How to Break Cryptography With Your Bare Hands

http://www.technologyreview.com/news/530251/how-to-break-cryptography-with-your-bare-hands/

by cgtyoder • 12 years ago

36 12 12 years ago

technologyreview.com

tptacek3• 12 years ago

The actual journal article this is taken from was on HN a few days back, and has some comments:

https://news.ycombinator.com/item?id=8153670

linuxlizard• 12 years ago

Obligatory XKCD apropos to "bare hands." https://xkcd.com/538/

bitL• 12 years ago

That was the first thing that popped up in my mind when I read the title ;-)

valarauca13• 12 years ago

The biggest issue with this is reliability.

There are dozens if not hundreds of ways to break crypto on hardware that can be done in laboratory conditions. But these are in laboratory conditions, not somebody touching your laptop in a coffee shop.

sp332• 12 years ago

These guys grabbed a signal of ~1 picowatt after filtering in a noisy environment https://www.blackhat.com/presentations/bh-usa-09/BARISANI/BH... While this doesn't say anything about reliability of the current experiment, it probably works better than you'd think.

valarauca13• 12 years ago

Okay read the slides. Its cool but completely impractical.

The problem is if two keyboards share the same ground plane and have roughly the same frequency (I.E.: same manufacturer), their signals will interfere with each other constructively and destructively based on who is typing what.

They say the ground plane is noisy, but not noisy in the frequency they are looking. Which is idiotic. The EM frequency band all around us is noisy, but in certain spectrum ranges its completely dead. If you sample the entire band its noisy...

They didn't test something directly interfering with the device. Which would roughly be equal to two radio stations broadcasting on the same channel, you couldn't hear anything sensible.

:.:.:

Not to mention their signals are still VERY noisy. I've worked/around signal processing so you have to understand that if you want to predictably read what is written.

http://i.imgur.com/sJ90YPu.png

As you can see that's 3 different triggers of on/off. Dynamic filtering is I guess possible, but you need to know what your searching for to start with. And build a model of likely signals, so you can compare post filtered with what you got post filter to check correctness, and repeat until you get within the tolerance of acceptable correctness. If its a computer generated encryption key then your looking for psuedo random bit pattern, and your just fucked.

Secondly

http://i.imgur.com/gDvd7M1.png

See, if you assume which trigger you use upper or lower this signal will actually change from 00100110001 to 00100111001. :\ The only way you can know which is correct is if you know what was given to start with.

:.:.:

I don't want to say its completely unreliable because of that, but if that literally the best example they had to put on a slide then their can't be many more good samples.

tptacek3• 12 years ago

The "bare hands" thing is a gimmick. The actual Tromer paper is much, much more interesting than that. See the link posted elsewhere in the thread.

Fando• 12 years ago

Mind blow.

markbernard• 12 years ago

For this to work they have to have the correct key in the first place. If I encrypt something with my key and send it down the wire and they intercept it and try it on a machine they own they wouldn't be able to decrypt it. This requires them to be hooked to my machine while I am decrypting to get at the key.

How to Break Cryptography With Your Bare Hands

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