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Always-on Processor magic: How Find My works while iPhone is powered off

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Re: Always-on Processor magic: How Find My works while iPhone is powered off

#51

Post by dcow »

trangus_1985 wrote: post #46
dcow wrote: post #14

Is Matthew Green some industry security personality that people respect? I appreciate this write up, it's interesting. But it seems motivated by his little Twitter rant the other day. Who is he beyond some Twitizen in a Guy Fawkes mask who hates HN? I don't particularly like his demeanor, at least from his rather naively uninformed tantrum the other day. Didn't seem very professional or respectable so I just wrote hi…

"who hates HN" This site, and this community, is great in my opinion. But it's not without valid criticism, especially considering the impact it can and has made in the industry and tech society. "naively uninformed tantrum" I'm unable to find the posts you're talking about.

Sorry if my distaste for these "I'm so cool look at me go" Twitter rants is seeping out here. If you go to his profile and scroll back a few days of posts you'll find them. Anyway it looks like he's humbled and corrected himself after seeing this writeup. Maybe I'll give him another chance.

Re: Always-on Processor magic: How Find My works while iPhone is powered off

#52

Post by imglorp »

EGreg wrote: post #3

Can a faraday cage backpack work well to block any of this stuffv

Some of it. There is still the ultrasonic channel: beacons are emitted by various tv's, stores, etc. which can be used to capture location and other data and exfiltrate from the phone with the right software running. And of course the regular microphone can capture conversations and media.

If the bag is not opaque, there is still an optical channel.

Plus there are still accelerometers and magnetometers which can do rough inertial and geo location estimation.

The bag may help with some exfiltration routes, but it can store locations and other info and upload it when it gets a signal back.

Re: Always-on Processor magic: How Find My works while iPhone is powered off

#53

Post by trangus_1985 »

saagarjha wrote: post #44
trangus_1985 wrote: post #42

Earlier quoted context omitted.

They do yearly updates, the 2022 doc will very likely have more information. Regardless, the 2021 doc has some key foundations of the technology that are worth knowing. The contract tracing docs _should_ be almost the same technology, and knowing how that works _should_ be a good start. At least, from my eyeing the OP's article as a lay person.

AOP has been a thing since iPhone 6s, so they're not particularly rushed in documenting it.

I can't go too into details, but now that the AOP is doing cryptographical operations and key escrow, the internal bus is likely to show up in future documents. Maybe not the AOP but certainly the mechanisms it uses to interact with the find my network. It may also be a separate find my network whitepaper.

Re: Always-on Processor magic: How Find My works while iPhone is powered off

#54

Post by user-the-name »

nudpiedo wrote: post #5

I like a lot apple products and how they achieved popularizing many technologies, being the next one LIDAR but, for the first time ever I feel this is just going way too far. Sure I want to find my stolen phone even when it is off, but it is way too much loss of freedom having a permanent personal tracker even when the phone is off…

The Find My network is designed so that only you can track your own devices using it, nobody else can.

Re: Always-on Processor magic: How Find My works while iPhone is powered off

#55

Post by user-the-name »

notjesse wrote: post #41
Jtsummers wrote: post #25

Earlier quoted context omitted.

Apple has made it easier for users to locate lost (by being misplaced, forgotten, or stolen) devices with a feature that the user can opt out of on a temporary or permanent basis. What is controversial about this?

Many will misinterpret it. We have seen how much the public can fundamentally misunderstand technical information over the past year. People will just see that: 1. You can never disconnect your iPhone from the grid and stop it from being tracked. Even if you turn it off. 2. Governments, companies, and other (from the conspiracy theorist's standpoint) will be able find you whenever they want. I am sure there are some…

Many Hacker News people, who are prone to conspiratorial thinking will.

Regular people, not so much.

Re: Always-on Processor magic: How Find My works while iPhone is powered off

#56

Post by dcow »

sillysaurusx wrote: post #35
dcow wrote: post #27

Earlier quoted context omitted.

Somehow those bumbling buffoons over on HN found my tweet and half of them LIKE this feature. WTF! They're even discussing this thread like they like to do.

You're gonna get yourself rate limited. It's no fun.

You mean "a little bird told you I was going to get rate limited", don't worry I gotchu.

Re: Always-on Processor magic: How Find My works while iPhone is powered off

#57

Post by user-the-name »

m0zg wrote: post #37
Jtsummers wrote: post #25

Earlier quoted context omitted.

Apple has made it easier for users to locate lost (by being misplaced, forgotten, or stolen) devices with a feature that the user can opt out of on a temporary or permanent basis. What is controversial about this?

If there is such a capability (a rather technically involved one, I might add, all the way down to the silicon), do you really believe Apple can't turn it on at CIA/NSA's request without popping that dialog? And you wouldn't even know due to gag orders. And before you say this can't happen in the US, I can give you a few publicized examples of illegal spying on US citizens just in the past few years.

Even when on, the system is designed so that Apple themselves can't use it.

Re: Always-on Processor magic: How Find My works while iPhone is powered off

#58

Post by burkaman »

dcow wrote: post #31
josh2600 wrote: post #24

Earlier quoted context omitted.

Matthew Green wrote zerocash, the protocol behind zcash, and he teaches cryptography at John Hopkins. When it comes to cryptography he knows enough to have opinions. It's hard to opine about black box systems, which is why open-source is so important. It's hard to trust what you can't verify.

I don't disagree but like if you want an open system why are you using an iPhone? Maybe Green is a little guilty of slurping up Apple's privacy marketing?...

You can read more of his iPhone-related writing here: https://blog.cryptographyengineering.com/category/apple/

I'm not sure how concerned he is that it's closed source, I think in this case he was just surprised that the implementation details and security considerations weren't documented anywhere: https://twitter.com/matthew_d_green/status/14433822078386217...

Note that he was relatively positive about this feature when it came out two years ago: https://blog.cryptographyengineering.com/2019/06/05/how-does.... It seems like the motivation for this tweet was "wow I do a lot of iPhone security research and I didn't know this worked when the phone is off, I'm surprised Apple doesn't document the details of this anywhere." Remember that it's hard to interpret tone through the internet, and as someone that doesn't get a ton of engagement on Twitter, he probably doesn't feel like he's writing for a mass audience.

Re: Always-on Processor magic: How Find My works while iPhone is powered off

#59

Post by Jtsummers »

m0zg wrote: post #37
Jtsummers wrote: post #25

Earlier quoted context omitted.

Apple has made it easier for users to locate lost (by being misplaced, forgotten, or stolen) devices with a feature that the user can opt out of on a temporary or permanent basis. What is controversial about this?

If there is such a capability (a rather technically involved one, I might add, all the way down to the silicon), do you really believe Apple can't turn it on at CIA/NSA's request without popping that dialog? And you wouldn't even know due to gag orders. And before you say this can't happen in the US, I can give you a few publicized examples of illegal spying on US citizens just in the past few years.

People have been carrying around portable GPS devices in their pockets for over a decade now. This threat is not new, and if you fear it, don't carry around a GPS device or one that will connect to other devices to get its location reported to a central server.

Re: Always-on Processor magic: How Find My works while iPhone is powered off

#60

Post by semi-extrinsic »

eminence32 wrote: post #48

It's also interesting that this low-power mode is sufficiently low power for Apple to be feel comfortable sipping battery power continually. Any guesses about how much power this mode actually uses?

Other Bluetooth LE devices like an AirTag can last beyond one year on a CR2032 battery, so consuming about 2 milli-watt-hours (mWh) per day.

An iPhone has at least 10 000 mWh battery capacity (depends on model), so in 1 month something like this consumes around 0.6 percentage points of battery.

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