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Why I won't recommend Signal anymore

sandervenema.ch

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Re: Why I won't recommend Signal anymore

#91

Post by qwertyuiop924 »

heavenlyhash wrote: post #90
qwertyuiop924 wrote: post #82

Earlier quoted context omitted.

I heard from another thread that Matrix is bad a realtime messaging, and quite slow at it. Is this true?

Not even remotely. It's quite good at realtime, and especially reliable realtime. Compared with protocols like XMPP, Matrix scores way higher on reliability because it has message IDs and message ordering baked into the protocol, so it can actually converge on a correct state after network flakes. (I consider this a pretty big deal because silent message drops were a pretty regular issue for me in XMPP, and we all kn…

Ah. It was claimed by https://news.ycombinator.com/item?id=12880856, but that was an XMPP developer, so there's a bias.

Re: Why I won't recommend Signal anymore

#92

Post by wtbob »

SapphireSun wrote: post #39
kuschku wrote: post #28

Earlier quoted context omitted.

The biggest argument is that there is little of a difference between Signal and Telegram or Signal and WhatsApp for the user if they are forced to use the official servers, and those servers get to store their entire social graph.

Here's what Moxie said about this issue: https://whispersystems.org/blog/contact-discovery/

And here's my write-up of how a private set-intersection protocol could be used to enable users to securely swap contacts: https://news.ycombinator.com/item?id=11289223

It's a solved problem, but Signal doesn't implement it.

Re: Why I won't recommend Signal anymore

#93

Post by wtbob »

Joeboy wrote: post #16
reacharavindh wrote: post #6

This. I didn't know much of the insides of Signal. But, When WhatsApp decide to go in bed with FB to share my contacts and usage, one of the alternatives I explored was Signal. Threw it out the moment it asked for ownership of my contacts (no way to opt out). I for one am not going to trust a guy's pinky promise to be good with my contacts and meta-data. If I'm going to give up the convenience of reaching anybody by…

I doubt you'd want to use it if it didn't use your contacts, though. Not many people are prepared to deal with a whole separate set of contact ids for the sake of a small amount of arguable extra privacy.

It's entirely possible for Signal to work with contacts and yet not transmit address books to OWS. I sketched out a protocol for doing so awhile back: https://news.ycombinator.com/item?id=11289223

So people could use their address books securely if they wanted — if OWS would allow them.

Re: Why I won't recommend Signal anymore

#94

Post by qwertyuiop924 »

snvzz wrote: post #87
qwertyuiop924 wrote: post #76

Earlier quoted context omitted.

>the DHT addresses your contacts gave you are actual ec25519 public keys. For nontechnical users, that's a massive downside. The first tox client to integrate ToxMe into itself will get very popular, very fast, provided it's got the right marketing.

> For nontechnical users, that's a massive downside. I disagree entirely. It's an upside. They get to benefit from PKI without even understanding anything. A person's address gets them the actual person. ToxMe requires trusting the ToxMe identity provider, and is an obvious point of attack. And we'd no doubt see fake addresses that resemble other peoples, and other such nonsense. There's minimising the inconvenience…

>I disagree entirely. It's an upside. They get to benefit from PKI without even understanding anything. A person's address gets them the actual person.

Yes, but which messaging service will the nontechnical user use? The one where they can exchange usernames, or even phone numbers, and it Just Works? Or the one where they have to give their friends a long alphanumeric sequence of gibberish?

It doesn't benefit them if they don't use the protocol.

>ToxMe requires trusting the ToxMe identity provider, and is an obvious point of attack. And we'd no doubt see fake addresses that resemble other peoples, and other such nonsense.

Obviously. This is why it's a bad thing that nontechs will probably go in that direction, if they use Tox at all.

>(with ideas like the QR code feature they have)

I was hoping somebody had implement QR: that helps a lot, but I'm not sure if it's enough...

Re: Why I won't recommend Signal anymore

#95

Post by heavenlyhash »

qwertyuiop924 wrote: post #91
heavenlyhash wrote: post #90

Earlier quoted context omitted.

