Abstract: The subject of the disclosed technology is shown in the following. In the information processing device such as an IC card the overflow processing which occurs in the case of a modular multiplication operation to be performed during crypto-processing inside shows a particular pattern of a consumption current. It is the subject of the present invention to decrease the relationship between data processing and the pattern of the consumption current.

Abstract: The disclosed techniques are as shown below. The subject of the invention is to provide a crypto-processing method capable to confront an attack, which intentionally causes an erroneous operation and takes out secret information to be done against a device which performs a crypto-processing inside the device such as an IC card.

Abstract: An IC card having a storage memory including a program storage unit for storing a program and a data storage unit for storing data and a central processing unit for executing a predetermined process in accordance with the program to process the data, the program including one or more data process units each having a process instruction for giving an execution instruction to the central processing unit, wherein a data process order is randomly exchanged and a dummy process is added to thereby reduce the dependency of consumption current of an IC chip upon the data process.