Agreed. The whole thing seems to really miss the problem Snapchat exposed, turning an access control problem into a cryptographic problem. At least I assume this is being posted now because of snapchat.

The problem with how snapchat failed isn't so much that they weren't storing the information securely but that they had absolutely no gate on getting the information aside from a global api key. If you're running their app you've already exposed the phone numbers and are trusting them not to be too evil with them.

My expectation as a user of their service (I'm not, but if I were, and this applies to things like facebook as well, of which I am a user) is that they won't tell people I don't want to know who I am and if I'm using their service.

To this end what's needed is that before it gives another user a positive result (especially tied to my name) to my phone number it should have a reasonable expectation that I want them to have it. If they store the information that lets them derive this expectation in a way that keeps my info secure, that is also fantastic, but it's a second tier concern to becoming literally the whitepages by accident.

They are two separate problems.

The problem is that an application requests your contacts, uploads them to their server, and then who knows what they do with that information afterwards; maybe they store it, perhaps later that database is leaked, or they sell the stored information in the future.

If you trust the service you're using fully (you trust the server will not be compromised, the owners of the servers will not cave to demands to store/release data, the owners will not be malicious with your data) then this isn't a problem at all. Transmit the raw data over SSL then perform the checks and do not store the data.

Yes, this is what I'm saying. It is two separate problems but the only one people seem interested in addressing is the one that is probably not the problem for most people.

Like it or not, people do overtrust companies like snapchat. We need to change that too.

But in the mean time, snapchat's biggest and first mistake was to leave their database an open book without even having to compromise their service or servers. The people who did this used nothing that their client application doesn't use every day, and that is not an unsolvable problem at all. It's no different a problem than every single social network already has to solve, whether their users trust them to encrypt or otherwise obscure their data once obtained or not.

Yes this is a real problem. Being "paranoid about privacy" is not a yes/no decision for people to make. Different people have different things they would like to be private about and to different degrees. Some people may not want it to be possible for anyone to ever know anything at all about them. Those people don't use phones of any nature. Maybe some other people only trust phones that they build themselves. Other people are willing to trust open source software and the communities around it. Some people only care about making dragnet surveillance difficult or expensive. Others need perfect assurance of privacy because their lives are in danger. Others don't care if anyone listens to their calls.

But what you are saying is like looking at football players, seeing that they could still get hurt when they wear lots of padding, and deciding either no one should play the game or we should all play inside giant airbags.

They provide the source. Examine it and build it yourself.

To the end user probably not but if the encryption is performed on the client and the client code is open sourced and you don't auto-update your application then you'll know exactly what is happening to your data when you let it access your contacts.

Not realistic. If it's open-sourced I can go examine the code for sure, but it's not a good use of my time (and I can actually read code, but even if someone had the time but can't read code?). I also have no way of knowing if anyone else has looked at the code at all, and if they have, whether they're skilled enough to determine that the code is kosher. Again, if I struggle with that, how on earth is a non-technical-minded person even going to begin?

The second question I haven't seen asked here yet, is why we need everything to be social to start with? My social needs are covered by Facebook and Twitter, and I don't install their apps on my phone either.

Given those two things, if an app (any app!) requires access to my contacts I don't install it. Period.

You're right it isn't realistic, but it's the only way to fully know that the application is secure. Otherwise you're putting your trust in something/someone.