加密之DESCryptoServiceProvider加密解密

DESCryptoServiceProvider加密及解密須要先聲明一個key，根據這個能夠進行加密及解密，因此是可逆的，與MD5不可逆加密是不同的；話很少說，上案例：

public static readonly string myKey = "0Ja3c6K9";

        /// <summary>
        /// 加密方法
        /// </summary>
        /// <param name="pToEncrypt">須要加密字符串</param>
        /// <param name="sKey">密鑰</param>
        /// <returns>加密後的字符串</returns>
        public static string Encrypt(string pToEncrypt, string sKey)
        {
            try
            {
                DESCryptoServiceProvider des = new DESCryptoServiceProvider();
                //把字符串放到byte數組中


                //原來使用的UTF8編碼，我改爲Unicode編碼了，不行
                byte[] inputByteArray = Encoding.Default.GetBytes(pToEncrypt);

                //創建加密對象的密鑰和偏移量


                //使得輸入密碼必須輸入英文文本
                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();
            }
            catch (Exception ex)
            {
                //System.Web.HttpContext.Current.Response.Write("寫入配置信息失敗，詳細信息：" + ex.Message.Replace("\r\n", "").Replace("'", ""));
            }

            return "";
        }

        /// <summary>
        /// 解密方法
        /// </summary>
        /// <param name="pToDecrypt">須要解密的字符串</param>
        /// <param name="sKey">密匙</param>
        /// <returns>解密後的字符串</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;
                }

                //創建加密對象的密鑰和偏移量，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();
                //創建StringBuild對象，CreateDecrypt使用的是流對象，必須把解密後的文本變成流對象
                StringBuilder ret = new StringBuilder();
                return System.Text.Encoding.Default.GetString(ms.ToArray());
            }
            catch (Exception ex)
            {
                MessageBox.Show("讀取配置信息失敗，詳細信息：" + ex.Message.Replace("\r\n", "").Replace("'", ""));
            }
            return "";
        }