A method for protecting an operation sequence executed by a portable data carrier from spying out, wherein the data carrier has at least a processor core, a main memory and a cache memory with a plurality of cache lines. The processor core is able to access, upon executing the operation sequence, at least two data values, with the data values occupying at least one cache line in the cache memory and being respectively divided into several portions so that the occurrence of a cache miss or a cache hit is independent of which data value is accessed. A computer program product and a device have corresponding features. The invention serves to thwart attacks based on an evaluation of the cache accesses during the execution of the operation sequence.