Information processing device and information processing method

An information processing device, comprising:

• a calculation circuit that includes a first calculation circuit and a second calculation circuit;
• a control circuit;
• a counter circuit;
• and
• a comparison circuit, wherein
• the control circuit executes;
• processing a plurality of bits constituting confidential information one after another, each of the bits being a processing target bit;
• causing the calculation circuit to execute a first calculation by the first calculation circuit and a second calculation by the second calculation circuit when the processing target bit has a logic value of “1”;
• and
• causing the calculation circuit to execute only the second calculation of the first calculation and the second calculation when the processing target bit has a logic value of “0”,
• the counter circuit outputs a counter value based on the number of processing target bits subjected to only the second calculation of the first calculation and the second calculation by the calculation circuit, and
• the comparison circuit compares the counter value with an expected value for the counter value based on the confidential information.