[moggie]

How exactly do you identify the device? By phone number?

If that's the case, could it be possible to circumvent that through spoofing of the number and subsequent reception of the SMS message?

[harryf]

We began with using the device ID but of course we've had to change given that's deprecated - http://stackoverflow.com/questions/6993325/uidevice-uniqueid... - iOS6 seems to have perfect answers here - we're not interested in IDs you can share between apps - this is for our app only.

[andor]

You could generate a random number, let's call it a "cookie", and hand that to the device after a successful handshake.