US Patent 7907722 Protection against power analysis attacks

An electronic circuit for cryptographic processing, comprising a first combinatorial logical circuit, arranged to perform a first set of logical operations on input data and to produce output data, the output data having a functional relation to the input data, further comprising at least a second combinatorial logical circuit, arranged to perform a second set of logical operations on the same input data and to produce output data, the output data having an identical functional relation to the input data, wherein the first set of logical operations is different from the second set of logical operations, and wherein the electronic circuit is arranged to dynamically select one combinatorial logical circuit, of a set comprising at least the first combinatorial logical circuit and the second combinatorial logical circuit, for performing logical operations on the input data and producing output data.