DEVICE AND METHOD FOR CIPHERING, DEVICE AND METHOD FOR DECIPHERING, AND ARITHMETIC OPERATION DEVICE

摘要

PROBLEM TO BE SOLVED: To provide an ciphering device permitting highly uniform dispersion with a calculation cost suppressed. SOLUTION: Small local spreading is operated by each of non-linear converter modules 2 which are plurally arranged in parallel in each stage; following this, a large spreading over a block width is operated by a spread module 3; small and local spreading is operated by the non-linear converter modules 2 again; and this operation is repeated by the prescribed number of stages. Further, the non-linear converter modules 2 are configured of an alternate arrangement of the non-linear converter modules 4 and the spreading modules 5. Namely, a small SPN structure is recursively buried in an S-box part of an ordinary SPN structure into this nesting SPN structure.