iOS8 MAC Address Randomization Update

Interesting that "actual sleep mode" is mostly prevented because of cellular activity.

In any case the conclusion is mostly the same: the feature does not really appear to be effective at all.

For those tl;dr, what Nick's writing about here is that you don't need to turn off cellular data or location services -- the requirement that the phone as to be asleep is instead too restrictive, because your phone is rarely asleep for long. (Those two settings let your phone sleep longer.)

> Unfortunately, the requirement of the phone being asleep makes this feature nearly useless, albeit within the description of what Apple advertised at WWDC. In order to get random MACs to be used I had to turn off notifications for multiple apps, turn off push email, and stay up late at night when there was a greater chance of my phone getting to sleep, uninterrupted, for more than a minute or two. Even under these circumstances, I would only encounter one or two rounds of probe beacons (which seem go to out every couple of minutes) with a random MAC before seeing my phone blast a bunch of probes with my real MAC. My best guess is this would happen when some process of push had woken the device up. With cellular data turned on, only about 50% of the probes I saw go out had a randomly assigned MAC.

But there's a worse problem, as mentioned in the last paragraph below from the iMore article:

> Rendering this feature even more useless, when the probe requests went out with a random MAC, the probes contained SSIDs of 5 networks that the phone had previously connected to. This means even when my MAC is random, the SSIDs it's broadcasting can act as a fingerprint for my phone. My MAC can be different every time probes go out, but if it broadcasts the same set of 5 network names every few minutes, it may still be possible for monitors to track my device.

Should we change the url to that?

No hardware reasons, and probably no software ones. :/

Wi-Fi MAC is unrelated of the IMEI of the phone. It's on a different chip, and uses different antennae.

(Eg, you can browse over Wi-Fi while talking on your cell connection)

With randomization, you can keep using wifi and bluetooth and not be tracked.

Well, randomization was what everyone initially thought would be the case always.

So it's disappointing to find that it's only going to randomize in specific, somewhat unusual modes. :(

Well, that's just it. It was announced as, and should only work as, the ability to scan for wifi hotspots using a random, untraceable MAC address. This is because advertisers and other third-parties were beginning to use wifi hotspots as passive ways of collecting unique IDs for devices (their MAC addresses). So under this system, when it works, walking by a hotspot shouldn't identify you to it if you don't auto connect, while actually connecting would.

Edit: from their previous post:

In iPhone 5s, MAC randomization happens only under the following conditions: Phone is in sleep mode (display off, not being used); Wi-Fi should be ON but not associated ...

I would argue that the phone needing to be in sleep is also a bug. It should "just work"... Ideally even when scanning for new networks while associated.

I think it was only supposed to be random when not associated at all (only during probing)

This was downvoted but I feel this is an important counter-argument (open source vs closed systems), even if not articulated well.