Method for Combined Key Value-Dependent Exchange and Randomization of Two Input Values

A method, in circuitry configured for cryptographic operations, for a combined key value-dependent exchange and randomization of a first input value and a second input value, comprising:

• determining, in the circuitry, at least two shares of a key value;
• determining, in the circuitry, at least one modification value that depends on at least one of the first input value and the second input value;
• determining, in the circuitry, for each share, an intermediary value that depends on the share and at least one of the at least one modification value, wherein at least one intermediary value further depends on a randomization value;
• and
• arithmetically assembling the intermediary values, in the circuitry, to generate an output value for at least one of the first input value and the second input value.