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

namespace EncryptAndDecrypt
{
    public class CryptoUtil
    {
        //随机定义8个字节密钥和初始化向量
        private byte[] Key_64 = new byte[] { 1, 2, 3, 3, 4, 5, 6, 4};
        private byte[] IV_64 = new byte[] { 2, 3, 4, 5, 3, 4, 3, 2};

        /// <summary>
        /// 加密
        /// </summary>
        /// <param name="str">需要加密的字符串</param>
        /// <returns>加密后的字符串</returns>
        public string Encrypt(string str)
        {
            if (str == "") return str;

            DESCryptoServiceProvider cryptoProvider = new DESCryptoServiceProvider();
            MemoryStream ms = new MemoryStream();
            CryptoStream cs = new CryptoStream(ms, cryptoProvider.CreateEncryptor(Key_64, IV_64), CryptoStreamMode.Write);
            StreamWriter sw = new StreamWriter(cs);
            string cyrStr = "";
            try
            {
                sw.Write(str);
                sw.Flush();
                cs.FlushFinalBlock();
                ms.Flush();

                //将加密后的字节数组转化为字符串
                cyrStr = Convert.ToBase64String(ms.GetBuffer(), 0, (int)ms.Length);
            }
            finally
            {
                sw.Close();
                cs.Close();
                ms.Close();
                cryptoProvider.Clear();
            }
            return cyrStr;
        }

        /// <summary>
        /// 解密
        /// </summary>
        /// <param name="str">加密过的字符串</param>
        /// <returns>解密后的字符串</returns>
        public string Decrypt(string str)
        {
            if (str == "") return str;
            //将字符串转换成字节数组
            byte[] strbyte = Convert.FromBase64String(str);
            DESCryptoServiceProvider cryptoProvider = new DESCryptoServiceProvider();
            MemoryStream ms = new MemoryStream(strbyte);
            CryptoStream cs = new CryptoStream(ms, cryptoProvider.CreateDecryptor(Key_64, IV_64), CryptoStreamMode.Read);
            StreamReader sr = new StreamReader(cs);
            string uncryStr = "";
            try
            {
                uncryStr = sr.ReadToEnd();
            }
            finally
            {
                sr.Close();
                cs.Close();
                ms.Close();
                cryptoProvider.Clear();
            }
            return uncryStr;
        }

    }

    public class Program
    {
        public static void Main(string[] args)
        {
            CryptoUtil crypt = new CryptoUtil();
            string text = "KingSoft";
            string en = crypt.Encrypt(text);
            Console.WriteLine(en);

            string de = crypt.Decrypt(en);
            Console.WriteLine(de);
        }
    }
}