Not even remotely. It's quite good at realtime, and especially reliable realtime. Compared with protocols like XMPP, Matrix scores way higher on reliability because it has message IDs and message ordering baked into the protocol, so it can actually converge on a correct state after network flakes. (I consider this a pretty big deal because silent message drops were a pretty regular issue for me in XMPP, and we all kn…

Ah. It was claimed by https://news.ycombinator.com/item?id=12880856 , but that was an XMPP developer, so there's a bias.

It's true that it's a big hunk of JSON. And I'll readily concede that when efficiency matters, I'm more partial to binary formats like CBOR. But XMPP is XML, which... isn't exactly lighter.

There's another HN thread where I've talked more about XMPP vs Matrix here: https://news.ycombinator.com/item?id=9772968 -- long story short, I tried to write an XMPP client, and I got grey hairs, fast. The story for consistent delivery is pretty much bananas. (And huh, based on that date, I guess I've been a Matrix convert for almost TWO years now! Time flies.)

I'm not entirely sure what the comment about battery is about either. If anyone has a networking technology that can work without turning on the phone radio, I'm sure we'd all love to hear it...?

Practically speaking, I leave the Matrix Vector app open on my phone constantly. As of this morning, I have half a charge, and three more days of charge to go. I don't have any other apps to provide a good comparison here, but I'll leave this screenshot here for what it's worth: https://matrix.org/_matrix/media/v1/download/matrix.org/IgkU... Looks like my phone has spent about the same order of magnitude of battery on just plain paging the cell towers as I moved around the city. As other comments on this thread cover, if you use proprietary Google stuff, you can wake the phone up slightly more efficiently. But whatever this app is doing works pretty fine for me.

Re: Why I won't recommend Signal anymore

#96

Post by darklajid »

zigzigzag wrote: post #43

Like a lot of crypto-puritanism it is rather mixed up. He says he recommended Signal because it was easy to use (more consumer friendly I guess) and secure, then says he wouldn't have gone in the direction of making it easier to use and criticises the things that make it user friendly, like using phone numbers instead of usernames. He says he thinks the protocol is secure, then says he doesn't want it to use GCM beca…

I'm not a cryptographer. I .. am reasonably sure that no one would take me for a hipster.

But two issues - or call it 'differences in opinion' - in that article are relevant for me: The inability to use the service without a mobile number and federation.

I understand the rationale behind the former ("It's easier"), but I don't understand why it is mandatory. I could've been 1283783127356128531312 on Signal and optionally add my phone number to that identity for others to find me (and optionally let Signal use my contacts to search for someone). That could even be the default, opt-out during registration. But right now, I'm basically using my phone number, which I really hate to do.

Federation is probably hard to get right, and looking at Eric Lippert's "Every feature idea starts with -100 points" rationale I guess it is understandable that this isn't a thing. But I don't want to join another silo, even if it's the best of the crop so far.

For users like me, Signal, WhatsApp and yes, Telegram are basically the same thing, come with the same set of limitations and I feel that it is worth pointing them out from time to time. Just as the article did (I'm not agreeing with everything in there btw.)

People jump in to defend Signal whenever this comes up, but maybe that isn't necessary. Signal is a great project and most criticism I've seen here so far is not 'Signal sucks', it is usually more a long the line of 'Signal is not for me' and I have a hard time understanding why that is debatable or why this shouldn't be a valid position.

Re: Why I won't recommend Signal anymore

#97

Post by sandervenema »

sctblol wrote: post #48

Hmm... he mentions the Giphy thing at the beginning of the article, then never again. The Giphy mention seemed really dangerous to me. Now I don't use Signal but I imagine it's 1) optional and 2) requests are proxified/anonimised through an intermediary (the Signal servers in this case). And why is this dangerous? Because this "don't build cool stuff on this serious app" is what makes people not use the app. It's cre…

Hi there! The Giphy thing is what set me off writing the blog post in the first place. Maybe I should've expanded a bit more on that in the article. As far as I can tell, the idea is that requests to the Giphy API gets proxied through Signal.

I don't see anything in moxie's blog post about whether this is optional. If it isn't and it's sending everything you type to the Giphy API then we have a whole new problem.

In the blogpost by moxie, there's the example of typing "Im excited", which then gets sent in multiple API requests to giphy (basically one of 'I', one of 'Im', one for 'Im+' etc.). Now, if this is an action you don't do explicitly (like pressing a button or something, to search for gifs), then it would basically send everything you type in order to continually search for gifs and then offer suggestions? It's not clear from the blogpost. I hope at least that this is not what moxie had in mind.

