A sheet post-process apparatus includes a waiting tray and a processing tray. In one example, the removable cover is movable relative to the rooftop without requiring removal of the entire cover. With a configuration in which round keys are permuted or F-functions are permuted in the decryption processing, processing using a common function can be performed by setting swap functions for the encryption processing and the decryption processing to have the same processing style. The building block thus generated is substituted back into the algorithmic description and used in subsequent operations during the behavioral synthesis process, thereby leading to a more optimum design in terms of area, performance, power characteristics, or other characteristic.