(EN) In a system 300, a server 310 provides a cryptographic function F to an execution device in an obfuscated form. The function F composes output of a plurality of the mapping tables Ti (0< i< n; n>l) using an Abelian group operator x, A processor 312 chooses tables O and C such that C [x] x 0[x] = O, Vx ± Di and creates tables "T1 0< i
