Systems and methods for performing cryptographic data processing operations in a manner resistant to external monitoring attacks. An example method may comprise: executing, by a processing device, a first data manipulation instruction, the first data manipulation instruction affecting an internal state of the processing device; executing a second data manipulation instruction, the second data manipulation instruction interacting with said internal state; and breaking a detectable interaction of the first data manipulation instruction and the second data manipulation instruction by executing a third data manipulation instruction utilizing an unpredictable data item.