using System;

using System.Collections.Generic;

using System.Linq;

using System.Security.Cryptography;

using System.Text;

using System.Threading.Tasks;



namespace RSA

{

    public static class DESHelper

    {



        public static void CreateKeyAndIV(out string key, out string IV)

        {

            DESCryptoServiceProvider des = new DESCryptoServiceProvider();

            byte[] data = new byte[0x10];

            new RNGCryptoServiceProvider().GetBytes(data);

            string longkey = Convert.ToBase64String(data);

            key = longkey.Substring(0, 8);

            IV = longkey.Substring(0, 8);

        }



        /// <summary>

        /// 进行DES加密。

        /// </summary>

        /// <param name="pToEncrypt">要加密的字符串。</param>

        /// <param name="sKey">密钥，且必须为8位。</param>

        /// <returns>以Base64格式返回的加密字符串。</returns>

        public static string Encrypt(string pToEncrypt, string sKey)

        {

            using (DESCryptoServiceProvider des = new DESCryptoServiceProvider())

            {

                byte[] inputByteArray = Encoding.UTF8.GetBytes(pToEncrypt);

                des.Key = ASCIIEncoding.ASCII.GetBytes(sKey);

                des.IV = ASCIIEncoding.ASCII.GetBytes(sKey);

                System.IO.MemoryStream ms = new System.IO.MemoryStream();

                using (CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(), CryptoStreamMode.Write))

                {

                    cs.Write(inputByteArray, 0, inputByteArray.Length);

                    cs.FlushFinalBlock();

                    cs.Close();

                }

                string str = Convert.ToBase64String(ms.ToArray());

                ms.Close();

                return str;

            }

        }



        /// <summary>

        /// 进行DES解密。

        /// </summary>

        /// <param name="pToDecrypt">要解密的以Base64</param>

        /// <param name="sKey">密钥，且必须为8位。</param>

        /// <returns>已解密的字符串。</returns>

        public static string Decrypt(string pToDecrypt, string sKey)

        {

            byte[] inputByteArray = Convert.FromBase64String(pToDecrypt);

            using (DESCryptoServiceProvider des = new DESCryptoServiceProvider())

            {

                des.Key = ASCIIEncoding.ASCII.GetBytes(sKey);

                des.IV = ASCIIEncoding.ASCII.GetBytes(sKey);

                System.IO.MemoryStream ms = new System.IO.MemoryStream();

                using (CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(), CryptoStreamMode.Write))

                {

                    cs.Write(inputByteArray, 0, inputByteArray.Length);

                    cs.FlushFinalBlock();

                    cs.Close();

                }

                string str = Encoding.UTF8.GetString(ms.ToArray());

                ms.Close();

                return str;

            }

        }

    }

}