using System;
using System.IO;
using System.Security.Cryptography;
using System.Text;

namespace W.PlatformCore
{

    public abstract class DES_
    {
        private static DES mydes = new DESCryptoServiceProvider();
        public static string _ks = "public DES_()";
        public static string _sq = "728#$$%^TyguyshdsufhsfwofnhKJHJKHIYhfiusf98*(^%$^&&(*&()$##@%%$RHGJJHHJ";

        private static byte[] GetLegalKS()
        {
            string sTemp = _ks;
            mydes.GenerateKey();
            byte[] bytTemp = mydes.Key;
            int KeyLength = bytTemp.Length;
            if (sTemp.Length > KeyLength)
                sTemp = sTemp.Substring(0, KeyLength);
            else if (sTemp.Length < KeyLength)
                sTemp = sTemp.PadRight(KeyLength, ' ');
            return ASCIIEncoding.ASCII.GetBytes(sTemp);
        }

        private static byte[] GetLegalSQ()
        {
            string sTemp = _sq;
            mydes.GenerateIV();
            byte[] bytTemp = mydes.IV;
            int IVLength = bytTemp.Length;
            if (sTemp.Length > IVLength)
                sTemp = sTemp.Substring(0, IVLength);
            else if (sTemp.Length < IVLength)
                sTemp = sTemp.PadRight(IVLength, ' ');
            return ASCIIEncoding.ASCII.GetBytes(sTemp);
        }

        public static string Encrypt(string Source)
        {
            try
            {
                byte[] bytIn = UTF8Encoding.UTF8.GetBytes(Source);
                MemoryStream ms = new MemoryStream();
                mydes.Key = GetLegalKS();
                mydes.IV = GetLegalSQ();
                ICryptoTransform encrypto = mydes.CreateEncryptor();
                CryptoStream cs = new CryptoStream(ms, encrypto, CryptoStreamMode.Write);
                cs.Write(bytIn, 0, bytIn.Length);
                cs.FlushFinalBlock();
                ms.Close();
                byte[] bytOut = ms.ToArray();
                return Convert.ToBase64String(bytOut);
            }
            catch (Exception ex)
            {
                throw new Exception("在文件加密的时候出现错误！错误提示： \n" + ex.Message);
            }
        }

        public static string Decrypt(string Source)
        {
            try
            {
                byte[] bytIn = Convert.FromBase64String(Source);
                MemoryStream ms = new MemoryStream(bytIn, 0, bytIn.Length);
                mydes.Key = GetLegalKS();
                mydes.IV = GetLegalSQ();
                ICryptoTransform encrypto = mydes.CreateDecryptor();
                CryptoStream cs = new CryptoStream(ms, encrypto, CryptoStreamMode.Read);
                StreamReader sr = new StreamReader(cs);
                return sr.ReadToEnd();
            }
            catch
            {
                throw new Exception("在文件解密的时候出现错误！错误提示： \n" + ex.Message);
            }
            return null;
        }
    }
}