ProtectedConfigurationProvider
The base class to create providers for encrypting and decrypting protected configuration data.
                using System.Configuration.Provider;
using System.Xml;
namespace System.Configuration
{
    public abstract class ProtectedConfigurationProvider : ProviderBase
    {
        public abstract XmlNode Encrypt(XmlNode node);
        public abstract XmlNode Decrypt(XmlNode encryptedNode);
    }
}