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Researchers Calculate Capacity of a Steganographic Channel
KentuckyFC writes "Steganography is the art of hiding a message in such a way that only the sender and receiver realize it is there. (By contrast, cryptography disguises the content of a message but makes no attempt to hide it.) The central problem for steganographers is how much data can be hidden without being detected. But the complexity of this problem has meant it has been largely ignored. Now two computer scientists (one working for Google) have made a major theoretical breakthrough by tackling the problem in the same way that the electrical engineer Claude Shannon calculated the capacity of an ordinary communications channel in the 1940s. In Shannon's theory, a transmission is considered successful if the decoder properly determines which message the encoder has sent. In the stego-channel, a transmission is successful if the decoder properly determines the sent message without anybody else detecting its presence (abstract). Studying a stego-channel in this way leads to some counter-intuitive results: for example, in certain circumstances, doubling the number of algorithms looking for hidden data can increase the capacity of the steganographic channel"
How is that counter-intuitive? Many of us regularly backup our stuff here in slashdot, and no one has complained so far (which, being the slashdot crowd what it is, is definite proof that no one has noticed).
In fact, a port of gmail drive to slashdot is already in beta.
In the stego-channel, a transmission is successful if the decoder properly determines the sent message without anybody else detecting its presence (abstract).
When my girlfriend is talking on the phone, I am almost never aware that a message is being sent. She is so effective, in fact, that often when I am the intended recipient I am not aware that a message is being sent!
stegan O graphy i S T he a R t of hiding A message in su C h a way that only the sender and receiver realize it is there. (by contrast, cryptography disg U i S es the content of a message but makes no attempt to h I de it.)
there' S a secret messa G e in this post. c A n an Y one find it?
So, does anyone know how much data can be stuffed, undetectably, into a 700MB AVI file?
700 MB, if you do it in the dark.
I always thought Steganography was the act of writing on large, plate-backed dinosaurs. Ya learn something new every day here!
http://photobombers.com/ Funny pix
In south or terse, I touch in kelp. You are wrought on girls, but it's young urine poor obese ladle mate.
"In short, I think you are wrong, but it's your problem."
... of Pamela Anderson. There appears to be quite a bit of excess capacity available.
Have gnu, will travel.
Calculating this with any accuracy would require knowledge of both the width of a Stegasaur (which can be approximated from their fossils), but also how fast they ran. Given other arguments about the unknowns of dinosaurs, the figures we can guesstimate for their speed are just to varied to calculate this capacity to any meaningful value.
The The secure capacity C (W, g, A) of a stego-channel give W [noise], g [steganalyzer], and A [attack] is given by C (W, g, A) = sup I(X;Z) for X an element of S0.
I is the spectral inf-mutual information rate for the pair of general sequences.
Z is the stego channel after encoding, noise, and attack (before decoding).
S0 is the secure input set, the set of encoded data that remains impossible to steganalyze after the addition of noise (but not necessarily attack).
I think mathematicians like to make their papers overly complex.
It is generally a bad idea to play a smartass in front of a cop on duty.
In a friendly debate with a moderately drunk chick in the bar, that may be appropriate.