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I don't trust Signal

drewdevault.com

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Re: I don't trust Signal

#351

Post by tptacek »

ddevault wrote: post #347
tptacek wrote: post #312

Earlier quoted context omitted.

Did you read that work? I did: I was on the review board that made the decision to accept it for Black Hat. Could you map Yogesh's research to something Signal is actually proposing to do and explain in any detail what the actual threat you're talking about is? Thanks.

I could, but I'm probably ill informed. I want to hear your specific rebuttal to this: >Even in the idealized case, you can sniff traffic on the router to find out which user IPs are talking to each other and when.

That's a string that appears nowhere in Yogesh's research. Are you at this point conceding that the link you cited has nothing to do with this thread?

Re: I don't trust Signal

#352

Post by tptacek »

ddevault wrote: post #349
tptacek wrote: post #345

Earlier quoted context omitted.

I read your article, carefully, twice, once this morning (I briefly tweeted about it but didn't feel like I could do it justice and deleted the tweet) and again before writing this. I've read all of your comments in this thread to date and, as you can see, replied to some of them. I feel like I have fairly summarized your arguments. "It should use both", you say. Signal disagrees. That makes Signal evil, according to…

>"It should use both", you say. Signal disagrees. That makes Signal evil, according to your argument. You're oversimplifying this. For the full rebuttal, refer to the article. >Signal doesn't. You cannot know this. We don't need to have this conversation in two places, I'll just link it for others who want to follow along: https://news.ycombinator.com/item?id=17726574 >I'm satisfied that I've represented your argumen…

I don't think you understand that I can, in fact, just observe that Signal disagrees with you, without making a point-by-point rebuttal of your argument. Similarly, you don't indicate anywhere that you understand that Moxie can do the same without acting in bad faith, which is something you accuse him of doing.

You don't get to demand from strangers a debate on terms of your choosing.

Re: I don't trust Signal

#353

Post by tedunangst »

tptacek wrote: post #346
Avamander wrote: post #342

Earlier quoted context omitted.

Tell that to the VLC developers.

Not interested. I'm not litigating F-Droid and don't need to. F-Droid advocates, and some F-Droid critics, disagree: if F-Droid is implicated in an argument, we must fully adjudicate all its pro's and con's. No, that's not how the world works. I'm sufficiently well informed about F-Droid to know --- and I mean this in a benign sense, the same way I feel about OCaml or slab allocator design --- that I don't care.

What kind of monster doesn't care about slab allocator design?

Re: I don't trust Signal

#354

Post by eps »

ryanlol wrote: post #222
eps wrote: post #72

Earlier quoted context omitted.

Technically, Signal also uses homegrown crypto. The difference here was it was endorsed by Moxie's acquaintances from the crypto circles, followed by a very loud and aggressive disparaging campaign against Telegram led by some of these people. I've been on metzdowd list for a very long time and while cryptographers aren't the chummiest people in the slightest, there's always an underlying mutual respect. The Telegram…

You conveniently left out the fact that Telegram has a history of actual backdoors http://habrahabr.ru/post/206900/

This is completely unrelated to what I said.

Re: I don't trust Signal

#355

Post by lorenzhs »

xorcist wrote: post #334
bufferoverflow wrote: post #319

Earlier quoted context omitted.

Additionally, I'm pretty sure it's trivial to verify the APKs that Google Play serves are identical to the ones the devs published.

That's not the interesting question. How easy is it to verify that the APKs are built from the published source code, without any added funny business? The F-Droid devs put a lot of work on reproducible builds. Not all software complies, but with an interest in information security there's no exucse not to. That's the use case of F-Droid, and comparing it to self publishing APKs without even as much as a GPG signatur…

https://signal.org/blog/reproducible-android/ makes it very easy.

Re: I don't trust Signal

#356

Post by lmm »

3pt14159 wrote: post #316
lmm wrote: post #244

Earlier quoted context omitted.

> The HTTPS infrastructure is downgradeable and relies on DNS and a multitude of certificates. And not all the ciphers are safe. Yes it can be done securely-ish There's no reliance on DNS. We know what the right way to do HTTPS is, and an app that doesn't have to maintain compatibility with ancient browsers can use a strictly secure profile (no old ciphers, no downgrades etc.). HTTPS is older and more complex than th…

> There's no reliance on DNS. In practice there is for most situations. Are you going to get a static IP and go through the work of finding one of the rare cert authorities to get an HTTPS cert for it authorized? > Nonsense. Two layers of valid encryption are no more secure than one, and two layers of flawed encryption will almost certainly still be flawed. I hate arguing about this because I feel like there is a dif…

> In practice there is for most situations. Are you going to get a static IP and go through the work of finding one of the rare cert authorities to get an HTTPS cert for it authorized?

