1. A method of operating a data-processing device with an integrated circuit comprising two or more processors in which the integrated circuit performs cryptographic operations, the method comprising: performing cryptographic operations in the integrated circuit, wherein at least two processors perform the cryptographic operations simultaneously and in parallel, wherein the cryptographic operations of at least one processor are useful operations and the cryptographic operations performed by at least one other processor are dummy operations whose results are rejected, and wherein the selection as to which of the two or more processors performs a useful operation is randomly controlled, and wherein consumption characteristics of the data-processing device being a superimposition of consumption characteristics associated with performing both useful and rejected cryptographic operations, whereby reconstruction of the consumption characteristics associated with performing any of the useful cryptographic operations is impeded.