Cryptographic processing apparatus

摘要

According to an embodiment, a cryptographic processing apparatus performs processes to encrypt plain text or decrypt cipher text. The processes include a non-linear process using multiplication. The non-linear process is a process performed using intermediate data masked with mask data. The intermediate data is data in a middle of the plurality of processes. The mask data hides the intermediate data. The apparatus includes a non-linear processing unit configured to receive first data that is an exclusive OR of a product of the intermediate data and first mask data and second mask data, and output second data that is an exclusive OR of a product of data obtained by the non-linear process on the intermediate data and data obtained by the non-linear process on the first mask data and third mask data having a predetermined correspondence relation with the second mask data.

主权项

1. A cryptographic processing apparatus for performing a plurality of processes to encrypt plain text or decrypt cipher text, the plurality of processes including a non-linear process using multiplication, wherein the non-linear process is a process performed using intermediate data masked with mask data, the intermediate data being data in a middle of the plurality of processes, the mask data hiding the intermediate data, the apparatus comprising:
a hardware processor including
a non-linear processing unit configured to
receive first data that is an exclusive OR of A and B, where A is a product of the intermediate data and first mask data and B is second mask data, the first mask data being a random number or a value based on the random number,perform the non-linear process, which is one of the plurality of processes to encrypt plain text or decrypt cipher text, on the first data to generate second data that is an exclusive OR of C and D, where C is a product of data obtained by the non-linear process on the intermediate data and data obtained by the non-linear process on the first mask data and D is third mask data having a predetermined correspondence relation with the second mask data, andoutput the second data.