You don't need DNS to check whether the server purporting to be messenger.com has a valid certificate for messenger.com. An attacker who controls the network can of course cut you off entirely, but an attacker who controls DNS can't intercept you messages because that doesn't get them any closer to having a certificate.

> I agree that one of the layers should be HTTPS if the context allows for it, because it has a lot of eyes on it, as you mention; but I fail to see how layering encryption is bad from a privacy standpoint.

Do you feel safer behind two locked doors than one? I guess it can't hurt, but the effort would surely be better spent on virtually any other aspect of the system. E.g. if you double the key length in a single layer of encryption you've made it 2^128 (or whatever your key length was) times harder to crack, whereas if you stack two layers then you've only made it twice as hard.

Beyond that my argument would be: many security breaches happen because someone got confused about where the security boundary was. If you use one layer of encryption then everyone knows that the encrypted data is untrusted and the decrypted data is trusted. If you have two layers it's very easy to get lazy and introduce a small hole into one layer assuming the other will cover it, then you do the same for the other layer, and then an attacker figures out how to connect those two holes in a way you hadn't thought of and suddenly you're doomed.

Re: I don't trust Signal

#357

Post by ashooner »

ynniv wrote: post #338
ashooner wrote: post #263

Earlier quoted context omitted.

Because the theoretical possibility of being monitored on Signal is preferable to the near-certainty of being monitored on Facebook Messenger.

That's a strawman: you need to beat boring SMS and PSTN, not Facebook Messenger.

Until I started forcing them to when I quit Facebook, I had no acquaintances that used SMS, they all use FB Messenger. This is the problem.

Re: I don't trust Signal

#358

Post by lmm »

jdietrich wrote: post #341
lmm wrote: post #309

Earlier quoted context omitted.

I stand corrected - though, as another reply said, it makes little difference if you can't actually use a forked server in practice. I don't know what I could say to convince you I'm just an ordinary person concerned about my privacy, but ultimately it doesn't matter: you should definitely consider the possibility that I'm a bad actor and take nothing on faith. Equally, you shouldn't trust that Marlinspike hasn't bee…

GPG has an infinitesimally small user base. Many tech savvy users still struggle to use it correctly. Moxie has explicitly stated that his aim is not to build the perfect secure messenger app, but a messenger app that provides the greatest amount of security to the greatest number of users. He has explicitly stated that he has made some design decisions that slightly compromise the ultimate security of Signal, but ar…

> GPG has an infinitesimally small user base. Many tech savvy users still struggle to use it correctly. Moxie has explicitly stated that his aim is not to build the perfect secure messenger app, but a messenger app that provides the greatest amount of security to the greatest number of users.

But what's the threat model where Signal makes sense? For a less-than-nation-state attacker, basic TLS as virtually all messengers support is surely adequate. For a nation-state attacker, phone-number-as-ID is a bigger vulnerability than anything Signal helps with, and central servers means that Signal can simply be blocked outright in any case. If we're talking about, say, Turkey cracking down on protesters, they would probably rather those protesters were using Signal (where arresting one means you get the phone numbers - and therefore locations - of all their friends) than the likes of Facebook or Discord or what-have-you.

> Signal is not designed for you. Highly sophisticated, highly paranoid users already have a variety of options for securing their communications. Signal is designed to provide the greatest possible amount of security to the greatest possible number of users, which necessarily requires that some tradeoffs are made in the interests of ease-of-use.

I'd be fine with that if Marlinspike didn't also trash-talk those more secure tools.

Re: I don't trust Signal

#359

Post by tptacek »

Sir_Cmpwn wrote: post #350
lordlimecat wrote: post #291

Earlier quoted context omitted.

Maybe Moxie doesnt see it as his problem to address concerns of non-contributing critics. Are there any identified, non-state-level actor threats here, or is this just an ideological rant against proprietary software? If state-level actors are your concern, using android means you have already lost.

Moxie doesn't address the concerns of conctributors, either. Here's one from this very comment thread: https://news.ycombinator.com/item?id=17724893 Others have emailed me as well, thanking me for putting to words what they felt afraid to for fear of retribution from "Moxie and his religious following" (direct quote).

This kind of innuendo is beneath this thread.

Re: I don't trust Signal

#360

Post by ddevault »

tptacek wrote: post #359
Sir_Cmpwn wrote: post #350

Earlier quoted context omitted.

Moxie doesn't address the concerns of conctributors, either. Here's one from this very comment thread: https://news.ycombinator.com/item?id=17724893 Others have emailed me as well, thanking me for putting to words what they felt afraid to for fear of retribution from "Moxie and his religious following" (direct quote).

This kind of innuendo is beneath this thread.

What kind of innuendo? I don't understand.
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