| 摘要 |
PROBLEM TO BE SOLVED: To execute high-speed cipher processing and to assure the safety by determining the execution sequence of respective involution processing programs and the execution sequence of a substitution processing section and a transposition processing section accordance with the bit pattern of key data. SOLUTION: The encryption processing is divided into the process for forming data execution keys K1 to K8 from a data key 108 and a system key B 112 and a process for encrypting a plaintext by using these data execution keys. The four involution functions formed from the leftmost 32 bits of the algorithm determination key B among the cipher programs B formed by a support processor 101 are defined asπa,πbπc andπd and the involution functions formed from the rightmost 32 bits of the algorithm determination key B among the cipher programs B formed by a support processor 101 are defined asπe,πf,πg andπh. The process to form the data execution keys K1 to K8 is executed by the nine involution functionsπa,πb,πc,πd,πe,πf,πg,πh andπa.
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