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| Differential Analysis and Modification of the Key-Dependent S-Boxes of Twofish |
| Zhou Xuan①; Li Chao①② |
| ①Dept. of Math. and System Sci., Nat. Univ. of Defense Tech., Changsha 410073, China;②Key Lab. of Computer Sci., Inst. of Software, OAS, Beijing 100080, China |
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Abstract This paper proves that the longer the key of Twofish is,the smaller the differ-ential probabilities of the key-dependent S-boxes are. A new method is proposed to produce the key-dependent S-boxes. Theory and simulation results show that the XOR differential probability and modular addition differential probability of the modified S-boxes are smaller than those of the original S-boxes.
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Received: 27 February 2003
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2004, Vol. 26 
