Apparatus and method for enacting data security in a data storage device, such as by protecting against a differential power analysis (DPA) attack. In some embodiments, a programmable processor executes programming in a memory to perform a cryptographic function upon user data associated with a host command received from a host device. The cryptographic function involves multiple logical computations to arrive at an output value responsive to an input value over a time interval. During the time interval, the programmable processor is repetitively interrupted by a plurality of interrupt calls respectively selected responsive to a first series of random numbers and resumes operation by a corresponding plurality of function return calls respectively selected responsive to a second series of random numbers. Each of the interrupt calls causes the programmable processor to temporarily suspend the multiple logical computations and perform at least one non-cryptographic function.