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What is Differential Privacy?

blog.cryptographyengineering.com

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Re: What is Differential Privacy?

#91

Post by tjl »

xufi wrote: post #9
tjl wrote: post #6

Earlier quoted context omitted.

They talked a bit more about differential privacy in the State of the Union. Basically, they hash the data and add noise. By collecting data from a bunch of people that noise gets averaged out. They also limit the amount of samples (over a relatively short period of time) they can get from a single person so they won't be able to identify them.

Intersting. That's a smart way to collect data while not having too much noise flood in the dataset. I need to watch this State of the Union.

https://developer.apple.com/videos/play/wwdc2016/102/

You can find all the videos from WWDC 2016 some time after the session is done. I usually check the next day. They have the videos for several previous WWDCs up as well.

Re: What is Differential Privacy?

#92

Post by [deleted] »

kbenson wrote: post #49
spullara wrote: post #46

Earlier quoted context omitted.

Steve Jobs was pretty passionate about this and they are continuing on with it. http://www.recode.net/2016/2/21/11588068/heres-what-steve-jo...

Sure. But you can replace Apple in my comment with Jobs, and it would apply equally as well, had Jobs not passed away. The article you reference points this out specifically: > His comments arrived as Apple started to identify Google, and its ascending Android operating system, as its chief competitor. Here we see the first signs of the hardware seller deploying its privacy position as a branding and competitive tact…

[deleted]

Re: What is Differential Privacy?

#93

Post by tjl »

fauigerzigerk wrote: post #80
johncolanduoni wrote: post #76

Earlier quoted context omitted.

It doesn't have to support that prediction in specific instances, just in a general trend, where random noise tends to average itself out in a lot of cases. There are lots of different distributions with the same averages, the same conditional probablities, etc. with wildly different data. If you have some mathematical proofs that say you can not reach one of these other distributions by injecting random noise to mas…

I don't doubt the validity of Dwork's work. I think we're talking past each other. What I'm saying is that if Apple keeps data on its servers that is sufficient to predict some of my actions or likes with any accuracy greater than 50%, then that is a privacy concern. But if you're saying that the data in Apple's database does not have any predictive power on its own, then I agree that it is not a privacy concern. In…

I believe that's how it works.

They even limit the number of samples they get from a specific person so they can't filter out the noise for that person and get their individual response.

But, keep in mind that Apple will have records of all your iTunes rentals and purchases at least for billing purposes. However, at least in the US there's a law about keeping that data private (because of Robert Bork).

https://epic.org/privacy/vppa/

Re: What is Differential Privacy?

#94

Post by ianmiers »

This is something Apple really needs to release all the details of. Even if they got the crypto exactly right, they could have picked a privacy budget/ security parameters that just leaks everything.

And there is every reason to be skeptical about Apple's ability to design even mildly complex crypto given iMessage's flaws. Although the break in iMessage wasn't practically exploitable, that was luck and the fact that the only way to detect if a mulled ciphertext decrypted required attachment messages. The cryptographic mistakes were bad. Given any way to detect decryption of mulled ciphertexts for standard messages (e.g. sequence numbers, timing, actively synching messages between devices, delivery receipts from iMessage instead of APSD), Apple's crypto design bugs would have eliminated nearly all of the E2E security of iMessage.

Remember, this isn't a boon for user privacy. Apple is now collecting far more invasive data about users under the claim that they have protections in place. At best it preserves the status quo and does so only if Apple both picked the parameters correctly and implemented it correctly.

At this point Apple's position should be best summed up as: we have drastically reduced your privacy except not because magic that we (i.e. Apple) do not fully understand.

Re: What is Differential Privacy?

#95

Post by Natanael_L »

Twisell wrote: post #84
Natanael_L wrote: post #83

Earlier quoted context omitted.

AFAICT only storage is encrypted. They decrypt server side.

Do you suggest that Apple is blatantly lying in the article I just cited?

https://www.apple.com/privacy/approach-to-privacy/

> All your iCloud content like your photos, contacts, and reminders is encrypted when sent and, in most cases, when stored on our servers. All traffic between any email app you use and our iCloud mail servers is encrypted. And our iCloud servers support encryption in transit with other email providers that support it.

