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is there any evidence that the steganography here is undetectable? i would have thought that uniformly random data in the low bits of an image's data (pixels o
by andrewcooke 13y ago
is there any evidence that the steganography here is undetectable? i would have thought that uniformly random data in the low bits of an image's data (pixels or fourier coefficients or whatever) was a clear signature for anyone trying to find these things. aren't they naturally correlated in various ways?
also, something like tineye can be used to retrieve web-sourced images for comparison, which would make any hidden data really obvious (and a smooth gradient would be even more suspicious if the lowest bits weren't smooth).
what is the state of the art in steganography? is it feasible for reasonable bandwidth? what are the best carrier data to use? do phone cameras provide raw images or are they always jpegs? i guess a webcam video uploaded to youtube has the advantages of large data volume, unique content, and wide visibility. but do they reformat?
- ericras 13y agoOff course before you even get to all that, I'd be concerned about the steganographic problem where they go to your ISP's logs and see you've visited the site.
- harrytuttle 13y agoThat is the first thing I thought. Unless it runs on your computer and you can trust that, it's useless.
- nitrogen 13y agoalso, something like tineye can be used to retrieve web-sourced images for comparison, which would make any hidden data really obvious (and a smooth gradient would be even more suspicious if the lowest bits weren't smooth). Smooth gradients are only smooth if you add noise to the lower bits, due to having only 256 color levels per channel. A comparison: http://imgur.com/0cJWm8t http://imgur.com/0cJWm8t Those color bands are indeed only one color value apart per channel; the first visible band is rgb(50, 120, 50), while the second is rgb(51, 119, 51).
- anonymous 13y agoThe banding is almost imperceptible though. I had to get close to the monitor and squint a lot to see it.
- andrewcooke 13y agooh, good point. the site should explain this for people like me and also clarify how many bits are available.