Secret Data: Steganography v Steganalysis 280
gManZboy writes "Two researchers in China has taken a look at the steganography vs. steganalysis arms race. Steganography (hiding data) has drawn more attention recently, as those concerned about information security have recognized that illicit use of the technique might become a threat (to companies or even states). Researchers have thus increased study of steganalysis, the detection of embedded information."
Hmm (Score:5, Interesting)
Re:Hmm (Score:3, Interesting)
Or in the case of "The Bible Codes", you find what you want to find.
Already was an issue (Score:4, Interesting)
There was even an episode of Law and Order about this. Its nothing new, but I agree it does pose many questions about security. (Security through obscurity is really good if the level of obscurity is paramount.)
fun stuff (Score:5, Interesting)
The biggest problems were 1. most (actually, all) of the images that came back as good candidates for having embedded images came back as false positives and 2. lack of a brute-force steg break utility.
number 2 is probably a result of poor searching on my part, but I honestly couldn't find a recent, (and free) tool that would do a brute force crack on embedded images. At the time (a few months back) I was using stegbreak and stegdetect.
So, is there anything better? anyone else have any luck?
Passwords (Score:5, Interesting)
I can certainly see the use in espionage, hiding the real message in the static, as it were (Didn't a Tom Clancy book use this plot device? I think the message was sent in the connect noises for the modem). And NS's Baroque Cycle had some interesting steganographic bits in it (excessively long and boring letters about the nobility's obsession with fashion hiding an encrypted message for all to see). But on a day to day basis, I doubt this will affect most people.
Re:Hmm (Score:2, Interesting)
Any sufficiently advanced neural net should be able to deterministically find changes in common data communication where information can be hidden. And do you truly think that your data is not being checked by big brother?
[puts on tinfoil hat]
Problem with statistical analysis (Score:5, Interesting)
The problem here seems to be that if you were to compress your hidden data prior to hiding it, then the data inserted would appear random and should thwart statistical analysis. You'd need some redundancy there if you intent to jpeg compress the image, but it might work.
I've toyed with the idea of hiding data in the vectors used in a mpeg file. Exploiting the nature of the compression algorithm rather than the source data.
Re:An easy way to hide information (PART 2) (Score:5, Interesting)
Heck, post as ac with a unique subject and post encrypted (gpg) ascii in multiple parts. the data will be here still next year or five (plausible) and you can retrieve it, and decrypt (assuming you have the public key or password if it's symmetric
DCT + spread spectrum (Score:3, Interesting)
It works pretty well.. but I did it in PHP+GD, so it's pretty slow...
if anyone is interested, I have a paper that describes the methods, the PSNR and everything else... you can reach me at my gmail server, under the dangil alias
stegnography is security through obscurity (Score:1, Interesting)
how is this possible? (Score:2, Interesting)
Excecpt when I hide it I use the least significant bit of every n bytes where n is a 10 digit sequence.
[1,2,3,4,3,2,1,2,6,7]
the first source bit is stored in the lsb of the first image byte.
the second source bit is stored in the lsb of the [1+2] image byte.
the third source bit is stored in the lsb of the [1+2+3] image byte.
If the end of the image file is reached before the source file is embedded then wrap around and repeat using the second lest significant bit.
Using a unique noisy image source such as a crappy web cam taking a picture of a TV displaying white noise (to thwart a compressability test used for detecting images with hidden data), how could you detect this hidden message much less decode it without know specificaly how the algo works?
Re:Problem with statistical analysis (Score:2, Interesting)
The problem here seems to be that if you were to compress your hidden data prior to hiding it, then the data inserted would appear random and should thwart statistical analysis.
The problem is, the LSBs of a photo do not appear to be random; there are many subtle correlations between them, some of them human-visible and some of them computer-visible. A given known machine-visible one can be foiled with enough statistics (see Outguess), but when a new one comes along the steg will be broken (as is Outguess).
In any case, it is assumed that you are compressing the data to save space and protect your cipher, and then encrypting it (stripping any headers added by your encryption program) to give data that would be difficult to prove non-random. The question remains how to find places in the file which appear sufficiently random to hide your data.
You'd need some redundancy there if you intent to jpeg compress the image, but it might work.
No, you'd just fudge the low-order bits (after quantization) of the coefficients of the discrete cosine transform. Of course, these also have correlations that you'd have to watch out for.
Possibilities (Score:2, Interesting)
At the same time however, it seems like steganography has some inherent flaws in it. That is to say, the more people use is, the quicker people will be able to determine patterns in the method. This would allow people/groups/countries/etc. to find the message faster. Doesn't sound like too reasonable of an idea.
Additionally....I'd be interested to see what DJB [cr.yp.to] has to say about steganography...
Re:Can someone explain to me what is meant by... (Score:4, Interesting)
Re:Hmm (Score:5, Interesting)
Any sufficiently advanced neural net should be able to deterministically find changes in common data communication where information can be hidden. And do you truly think that your data is not being checked by big brother?
I doubt there's enough computational resources for a sufficiently advanced neural net.
If chunks of known ciphertext in something like AES-256 can't be broken in times measured in universe ages, then I can't foresee much success in wholesale scanning of all information, searching for embedded secret strings which, if properly encrypted, should be indistinguishable from random noise.
An old Slashdot story mentioned one of the most fertile fields for laying down stego messages: within spam [spammimic.com].
A stego method that actually works (Score:2, Interesting)
Remember the post 9/11 image-messaging concern? (Score:3, Interesting)
I seem to recall a distributed screen-saver type app that was being used to crunch through millions of hosted images. Not much to find online about this, but there are articles like this one [newscientist.com] at NewScientist.com suggesting that the effort was a washout. here [xtdnet.nl] are some more stats from a study that came up dry, but there always this reference [xtdnet.nl] to "first stenographic image in the wild" as reported by ABC back when.
Application more important than Technique? (Score:3, Interesting)
Using statistical methods, most steganography can be broken either now or in the near future if the steganalyst can spend a lot of time and computing resources on each candidate bit collection, and if you're hiding a lot of bits in each collection. The consequence: don't hide very many bits, and widen the search space by hiding your trees in a forest of significant size, so that the amount of CPU the analyst can use on any particular tree is low.
Key exchange is a great candidate for steganography. And to make sure the population of innocuous bit collections around yours is high, find a place where a lot of people around you are dealing in large quantities of bits: music collections at a university, or spam messages on an e-mail relay.
Re:Layered Implementation (Score:3, Interesting)
Re:fun stuff (Score:4, Interesting)
Re:Wasn't that his point? MOD PARENT DOWN (Score:5, Interesting)
Re:Hmm (Score:3, Interesting)
If ever they develop the notion that you require extra special treatment, they might catch on to your hidden messages, of course (or perhaps not). If they do, then I agree they have all the more reason to suspect you of foul play. It's something of a trade-off.