METHOD FOR APPLYING A HIGH ENTROPY MASKING COUNTERMEASURE IN A BLOCK ENCRYPTION ALGORITHM, AND A LOGIC INTEGRATED CIRCUIT IMPLEMENTING SUCH A METHOD

摘要

A method for applying a high entropy masking countermeasure in a block encryption algorithm, and a logic integrated circuit implementing such a method. The invention relates to a block encryption algorithm based encryption method implementing a masking countermeasure and comprising a step of non-linear substitution of the elements of the State matrix. According to the invention, this method comprises for each encryption of the block: - a precalculation step, during which several independent and masked substitution tables are generated in parallel, and - during the non-linear substitution step, the elements of the State matrix are substituted by elements from said independent and masked substitution tables.