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

namespace LQKJ.WebApi.Stub
{
    public class DESHelper
    {
        /// <summary>
        /// DES加密
        /// </summary>
        /// <param name="pToEncrypt"></param>
        /// <param name="sKey">密钥(8位字符)</param>
        /// <returns></returns>
        public static string Encrypt(string pToEncrypt, string sKey)
        {
            DESCryptoServiceProvider des = new DESCryptoServiceProvider();
            byte[] inputByteArray = Encoding.Default.GetBytes(pToEncrypt);
            des.Key = ASCIIEncoding.ASCII.GetBytes(sKey);
            des.IV = ASCIIEncoding.ASCII.GetBytes(sKey);
            MemoryStream ms = new MemoryStream();
            CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(), CryptoStreamMode.Write);
            cs.Write(inputByteArray, 0, inputByteArray.Length);
            cs.FlushFinalBlock();
            StringBuilder ret = new StringBuilder();
            foreach (byte b in ms.ToArray())
            {
                ret.AppendFormat("{0:X2}", b);
            }
            ret.ToString();
            return ret.ToString();

        }

        /// <summary>
        /// 解密方法
        /// </summary>
        /// <param name="pToDecrypt">需要解密的字符串</param>
        /// <param name="sKey">密匙</param>
        /// <returns>解密后的字符串</returns>
        public static string Decrypt(string pToDecrypt, string sKey)
        {
            try
            {
                DESCryptoServiceProvider des = new DESCryptoServiceProvider();
                byte[] inputByteArray = new byte[pToDecrypt.Length / 2];
                for (int x = 0; x < pToDecrypt.Length / 2; x++)
                {
                    int i = (Convert.ToInt32(pToDecrypt.Substring(x * 2, 2), 16));
                    inputByteArray[x] = (byte)i;
                }

                //建立加密对象的密钥和偏移量，此值重要，不能修改
                des.Key = ASCIIEncoding.ASCII.GetBytes(sKey);
                des.IV = ASCIIEncoding.ASCII.GetBytes(sKey);
                MemoryStream ms = new MemoryStream();
                CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(), CryptoStreamMode.Write);
                cs.Write(inputByteArray, 0, inputByteArray.Length);
                cs.FlushFinalBlock();
                //建立StringBuild对象，CreateDecrypt使用的是流对象，必须把解密后的文本变成流对象
                StringBuilder ret = new StringBuilder();
                return System.Text.Encoding.Default.GetString(ms.ToArray());
            }
            catch (Exception ex)
            {

            }
            return "";
        }
    }
}
