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研究了流密码体制中抗攻击前馈网络的构造。通过对有限状态机（ＦＳＭ）输出函数的Ｗａｌｓｈ谱及Ｎ元布尔函数是Ｎ－１阶相关免疫的充要定理的讨论，证明了ＦＳＭ组合器是Ｎ１阶相关免疫的。论述了用Ｂｅｎｔ函数做前馈网络的非线性组合函数可很好的抗相关攻击和线性逼近攻击。文中给出一种可用其实现任意Ｎ元布尔函数的多功能程控逻辑门，使布尔函数的线路实现极为经济。最后用ＦＳＭ组合器及给出的多功能程控逻辑门构造了实现一大类Ｂｅｎｔ函数的前馈网络。此流密码体制具有强的抗攻击能力。
The structure of anti-attack feedforward network in the stream cipher system is studied. By discussing the Walsh spectrum of finite state machine (FSM) output function and the necessary and sufficient theorem that N-ary Boolean function is N-1 order-dependent immunity, it is proved that the FSM combiner is N1 order-dependent immune. The non-linear combination function of the feedforward network using Bent function is discussed, which is very good for anti-correlation attack and linear approximation attack. In this paper, a kind of multi-function programmable logic gate that can be used to realize arbitrary N-ary Boolean functions is given in this paper, which makes the Boolean function circuit extremely economical. Finally, a feedforward network for implementing a large class of Bent functions is constructed by using FSM combiner and given multi-function programmable logic gates. This stream cipher system has a strong anti-attack capability.