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

Re: How does Apple privately find offline devices?

#41

Post by JulianMorrison » Wed, Jun 05, 2019, 10:35 PM UTC

JohnFen wrote: post #18

> The good news is that Apple claims that their system actually does provide strong privacy, and that it accomplishes this using clever cryptography. But that does nothing to protect your privacy against Apple. I already have to make sure that I disable WiFi and Bluetooth when I enter commercial establishments. Now I have to stop using Bluetooth whenever I leave my house?

If this "no privacy from Apple" widget is using separate low power or parasitic power circuitry, it is entirely possible for it to be running and operational in a switched off phone with a battery on 0% charge.

Buy a Nokia, perhaps?

Re: How does Apple privately find offline devices?

#42

Post by Nition » Wed, Jun 05, 2019, 10:35 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.

Just cycle though every website on the Internet and have the PC pause when the requested page is loaded obviously. It worked for Teletext.

Re: How does Apple privately find offline devices?

#43

Post by sixstringtheory » Wed, Jun 05, 2019, 10:36 PM UTC

judge2020 wrote: post #32

berbec wrote: post #21

Earlier quoted context omitted.

It gets worse: if you turn off wifi/bluetooth in control center, it only disconnects, keeping the radio active. 1: https://support.apple.com/en-us/HT208086

As it says on the page, this is to make sure a bunch of things still work (eg. you wouldn't really thing you need to keep Bluetooth enabled to use the pencil). Maybe the toast text "disconnecting nearby Wi-Fi until tomorrow" could be a little clearer.

From day one I’ve wanted a way to disable the automatic-reenabling feature.

Re: How does Apple privately find offline devices?

#44

Post by JohnFen » Wed, Jun 05, 2019, 10:36 PM UTC

ladberg wrote: post #23

JohnFen wrote: post #18

> The good news is that Apple claims that their system actually does provide strong privacy, and that it accomplishes this using clever cryptography. But that does nothing to protect your privacy against Apple. I already have to make sure that I disable WiFi and Bluetooth when I enter commercial establishments. Now I have to stop using Bluetooth whenever I leave my house?

Why do you do that? All Apple devices generate randomized MAC addresses for networks that they haven't connected to, so they shouldn't be able to track you. In addition, no other actors will be able to gain useful information from the bluetooth pings, they simply forward the encrypted data to Apple. All they can tell is that an Apple device exists nearby, but not who owns it or if they've seen the same device before.…

> Why do you do that?

The short answer is because it makes me feel better.

The long answer is that it prevents tracking my movements within a store. Stores appear to be increasingly installing and using such trackers, and I do not wish to be tracked.

Not being able to be identified personally, or to be identified as the same person who was there last week or that I also went into other stores isn't sufficient to me.

Re: How does Apple privately find offline devices?

#45

Post by president » Wed, Jun 05, 2019, 10:36 PM UTC

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…

Also, couldn't the BLE beacon be used by "smash and grab" thieves to find devices in your car?

Re: How does Apple privately find offline devices?

#46

Post by stouset » Wed, Jun 05, 2019, 10:42 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.

BLE is insanely battery-efficient. And in most scenarios with a lost device, it's either stationary or will be stationary for a sufficient period of time to be discovered, so a ping only once every hour is probably more than enough to locate it. Or a ping with exponential backoff as battery depletes.

Sending the locations from these pings likewise also uses negligible battery, as Apple already coalesces timers and network traffic like push notifications.

I don't understand the mentality where people think Apple would have announced this without doing any testing on its battery life impact.

Re: How does Apple privately find offline devices?

#47

Post by MBCook » Wed, Jun 05, 2019, 10:43 PM UTC

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.

Re: How does Apple privately find offline devices?

#48

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

machinesmachine wrote: post #34

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?

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.

Re: How does Apple privately find offline devices?

#49

Post by saagarjha » Wed, Jun 05, 2019, 10:44 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.

It's Bluetooth Low Energy, though. Should last for quite a while?

Re: How does Apple privately find offline devices?

#50

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

SlowRobotAhead wrote: post #2

>can use a single [private] key regardless of which randomized version of her public key was used to encrypt. I have not seen this before. Trying to wrap my brain around how this works. In terms of ECC I thought public and private were a single pair. Can anyone explain what is going on with public key randomization?

You can derive a new public key from someone's ECC public key, and they can derive the corresponding private key by applying the same transformation. It's somewhat magical! I wouldn't be surprised if Apple is using a scheme based on this instead of ElGamal, they already use ECC extensively.

https://github.com/bitcoin/bips/blob/master/bip-0032.mediawi...