METHOD AND SYSTEM FOR OBFUSCATING A CRYPTOGRAPHIC FUNCTION

摘要

Embodiments include a system, wherein a server 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≧1) using an Abelian group operator. A processor chooses tables O and C such that C[x] O[x]=0, x Di and creates tables T′i, 0≦̸i≦̸m; n≦̸m≦̸n+1, where for 0≦̸i≦̸n, each Table T′i represents the respective corresponding table Ti and at least one table T′o1, 0≦̸o1≦̸n, being formed through an Abelian composition of To1 and O, and at least one table T′c1, 0≦̸c1≦̸m, c1≠oj; being formed through an Abelian composition that includes C.