分组密码的设计者总是在安全性和简捷性之间回旋，因此一般的设计方法都是用一些简单的计算部件通过组合成为复杂的、能抵抗各种攻击的加密函数。密码设计者希望这些部件的安全性可以互补，而不是相互抵消。-Block cipher designers are always in a safe and simple maneuver between, so the general design method are calculated using some simple parts through the portfolio to become complex and resistant to various attacks on encryption function. Password designers hope that the safety of these parts can be complementary, rather than cancel each other out.