ENCRYPTION DEVICE, DECRYPTION DEVICE, ENCRYPTION METHOD, AND INTEGRATED CIRCUIT

摘要

When a power analysis attack countermeasure employed for AES encryption is the masking method in which S-Box is mounted by using the inverse element calculation in a composite field, there arises a problem that the maximum number of logical stages becomes too large and the processing speed is lowered. An encryption device (1) for generating an encrypted text from a plain text by using a key includes a randomization 8-bit inverse element calculation unit (101) which receives: randomized input data obtained by adding a predetermined input mask value decided by a random number to input data subjected to a predetermined process by using the key,and the input mask value, so as to generate randomized output data by adding an output mask value as an inverse element of the input mask value to the inverse element of the input data. An encrypted text is generated from the randomized output data which has been generated.