The article focuses on how their recommended device identifier, the Bluetooth MAC, will become inaccessible in iOS 7, just like the UDID did in a past update.<p>I'm not that familiar with the mechanics of fraud detection, and I wish the article had delved into why a physical device ID is necessary for it. What is the advantage of the MAC over, say, a hidden ID created randomly by the app on first launch?<p>There's an obvious difference in that the MAC would allow you to correlate identifiers across multiple apps (which is also a privacy weakness), but the given example apps aren't particularly likely to be used in concert.