Apparatus and method for protecting a reference number against differential power analysis attacks and template attacks

摘要

An apparatus for calculating a result of scalar multiplying a reference number by a reference point on an elliptic curve comprises a random number generator and a processor. The random number generator generates a random bit, and the processor calculates the result of the scalar multiplication based on a calculation algorithm using a first auxiliary variable storing a first intermediate result representing an integer multiple of the reference point or an integer multiple of the reference point, and a second auxiliary variable which stores a second intermediate result representing another integer multiple of the reference point or a coordinate of another integer multiple of the reference point. Further, the processor interchanges a value stored by the first auxiliary variable and a value stored by the second auxiliary variable during the calculation of the result of the scalar multiplication when an interchangeable condition dependent on the generated random bit is satisfied.