根据设计要求：1）具有文件加密和解密功能；2）具有加解密速度统计功能；3）采用密文反馈链接和密文挪用短块处理技术。我们可以知道，程序要有加密模块、解密模块、子密钥生成模块，这三个模块构成DES算法。DES算法再构成3DES，这很简单，只要加个密钥便可实现。3DES还必须工作在密文反馈连接模式下和使用密文短块挪用技术。至于速度统计功能就很好实现，用文件长度除以处理时间便是加解密速度。-based on the design requirements : 1) with file encryption and decryption function; 2) the speed with the encryption and decryption functions of statistics; 3) Use of dense text links and feedback secret misappropriation short pieces of text processing technology. We know that procedures have encryption module, decryption modules for key generating modules, which constitute three modules DES algorithm. DES algorithm constitute 3DES, this is very simple, as long as add key can be reached. 3DES must also work in close link text feedback mode and the use of short text block secret misappropriation of technology. As for the speed of statistical functions properly achieved, divided by the length of documents with the processing time is the speed encryption and decryption.