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Blocking Steganosonic Data In Phone Calls
psyced writes "Steganography is a technique to encode secret messages in the background noise of an audio recording or photograph. There have been attempts at steganalysis in the past, but scientists at FH St. Pölten are developing strategies to block out secret data in VoIP and even GSM phone calls by preemptively modifying background noise (link is to a Google translation of the German original) on a level that stays inaudible or invisible, yet destroys any message encoded within. I wonder if this method could be applied to hiding messages in executables, too."
That's completely pointless. All it does is create an arms race. Any amount of noise you add can simply be dealt with by including the stego data more than once or using checksums or whatever. Any amount of damage sufficient to prevent any possibility of hidden messages would result in significant audible alteration of the sound to the point of unusability....
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Could this just be subliminal white noise? (as opposed to superliminal).
I guess its one way to prevent getting the alien infection from over the phone (anyone remember Threshold)... might mitigate some people's fears of harmful sensation. http://en.wikipedia.org/wiki/Motif_of_harmful_sensation
I wonder if it will foil over the phone lie-detectors like this one: http://www.liarcard.com/ ?
I can only see bad things coming from this.
Imagine the worst-case scenario; Congress forces all telcos to install this sort of technology on all phone lines. Why not? If you don't put up with hissing on your phone line, you're helping a terrorist, no?
The butterfly flaps its wings twice.
I repeat, the butterfly flaps its wings twice.
Um, no.
No sig today...
I wonder if we will ever have widespread end-to-end encryption for all of our private communication, so that "service providers" cannot mess with our actual message and/or data stream. I guess there will always be someone making a profit by preventing this on a legal level, sadly. When will the "mindless consumer" finally wake up and kick the government that allows all this?
I wonder if this method could be applied to hiding messages in executables, too.
Yes, a similar method has been employed by Microsoft to all the executables it ever released, ever since the times of MS-DOS.
After compilation they run the program through a special utility that modifies a few bits in the executable at random. Then they run the resulting executable through some tests and if it passes, they release it, if it crashes, they try with a different random bits.
45 5F E1 04 22 CA 29 C4 93 3F 95 05 2B 79 2A B2
I wonder if this method could be applied to hiding messages in executables, too.
Eh? A programme does not have white noise.
You can add "random noise" to an .exe file - most processors have at least some opcodes with "don't care" bits. You can alter those bits without affecting the semantics of the code.
It doesn't have white noise, but a program has enough places where you can replace code by a functional equivalent that you can pass messages in modified executables: http://www.crazyboy.com/hydan/.
If they can detect and change the patterns of car sounds and honks while you're making a phone call in Manhattan (in case it's steganography) then it means the same technology could *remove* the honks and make our conversations clearer, which would be much more useful and economically valuable.
If on the contrary they're unable to change background traffic sounds, then that's how people will do steganography and their method fails to block it.
Truely, If I want to get info secretly from me to you, then why would I use background noise in a phone message ? That leaves a clear record that we spoke.
Why not post a high iso (noisey) picture on flickr with a hidden message in the noise.
Then it's harder to even verify that we had any comunication, never mind figure out what was transmitted.
IS THIS A REAL PROBLEM ?
Or has someone just been paid to find a solution to the problem of chocolate teacups melting.
D
Simply, this just takes a known method for steganography and encodes random noise, wiping out any messages already there.
It can only block known steganography methods, so simply think up another method and your safe... Its just one big arms race
Or just jump over a group of random bytes that will never be executed. In a high level language have some unused variable
myString = "FooFoogh234h2j4hj23hj";
search the executable for FooFoo then read the following bytes.
I hate to be forced to use even lossier sound formats.
Reminds me of Creative's AC3 pass-through (non existing for several years).
I want bitperfect, non-lossy sound compression. Multichannel.
scientists at FH St. Polten are developing strategies to block out secret data in VoIP and even GSM phone calls by preemptively modifying background noise
...And once again, they treat all of us like criminals for the sake of annoying (not even
preventing or catching) the 0.0001% that really pose a threat.
Good work, guys - Even a classic BOFH has higher efficacy and useability standards than anything related to the War on Non-Western, Non-Irish, Non-Russian (and "non-former-Soviet") Terror. At least the BOFH's systems work for him, you asshats can't even manage that despite taking all that daaaaaaangerous toothpaste away from us.
However, even I overstate the case here - Encoding data in background noise doesn't break any laws!
We all have every right to send hidden data, or even to use hard encryption right in plain sight. However, exercising that right may lead to some undue scrutiny, and thus we expose the real reason for techniques like this... Erosion of plausible deniability, which The Powers That Be loathe far, far more than any actual threat. It looks bad to just deport and torture someone with no evidence. But if you can demonstrate that he had (gasp!) something he didn't want the whole world to know about (because only criminals have secrets, of course), well then the sheep will approve of going all Jack Bauer on him.
