My Take on FBI's “Alternative” Method
zdziarski.com
zdziarski.com
When we get a failed SSD, I would read the internal logs and try to root cause it. Sometimes, we have to power up the firmware or change contents of the NAND to help determine the root cause and the concern is the problem is no longer reproducible. By keeping a backup, I have a good chance of recovering things back to the original state.
Having a backup gives me lots of freedom to experiment. I've seen weird multi-factor failures where a batch of NAND parts would fail due to high temperature, with particular data pattern written using specific commands. One of those things that even manufacturing screening could catch in reasonable time. Debugging these failures was always one of those moments where I would go in wondering "what the heck is going on" to ... "ah now it makes sense."
So with this technique, assuming the iPhone has no other persistent media, they could save the contents, attempt a password unlock and then restore the NAND contents when it gets too many retries.
As for ways to thwarts these attempts, most NAND memory have a pseudo OTP section and unique serial numbers which could be combined to make things more difficult. But these were not meant for cryptographics secure protection so I'm sure someone could find a way around them.
Do you accept our authority? You defy it? Okay, the misdemeanor we charged you with, if you don't plea we will file an unrelated felony against you.
Oh you resisted, oh you showed the evidence we have against you actually exonerates you?
Okay, the prosecution moves to withdraw the case citing lack of evidence. We won't give you the opportunity to win against us.
(This happened to me when I was a kid. I won my case. The FBI is acting just like that. Threaten and lie, then when everyone doubts them, they run. But as they run, I run after them faster, and in the end they lose.)
Yes indeed, let's not forget that nobody cares about this particular phone! FBI has got archives until 6 weeks ago, they should have had full access, hadn't they fucked up (or sabotaged?), and it's a professional phone that's most unlikely to contain anything interesting anyway.
The FBI thought it has a perfect opportunity to establish a precedent: Apple wouldn't fight against this case, because TERRORISM! It looks like it's failing, so of course they won't help establish a precedent against them.
If you have a hammer, everything looks like a nail; and if you're a techie, everything looks like a technical issue. But this is not a technical issue, it merely masquerades as one.
The iPhone's NAND Flash is in BGA packaging and de-soldering / soldering aren't too much of an issue for a skilled technician (even Foxconn workers can do it!)
And did the timing suggest this "3rd party" in the far east? Sunday night in the U.S. is day time in the far east.
This is getting interesting!
I read those posts and was interested ... and I am sorry to digress now in this thread, but:
If you upgrade your iphone with an amount of memory that no iphone has ... what does iOS do ? Does it care ? Does it object ?
If I upgraded a 16GB to a 32GB, I would expect iOS not to notice or care. However, I would be worried about upgrading a 32GB to, say, a 128GB, which is a flash memory size that no iphone SE ships with.
What does iOS do ?
You have to also consider the memory chip availability at that specific size and BGA packaging - since Apple is a top consumer of those flash memory chips with only 32GB, 64GB and 128GB in sizes (omitting 8GB/16GB), the production of of those memory chips might very well be coming in ONLY those sizes due to the economies of scale in manufacturing cost.
This seems like very flimsy logic. Not to say that an NSA 0-day is clearly the answer, but ruling it is non-sensical. Both the NSA and FBI are well are well practiced with "parallel construction": http://www.dailydot.com/politics/nsa-dea-fbi-snowden-doj-oig...
It's only a poor choice if there's anything worth securing on the phone, and most people think that there's not, he destroyed his personal phone while leaving this phone intact.
In any case, most people unlock their phone dozens of times a day, perhaps hundreds of times a day (for some). So expecting users to use a secure passphrase as an unlock code is unreasonable. It seems that it would be better to have a 2 stage system -- if the phone hasn't been unlocked with the passcode in X hours (user configurable), then it has to be unlocked with the secure passphrase -- even if someone knows the passcode the phone can't be unlocked with it after that timer expires. And on reboot, only the passphrase should be accepted.
So someone that unlocks their phone frequently can use a simple passcode, but once the phone has been out of their possession for a few hours, only the passphrase can unlock it.
