The differential cryptanalysis is introduced. The properties of construction and difference on the S boxes of the date encryption standard (DES) are discussed. The local property of S boxes is extended to the entire cipher structure through F function.

• 介绍了差分密码分析，讨论了数据加密标准（DES）的S－盒的结构与差分特性，然后通过F－函数将S－盒的局部特性扩展到整个密码结构。