实现md5文件电子签名，md5hash值计算，比较文件，自己可扩展功能实现几个文件对比，从而找出重复文件-Md5 files to achieve electronic signature, md5hash calculated to compare documents, they can extend the functionality to achieve a number of document comparison, and to find duplicate files

md5 ciphering type of ciphering call md5 algorithm