Data can only be defined as varying bits of a defined pattern. So if the pattern is defined as 'a bunch of numbers that are either 0s or 1s', then the data stored within it is defined as varying the positions of 0s and 1s.
Obscuring data equals obscuring the patterns. So, to obscure the data within a 0 and 1 pattern, you might switch around the 0s and 1s.
For a message embedded in the background noise in a phone call, data may be modulated as 'loudness of background noise within a certain frequency range' or whatever. Obscuring this would be to add random data in the frequency range or whatever.
But that actually takes knowledge of the pattern used. If the pattern is rather the speaker knocking on a table, then any method designed to obscure background noise wouldn't register it or obscure it. It's similar to a scrambling technique that randomizes the 0s and 1s on a diskette sent in the post, while the actual message may be morse code holes punched in the plastic.
Conclusion: To void steganographic data, you need to know the method used to embed it.
They key to hiding data in executables is to realize that there are many instructions with multiple possible encodings.
You can also reverse the order of many comparison operations as long as you also modify the following branch/set instructions.
If you want to jam such a channel you would have to do the same job, first identifying all the possible locations for such transformations, then randomly flip half of them.
(Un?)fortunately neither the encoding nor the jamming process can be totally secure, because you can check (or know up front) which compiler had generated the original executable, then decompile/recompile and check which encodings the compiler tend to use.
Terje
"almost all programming can be viewed as an exercise in caching"
I've been wondering when the governments of the world would start doing something like this. No need to overtly outlaw encryption, just arm-twist the folks on the backbone to drop or block encrypted traffic or just modify it so that it can't be decrypted.
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I see the parents sig as a sort of darwinian filter on how careful one is the slashdot reader at clicking link.
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This could be better spent on more cell towers, or not allowing bastard fone companies to charge $200.00 termination fees.
Stopping secret messages? , puleeese.
"John has a long mustache"
"The chair is against the wall"
Stop that!
* Carthago Delenda Est *
They can send a 'secret' message if they so desire. That can be by asking if aunt Lilly is still sick. This could trigger an event or it could be that aunt Lilly was sick. Or even both.
What is more important very often is being able to link people. To see who is talking to who. The fact that a secret message is send will highten the importance.
So what could a wannabe terrerist do to avaid that? Usenet! No direct connection between the two and everybody can connect from everywhere and post to any group. As long as you keep to the rules of a (binary) group, you should be OK.
Even when caught, the person sending might not even KNOW who the reciever might be.
Disadvatage is that there is no or only slow interaction possible.
Don't fight for your country, if your country does not fight for you.
I'm sure someone will correct me if I have missed something, but it seems to me that the desire by some to hide irremovable watermarks within digital streams is a similar technical challenge to adding steganographic content. Similarly, those attempting to destroy watermarks will face the same problems as those wishing to remove or destroy steganographic content.
The interesting thing is who is on which side of the battle.
Generally it's corporations who like the idea of watermarks, and individuals who don't. Individuals do however like steganography, but the authorities don't. It will be interesting to see who develops what technologies and who, if anyone, wins this arms race.
-- MartinG To mail me: echo kewyjlcxyzvjfxbqwh | tr bcefhjklqvwxyz
It's along the lines of "How do you tell if there are stego images on someone's computer?"
Answer:You find the stego converter tool on their harddrive.
It just occurred to me with the recent release of "fully unlimited" voice plans by major carriers(at least in the US) this practice actually would break something.. mobile data carrier pocket books.
Imagine if someone were smart enough to re-invent the accoustic modem for modern thrifties on the go. Slow but otherwise free methods to check email while evading mobile broadband fees? yes please.
VLC FOR MAC IS DYING! IF YOU DEVELOP, PLEASE SAVE IT!!
I want end-to-end encryption on all my calls. This could be added to cell phones with some modest changes. Not having it on VOIP is just inexcusable. If the FBI wants to tap my phone, why don't they get off their lazy asses, obtain a warrant, and do some actual work, rather than expecting everything to be handed to them on a silver platter, complete with booze and hookers. I'm under no obligation to make it easy for them.
Mea navis aericumbens anguillis abundat
It's been a while since I did any of this, but I checked, and GSM, like most of the low-bit-rate systems, uses a vocoder-based codec. Vocoders do one thing well, encode the human voice (they do this by using a vocal tract model and transmitting the time-varying parameters of this model). They typically don't handle background noise well, if at all, because it can't be reproduced using a model of the vocal tract.
So, anyone trying to use a modern cellular phone to transmit steganosonic background noise, is going to find that they have an abysmally small data throughput rate.
I'm thinking that the earlier poster is right, this is someone solving a problem that doesn't exist (and probably getting a nice chunk of grant money for their trouble). The cell phone itself will garble any background noise quite well enough!
