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On Ghost Users and Messaging Backdoors

blog.cryptographyengineering.com

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Re: On Ghost Users and Messaging Backdoors

#41

Post by krageon »

dingaling wrote: post #40
RcouF1uZ4gsC wrote: post #3

With the spread of misinformation and rage using messaging apps that have literally resulted in people getting killed by mobs (see for example https://www.nytimes.com/interactive/2018/07/18/technology/wh... ) maybe we should re-evaluate our belief that making it impossible for governments to see what is spreading through messaging apps is an unmitigated good?

Meta, but this parent comment is a good example of the mis-use of downvoting on HN. If you don't agree with the poster then engage in debate, don't just click the little arrow to try to grey it into oblivion. We're all here to learn. Why not learn how to challenge this fairly widely-held view. Imagine you're talking with a 'normal' at a Christmas party and they say that; do you just stomp away singing LALALA?

It's possible this got downvoted because it is seen not as a misunderstanding of reality to be corrected, but in fact a harmful meme that the original poster doesn't actually believe themselves. Viewed through that lens, it certainly does deserve to be downvoted and it does not deserve to be interacted with. Not that I advocate either action.

Re: On Ghost Users and Messaging Backdoors

#42

Post by krageon »

SmellyGeekBoy wrote: post #39
rosser wrote: post #19

Earlier quoted context omitted.

That's a little hard to do in a world where this kind of thing is done by National Security Letter.

I'm pretty sure NSLs are only enforceable in the US.

Plenty of other countries have similar mechanisms, where the user is also not informed (because of a court order or similar). The US is certainly not the only culprit here, although they may or may not be the worst.

Re: On Ghost Users and Messaging Backdoors

#43

Post by zAy0LfpBZLC8mAC »

RcouF1uZ4gsC wrote: post #3

With the spread of misinformation and rage using messaging apps that have literally resulted in people getting killed by mobs (see for example https://www.nytimes.com/interactive/2018/07/18/technology/wh... ) maybe we should re-evaluate our belief that making it impossible for governments to see what is spreading through messaging apps is an unmitigated good?

And how many people need to be killed by authoritarian states or rogue elements in the government of states with totalitarian powers before we consider a possible occasional death due to lack of surveillance acceptable?

I mean, yeah, sure it's something to consider. But it's not exactly like too much surveillance hasn't ever killed anyone.

Re: On Ghost Users and Messaging Backdoors

#44

Post by Arnt »

xorcist wrote: post #38
gepoch wrote: post #23

Earlier quoted context omitted.

Yeah security is not really "proveable" in any software system. However, a few points to consider: 1. The signal server can't "see" the group. Clients are just sending N messages to everyone in the group with some encrypted metadata that says it's a group message. 2. The client app is open source. You can go look for a ghost user or backdoor mechanism yourself. 3. The build is reproduceable. You can build it yourself…

> The build is reproduceable. You can build it yourself and sideload your own APK, or compare it to the APK Have you tried this? Most people seems content that there is some source available and trust the binary. That may not be an option for everyone.

I have tried it.

There's a non-zero number of people around the world who check the builds. Your security rests on the difficulty of feeding you a subverted APK without feeding any of them the same APK.

Re: On Ghost Users and Messaging Backdoors

#45

Post by tjoff »

maxerickson wrote: post #28
tjoff wrote: post #17

Earlier quoted context omitted.

If the point of a law is to circumvent encryption you shouldn't be surprised that it doesn't satisfy anyone who wants the encryption to be safe. Either the backdoor works and the system is bad. Or the backoor doesn't work and the system is illegal. At least if the law doesn't have a loophole. So not sure why the article complains about the design whereas the intent and goal are the real issue. Seems like the design w…

Consider that the article may be written for people on the law enforcement/policy side of the debate.

Not sure what that changes. If I was law enforcement / pro backdoor I'd say that this article supports my view.

The main complaint seems to be that Over time what seems like a “modest proposal” could lead us to world where GCHQ becomes the ultimate architect of Apple and Facebook’s communication systems.

But that is of course inevitable if the proposal is to be successful. What other solution would the author propose?

