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Battling Steganography
An anonymous reader submitted a fairly thin little story about a researcher who is Battling
Steganography. I can certainly see the appeal of the study but it really seems like a needle in a hay stack sort of project. And when you actually can detect one technique, new and better techniques will crop up and take its place.
Was it just me, or did the article make it seem like anyone that would use steganography would be a criminal? Since when in a 'free' country should the ability to hide a message be of interest to the "legal community"?
It's hard to tell the cool to chill, my favorite hotel room has a view to an ill.
Good steganography is essentially the same as adding random noise to an image. You can structure the noise any way you like. There are lots of images that plausibly contain lots of noise, for example images taken in low light and images scanned from film. As long as you don't insist on a very efficient steganographic embedding, there are undetectable steganographic methods. Farid's research is pointless, and it is scary to think that courts may start relying on it.
While it's true that human beings can interpret images to mean something that a machine could never pick up on, that's not the thrust of the research being done here.
He is doing research into a very particular kind of steganography, whereby messages are concealed within an image via slightly altering the least significant bits of an image.
When you encode information in this way, somebody knowing how to extract it can pull out a message which is not subjective (as in the example of interpreted images given by another poster), but rather is very concrete.
There is some evidence that this form of encoding has been used to communicate information throughout terrorist cells.
What the researcher is doing is developing a method to detect when the LSB's in an image have been manipulated slightly. He is not trying to decode the message, but only to flag particular images as being suspicious.
Decoding would be a matter for someone completely different -- like the FBI, for instance.
His method does have applications, and if it is through alteration of LSB that a message is embedded in an image, it will apparently detect such 90% of the time.
This is a vast improvement over any existing methods I know of for detecting LSB manipulation.
So he's not quite looking for a needle in a haystack. He's examining millions of haystacks, and pinpointing the ones that probably *do* have needles in them.
Quite a large difference, really.
-l
I don't see how anyone with a conscience could decide to intentionally try to destroy methods with which people can protect their privacy.
Now we have more people looking at steganography. This can only make it more effective. Sure, the methods we have now might be broken but what about the next ones, the ones that don't show up on the statistical analysis that he appears to be using.
Bleh!
How come Dr. Farid is not
battling Guns?
Sounds like someone who should work for
a totalitarian government.
Nice idea, but it is easily thwarted. /dev/random) we do this to EVERY image and generate several versions of each image with trash in it. we make a neat-o plugin for the gimp that does this quietly without the user's info and we do the same for photoshop. over a years time 5-10 people could spread hundres-of-thousands false positive images onto the net. now.. you send a message, a real one. there is no way to detect if it is a decoy or the real thing.
I and my friends generate every image with random trash in it (the output of
and this is where prof-bean's idea falls on it's face. as anyone using this system for real work is doing what I just mentioned or something that is generating massive amounts of decoys in a more effient manner. (hell the decoys now become perfect carriers too! espically if you generated several version of the decoys with different junk in them.)
It's simple to defeat stenography detection. you saturate the detector to the point where the real items get through.
Do not look at laser with remaining good eye.
A 10% miss rate doesn't mean that there is also a 10% false alarm rate.
1) Take the first letter of each line.
2) Take the first work of each paragraph.