C#生成注册码

string t = DateTime.Now.Ticks.ToString();

            t = DESKey.DESEncrypt(t, DESKey.DesKeyStr);
            string[] strid = new string[t.Length];//
            for (int i = ; i < t.Length; i++)//把字符赋给数组
            {
                strid[i] = t.Substring(i, );
            }
            string s = "";
            Random rdid = new Random();
            for (int i = ; i < ; i++)//从数组随机抽取字符组成新的字符生成机器三
            {
                s += strid[rdid.Next(, strid.Length)];
            }

class DESKey
    {
        public const string DesKeyStr = "BLUE2013";

        #region DES加密
        /// <summary>
        /// DES加密
        /// </summary>
        /// <param name="pToEncrypt">需要加密的字符串</param>
        /// <returns>加密后的字符串</returns>
        public static string DESEncrypt(string pToEncrypt, string DesKeyStr)
        {
            try
            {
                DESCryptoServiceProvider des = new DESCryptoServiceProvider();
                byte[] inputByteArray = Encoding.Default.GetBytes(pToEncrypt);
                des.Key = ASCIIEncoding.ASCII.GetBytes(DesKeyStr);
                des.IV = ASCIIEncoding.ASCII.GetBytes(DesKeyStr);
                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();
            }
            catch
            {

                return "";
            }

        }
        #endregion

        #region DES解密
        /// <summary>
        /// DES解密
        /// </summary>
        /// <param name="pToDecrypt">加密后的字符串</param>
        /// <returns>解密后的字符串</returns>
        public static string DESDecrypt(string pToDecrypt, string DesKeyStr)
        {
            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;
                }

                des.Key = ASCIIEncoding.ASCII.GetBytes(DesKeyStr);
                des.IV = ASCIIEncoding.ASCII.GetBytes(DesKeyStr);
                MemoryStream ms = new MemoryStream();
                CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(), CryptoStreamMode.Write);
                cs.Write(inputByteArray, 0, inputByteArray.Length);
                cs.FlushFinalBlock();

                StringBuilder ret = new StringBuilder();

                return System.Text.Encoding.Default.GetString(ms.ToArray());
            }
            catch
            {

                return "";
            }
        }
        #endregion

    }