DES是Data Encryption Standard（数据加密标准）的缩写。它是由IBM公司研制的一种加密算法，美国国家标准局于1977年公布把它作为非机要部门使用的数据加密标准；它是一个分组加密算法，他以64位为分组对数据加密。同时DES也是一个对称算法：加密和解密用的是同一个算法。它的密匙长度是56位（因为每个第8 位都用作奇偶校验），密匙可以是任意的56位的数，而且可以任意时候改变．-DES is the Data Encryption Standard (Data Encryption Standard) abbreviation. It is developed by IBM as a encryption algorithm, the United States National Bureau of Standards published in 1977 as the use of non-confidential data encryption standards　it is a sub-encryption algorithm, he has 64 for the packet of data encryption. At the same time, DES is a symmetric algorithm: encryption and decryption using the same algorithm. Its key length is 56 (since each section 8 are used for parity), keys can be arbitrary number of 56, but can also change any time.