string JiaMi = Md5Encrypt(LoginPwd);string JieMi = Md5Decrypt(JiaMi);#region MD5加密/// <summary>     /// MD5加密     /// </summary>     /// <param name="strSource">需要加密的字符串</param>     /// <returns>MD5加密后的字符串</returns>     public static string Md5Encrypt(string strSource){//把字符串放到byte数组中     byte[] bytIn = System.Text.Encoding.Default.GetBytes(strSource);//建立加密对象的密钥和偏移量             byte[] iv = { 102, 16, 93, 156, 78, 4, 218, 32 };//定义偏移量     byte[] key = { 55, 103, 246, 79, 36, 99, 167, 3 };//定义密钥     //实例DES加密类     DESCryptoServiceProvider mobjCryptoService = new DESCryptoServiceProvider();mobjCryptoService.Key = iv;mobjCryptoService.IV = key;ICryptoTransform encrypto = mobjCryptoService.CreateEncryptor();//实例MemoryStream流加密密文件     System.IO.MemoryStream ms = new System.IO.MemoryStream();CryptoStream cs = new CryptoStream(ms, encrypto, CryptoStreamMode.Write);cs.Write(bytIn, 0, bytIn.Length);cs.FlushFinalBlock();return System.Convert.ToBase64String(ms.ToArray());}#endregion#region MD5解密/// <summary>     /// MD5解密     /// </summary>     /// <param name="Source">需要解密的字符串</param>     /// <returns>MD5解密后的字符串</returns>     public static string Md5Decrypt(string Source){//将解密字符串转换成字节数组     byte[] bytIn = System.Convert.FromBase64String(Source);//给出解密的密钥和偏移量，密钥和偏移量必须与加密时的密钥和偏移量相同     byte[] iv = { 102, 16, 93, 156, 78, 4, 218, 32 };//定义偏移量     byte[] key = { 55, 103, 246, 79, 36, 99, 167, 3 };//定义密钥     DESCryptoServiceProvider mobjCryptoService = new DESCryptoServiceProvider();mobjCryptoService.Key = iv;mobjCryptoService.IV = key;//实例流进行解密     System.IO.MemoryStream ms = new System.IO.MemoryStream(bytIn, 0, bytIn.Length);ICryptoTransform encrypto = mobjCryptoService.CreateDecryptor();CryptoStream cs = new CryptoStream(ms, encrypto, CryptoStreamMode.Read);StreamReader strd = new StreamReader(cs, Encoding.Default);return strd.ReadToEnd();}#endregion   

FormsAuthentication.HashPasswordForStoringInConfigFile(str, "MD5").ToLower();