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Subrosa – An encrypted communication platform

subrosa.io

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Re: Subrosa – An encrypted communication platform

#41
A quick check with wireshark reveals the use of a VBR codec for audio, so there's another probable side channel besides the Javascript related issues already discussed.

I don't know much about WebRTC, but I think it's something you can set and Subrosa should be doing so in app-webrtc.js.

Re: Subrosa – An encrypted communication platform

#42
post #38

Earlier quoted context omitted.

Sure, but if you run your own server, then the site's claim that there was "no download or install needed" doesn't apply to you. If you don't run your own server, the site's claim that "nobody, not even us, can read or listen into your conversations" doesn't apply to you. There's nobody to whom both claims apply at the same time!

If you run your own server, you can make trusted calls from machines that don't have any client software set up, as can others using your server. Seems straightforward enough. It's clear the "no install" claims are about the client.

I read the claims on their home page as referring to the use case where someone starts using it immediately. (The benefit that they mention on the home page from open source is third-party auditability; the home page doesn't even mention the ability to create your own instance!)

The developers might well be thinking along the lines that you describe, but I don't think that a visitor to the site is likely to understand the threats that way.

Edit: Looking at https://subrosa.io/security I think it's even more clear that they're making these claims for their own hosted instance of their software -- and that's what people here are most skeptical of.

Re: Subrosa – An encrypted communication platform

#43
post #38

Earlier quoted context omitted.

Sure, but if you run your own server, then the site's claim that there was "no download or install needed" doesn't apply to you. If you don't run your own server, the site's claim that "nobody, not even us, can read or listen into your conversations" doesn't apply to you. There's nobody to whom both claims apply at the same time!

If you run your own server, you can make trusted calls from machines that don't have any client software set up, as can others using your server. Seems straightforward enough. It's clear the "no install" claims are about the client.

You can use github or you can run a private gitorious install (assume here function parity.) Most people will choose github because that's where the people are.

Subrosa's value proposition is more as a meeting place then as a "secure" chat software.

Re: Subrosa – An encrypted communication platform

#44

In the description of the key exchange mechanism (section 'Conversation Keys' under 'Security') it sounds like they're using one symmetric key for both directions of a two-way channel. If true, this is a pretty serious security flaw. Anyone from Subrosa care to comment?

More importantly, one of the party is trusted to come up with the key alone. The other party just has to accept that it's a good key with no other proof then that it was encrypted with their public key. The description is really weak on details.

They keep repeating they've been audited but not naming the auditors.

Re: Subrosa – An encrypted communication platform

#46
post #29
post #11

Earlier quoted context omitted.

Everything this article says is true. That being said, it also applies to any regular application that can be upgraded automatically or that's upgraded at all by a third party. Anything you get off an app store can have its code switched out from under it with minimal and routine or in some cases even no user interaction. All someone has to do is compromise the signing key, which is probably not that hard in many cas…

Sure; but there's a world of difference between communicating with a webapp that claims to protect your privacy even from the NSA (but actually cannot) vs. "any regular application", which makes no such security claims, and from whom savvy users won't expect that kind of protection. People with important information to communicate that they must protect from the powers that be (quite possibly to protect their own liv…

This application doesn't protect communications from the owners of the application under any circumstances. Forget about the NSA.

Re: Subrosa – An encrypted communication platform

#47
post #27
post #9

"Nobody, not even us, can read or listen into your conversations." This cannot possibly be true, given they are the root of trust for establishing the recipient's authentic public key. Also, minified javascript really does not count as a source code release.

Quite right. If they were compelled -- e.g., "insert this backdoor or we'll imprison you" -- they might trivially serve up a tweaked version of their JavaScript to the one user the NSA was interested in. And it wouldn't take a complicated tweak at all to sneak the real password (or some sufficient version of it) back to the server, after which point certainly "even us" can read & listen in to all of that user's conve…

(Comment moved to today's topic.)

Re: Subrosa – An encrypted communication platform

#48
Why have both "username" and "display name"?

At first I thought it was an extra layer of security , like most online games have, to discourage username/password bruteforcing. (It's an obscurity layer, but obscurity layers are not by definition bad.) But you need to tell others your username to communicate with them.

Re: Subrosa – An encrypted communication platform

#49
post #11

Earlier quoted context omitted.

Everything this article says is true. That being said, it also applies to any regular application that can be upgraded automatically or that's upgraded at all by a third party. Anything you get off an app store can have its code switched out from under it with minimal and routine or in some cases even no user interaction. All someone has to do is compromise the signing key, which is probably not that hard in many cas…

Scarily true. The amount of damage malicious actors with keys can do is greatly magnified by the auto-update mechanisms that developers love.

I have an app with auto-update, and one day I realized that I had (more or less) root on hundreds of users' machines. I'm not special in this regard.

I take fairly strong precautions with my keys: offline storage, encrypted, signing on an air-gapped machine. I'd bet you money that most people aren't so careful. There are probably a lot of secret signing keys sitting in DropBox.

Re: Subrosa – An encrypted communication platform

#50
post #10
post #3

First impression: - There is no demo, i can only guess that this is a "browser-based skype". I hate when i can't try it but it's free. - Open-source, but no git repo? Btw I had the same idea before (I posted it to an Idea Sunday thread) but I dropped the idea because i realized that no one needs this level of security, NSA is not interested in your chat with family and friends...

"There is no demo" -- just make an account quickly and try it out. I did this and it was easy. "Open-source, but no git repo" -- Open-source does not always entail git or Github. "I dropped the idea because i realized that no one needs this level of security, NSA is not interested in your chat with family and friends..." -- I'm glad you dropped the idea because someone who doesn't understand why privacy is important…

The published source code is only the client-side. So not quite open-source, at least in my book if a client is open-source the protocol it implements ought to be documented somewhere or the implementation provided.
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