[cryptography] Here's What Law Enforcement Can Recover From A Seized iPhone

Jeffrey Goldberg jeffrey at goldmark.org
Fri Mar 29 01:27:51 EDT 2013


On 2013-03-28, at 10:42 PM, Jon Callas <jon at callas.org> wrote:

> On Mar 28, 2013, at 6:59 PM, Jeffrey Walton <noloader at gmail.com> wrote:
> 
>> We've seen it in the past with for example, Apple and location data,

> Well, with locationgate at Apple, that was a series of stupid and unfortunate bugs and misfeatures. Heads rolled over it.

There are a couple interesting lessons from LocationGate. The scary demonstrations were out and circulated before the press and public realized that what was cached were the location of cell towers, not the phones actual location and that there was a good reason for caching that data. But I suspect that the large majority of people who remember that, still are under the impression that Apple was arbitrarily storing the the actual locations of the phone for no good reason.

The scare story spread quickly, with the more hyperbolic accounts getting the most attention. The corrective analysis probably didn't penetrate as widely.

The second lesson has to do with the the status of iOS protection classes that can leave things unencrypted even when the phone is locked. There are things that we want our phones to do before they are unlocked with a passcode. We'd like them to know which local WiFi networks they can join and we'd like them to precompute our locations so that that is up and ready as soon as we do unlock the phones. As a consequence things like WiFi passwords are not (or at least, were not) stored in a way that are protected by the device key. The data protection classes NSFileProtectionNone and NSFileProtectionCompleteUntilFirstUserAuthentication have legitimate uses, but it does lead to cases where people may thing that some data is protected when their device is off or locked which in fact isn't.

The trick is how to communicate this the people, most of whom do not wish to be overwhelmed with information.  There are lots of other things like this (encrypted backups and thisDeviceOnly, 10 seconds after lock before keys are erased, etc) that really people ought to know. The information about these isn't secret, Apple publishes it. But it takes some level of sophistication to understand; but mostly what it takes is interest.

> In neither of those cases was anyone trying to spy. In each differently, people were building cool features and some combination of bugs and failure to think it through led to each of them. It doesn't excuse mistakes, but it does explain them. Not every bad thing in the world happens by intent. In fact, most of them don't.

What's the line? Never attribute to malice what can be explained by incompetence.

At the same time we are in the business of designing system that will protect people and their data under the assumption that the world is full of hostile agents. As I like to put it, I lock my car not because I think everyone is a crook, but because I know that car thieves do exist.

Cheers,

-j


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