How does Apple privately find offline devices? • Hacker News Board

Re: How does Apple privately find offline devices?

#51

Post by etaoins » Wed, Jun 05, 2019, 10:44 PM UTC

snazz wrote: post #31

ladberg wrote: post #28

Earlier quoted context omitted.

Complete speculation here, but I wouldn't be surprised if devices could keep broadcasting the ping after they're "dead". Tiles last for years without charging, so I bet if Apple can leave on only the bluetooth beacon after the battery drains past where it can power the rest of the phone then this would be doable. Again complete speculation, I have zero clue if the current hardware is even capable of doing this.

The current hardware might not be, but you could run this on a secondary chip similar in specs to the T2 or Secure Enclave. You could theoretically even have a second battery specifically for this purpose, but that would likely be cost-prohibitive.

The T2 chip is a derivative of the A10. It has similar power requirements to the SOC in modern iPhones.

They could probably use a cut down derivative of the W2 chip used in AirPods with the audio codec etc. removed. I’m guessing phone batteries reach a point where they’re still storing energy but can’t provide enough current to safely boot the whole phone. The BLE chip could sip on the remainder of the battery for a long time.

Re: How does Apple privately find offline devices?

#52

Post by icelancer » Wed, Jun 05, 2019, 10:45 PM UTC

RosanaAnaDana wrote: post #48

machinesmachine wrote: post #34

Earlier quoted context omitted.

Also interested. Could you describe the process?

Sure. I pulled my data in the standard takeout.google.com/ process. The result is a json (? iirc). I parsed the json into x, y, and rasterized it using gdal. https://imgur.com/a/ZhyTsDV See I wasn't sure if I lost it in the couch in the living room, the office, or the bedroom. This got me within a few feet.

Ha, this is an awesome use of the data. What a cool plot showing the "density" of pings.

Re: How does Apple privately find offline devices?

#53

Post by MBCook » Wed, Jun 05, 2019, 10:48 PM UTC

pwinnski wrote: post #12

RIMR wrote: post #10

Okay, so this would make it insanely easy to stalk any iPhone user. 1. Get BLE tracking tags, and register them with Find My. 2. Covertly attach the BLE tracking tags to things your target owns (backpacks, cars, bikes, etc). 3. You constantly get updates on your tags locations via their iPhone and other iOS devices near the BLE tag(s). This gives you their approximate location and movement history, facilitated primar…

The only "BLE tracking tags" reported to use Find My are Apple devices, and if you can attach an Apple device to something your target owns, there are many means you can use other than Find My to track them. I mean, if you can accomplish step 2, you don't need Apple at all.

They are widely expected to introduce such tags later this year.

Re: How does Apple privately find offline devices?

#54

Post by RosanaAnaDana » Wed, Jun 05, 2019, 10:52 PM UTC

jdironman wrote: post #35

mehrdadn wrote: post #27

Earlier quoted context omitted.

This is interesting. By the raw data you mean from Google Takeout, or something else? Did you have to filter/smooth the data points?

Probably just looked at the last data point depending on the type of data was available. If its longitude / latitude values then its going to be pretty precise, although I would also like to know where to pull more granular data.

The GPS receiver isnt' sufficiently accurate for one point to be useful, but in aggregate, it was accurate 'enough'.

So although the numerical precision is pretty high, the actual accuracy is pretty low, I think I pulled all the points from 2am-6pm in the final time stamp to figure out where the phone was.

Re: How does Apple privately find offline devices?

#55

Post by ShakataGaNai » Wed, Jun 05, 2019, 10:59 PM UTC

MBCook wrote: post #47

ShakataGaNai wrote: post #6

The problem I see with this is that your phone always has to be broadcasting the BLE beacon, regardless of if it is lost or not. Otherwise it could randomly end up lost in a place with poor/no service... and would never be found For phones, how often is this really an issue? Sure, this is useful for the Tile type "dumb" devices... but if my phone has no cell or data service... it's probably because the battery is dea…

Don’t think phone. In the keynote I think they showed it with a Mac, which isn’t available with cell service. Or as someone else mentioned maybe you have an iPad without cellular. It would be useful for those.

