Windows Azure Web Service, returns JSON for authenticated (mobile) Users

The system should enable mobile users to access data stored in SQL Azure. The web service (which you need to develop) authenticates the user, select data from the DB and returns it as JSON.
Building the mobile app is not in the scope of this project.
Building the SQL Azure DB is also not in the scope of this project. You only need to implement the Web Service WS Publisher.
The solution should be developed using Microsoft WCF services for Windows Azure.

All the details in the attached doc

This is just a small PoC. The customer wants much larger project. If all goes well we’ll continue with you to the next phase.
If the price is good, I’ll ask you to develop the admin site too