Encrypting appSettings and connectionStrings sections in web.config :
 
   aspnet_regiis.exe –pef "appSettings" "<Path.to.website.directory>"
 
   aspnet_regiis.exe –pef "connectionStrings" "<Path.to.website.directory>"
 
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Encrypting appSettings and connectionStrings sections in web.config and specifying the Data Protection Provider:

To Encrypt, run the following from the Visual Studio command prompt:
 
  aspnet_regiis -pe "connectionStrings" -app "/AppName" -prov "RsaProtectedConfigurationProvider"
 
To Decrypt, run the following from the Visual Studio command prompt:
 
  aspnet_regiis -pd "connectionStrings" -app "/AppName"