Encryption apparatus, the encryption method and encryption device computer-readable recording medium and decoding apparatus recording a program for causing a computer to function as a computer reads and records a program for causing a computer to function as a decoding method and a decoding apparatus a recording medium

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.;COPYRIGHT: (C)2001,JPO