| 主权项 |
1. A system for performing a secure sequence of n transformations Ψ_i, wherein i=1, . . . ,n, of a data value w_0, using encrypted representations of the data value, the system comprising
first transformation means for applying a transformation to an input data value w_0 to obtain an obfuscated representation (X_0,Y_0) of w_0, wherein the obfuscated representation (X_0,Y_0) contains a redundancy that depends on an input variable r; second transformation means for, for each of_i=1, . . . ,n−1, applying a transformation_u_i to compute (X_i,Y_i) from (X_(i-1),Y_(i-1)), such that (X_i,Y_i)=_u_i(X_(i-1),Y_(i-1)); third transformation means for applying a transformation G that depends on X_(n−1), Y_(n−1), and r, by computing w_n=G(X_(n−1),Y_(n−1),r), to obtain an outcome of the sequence of transformations, wherein w_n=Ψ_n ∘ . . . ∘ Ψ_1 (w_0); wherein (X_i,Y_i)=Ψ_i(w_i,σ_i), for i=0,1, . . . ,n, wherein Ψ_i is a predefined obfuscation function that defines a one-to-one relation between (X_i,Y_i) and (w_i,σ_i), and wherein Ψ_i satisfies a condition that there is a one-to-one mapping that maps any value of (X_i,σ_i) to a value of (w_i,Y_i) in such a way that (X_i,Y_i)=Ψ_i(w_i,σ_i); σ_0 depends on r; and wherein w_i=Ψ_i(w_(i-1)) and σ_i=g_i(σ_(i-1)) for i=1, . . . ,n, for predetermined functions Ψ_i and g_i, wherein the first transformation means, the second transformation means, and the third transformation means are configured to obfuscate the values of w_1, . . . ,w_(n−1) and σ_0, . . . σ_n. |
