字符串加密,解密

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加密或解密，先設置一個偏移量也就是密鑰，注意：只支持8字節密鑰

在配置文件中設置密鑰，而後讀取

private static readonly string sKey = ReadConfig.ReadAppSetting("DecKey");

加密過程

/// <summary>
        /// DEC 加密過程
        /// </summary>
        /// <param name="pToEncrypt">被加密的字符串</param>
        /// <param name="sKey">密鑰（只支持8個字節的密鑰）</param>
        /// <returns>加密後的字符串</returns>
        public static string Encrypt(string pToEncrypt)
        {
            //訪問數據加密標準(DES)算法的加密服務提供程序 (CSP) 版本的包裝對象
            DESCryptoServiceProvider des = new DESCryptoServiceProvider();
            des.Key = ASCIIEncoding.ASCII.GetBytes(sKey);　//創建加密對象的密鑰和偏移量
            des.IV = ASCIIEncoding.ASCII.GetBytes(sKey);　 //原文使用ASCIIEncoding.ASCII方法的GetBytes方法

            byte[] inputByteArray = Encoding.Default.GetBytes(pToEncrypt);//把字符串放到byte數組中

            MemoryStream ms = new MemoryStream();//建立其支持存儲區爲內存的流　
            //定義將數據流連接到加密轉換的流
            CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(), CryptoStreamMode.Write);
            cs.Write(inputByteArray, 0, inputByteArray.Length);
            cs.FlushFinalBlock();
            //上面已經完成了把加密後的結果放到內存中去

            StringBuilder ret = new StringBuilder();
            foreach (byte b in ms.ToArray())
            {
                ret.AppendFormat("{0:X2}", b);
            }
            ret.ToString();
            return ret.ToString();
        }

解密過程

/// <summary>
        /// DEC 解密過程
        /// </summary>
        /// <param name="pToDecrypt">被解密的字符串</param>
        /// <param name="sKey">密鑰（只支持8個字節的密鑰，同前面的加密密鑰相同）</param>
        /// <returns>返回被解密的字符串</returns>
        public static string Decrypt(string pToDecrypt)
        {
            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(sKey);　//創建加密對象的密鑰和偏移量，此值重要，不能修改
                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)
            {
                BLL.NLogHelper.Instance.ErrorException("解密失敗(" + pToDecrypt + "):", ex);
                return "";
            }
        }