BLOCK CIPHER USING KEY DATA MERGED WITH AN INTERMEDIATE BLOCK GENERATED FROM A PREVIOUS BLOCK

A cryptographic processing apparatus for performing cryptographic processing using input data to generate output data is provided. The cryptographic processing apparatus includes a storage unit for storing chain data which is used for reflecting present cryptographic processing on next cryptographic processing, and for renewing the chain data each time cryptographic processing is performed, a merging unit for merging the chain data stored in the storage unit with the input data to generate merged data, and a main cryptographic processing unit for performing main cryptographic processing using the merged data to generate output data and for outputting intermediate data generated during a generation of the output data, wherein the storage unit renews the chain data by storing the intermediate data outputted by the main cryptographic processing unit as the new chain data, which is used for the next cryptographic processing.