VS 2008 Read Encrypted .dat Into Text String?

I'm working on a way to authenticate users in my app, and what I've come up with is the following method.To write to a database, the user must have an account in SQL server 2008. However, I still want people to be able to view the application if they don't have access, but only read, they can't sync any changes. This is working well, as I have a string array hard coded containing approved users:

Dim Users() As String = {"BWANG", "EDASALLA", "ERICHARDSON", "HALONZO", "JCHAPMAN", "SKIM", "PMACK"}

The one problem with hardcoding is that if I need to ever add a user later on, I'd have to release an update to the program. (which isn't hard as I already have updating built into the app, and users can still download updates even if they can't sync.)

What I'd like to do, is use an encrypted .dat file that contains the user names, and store that with the application, so that i could always be added to, and only one file would need to be downloaded.

I have code in place to encrpt and decrypt the .dat file (called users.dat) and this code works for single text entries in the file. I need to figure out how to load a list however into the array in place.

Imports System
Imports System.IO
Dim userfile as String = "C:users.dat"
Dim Users() As String = Data.Decrypt(File.ReadAllLines(path))

Basically each line in the file will have an encrypted user name, and i want it to decrypt each line and store it back into that authorized user list.