I'm trying to create an authorization scheme for my ASP.NET MVC application where an Enum is used to set permissions. For example:

[Flags]
enum Permissions
{
    ReadAppointments = 1,
    WriteAppointments = 2 | ReadAppointments,
    ReadPatients = 4,
    WritePatients = 8 | ReadPatients,
    ReadInvoices = 16,
    WriteInvoices = 32 | ReadInvoices
    ...
}

But I don't really like that because it really doesn't make it clear that Write always includes Read.

I then realized that a requirement would be that a user might have NO access to, for example, Appointments.

Essentially, I'd want a "bitfield" with 3 states: none, readonly, full (read/write). I'd like to still use an enum bitfield since it's easy to store in a DB (as an int). Also it's very easy to see if a permission is set.

Does anyone have any idea how this could be easily accomplished using an Enum... or am I going in the completely wrong direction?