What you describe is essentially how Touch ID works on newer iPhones, just with your fingerprint as the simple passcode. On a fresh boot, you have to put in your full passphrase, and every 48 hours after that. After you put in your passphrase, fingerprint unlock is available until either you turn the phone off, 48 hours passes, or fingerprint authentication fails five times in a row.
Unfortunately, the 48 hours thing isn't configurable, so it's not quite perfect, but it's pretty decent.
Certainly for me, it has immensely improved the security of my phone. In situations where I don't trust the fingerprint authentication (e.g. crossing an international border), I can just shut the phone off. Otherwise, it provides "good enough" security. Yes, there are potential attacks on the system, by copying my fingerprints and replicating it, but the five-attempt limit and the 48-hour timeout are good enough. For me, it's a vast improvement over what came before, when I had a passcode of 0000 just to satisfy some apps that wouldn't offer certain features unless a passcode was set.
There are some improvements I'd like to see. The timeout should be customizable. I'd like to be able to set up a "duress fingerprint" which immediately disables fingerprint authentication, as an easier alternative to turning off the phone. But overall it seems like a good blend of security and usability.
I like your idea of the duress fingerprint since the police can demand that you supply a fingerprint to unlock a device (but can't demand a passphrase). If you use the wrong one then "Oops, I was so stressed out I forgot which fingerprint to use".
I really think it's unlikely that law enforcement will ever take an interest in my phone, yet I still like knowing that my data is my data.
There are cases where a judge can force you to supply a password.
I personally just don't use the tip of my thumb, so unless you knew that I would just try it 5 times and lock out touch id.
Coercion codes would certainly be a great next step for Apple to implement, not just with fingerprints but with actual pass phrases/PINs as well. Ideally a coercion code system would allow a couple of different levels of response depending on a user's needs and the situation they faced. For example, one simple PIN/finger print could just revert the system to needing the full passphrase, while another (or a longer passphrase for that matter) could cause the machine to activate pre-scripted actions, wipe itself, or even simulate a malfunction.
For what it's worth you can actually already do a limited version of this under iOS if you jailbreak. Touch ID can handle up to five separate fingerprints, and in vanilla iOS AFAIK any successful read is the same as any other in terms of system action. Interestingly however, internally Apple actually registers a separate system event for each different finger. Either writing your own tool or using a tweak like Activator, you can thus set different fingers to trigger different actions, including shutting down/rebooting the device (which in turn activates a long pass phrase) or running a script (which allows alerts, photos, erasure, boot looping, or potentially even something proximate to bricking via messing with nvram).
I'm actually quite curious what, if anything, Apple plans to do with Touch ID in the future because they've clearly left themselves some flexibility in the underlying system that I don't think they're presently using anywhere in iOS. Maybe they're more leaning towards features like "select a different payment system with a different finger" or "unlock and launch straight into a favorite app with different fingers", or even some form of multiuser access based on different finger prints, but if Apple decided to start implementing features against rubber-hose cryptanalysis in iOS 10 it'd genuinely be pretty exciting. I'm not aware of any mainstream consumer electronics even attempting anything like that yet, though if anyone has some existing/historical examples I'd really love to read about them.
Sadly, it's not straightforward to make a remote reboot-phone button that's usable by the general public.
[0] IIRC, calling halt(8) from the shell didn't work, either.
I have fingerprint set up to unlock the screen - but at least once a day ill have to enter the passphrase and it wont accept fingerprint. It says something like "for additional security, please enter your passphrase" instead of "finger moved too fast" or whatever
Every reboot you have to use the passphrase to unlock the phone the first time.
I dont see any options for configuring the time period when it asks for the passphrase again though.
I would like to be able to shut down the phone when the risk of attacks/theft/loss is high, knowing that a high-entropy password protects it, but without having to enter it all the day.
A simpler and more likely explanation is that the FBIs lawyers, having overreached, have gone back on an earlier lie and concocted a new lie: Oh yeah, we need just a couple weeks to try this out. (And for the furore to die down.)
Don't let these little John Yoos off the hook. They are over-aggressive, unethical, and unprofessional.
In a Congress where the majority (!!!) does not believe that humans contribute to climate change, it's rare to find someone who actually thinks. Congratulations to Rep. Issa for his role in protecting our Constitutional rights.
