Security controller and method for processing data elements of a data array

A method for processing data elements of a data array stored in a memory of a security controller, wherein the data array has a number of data elements given by a length of the data array, the method comprising:

• determining a power of two such that number of data elements is higher than the power of two but at most equal to double the power of two;
• determining a random first integer;
• determining a random second integer;
• changing indices of a predefined sequence of indices between zero and the length of the data array minus one, wherein changing an index comprises:
• performing a first change of the index if the index is lower than the power of two, wherein the first change comprises changing the index according to a first permutation of non-negative numbers smaller than the power of two and wherein the first permutation depends on the random first integer;
• performing a second change of the index, wherein the second change comprises adding a third integer to the index modulo data array length;
• and
• performing a third change of the index if the index, following the second change, is lower than the power of two, wherein the third change comprises changing the index according to a second permutation of non-negative numbers smaller than the power of two and wherein the second permutation depends on the random second integer;
• and
• processing the data elements in an order given by the changed indices.