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Re:CryptoCat iOS Application Penetration Test [pdf] by natdempk on Wednesday April 02, 2014 @05:19PM (#7519114)
Also of interest is their blog post about how they plan to handle the issues described in this report: https://blog.crypto.cat/2014/04/recent-audits-and-coming-imp...

Reading that, I still am not sure why anyone would use CryptoCat especially with things like TextSecure on the market that seem to take crypto far more seriously. The only reason I can see for that is that they have clients on more platforms, but if this is similar to the state of all of them, then what's the point?

Re:CryptoCat iOS Application Penetration Test [pdf] by kaeporan on Wednesday April 02, 2014 @05:32PM (#7519204)
Thanks for linking to the blog post. This audit concerns a pre-release version of Cryptocat for iPhone. Many of the bugs were due to debugging code and were fixed before release.
Re:CryptoCat iOS Application Penetration Test [pdf] by tptacek on Wednesday April 02, 2014 @07:13PM (#7519721)
Which of the bugs were due to debugging code?
Re:CryptoCat iOS Application Penetration Test [pdf] by daira on Thursday April 03, 2014 @12:16AM (#7520913)
Findings iSEC-RFACC0114-1 and iSEC-RFACC0114-3. (2 out of the 17 vulnerabilities found by iSec, of varying severity.)
Re:CryptoCat iOS Application Penetration Test [pdf] by sneak on Wednesday April 02, 2014 @09:07PM (#7520204)
Why use donated money to pay for an audit of software that has known bugs and isn't ready yet? That's wasteful. The point of an audit is to find bugs you don't already know about.
Re:CryptoCat iOS Application Penetration Test [pdf] by ibmthrowaway218 on Thursday April 03, 2014 @04:53AM (#7521657)
It can be a useful technique for testing the quality of the audit.

At a previous company we had to have words with a company that performed a software audit as they failed to find two issues we'd planted to test them. (Of course, they did find several things we didn't know about.)

Re:CryptoCat iOS Application Penetration Test [pdf] by mandalar12 on Wednesday April 02, 2014 @06:01PM (#7519383)
Has anyone done the same level of analysis on TextSecure ? I feel like their model/seriousness is better but there might be flaws in the implementation (or protocol) and being audited might highlight some of them.
Re:CryptoCat iOS Application Penetration Test [pdf] by natdempk on Wednesday April 02, 2014 @06:50PM (#7519619)
I don't believe they've had an independent security audit. I think their team however is comprised of more respected cryptographers like Moxie Marlinspike, who introduced the concept of SSL stripping, one of the issues that was found in the CryptoCat app. I mean no disrespect to CryptoCat, and more eyes can always find something someone overlooked, but I think the Open Whisper Systems (TextSecure) team is stronger and using better cryptographic techniques.
Re:CryptoCat iOS Application Penetration Test [pdf] by tptacek on Wednesday April 02, 2014 @06:55PM (#7519638)
TextSecure also has design contributions from Trevor Perrin, who is also amazing.
Re:CryptoCat iOS Application Penetration Test [pdf] by nathan-at-least on Friday April 04, 2014 @07:29PM (#7535130)
natdempk and tptacek have both asserted that TextSecure is trustworthy and solid by dint of being implemented and designed by reliable experts. This pretty much boils down to argument by authority.

mandalar12 asks about "the same level of analysis on TextSecure". Since our (Least Authority's) audit and the iSEC audit are public, random people on the internet can know what that level is, without having to know or rely on Least Authority or iSEC to be non-malicious.

With enough eyes all bugs are shallow, but to whom? We need to communicate transparently to achieve this ideal.

Disclaimers: I worked on the Least Authority audit of Cryptocat; I've worked at iSEC in the past; I've met Moxie Marlinspike and Trevor Perrin and greatly respect their expertise and motivations; I also don't know if they've been infected by malicious puppetmaster aliens since I last saw them.

Re:CryptoCat iOS Application Penetration Test [pdf] by daira on Friday April 04, 2014 @08:56PM (#7535496)
I don't actually see any assertions on this thread by natdempk or tptacek claiming that TextSecure is "trustworthy" and/or "solid". Did I miss something?

My own opinion is that both strong cryptographic and security engineering expertise on the part of designers and implementors, and multiple independent published security audits, are necessary to consider an app trustworthy -- but still not sufficient, given the poor state of platform security and the lack of support most current platforms (operating systems, browsers, etc.) give for isolation between apps.

Disclaimer: I worked on the Least Authority audit of Cryptocat, and in general get paid for similar auditing. I'm also designing a programming language (Noether) that is intended to facilitate security reviews.

Re:CryptoCat iOS Application Penetration Test [pdf] by illumen on Wednesday April 02, 2014 @07:47PM (#7519876)
No need for an of audit TextSecure... just go to their github issues page. Plenty of open bugs and regressions, some of them as serious as some of the ones in the latest CryptoCat app audits. For example, one issue where some messages sent are not being encrypted.

