DES 使用一个 56 位的密钥以及附加的 8 位奇偶校验位，产生最大 64 位的分组大小。这是一个迭代的分组密码，使用称为 Feistel 的技术，其中将加密的文本块分成两半。使用子密钥对其中一半应用循环功能，然后将输出与另一半进行“异或”运算；接着交换这两半，这一过程会继续下去，但最后一个循环不交换。DES 使用 16 个循环，使用异或，置换，代换，移位操作四种基本运算-DES uses a 56 key , as well as 8 additional parity bit , resulting in the largest group size of 64 . This is an iterative block cipher , using called Feistel the technology , which will encrypt the text block in half . Use the sub- key half of the application cycle function , and then the output and the other half of the " exclusive OR " operator　 then exchange the two halves , this process will continue , but in the end a loop exchange . DES uses 16 cycles , using XOR , replacement , substitution , shift operations are four basic operations