A small snippet to encrypt any VB.Net WinForms application using the RSA algorithm. Decryption is handled automatically on runtime, due to the proper implementation.

rsa_settings.vb

Dim Configuration As Configuration = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.PerUserRoamingAndLocal) ' Take the configuration file in %APPDATA%\..\Local\<Application.Info.Title>\<Version>\user.config
Dim Section As ConfigurationSection = Configuration.GetSection("userSettings/" & My.Application.Info.Title & ".My.MySettings") ' Take the sections group of the file called userSettings and select the section <Application.Info.Title>.My.Settings (i.e.: WindowsApplication1.My.Settings).

If Not Section.SectionInformation.IsProtected Then ' If it's not encrypted...
    Section.SectionInformation.ProtectSection("RsaProtectedConfigurationProvider") ' Encrypt it. Note the selection of the proper provider "RsaProtectedConfigurationProvider".
End If
Section.SectionInformation.ForceSave = True ' Force save, it might not work else because it might think it shouldn't be saved (i.e.: already protected, but with changes).

Configuration.Save(ConfigurationSaveMode.Full) ' Force saving the full configuration file, just in case, it might skip it too (it happens just too often).