Using a web service for retrieving secured data from iphone app

Hi All,

In my application I want on each execution to send a unique identifier to a remote server where this identifier will be stored in a database. The identifier does not contain any information about the user but I still need it to be sent in a secured manner (so no hackers could send fake identifiers). According to the identifier the server will send a response to the application.

My questions are:
- How do I receive secured requests (and requests in general) on my server. What is the best way to do it ?
- How do I send responses back to the application ?
- What security technique I should use to implement the above ?

Any help/references will be welcomed.

Thanks