Re: On Ghost Users and Messaging Backdoors

#46

Post by Spooky23 »

rosser wrote: post #19
Spooky23 wrote: post #14

Earlier quoted context omitted.

No. The state should be able to get a warrant to intercept communications for reasonable cause, and the accused should be able to litigate the validity of the search.

That's a little hard to do in a world where this kind of thing is done by National Security Letter.

You may notice that I didn’t include any advocacy for NSL in my comment.

Pretending that technology is infallible is a defect equally as bad as NSL with respect to the rule of law.

Obviously no complex IT system is infallible, and now we have a situation that with no legal remedy, the police and intelligence services are compromising or allowing latent defects to remain in order to fulfill their missions.

You never hear about law enforcement concerns with respect to iMessage or Signal, so it is likely that whatever security you think you have from the state is not meaningfully there.

Re: On Ghost Users and Messaging Backdoors

#47

Post by shakna »

Spooky23 wrote: post #14
bigiain wrote: post #11

Earlier quoted context omitted.

So we should just go ahead and put Orwell's Telescreens in everyone's house so the governments can see what we're plot^h^hannng all the time? (Looks around the office and sees the Echo and Google Home, remembers how many friends have those and/or Samsung "Smart TVs" in their home, or who have their phones constantly listening for "OK Google" or "Hey Siri". Right. As you were...)

No. The state should be able to get a warrant to intercept communications for reasonable cause, and the accused should be able to litigate the validity of the search.

Unfortunately, in the world of crypto, if the state can intercept communications, then it's equally possible that a determined attacker can. Encryption either works for everyone, or it doesn't.

Governments are more powerful actors on this playing field, but they are far from the only ones on the field.

A warrant doesn't expose something your saying to the government, it exposes what you're saying to anyone who might be listening.

We're not talking the equivalent of handing some documents over to the police, we're saying the police are ordering us to stick the documents to the window of our house so that they can see them.

Re: On Ghost Users and Messaging Backdoors

#48

Post by Tsubasachan »

merlincorey wrote: post #2

Apparently some researchers from the GCHQ in the UK are proposing that "secure" messaging systems like iMessage and WhatsApp which manage group chats centrally in a manner that bypasses the end to end encryption should: - Add "ghost" users/devices to existing chats - Suppress notifications of these additions to users This would perpetuate a currently known bug in secure communication protocols, effectively turning it…

Signal is great and all but does it scale? If half a billion people sign up tomorrow can they cope? How deep are their coffers?

Re: On Ghost Users and Messaging Backdoors

#49

Post by clubm8 »

RcouF1uZ4gsC wrote: post #3

With the spread of misinformation and rage using messaging apps that have literally resulted in people getting killed by mobs (see for example https://www.nytimes.com/interactive/2018/07/18/technology/wh... ) maybe we should re-evaluate our belief that making it impossible for governments to see what is spreading through messaging apps is an unmitigated good?

>With the spread of misinformation and rage using messaging apps that have literally resulted in people getting killed by mobs (see for example https://www.nytimes.com/interactive/2018/07/18/technology/wh...) maybe we should re-evaluate our belief that making it impossible for governments to see what is spreading through messaging apps is an unmitigated good?

People get killed by mobs in China[1] as well, a country which backdoors all major social networks (Weibo etc) + at network edge (great firewall).

https://en.wikipedia.org/wiki/Human_flesh_search_engine

Re: On Ghost Users and Messaging Backdoors

#50

Post by tivert »

Tsubasachan wrote: post #48
merlincorey wrote: post #2

Apparently some researchers from the GCHQ in the UK are proposing that "secure" messaging systems like iMessage and WhatsApp which manage group chats centrally in a manner that bypasses the end to end encryption should: - Add "ghost" users/devices to existing chats - Suppress notifications of these additions to users This would perpetuate a currently known bug in secure communication protocols, effectively turning it…

Signal is great and all but does it scale? If half a billion people sign up tomorrow can they cope? How deep are their coffers?

> Signal is great and all but does it scale? If half a billion people sign up tomorrow can they cope? How deep are their coffers?

At least $50 million, courtesy of a WhatsApp founder: https://www.wired.com/story/signal-foundation-whatsapp-brian...

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