Abstract: The method of protection of a microcircuit against an attack includes: a step (205) of determining if an attack has been detected, if an attack has been detected, a step (210, 510) of executing a protection function, and if no attack has been detected, a step (215, 515) of executing a decoy function simulating the protection function and perceptible from outside the microcircuit in a manner substantially identical to the protection function. In some embodiments the decoy function has a power consumption substantially identical to that of the protection function, the protection function effects a step of writing predetermined data at a first address of a non-volatile memory, and the decoy function effects a step of writing in non-volatile memory at a second address different from the first address.