Performing cryptographic data processing operations in a manner resistant to external monitoring attacks

A method, comprising:

• executing, by a processing device, a sequence of data load instructions modifying an architecturally-invisible register of the processing device, wherein modifying the architecturally-invisible register affects electric current flows in the processing device, and wherein a certain data load instruction of the sequence loads secret data;
• and
• protecting the processing device from a differential power analysis (DPA) attack by breaking a DPA-detectable interaction of two or more data load instructions of the sequence by executing, within the sequence, a first data load instruction to load a first data item and a second data load instruction to load a second data item, wherein the first data item is provided by one of:
• a first secret data item or a first constant data item, and wherein the second data item is provided by one of:
• a second secret data item or a second constant data item, wherein the third data manipulation instruction produces a random value of the architecturally-invisible register.

A computer-readable non-transitory storage medium comprising executable instructions that, when executed by a computing device, cause the computing device to perform operations, comprising:

• executing, by a processing device, a first data manipulation instruction, the first data manipulation instruction modifying an architecturally-invisible register of the processing device, wherein modifying the architecturally-invisible register affects electric current flows within the processing device;
• executing a second data manipulation instruction, the second data manipulation instruction interacting with the architecturally-invisible register;
• and
• protecting the processing device from a differential power analysis (DPA) attack by breaking a DPA-detectable interaction of the first data manipulation instruction and the second data manipulation instruction by executing a third data manipulation instruction with an input comprising an unpredictable data item, wherein the third data manipulation instruction produces a random value of the architecturally-invisible register.