The AppSettings node requires a specific format.
Instead you can use the config section.
Define the config section at the beginning of config file as :
<configSections>
<section name="SecurityNode" type="<namespace of the dll that is going to read this", <dll name>"/>
</configSections>
Then use the ConfigurationManager.GetSection("SecutiryNode") statement to read the whole node and process it as normat xml.
Hope this helps