Fair point. For wifi only devices, I could see it having some use.

Re: How does Apple privately find offline devices?

#56

Post by randyrand » Wed, Jun 05, 2019, 11:01 PM UTC

imhoguy wrote: post #13

I see lots of poor Lassies in airports, conferencies and generally in crowded places. Not even mentioning flood or replay attacks. Lassie's help needs to have some limits otherwise it may quickly drain batteries or mobile plans especially in roaming.

"Apple's recommended setting of 100 ms advertising interval with a coin cell battery provides for 1–3 months of life, which increases to 2–3 years as advertising interval is increased to 900 ms."

iPhone's have about at 10X larger batter than that. So iPhones can do this for ~20-30 years if configured correctly.

Re: How does Apple privately find offline devices?

#57

Post by m463 » Wed, Jun 05, 2019, 11:03 PM UTC

Xylakant wrote: post #9

m463 wrote: post #4

Can we turn this off? please? I would like 100% passive bluetooth. (and wifi, and nfc)

How is that going to work? All communication that you initiate must be active. The only passive option would be broadcasts like TV or radio stations, but that’s not particularly useful if you want to view a specific website.

I meant, don't turn your phone into a beacon. (as a setting is ok)

The idea would be yes -- connect to bluetooth headphones or your car. Connect to wifi in your home. Allow NFC transactions on command.

But no, don't promiscuously advertise your device. Don't look up every bluetooth beacon you encounter or crowdsource every wifi access point.

Re: How does Apple privately find offline devices?

#58

Post by dmitrygr » Wed, Jun 05, 2019, 11:05 PM UTC

bdcravens wrote: post #22

dmitrygr wrote: post #11

Earlier quoted context omitted.

I have no idea how the FindMy BLE system works, but i strongly suspect that the cheaperst compatible "tag" you will find will be an iPhone. Might get a tad expensive to do this...

The potential of low cost tags is in the first paragraph, and an overview of how the system would work is in the second. My takeaway is that you will be able to use something far cheaper than an iPhone.

Cheap ble tags do NOT use fancy rotated private keys or anything of the like. At best they use BLE privacy mode. That is as private as the spec gets.

Source: worked on Bluetooth for years

Re: How does Apple privately find offline devices?

#59

Post by m463 » Wed, Jun 05, 2019, 11:06 PM UTC

ladberg wrote: post #28

ShakataGaNai wrote: post #6

The problem I see with this is that your phone always has to be broadcasting the BLE beacon, regardless of if it is lost or not. Otherwise it could randomly end up lost in a place with poor/no service... and would never be found For phones, how often is this really an issue? Sure, this is useful for the Tile type "dumb" devices... but if my phone has no cell or data service... it's probably because the battery is dea…

Complete speculation here, but I wouldn't be surprised if devices could keep broadcasting the ping after they're "dead". Tiles last for years without charging, so I bet if Apple can leave on only the bluetooth beacon after the battery drains past where it can power the rest of the phone then this would be doable. Again complete speculation, I have zero clue if the current hardware is even capable of doing this.

recent apple phones have NFC, which cannot be disabled.

Re: How does Apple privately find offline devices?

#60

Post by applecrazy » Wed, Jun 05, 2019, 11:06 PM UTC

RIMR wrote: post #10

Okay, so this would make it insanely easy to stalk any iPhone user. 1. Get BLE tracking tags, and register them with Find My. 2. Covertly attach the BLE tracking tags to things your target owns (backpacks, cars, bikes, etc). 3. You constantly get updates on your tags locations via their iPhone and other iOS devices near the BLE tag(s). This gives you their approximate location and movement history, facilitated primar…

One of the fundamental rules of security is that if your adversary has physical access, it's over. This sounds like that but with extra steps. If somebody has access to your equipment and am able to attach arbitrary items to your bag, then it could be any tracker (Tile, cheap GPS tracker, iPhone, etc.), then of course it's over from a security perspective.