DES算法为密码体制中的对称密码体制，又被成为美国数据加密标准，是1972年美国IBM公司研制的对称密码体制加密算法。 明文按64位进行分组, 密钥长64位，密钥事实上是56位参与DES运算（第8、16、24、32、40、48、56、64位是校验位， 使得每个密钥都有奇数个1）分组后的明文组和56位的密钥按位替代或交换的方法形成密文组的加密方法。

-DES algorithm for the key system of symmetrical cipher system, also known as the United States of America data encryption standard, is a 1972 American IBM company developed the symmetric encryption algorithm. Express according to the64group, the key length of 64bits, the key is in fact56 to participate in DES operation ( eighth,16,24,32,40,48,56,64is the check digit, so that each key has an odd number of1) after grouping expressly group and a 56 bit key according to a replacement or exchange method of forming ciphertext encryption method.