An apparatus for calculating a representation of a result operand of the non-linear logical operation between a first operand and a second operand includes a first logic gate and a second logic gate. Each operand is represented by two auxiliary operands, which, when linearly combined together result in the respective operand. The first and second logic gates are designed such that an average energy consumption of the first or second logic gate is substantially equal to a plurality of combinations of auxiliary operands at the beginning of a first operation cycle and auxiliary operands at the beginning of a second operating cycle, the average energy being derivable from a plurality of different orders of occurrences of the first to fourth auxiliary operands.