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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

#211

Post by haffenloher »

codedokode wrote: post #208
tptacek wrote: post #143

Earlier quoted context omitted.

Signal and Telegram are not the same thing. Telegram has, according to Reuters, been actively compromised by people working for oppressive regimes (Iran, in particular). If you're just using a secure messenger on general principles, it doesn't matter much which one you use. Probably WhatsApp is your best choice. But if you actually need secure messaging, you should be using the safest secure messenger. Since we don't…

> Telegram has, according to Reuters, been actively compromised by people working for oppressive regimes (Iran, in particular). I just wanted to add some details: someone checked the Iranian phone numbers range at Telegram servers and learned which of them are registred with Telegram. Message contents or contact lists were not obtained. I guess this attack could be done with other apps that use phone numbers and phon…

I think tptacek was talking about actual takeovers of Telegram accounts. AFAIK there have been documented cases of this in Iran and Russia. See e.g. https://www.fredericjacobs.com/blog/2016/01/14/sms-login/

Re: Why I won't recommend Signal anymore

#212

Post by codedokode »

trimbo wrote: post #37
EugeneOZ wrote: post #29

Any messenger, tied to phone number, is not safe. possible attacks are: 1) create copy of sim-card; 2) force mobile operator to intercept password-code, sent to your number, and "restore" password this way. It may sound ridiculous for you, but in Russia it's reality (both vectors), it's real cases from life. And when user really need safe messenger, all of them are too careless to implement really safe way of messagi…

This is why there is a fingerprint ("Safety Numbers" in Signal), and a warning on every message when that fingerprint changes.

Warning still does not fully prevent the attack. The attacker can still access the account and obtain the data stored at a server (like contact list if it is stored there).

Re: Why I won't recommend Signal anymore

#213

Post by codedokode »

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.

There could be two separate versions, one for paranoid users, one for those who don't care. The number of permissions Signal app requires is scary. It gets almost full control over your phone including reading SMS messages.

Re: Why I won't recommend Signal anymore

#214

Post by codedokode »

haffenloher wrote: post #211
codedokode wrote: post #208

Earlier quoted context omitted.

> Telegram has, according to Reuters, been actively compromised by people working for oppressive regimes (Iran, in particular). I just wanted to add some details: someone checked the Iranian phone numbers range at Telegram servers and learned which of them are registred with Telegram. Message contents or contact lists were not obtained. I guess this attack could be done with other apps that use phone numbers and phon…

I think tptacek was talking about actual takeovers of Telegram accounts. AFAIK there have been documented cases of this in Iran and Russia. See e.g. https://www.fredericjacobs.com/blog/2016/01/14/sms-login/

Then it is a serious problem for Telegram and any app that relies on SMS or some phone identity to restore access to an account.

Re: Why I won't recommend Signal anymore

#215

Post by tptacek »

sandervenema wrote: post #206
haffenloher wrote: post #205

From the post: " The Google Cloud Messaging service basically handles message handling from/to the user’s devices to the Signal servers. The GCM service then handles all the aspects of queueing all messages and delivery from/to users. " This is not true. Messages are delivered via Signal's own servers only. GCM messages are empty; their only purpose is to wake up your device. [1] " The phone component of Signal is ca…

Hmm. You seem to be right. Article corrected there to reflect that Signal is using empty GCM messages. I must have still had the old situation of TextSecure in my head when I wrote that. Nice to know re the reason Redphone doesn't work, thanks for that insight!

(had suggested the author add an endnote; they did)

Re: Why I won't recommend Signal anymore

#216

Post by sandervenema »

tptacek wrote: post #215
sandervenema wrote: post #206

Earlier quoted context omitted.

Hmm. You seem to be right. Article corrected there to reflect that Signal is using empty GCM messages. I must have still had the old situation of TextSecure in my head when I wrote that. Nice to know re the reason Redphone doesn't work, thanks for that insight!

(had suggested the author add an endnote; they did)

Yes, I agree that's more transparent. I've added an endnote, and linked to it from the place where the edit was made.

Re: Why I won't recommend Signal anymore

#218

Post by throwaway101416 »

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…

What about all the other alternatives like Wire and Wickr? Wickr went through crypto reviews. Wire is open source.

They don't require using phone numbers so it's not really annoying to sign up without giving away anonymity.

Re: Why I won't recommend Signal anymore

#219

Post by tptacek »

throwaway101416 wrote: post #218
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…

What about all the other alternatives like Wire and Wickr? Wickr went through crypto reviews. Wire is open source. They don't require using phone numbers so it's not really annoying to sign up without giving away anonymity.

Serious question: what does "went through crypto reviews" even mean? One of these messaging systems is designed and implemented by experts; the others, not, but they've gotten 1-2 person/weeks of attention by (one hopes) a crypto experts.

Re: Why I won't recommend Signal anymore

#220

Post by majewsky »

hannob wrote: post #203
SamWhited wrote: post #5

I highly recommend Conversations (disclaimer: I've worked on it in the past, although I'm not a project "member" per say): https://conversations.im/ It's open source, uses a federated, open protocol, and can do multiple types of encryption including OTR and OMEMO (an XMPP wire format that uses the Axolotl ratched devised for signal). It does not do VoIP, so it would just be for chat (although there is a large bounty…

I think Conversations is probably getting a lot right, but you also mention its biggest flaw: > do multiple types of encryption including OTR and OMEMO Oh and it can also do something else: no encryption at all. That's the problem with XMPP: The user is faced with three different encryption modes, none of them is the default. There shouldn't be multiple types of optional encryption. There should be one that works and…

The practical problem is that a lot of power-users have strong opinions about which e2e scheme to use in which case. That may include "none". [1] If you enforce a single e2e scheme (no matter which), you will lose a lot of potential power-users, who would double as multipliers to spread your app.

I don't say that Conversations (and the XMPP community at large) couldn't do better, though. For example, there could be a standardized, automated, transparent process for determining which e2e schemes are supported by the clients involved in the conversation.

[1] For example, I skip e2e when talking to my several XMPP bots. They run on the same host as the XMPP server, so e2e won't reduce my attack surface when I already have TLS enforced along the way, but make the bot implementation considerably more complex.

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