Home > Uncategorized > Cryptocat — encryption can make you safe, or very very unsafe

Cryptocat — encryption can make you safe, or very very unsafe

One of the first rules of security is that you never use a product that employs any form of proprietary cryptography. And if a security guy then says ‘be careful’, you’d best be very very careful — no matter how many magazines or newspapers say the product is the real deal.

That’s what happened with Cryptocat which is a secure chat product that “could save your life and help overthrow your government,” according to Wired — it could “save lives, subvert governments and frustrate marketers.” Forbes said that it “establishes a secure, encrypted chat session that is not subject to commercial or government surveillance.” Sounds good.

But security folk weren’t so sure. “Since Cryptocat was first released,” warned Christopher Soghoian in July 2012, “security experts have criticized the web-based app, which is vulnerable to several attacks, some possible using automated tools.”

Patrick Ball expanded in August 2012:

CryptoCat is one of a whole class of applications that rely on what’s called “host-based security”… Unfortunately, these tools are subject to a well-known attack… but the short version is if you use one of these applications, your security depends entirely the security of the host. This means that in practice, CryptoCat is no more secure than Yahoo chat, and Hushmail is no more secure than Gmail. More generally, your security in a host-based encryption system is no better than having no crypto at all.
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Security professionals, then, were not surprised when last week Steve Thomas wrote about his DecryptoCat — which does what it says on the can: it cracks the keys that let you read the messages.

If you used group chat in Cryptocat from October 17th, 2011 to June 15th, 2013 assume your messages were compromised. Also if you or the person you are talking to has a version from that time span, then assume your messages are being compromised. Lastly I think everyone involved with Cryptocat are incompetent.

This is a big deal, because Cryptocat has been marketed towards dissidents operating in repressive regimes. As Soghoian wrote:

We also engage in risk compensation with security software. When we think our communications are secure, we are probably more likely to say things that we wouldn’t if our calls were going over a telephone like or via Facebook. However, if the security software people are using is in fact insecure, then the users of the software are put in danger.
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Add to that the current revelations on the NSA/GCHQ mass surveillance, and our understanding from last week’s Snowden revelations that the NSA automatically and indefinitely retains encrypted messages, then we can say with pretty near certainty that if you have been using Cryptocat, at least the US and UK governments are aware of everything you said.

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