Even with 'amazing' contributors, bugs are still there in TextSecure.

Re:CryptoCat iOS Application Penetration Test [pdf] by tptacek on Wednesday April 02, 2014 @07:57PM (#7519915)
I just reviewed all open and closed bugs in TextSecure's Issues page and didn't see a single crypto protocol bug. Admittedly, I looked quickly and casually. Could you point us to one?
Re:CryptoCat iOS Application Penetration Test [pdf] by illumen on Wednesday April 02, 2014 @09:03PM (#7520182)
"I just reviewed all open and closed bugs in TextSecure's Issues page and didn't see a single crypto protocol bug. Admittedly, I looked quickly and casually. Could you point us to one?"

You could not have reviewed all open and closed bugs in 8 minutes ;)

Issue 1073: https://github.com/WhisperSystems/TextSecure/issues/1073

Another one: Just sent an encrypted photo to someone? The photo is stored unencrypted on your phone.

Edit: group messages were also sent unencrypted, but this was fixed. https://github.com/WhisperSystems/TextSecure/issues/32

Edit2: ok, I see your point. Maybe they do crypto well as you say, but they don't seem to do software engineering well, or UI design for secure text messaging well. Sending messages unencrypted, and leaving messages unencrypted on the phone is a big fail in overall security of the app. It's meant to encrypt things, and it doesn't. That it doesn't put in tests for these things, and that it did not publish the independent security audit should cause everyone to reconsider using the TextSecure app for its stated purpose.

Re:CryptoCat iOS Application Penetration Test [pdf] by tptacek on Wednesday April 02, 2014 @09:13PM (#7520240)
I read that issue especially carefully since it was on the front page, and it doesn't look like a crypto protocol bug. I'm actually not sure what that bug is.

A crypto protocol bug is something like "TextSecure tried to implement secure file transfer, used the CTR block cipher mode, and managed to make the keystreams collide, so that passive attackers could recover file contents from encrypted streams".

The general point you made, that all applications have bugs (and thus security bugs) is valid. I'm drawing a line that you're not drawing, between design flaws in cryptosystems and random iOS/Android mistakes.

Re:CryptoCat iOS Application Penetration Test [pdf] by moxie on Wednesday April 02, 2014 @10:24PM (#7520527)
These are bugs, but I'm not sure they are what you think they are. I would be worried if TextSecure indicates a message is going to be sent securely, but it is sent insecurely. This bug, however, is an edge case where TextSecure indicates that it is going to send a message insecurely, and that's what it does.

It's also true that until recently we didn't have an encrypted group chat protocol, but at no point in the past did TextSecure ever indicate that group chat was encrypted. Just the opposite.

It's important to realize that TextSecure is simultaneously a standard unencrypted SMS app as well as an encrypted chat app.

Re:CryptoCat iOS Application Penetration Test [pdf] by drdaeman on Thursday April 03, 2014 @04:59AM (#7521678)
> encrypted group chat protocol

Sorry to bother, but is there any article/blog post/something to read about that?

As XMPP MUCs don't seem to have E2E encryption, mpOTR seems to be in infancy, and I'm unaware of anything else, this sounds really interesting.

Re:CryptoCat iOS Application Penetration Test [pdf] by rancor on Wednesday April 02, 2014 @10:36PM (#7520570)
I'd also add as a TextSecure user that I assumed both of those scenarios were plausibly insecure until the recent release with secure group messengering. They're pretty open about the weak points in the application generally speaking.

I will agree with you about the UI design until the revamp in the latest release, though.

Re:CryptoCat iOS Application Penetration Test [pdf] by kaeporan on Wednesday April 02, 2014 @08:59PM (#7520165)
iSEC also audited TextSecure, but TextSecure chose not to publish the audit.
Re:CryptoCat iOS Application Penetration Test [pdf] by epsylon on Thursday April 03, 2014 @04:27AM (#7521563)
They didn't choose not to publish.

https://news.ycombinator.com/item?id=7520581

Re:CryptoCat iOS Application Penetration Test [pdf] by tptacek on Wednesday April 02, 2014 @08:59PM (#7520167)
And? What does this have to do with the parent comment?
Re:CryptoCat iOS Application Penetration Test [pdf] by aeontech on Wednesday April 02, 2014 @09:09PM (#7520215)
The grandparent asked whether they have had a security audit, and parent said "I don't believe they've had an independent security audit." Seems like a straightforward reply to those.
Re:CryptoCat iOS Application Penetration Test [pdf] by tptacek on Wednesday April 02, 2014 @09:10PM (#7520220)
Oh. Duh. You're right. I was skimming my threads and lost the context. Thanks for pointing this out.