I guess the same kind of technique could be applied to steganographic data contained in HD playback or mp3s.
:P
Nice to know someone is actually looking for a way to destroy these
Your problem is not interception of the radio signals, your problem is the (US) federally mandated CALEA interface on every switch in the network.
A mobile-to-mobile call almost always (unless you're both on the same tower) needs to pass over a landline, and to do that, it needs to be unencrypted.
Well, I think this is a really bad idea, and is going to cause massive trouble. If you stop stegosaurs using the phone, they are going to get really pissed off, and well, have you ever seen a pissed off stegosaurus? Trust me you don't want to, those spiky tails, eek!
What if Tetris was invented by Nazis?
Steganosonic? Sounds like a really fast dinosaur.
That said, it is relatively easy to disrupt stego by lossy compression/decompression or vice-versa if the source is compressed. Low-order bits will get stripped in JPEGs & MP3s. This obviously doesn't work for loss-less compression as is needed for binaries. If hash or other non-compressibles found, just rehash. Once you've decided to meddle inthe datastream, some eggs will get broken. You'll have both alpha and beta errors (misses and false postives).
I wonder if this method could be applied to hiding messages in executables, too."
Um, no, because the two technologies are completely different?
Yes, there is an analogue for "background noise" in an executable, and there is a lot of redundancy there too. But I can't imagine how any approach to removing encoded data there could share anything except on the most basic conceptual level.
A Minor Correction:
You have the association arrow backward. Hiding a message in radio or telephone background noise is one of many techniques collectively called steganography (literally "hidden writing"). Also, breaking this form is yesterday's war.
I'm a Programmer. That's one level above Software Engineer and one level below Engineer.
Try introducing random bit changes into an executable. Let us know how it goes for ya.
Coding with assembly is like playing with Legos. Coding an application in assembly is like building a car with Legos.
" ...And once again, they treat all of us like criminals for the sake of annoying (not even preventing or catching) the 0.0001% that really pose a threat."
And your source for that stat is?
If you could detect and modify the background noise, then you could simply eliminate it. But I don't think that is possible, since what makes something "background noise" is the fact that it can't really be removed without damaging the foreground signal. If it could, you would have a perfect signal-to-noise ratio. Such a technology could be used to improve the bandwidth, compression ratios, etc. - which is something far more useful than fearmongering.
Unfortunately, I don't real have anything to go on other than a Google translated abstract, a Slashdot headline, and armchair knowledge of electronics. Anyone care to correct me?
Does this mean next time Coca Cola or Pepsi changes their root beer formulae, if they use this method there is some chance one of the bottling plants might get a garbled message specifying or bleach rather than anise? ZOMG!!!111!!!ONEONEELEVEN
And your source for that stat is?
Six(+) billion people on the planet. Pretty much every "expert" (whatever that means, given their track record on this one) I've seen/heard quoted, estimates "a few thousand" actual terrorists. That gives in the ballpark of 0.0001%, which would equal 6,000(+) humans.
Do you call that "arrogant" for trusting that those experts probably at least have the right order of magnitude, or did you just not bother doing the math to see that it does indeed yield a reasonable, if approximate, figure?
bug+1
4e:45:56:45:52:20:47:4f:4e:4e:41:20:47:49:56:45:20:59:4f:55:20:55:50
4e:45:56:45:52:20:47:4f:4e:4e:41:20:4c:45:54:20:59:4f:55:20:44:4f:57:4e
4e:45:56:45:52:20:47:4f:4e:4e:41:20:52:55:4e:20:41:52:4f:55:4e:44
41:4e:44:20:48:55:52:54:20:59:4f:55
Osama, the CDs are on the plane.
--
BMO
It is slightly amusing that state is so far behind in this one area of surveillance. The method proposed here to futz with the voice content aspect of the call would have been effective up to, say, 1988, after which point it became easier to encode and retrieve the juicy bits in some other aspects of the call.
Without giving away too may secrets (from the 1990s, even though the state of the art is now significantly more advanced), think about the temporal and spatial information is transmitted by the act and protocol of initiating one phone call (from or to a cellular or landline endpoint). Think about the possibilities with initiating and (optionally not) terminating a series of phone calls. Any Asterisk admins lurking here will be familiar with the type of instrumentation required to execute this technique, putting as much or as little in the clear as desired. Now recall that some organizations using these techniques also use particular codebooks which need not be hidden and carry very specific meanings in context understood only by members of a specific group.
And remember: sometimes the most important part of a message is that which is not said.
They say stegosaurus was the sneakiest of the dinosaurs, and could hide in plain sight.
The enemies of Democracy are
Why are dinosaurs making noises during my phone calls?