Re: Why I won't recommend Signal anymore

#98

Post by joecool1029 »

sandervenema wrote: post #80
tptacek wrote: post #41

The author of this post believes that by making a stand over Signal policies he doesn't like (the superficial GCM dep, the OWS-only server policy, the contact list discovery system), something more like LibreSignal will grow to take Signal's place. The author is wrong. LibreSignal won't replace Signal. Something like Telegram will: an "open source" messaging system with inferior cryptography, "opt-in" end-to-end mess…

Hi, author here. I don't think LibreSignal or indeed Signal will ever be the dominant mobile messenger out there. There's simply a lot of inertia to fight against. It's the same reason why it's hard to convince e.g. Facebook friends to move to a different social network, why Google+ failed, etc. Whenever the social aspect gets involved, companies can very easily create lock-in by being early, and then the social aspe…

>We all want to prevent people hanging from cranes, but crypto alone does not equal privacy, does not keep you safe, especially not in those countries, where rubber hose cryptanalysis (https://xkcd.com/538/) is much more common. In those dangerous situations/countries, good operational security practices are better to avoid detection/suspicion than using any 'magic' crypto messaging app.

Then just put a TL;DR at the end of your article and say 'use iMessage/Facetime, it's probably good enough for operating in an unstable region' If it worked for Erdogan it will work for you!

EDIT: (While I intend to come off as cocky, I'm serious:

https://www.apple.com/business/docs/iOS_Security_Guide.pdf page 41

http://www.independent.co.uk/news/world/europe/turkey-coup-e...

)

Re: Why I won't recommend Signal anymore

#99

Post by kardos »

tptacek wrote: post #41

The author of this post believes that by making a stand over Signal policies he doesn't like (the superficial GCM dep, the OWS-only server policy, the contact list discovery system), something more like LibreSignal will grow to take Signal's place. The author is wrong. LibreSignal won't replace Signal. Something like Telegram will: an "open source" messaging system with inferior cryptography, "opt-in" end-to-end mess…

The author of the post is making the point that Signal's tradeoffs/policies are eroding support from the privacy-conscious end of the user spectrum. Crypto-soundness is excellent but when you staple an infoleak to it (contact list) it's much less compelling. So you can start to make the case to an end user that sharing all your info with Whatsapp or Telegram is a Bad Thing, and here let's install this Signal thing that's much better, except hold on what's this permission list that it requires?

I see Signal as having positioned itself as a compromise that makes nobody happy.

Re: Why I won't recommend Signal anymore

#100

Post by sandervenema »

darklajid wrote: post #96
zigzigzag wrote: post #43

Like a lot of crypto-puritanism it is rather mixed up. He says he recommended Signal because it was easy to use (more consumer friendly I guess) and secure, then says he wouldn't have gone in the direction of making it easier to use and criticises the things that make it user friendly, like using phone numbers instead of usernames. He says he thinks the protocol is secure, then says he doesn't want it to use GCM beca…

I'm not a cryptographer. I .. am reasonably sure that no one would take me for a hipster. But two issues - or call it 'differences in opinion' - in that article are relevant for me: The inability to use the service without a mobile number and federation. I understand the rationale behind the former ("It's easier"), but I don't understand why it is mandatory. I could've been 1283783127356128531312 on Signal and option…

Agree. I'm not a cryptographer and never claimed to be either. -- and I think it would be difficult to mistake me for a hipster. For one, I don't have that snazzy majestic beard.. Anyway, on to the point. :)

Yes, the phone number thing is a policy decision by the Signal people. As I write in my article, it's maybe marginally easier to get connected using phone numbers, but I may want to communicate via Signal with someone I don't want to give my phone number to. Handing out personal phone numbers on the willy nilly is not something I'm comfortable with. There's no reason why we couldn't have some other identifier, possibly easy to remember to connect us to via Signal. So this was a policy decision by the Signal people.

Federation is indeed hard to get right, but I think with proper versioning, and various teams keeping their software up-to-date and close to the reference paper/the Signal protocol, I see no reason why it cannot be overcome. For XMPP/Jabber it also works quite well.

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