My broader point remains that in general, Rep. Issa takes the time to analyze things and write about them, often bringing up issues that are otherwise neglected. Even in his support of the PATRIOT act, he lodged unique complaints about the constitutionality of the law under the fourth amendment.
On the other hand, I think that the vast majority of politicians from any party with any views in Congress are so ridiculously brain-dead that I could not vote for them either, even if they were a carbon copy of me on the issues.
There are only 100 US Senators, and they make the most important decisions in the US. If an important decision came down the line, I have no hesitation saying that the vast majority of senators with my viewpoints would make a ridiculously uneducated, stupid decision.
Given how sharply Issa diverges from me on pretty much all issues, it's very likely that his decision on any topic would be something I disagree with strongly. It might drive climate change in the wrong direction, it might discriminate (in my view) against certain people, and any related law may be something that I spend quite a bit of time and money fighting against (I say this as someone who is very politically active.) But I have no doubts it would be an intelligent, researched decision.
Also wonder if any of that "wear and tear" would show up in the circuits that detect taps. Again, if only specific places on the screen are tapped for the pin (never changed) it may leave enough evidence somewhere somehow at the molecular level.
Anyone here with knowledge in this area that could debunk or validate this concept?
They might be calculating that it's too risky now, and this is the cleanest way out without losing face.
They may not even care if the alternative method works or have a viable one.
Or:
https://webcache.googleusercontent.com/search?q=cache:8zcNEr...
So manufacturers are helping them break in earlier by providing early access? Why would they do that?
I would speculate that the relationship is either commercial in nature, or that it also serves as a pentest to prevent things like unlocking/jailbreaking contract phones.
Maybe Apple got hit with an NSL and were actually required to backdoor their products? Now Apple is delivering the full encryption keys to interested parties? </conspiracy theory>
I know it's silly, but the coincidence of the release of iOS 9.3 and the FBI backing off from its position was striking.
The more reasonable theory is, of course, that the FBI realized that they overstepped their boundaries and put a tool they've used for decades ex parte at risk of being taken away from them by butting heads with a determined adversary.
AFAIK there is no law requiring them to do so... (?)
Is there nothing like this for Flash memory?
Is this some bastardized take-off of responsible disclosure? Why the hesitation in naming the suspected firm?
There are thousands to ten of thousands commercial forensic companies (domestic and international; not including Shenzhen one-man shops) that can de-package a chip and hook into the ARM AHB.
(Yes, I know, gov't agencies are probably exempt from DMCA enforcement and/or the FBI doesn't really care if they're violating it anyway).
Which, as I said, refers to encryption protecting copyrighted works as a means of control.
Edit:
>a technological measure "effectively controls access to a work" if the measure, in the ordinary course of its operation, requires the application of information, or a process or a treatment, with the authority of the copyright owner, to gain access to the work.
So encryption that doesn't depend on the authority of a copyright owner isn't affected.
JTAG can be used to inject test data into device. Basically you put data into device flip-flops (registers) by shifting a long series of bits into special port. Then you perform a single step (computation of a function) and read resulting state from registers back.
I think it is possible to inject PIN attempts into device and prevent device (by resetting it instead of performing step) to write over the key. Or even simpler - I think it is possible to read the key from device by JTAG operations.
However Apple allows something like a 35-char max with numbers and letters so in the worst case they will never crack it.
After they enter the 4-digit passcode, then they can enter the new iCloud password.
It would be more believable to me that FBI will try to steal the Apple's secret signing key or to bribe the Apple engineers in two weeks.
NAND mirroring is hard, but not impossible. (Whether the FBI can do it may be approaching absurd.)
I leave judgement of the ethics of the practice and integrity of the organization as an exercise to the reader.
Doing it with legally-provable assurance that you won't permanently screw it up, and proving chain-of-custody issues along the way, is hard.
Problem- every holiday your phone thinks youre a phonethief
I think that kind of approach would be better handled by implants or wearables like watches with super long battery life but Bluetooth tokens already so most of that with half the invasiveness.
Two-factor where your phone supplies the second-factor over a sidechannel if you're in the right place, doing the right thing, at the right time.