A METHOD FOR PROTECTING A SUBSTITUTION OPERATION USING A SUBSTITUTION TABLE AGAINST A SIDE-CHANNEL ANALYSIS

摘要

The invention relates to a method for executing by a circuit a substitution operation whereby an output data is selected in a substitution table using an input data as an index, wherein the substitution operation is performed using a new masked substitution table, the input data being combined by XOR operations with a new value of a first mask parameter, and the output data being combined by XOR operations with a new value of a second mask parameter, the new masked substitution table being generated by computing the new value of the first mask parameter by applying XOR operations to a previous value of the first mask parameter and to a first input mask; computing the new value of the second mask parameter by applying XOR operations to a previous value of the second mask parameter and to a second input mask, and generating the new masked substitution table using a previous masked substitution table and the first and second input masks.