There is a very interesting program named hydan http://www.crazyboy.com/hydan/ that does something very interesting.
It looks for numeric operators and, using certain rules such as change a subtracting a constant to adding a negative constant, will change some and leave others alone to encode binary data. The executable's hash is changed, obviously, but its functionality is not, and you can encode a message within an executable in a manner that would be difficult to detect, especially if people do things like subtracting negatives as a sort of "signature" to detect stolen code.
Share and enjoy.
If you can remove stego'd data from the audio recording then you can remove watermarking. Circumvention of copy right protection measures, so it's a criminal offence. Send round the bobbies and nail 'em up.
No, it's because your point TOTALLY falls apart if you replace that figure with 0.01% or - God help us - 0.1%. AC is a dorkwad.
DRM: Terminator crops for your mind!
I know it's tempting to think of all Geek Enemies as one big evil oppression machine, but I don't think the content industry associations are the ones pushing this. Some people want to block steganographic content, and some other people want to keep watermarks permanent.
DRM: Terminator crops for your mind!
"Ixnay on the ecretsay odecays."
Have gnu, will travel.
I thought that modern codecs compress audio data by removing audio information deemed 'unimportant'. Codecs targetted at voice-only applications, I've always thought, were far more aggressive in this 'filtering out' of 'unneeded' audio information that more general-purpose compression like mp3, aac, ogg, etc. So, I would think that the codecs would normally tend to reduce the capability to do stegonography to begin with. Of course, someone might code up a new (or modified) version of the coded that is still compatible with other codecs, but still generates audio data that other implementations would normally filter out during encoding.
So, why not just have some equipment at the VoIP gateway that that just 'more aggressively' filters out background noise (e.g. re-compress the data, to make sure non-audible audio data is stripped out)? Why bother with adding random noise? If you remove the background noise, you can plausibly 'sell' that as increasing call quality while reducing bandwidth usage, and it would, I think, have the side-effect of also having the possibility to disrupt some stegonographic techniques, whereas adding random noise to my phone call is just degrading the quality of my calls and increasing my bandwidth usage.
I'd be satisfied if my current provider quit modifying my foreground noise so badly.
Isn't there a Skype plugin that does this or something?
Encoding data in the background noise dumb, because you can't assume that ambiance will be transmitted to the receiver. The telco is likely to drop packets when audio drops below a certain threshold, and use the bandwidth for moving other data on their network.
Smarter spies will hide data by modulating foreground sounds, which are much more likely to get transmitted, and much harder to f**k with without being noticed.
I wonder if instead of utilizing "inaudible" background hiss to carry (compressed, encrypted) data you selectively modify certain human vocalization(s), by using the actual sound of the conversant voices selectivly you not only (hide, encrypt, compress) but you can also change which speech characteristics you utilize for the purpose.
I killed da wabbit -Elmer Fudd
It would do SMS and email (smtp, imap) quite handily.
This whole situation boils down the the ~"conversations may not be private" rule for Amateur Radio. If private communications had been allowed, hams would have multiple awesome, free cell services set up with none of this charging for minuscule SMS messaging or data garbage.
They ARE out to get you simply because They are in it for themselves and they don't care about you.
For starters, of the 60 or so you claim to be in close proximity, only the ones actively moving data or carrying a conversation will be actually transmitting anything more than house keeping messages. That alone thins the pool quite a bit. If you are monitoring conversations from a particular set of towers and discover something interesting, then you will be able to know which phone is carrying that conversation in an instant.
;-)
Even if you don't know which conversation is interesting, you can still localize each phone by triangulation one at a time, continuously. If you discover that one or more of them is near a "location of interest" then you can tag that phone for closer monitoring in the future. If you notice such anomalies like a phone switching off before entering a certain locale(where you know the signal is good and so it is not a drop), you can tag it for later surveillance. If any phone in question has a GPS, it can be commanded to *send* the location data without notifying the user. Sooo easy.
More, the base station can command any nearby phones to lower their output power or even switch off, and the inverse, the cell tower can command the desired phone to increase output power to the maximum available, and cause it to transmit continuously, EVEN IF THE PHONE IS IDLE. If the spy folks are anywhere near the target phone with a couple of directional antennas, then the phone is readily located and the game is over.
All of these 'features' are documented in the standards. No special code versions or hacking required. If you 'own' the cell systems as any gov effectively does, then special versions of the software can be loaded at will, with even more 'features' available for tracking and even eavesdropping.
Believe me, if you want to hide from the gov, don't carry a cell and don't let anyone that has one near you.
Good judgement comes from experience, and experience comes from bad judgement.
- W. Wriston, former Citibank CEO
contain encrypted messages. . . the ones with random character sequences in the header and/or at the end of the post.
Tech Public Policy stuff
I am fully in favor of blocking Stegosauruses from making phone calls.