Encrypt application/web configuration file

Under some scenarios the developers want to encrypt some sections inside app.config or web.config file, this article How To: Encrypt Configuration Sections in ASP.NET 2.0 Using RSA describes how to do so clearly, Scott Guthrie also posted one: Encrypting Web.Config Values in ASP.NET 2.0.

However, in the posts above they uses aspnet_regiis.exe and seems it doesn’t directly support app.config, if we want to encrypt app.config for Windows Form or WPF applications, while I tried use it to encrypt my app.config file, it generates a web.config which means my Winform definitely can’t use it, even if I copy the encrypted appSettings section from this generated web.config to my own app.config (ConfigurationManager.AppSettings[EncryptedKeyName] is null after I did that).

 

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After several minutes google search and testing I found the code below is simple and very straight forward to achieve this:

            Configuration config = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);

            SectionInformation appSettingsSecInfo = config.GetSection("appSettings").SectionInformation;
            if (!appSettingsSecInfo.IsProtected)
            {
                Console.WriteLine("The configuration file has NOT been protected!");

                // Encrypt this section by using security provider (RsaProtectedConfigurationProvider or DpapiProtectedConfigurationProvider).
                appSettingsSecInfo.ProtectSection("RsaProtectedConfigurationProvider");
                appSettingsSecInfo.ForceSave = true;

                config.Save(ConfigurationSaveMode.Full);
            }

This code snippet will do the encryption job and works for both app.config/web.config, here is the MSDN definition page for SectionInformation.ProtectSection:
http://msdn.microsoft.com/en-us/library/system.configuration.sectioninformation.protectsection.aspx

References:
Overview of Protected Configuration:
http://msdn.microsoft.com/en-us/library/hh8x3tas.aspx

RsaProtectedConfigurationProvider Class:
http://msdn.microsoft.com/en-us/library/system.configuration.rsaprotectedconfigurationprovider.aspx

DpapiProtectedConfigurationProvider Class:
http://msdn.microsoft.com/en-us/library/system.configuration.dpapiprotectedconfigurationprovider.aspx