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Why can't Apple decrypt your iPhone?

blog.cryptographyengineering.com

41–50 of 132 posts

Re: Why can't Apple decrypt your iPhone?

#41
post #27

> The Secure Enclave is designed to prevent exfiltration of the UID key. On earlier Apple devices this key lived in the application processor itself, and could (allegedly) be extracted if the device was jailbroken and kernel patched. Speaking as a jailbreaker, this is actually incorrect. At least as of previous revisions, the UID key lives in hardware - you can ask the hardware AES engine to encrypt or decrypt using…

Technically, this sounds about right (am mostly a n00b though) but the comments on this thread seem to me terrifyingly naive for a post-Snowden world. Apple has semi-convincingly denied the presence of a few, very specific attack vectors, and the article is speculating about the details of those denials, which is all well and good.

But it is an absolute certainty that communications technologies built and operated by major American industry are wholly compromised. To believe otherwise is to grossly misunderestimate the nature of State intelligence actors. The historical record is clear that big telecom + hardware providers have always been in bed with State power, both in America and elsewhere, and the Snowden docs pretty clearly show that's still true today.

Maybe Apple's announcement means that the county sheriff can't read your teenage son's weed-dealing text messages. But if bin Laden had an iPhone, the men in the windowless buildings would beyond a shadow of a doubt be reading his communications, probably via seven or eight independent attack vectors (not counting the compromised publicly switched telephone network, over-the-air signals, etc.)

If you have secrets, keep them off of communication technologies run by large companies. Especially when those technologies are 100% closed source and the companies in question have openly admitted including backdoors in previous versions of the tech you're currently using.

Re: Why can't Apple decrypt your iPhone?

#43
post #17

If someone obtains your phone, and prevents you from initiating a remote wipe (perhaps they have you in custody, or perhaps they have isolate the phone so that it cannot receive the wipe command), it sounds like this technology will do a good job of preventing them from decrypting your data from the phone if you have a decent passcode. They cannot throw GPUs or FPGAs or clusters or other custom hardware at the proble…

Yes, currently iCloud backups are not encrypted so they can be extracted by law enforcement, but on the other hand they are not mandatory, as Apple also offers a full local backup solution through iTunes (albeit, admittedly, they could make it work automatically like Time Machine, instead of manually; I guess they'll get there, now that they're using privacy in marketing). On the other hand, it is perfectly possible…

That would be better and it would prevent certain types of attacks. But at the end of the day you cannot verify what software is running on the phone so circumventing encryption for targeted individuals remains trivial.

Re: Why can't Apple decrypt your iPhone?

#45
post #38

Is Apple's "Secure Enclave" anything more than ARM's TrustZone? http://www.arm.com/products/processors/technologies/trustzon...

Contrary to speculation ( there are whole articles which "explain" the secure enclave to be ARM trustzone) secure enclave is documented ( only very recently) to be a _seperate_ chip inside the A7 chip running it's own L4 based microkernel. (From https://www.apple.com/privacy/docs/iOS_Security_Guide_Sept_2... ) " The Secure Enclave is a coprocessor fabricated in the Apple A7 or later A-series processor. It utilizes it…

That's pretty much exactly how AMD implements TrustZone. http://www.anandtech.com/show/6007/amd-2013-apus-to-include-...

Re: Why can't Apple decrypt your iPhone?

#46

Now if only it was possible to turn off remote installation of applications on both iOS and Android devices, this kind of security would actually mean something. Right now, you can do full disk encryption on an Android device (which seems likely to become hardware-assisted on future devices similar to the solution mentioned in the article). If you pick a sufficiently strong passphrase, that should keep your data secu…

I've been thinking about the possiblity of commercial software updates being used as an attack vector to overcome WDE. Could you imagine if the NSA went to Apple or Microsoft and said "push this compromising update to computers from this IP address/MAC address/serial number"?

That's quite possibly no longer a theoretical scenario at this point. It would really surprise me if you were the first person to think of that trick (it's pretty obvious) and that + gag orders would do nicely. Parallel construction to plug any holes in case someone wises up that this is already done in practice.

Re: Why can't Apple decrypt your iPhone?

#47

Now if only it was possible to turn off remote installation of applications on both iOS and Android devices, this kind of security would actually mean something. Right now, you can do full disk encryption on an Android device (which seems likely to become hardware-assisted on future devices similar to the solution mentioned in the article). If you pick a sufficiently strong passphrase, that should keep your data secu…

As far as I know, it can install an app but not run it (EDIT: on Android, that is). So it shouldn't be able to do any such decryption.

It could be an update of an app that runs by default, or an update of a core component of the OS.

Re: Why can't Apple decrypt your iPhone?

#48

Earlier quoted context omitted.

Yes, currently iCloud backups are not encrypted so they can be extracted by law enforcement, but on the other hand they are not mandatory, as Apple also offers a full local backup solution through iTunes (albeit, admittedly, they could make it work automatically like Time Machine, instead of manually; I guess they'll get there, now that they're using privacy in marketing). On the other hand, it is perfectly possible…

That would be better and it would prevent certain types of attacks. But at the end of the day you cannot verify what software is running on the phone so circumventing encryption for targeted individuals remains trivial.

Agreed, but that's true of any system where you regularly install updates without checking and compiling them one by one, and that cover most computers nowadays.

Let's say I have infinite resources and I want to target your Debian server; it's sufficient to bribe one Debian maintainer of a default package and you're basically doomed. Until they don't get to the point of reproducible builds and don't embed something in apt to make sure the build is correct, you still need to trust the whole Debian community.

Any time you run an operating system released by a vendor, you're basically trusting the vendor. It doesn't strictly have to be like that for FLOSS systems, but it is like that right now.

So your comment is indeed correct, but doesn't specifically highlight a defect in iOS.

Re: Why can't Apple decrypt your iPhone?

#49
There's another technical surveillance method here that I feel more people should be talking about: monitoring iMessage communication.

iMessage is extremely secure[1], except for the fact that Apple controls the device list for iCloud accounts. The method would simply be for Apple to silently add another device to a target's account which is under law enforcement's control. I say "silently" in that they would need to hide it from the target's iCloud management UI to stay clandestine, but that's it, just a minor UI change. iMessage clients will then graciously encrypt and send a copy of every message to/from the target to the monitoring device.

This would still work even with impossible-to-crack encryption. It wouldn't allow access to old messages, just stuff after the monitoring was enabled. It's the modern wiretap.

It mirrors wiretapping in that sufficiently sophisticated people could discover the "bug" by looking at how many devices iMessage is sending copies to when messaging the target (just inspecting the size of outgoing data with a network monitoring tool would probably suffice), but it would go a long way and probably be effective for a high percentage of cases.

The main thrust of the article is that encryption is not new, just the extent of it, particularly iMessage. Here's a way around that.

[1] http://images.apple.com/iphone/business/docs/iOS_Security_Fe...

Re: Why can't Apple decrypt your iPhone?

#50
post #38

Earlier quoted context omitted.

Contrary to speculation ( there are whole articles which "explain" the secure enclave to be ARM trustzone) secure enclave is documented ( only very recently) to be a _seperate_ chip inside the A7 chip running it's own L4 based microkernel. (From https://www.apple.com/privacy/docs/iOS_Security_Guide_Sept_2... ) " The Secure Enclave is a coprocessor fabricated in the Apple A7 or later A-series processor. It utilizes it…

That's pretty much exactly how AMD implements TrustZone. http://www.anandtech.com/show/6007/amd-2013-apus-to-include-...

It sounds more like they are using a Cortex-A5 to gain access to TrustZone with an existing x86 core.
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