> If we use third-party vendors to store your information, we encrypt it and never give them the keys. Apple retains the encryption keys in our own data centers, so you can back up, sync, and share your iCloud data. iCloud Keychain stores your passwords and credit card information in such a way that Apple cannot read or access them.

The End.

I always find it amusing when people downvote me for telling them Apple is doing what they admit to be doing.

Re: What is Differential Privacy?

#96

Post by 7Z7 »

hfsbtnye wrote: post #16
forgotpwtomain wrote: post #7

Earlier quoted context omitted.

> I only wish that they would go ahead and put everything under a free software license, since they're in the business of selling hardware that's coincidentally bundled with their software. That's never going to happen. Apple sells a 'User Experience' not just hardware - having a complete and mostly closed product is an inevitable consequence of the former - and the number of Linux users that would buy a Macbook isn'…

In what way does changing the software license impede user experience? No other company would have the proverbial balls to straight up copy their software either.

>No other company would have the proverbial balls to straight up copy their software either.

How can you say this looking at the hardware landscape?

Re: What is Differential Privacy?

#97

Post by kbenson »

peteretep wrote: post #60
kbenson wrote: post #41

Earlier quoted context omitted.

> the cultural difference Apple claims is "we consider privacy in everything we do" I'm pretty sure that should be interpreted as "we've determined privacy is a differentiator in the market, so as of some indeterminate time in the past, ranging from a few years ago to our inception, we consider privacy in everything we do." Now, there's nothing wrong with that, and that's not to say they haven't been privacy consciou…

If Tim Cook wasn't part of a frequently and historically persecuted minority, I'd be more cynical too.

I don't see it as being cynical, just as being rational. People rarely have a single motivation for their actions, even if they may report a singly motivation if asked (possibly the primary reason, or the one they feel comfortable talking about). I don't see why this would be any different for a corporation, generally being made up of many people.

Like I said, there's nothing wrong with this. We just need to be sure we don't fall into the trap of thinking we can take what is presented at face value as the whole story, just as you can't when dealing with individuals much of the time. Apple is not our trusted old friend, that will look out for our best interests. They are at best an acquaintance that we have a business relationship with. That doesn't mean they won't act in a manner we appreciate, but it does mean we should not assume they will act as a good friend.

Re: What is Differential Privacy?

#98

Post by aub3bhat »

cyphar wrote: post #10
aub3bhat wrote: post #8

Earlier quoted context omitted.

Good luck selling that to doctors. People who are trained to cut open a patient aren't receptive to hypothetical harms and imaginary "budgets". Consider the fact that cause of death records are public. The usual perception of privacy by theory and security researchers and norms practiced in healthcare differ enormously.

The point of differential privacy is to allow for aggregate analysis, without destroying the privacy of outliers. Researchers deal with noise all the time, so is it so odd that a field of researchers believe that adding enough noise to data released with studies will allow for conclusive analysis without ruining privacy for individuals?

As someone with access to data on 50 million patients and having studied aggregation of medical data for last 5 years I can assure you that its not easy as it sounds.

The amount of noise that "theoretically guarantees" privacy protection in terms of epsilon renders any reasonable analysis impossible. E.g. How about CDC telling you that there are 0 - 2000 cases of Ebola in Massachusetts.

There are theoretical guarantees provided by Differential privacy and then there are actual requirements of conducting public health or biostatistical reaseach with certain evidence value. The gap between the noise added by the former and tolerated by the latter is enormous.

Re: What is Differential Privacy?

#99

Post by mnem »

ianmiers wrote: post #94

This is something Apple really needs to release all the details of. Even if they got the crypto exactly right, they could have picked a privacy budget/ security parameters that just leaks everything. And there is every reason to be skeptical about Apple's ability to design even mildly complex crypto given iMessage's flaws. Although the break in iMessage wasn't practically exploitable, that was luck and the fact that…

Apple have designed/implemented several quite successful crypto and security systems too.
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