MD5加密

 public string GetMD5String(string str)
        {
            MD5CryptoServiceProvider md5 = new MD5CryptoServiceProvider();
            //md5 = new MD5CryptoServiceProvider();
            byte[] data = System.Text.Encoding.Default.GetBytes(str);// 返回结果:一个字节数组，包含对指定的字符集进行编码的结果。
            byte[] md5data = md5.ComputeHash(data);//计算指定字节数组的哈希值。
            //md5.Clear();
            StringBuilder builder = new StringBuilder();
            for (int i = 0; i < md5data.Length; i++)
            {
               //Console.WriteLine(md5data[i].ToString());
                builder.Append(md5data[i].ToString("X2"));
            }
            //返回加密后的字符串
            return builder.ToString();
        }

 public  string GetFileMd5(string path)
        {
            string ctyptStr = "";
            byte[] cryptBytes;
            using (FileStream fs = new FileStream(path,FileMode.Open))//选择文件
            {
                MD5CryptoServiceProvider md5 = new MD5CryptoServiceProvider();
                cryptBytes = md5.ComputeHash(fs);
            }
            for (int i = 0; i < cryptBytes.Length; i++)
            {
                ctyptStr += cryptBytes[i].ToString("X2");
            }
            return ctyptStr;
        }