Schneier on Security

Nick P • July 27, 2013 10:07 AM

@ Noth

Gith Security Review (Preliminary)

If inspired by PRISM, it’s ironic that most of these solutions popping up can be subverted by NSA using their legal approaches. There was one security writer that pointed out that we must distinguish domestic and foreign TLA’s because the legal support of domestic TLA’s makes them quite effective: they just tell you to do it, then you do it or suffer the consequences.

Here’s the security page of this
http://www.gith-systems.com/security/

The three properties it mentions are good. They are very similar to the promises of Hushmail a long time ago. Of course, Hush eventually began subverting its own software for the government in a way that seams to undo its end-to-end encryption trait. Like Hush, the binary is closed and should be easy to backdoor. Positive point for Hush is that they at least provided their crypto source code for independent review.

(Although, I’ve often criticized the alleged value of this saying there’s been more compromising flaws in how crypto is used and how apps are configured than the crypto engines themselves. Their providing the source for review is still A Good Thing, though. Cryptophone also does this.)

Their algorithms are RSA-2048, AES-256 CBC, and SHA1. A combination that’s starting to feel old. 😉 I see why they might use the algorithms though: maturity of implementations and widespread support for each cipher. Matter of fact, those are the same algorithms I posted here a year or two ago when discussing my VIA Padlock accelerated options. Padlock would make the crypto almost invisible. I’d prefer new projects to use Bernstein’s NaCl library for the same reasons, though.

“All security parameters (private key, password) don’t leave your computer to guarantee a complete security. ”

Less information on their systems is good. Phrases such as “to guarantee a complete security” always bother me though. There’s not a single product (outside fixed-purpose devices) that can make that claim. Second, this application of the claim ignores that the most common threat, malware, would circumvent the practice. So, extra bogus marketing.

“To limit this risk, when creating your account, you will be asked to export this private key as a QRCode. This is a representation of your key, ciphered with your username.”

Exporting the private key to a QR code is a cool idea. It has a benefit they might not have noticed: the user is more likely to spot the paper with the private key in a file cabinet of otherwise identical looking papers. It does require a scanner, camera or interface with a smartphone. These might create additional risks. If they have a plaintext private key export and import option, that would be nice for people who keep simple PC’s.

Enciphering with the username sounds pointless: anyone that can get the enciphered key could get the username even more easily. And the cipher strategy is built into the executable for black hats ease of discovery. 😉 If they really want to obfuscate, they can just use a XOR-based steam with preplaced key. I’ve previously used xorshift128 w/ truly random seed for non-security-critical, high-speed, simple obfuscation. It takes a decent amount of data before the patterns in the stream become obvious to a non-expert. A black-box test might think you are using real crypto.

“When you travel, you simply need to take this QRCode with you to get access to your mails from any computed connected to the internet !”

Something about this seems unsafe… something…

“When you want to add a new contact, a request is sent to them.
If accepted, Gith server sends your respective public keys which will be store locally on your KeyStore.
This keystore is protected with your password, your contact list is then protected and no-one will known with whom you’re in contact.. ”

Sounds much like the old PGP type systems. That’s a good thing.

“To prevent this, Gith stores all received data on their ciphered form. Gith deciphers them on the fly when accessed by you. An internal mecanism is used to erase all memory traces after viewing a message (the RAM memory zone containing clear data is overwritten after usage).By default, our servers do not store your messages. Once delivered to all their recipient, we keep no trace of them.
The Gith interface allows you to choose what you want to store “online” if you want to consult some of them from another computer/smartphone. ”

This is good. I assume, but someone should test, that the files stored online remain encrypted with AES so that Gith can’t read them.

“Gith uses very few external libraries and those appear only in “non-critical” parts of the software (graphical libraries, etc.).
This guarantees a complete control over the executed code and fast response time in case of discovery of bugs.”

It’s good that they are minimizing external libraries. That has proven value. The rest of the claim is too vague for me to evaluate.

“The software is distributed freely on Windows and MacOS X and available on iPhone and Android.”

And it runs on the most important platforms. Well, the Linux desktop people might claim to have been slighted. But they always do/are so who cares. 😉

Conclusion

It seems like an extension of the PGP model for new content. It will inherent the end-to-end properties of that model for messages, keys and contacts. That assumes it’s implemented properly. I’m unsure of it’s usability without a hands-on review. If usability beats PGP-type solutions, that would be a huge plus by itself. Lacking independent review, we can’t verify any claim they make without reverse engineering.

I’d say one nice thing they could do is have a third-party lab such as Matasano or even a well-known cryptographer assess the security claims. This would give users confidence that they are using the crypto right, the software does what they say it does, and that there were no backdoors at time of review. Plus, it might differentiate them from the competition.

Nick P • July 27, 2013 2:50 PM

@ Different View re INFOSEC in classroom

Honestly, it’s not yet appropriate to worry about this for K-12. Teaching some basics as part of computer courses in upper middle or high school should do for now. A prerequisite to INFOSEC would be understanding the basics of managing risk in general. A prerequisite to that would be critical thinking: esp. rational thinking, identifying fallacies, and the scientific method. The underlying critical thinking skill will help the students solve more problems than many specific instances of it put together.

There are two similar obstacles to this: politics and religion. Any belief system or authority structure built on something other than reason can be challenged by it. Teachers, preachers and such don’t like students that question their dogma/methods. That is a side effect of critical thinking. Creativity can be a nice aid to critical evaluation of policies, processes and ideas in general. However, the rote memorization and rigid nature of the educational system also punish it. So, currently, there’s too many forces working against both critical thinking and its byproducts in the school system.

The conclusion is that the best battle to win is the one for critical thinking. A longterm goal would be to make it second nature to most people growing up. They should also learn the proper place for and value of intuition, which is good for things you have experience in. With these in place, more scientific disciplines such as risk management can be built on top.

Nick P • July 31, 2013 12:03 PM

@ figureitout

“Does anyone remember the scene from “Catch Me If You Can” where Hanratty asks Abagnale’s father where his son is? “You aren’t a father, are you? I won’t give up my son.” Powerful scene, a father will rarely give up his son; even when he’s former military.”

It was a good scene in a great movie. Another one like that is in Jumper where the failure of a father is confronted about his son, then makes the one good choice in his life. I really like how that part happens so subtly and quickly.

Snowden’s dad seems honest. Mentioning a “firewall” between him and his son was an odd choice of words. All in all, though, he comes off as genuine and having his son’s back all the way. Good man.