| 摘要 |
A block cipher algorithm is based on the prior Feistel type block cipher algorithm (or similar to DES algorithm). Usually the security of a Feistel type block cipher algorithm depends on the structure of its round function. More specifically, this disclosure relates to the round function structure of the Feistel type block cipher algorithm, in the instance that the round input data block is divided into 8-bit blocks and the divided sub blocks are fed, with the combined output data of the previous S-box, into 256 x 8 S-box, except for the first input sub-data block. The first sub-data block one is directly fed into the first S-box. The total output data block, after these steps, is rotated by 8-bits and this rotated result is the output of the current round function. This is to resist linear and differential cryptanalysis.
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