating the coefficients again, —computing (4) n linear combinations Ci=a_i1S₁+ . . . +a_ijS_j+ . . . +a_in·S_n, for i=1, n,—choosing (5) n storage service providers O_i, . . . , O_n among said plurality of storage service provider, —generating (6a; 6b; 6c) n file identifiers ID′₁, . . . , ID′_n designating said file (F),—storing (6a; 6b; 6c) the combination Ci at the storage service provider O_i in association with the file identifier ID′_i, for i=1, . . . , n,—storing the file identifier ID′_i and the provider identifier O_i, for i=1, . . . , n, in a file descriptor corresponding to the file (F), this file descriptor being stored in a local memory (LM),—storing the set of coefficients a_i,1, . . . , a_in so that it can be re-associated with the combination C_i, for i=1, n;—randomly choosing n super-coefficients a′₁, . . . , a′_j, . . . , a′_n for j=1, . . . , n,—computing a linear over-combination OC′=a′₁-C₁+ . . . +a′_j·C_j+ . . . +a′_n·C_n,—and storing the over-combination OC′ and the coefficients a′₁, . . . , a′_j, . . . , a′_n for j=1, . . . , n.