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I always expected steganography to be used to encode a compressed and encrypted datastream, not uncompressed images. Such a compressed and encrypted datastream

by dzdt 11y ago

I always expected steganography to be used to encode a compressed and encrypted datastream, not uncompressed images. Such a compressed and encrypted datastream should be indistinguishable from noise, so not show in this kind of analysis. My pet idea for doing steganography was to use nonstandard or suboptimal encoding sequences. For compressed data formats, including images, music, video, and general files, there is almost always a choice of various encodings which will decompress to the same result. Systematically varying a compression choice gives an invisible way to encode data.

Arkanum 11y ago
Actually there are properties of images that meant that the noise introduced through stego is actually, especially for LSBR, VERY easy to detect. https://www.cs.ox.ac.uk/teaching/materials15-16/advsec/advsec-notes-ch01234.pdf https://www.cs.ox.ac.uk/teaching/materials15-16/advsec/advse...
- progressive_dad 11y ago
  That page requires an Oxford University username and password. I'd be interested to read this.
progressive_dad 11y ago
You too? That's #2 on my retirement list after releasing a library of open source epistemology enhancements for common game engines with demo UI. Maybe, together, we can finally kill the dialogue tree.
yaur 11y ago
I wrote something like that for an ARG. Basically I used GIF images with sets of 2 visually identical entries in pallet and encoded bits by picking either the first or second. Not quite as sophisticated as something like varying which dct coefficients to keep in a jpeg, but it was intended to be breakable with a hex editor. The problem was that most image hosts were smart enough to detect the sub-optimal encoding and "helpfully" fix it.
Scea91 11y ago
About 2 years ago I have implemented the Steganalysis method based on paper "Steganalysis by Subtractive Pixel Adjacency Matrix" http://www.ws.binghamton.edu/fridrich/Research/paper_6_dc.pdf http://www.ws.binghamton.edu/fridrich/Research/paper_6_dc.pd.... The whole evaluation was done by embedding random messages and the method worked well so I guess encryption of the datastream won't help much.

by dzdt 11y ago

Arkanum 11y ago

Actually there are properties of images that meant that the noise introduced through stego is actually, especially for LSBR, VERY easy to detect. https://www.cs.ox.ac.uk/teaching/materials15-16/advsec/advsec-notes-ch01234.pdf https://www.cs.ox.ac.uk/teaching/materials15-16/advsec/advse...

progressive_dad 11y ago
That page requires an Oxford University username and password. I'd be interested to read this.

progressive_dad 11y ago

You too? That's #2 on my retirement list after releasing a library of open source epistemology enhancements for common game engines with demo UI. Maybe, together, we can finally kill the dialogue tree.

yaur 11y ago

I wrote something like that for an ARG. Basically I used GIF images with sets of 2 visually identical entries in pallet and encoded bits by picking either the first or second. Not quite as sophisticated as something like varying which dct coefficients to keep in a jpeg, but it was intended to be breakable with a hex editor. The problem was that most image hosts were smart enough to detect the sub-optimal encoding and "helpfully" fix it.

Scea91 11y ago

About 2 years ago I have implemented the Steganalysis method based on paper "Steganalysis by Subtractive Pixel Adjacency Matrix" http://www.ws.binghamton.edu/fridrich/Research/paper_6_dc.pdf http://www.ws.binghamton.edu/fridrich/Research/paper_6_dc.pd.... The whole evaluation was done by embedding random messages and the method worked well so I guess encryption of the datastream won't help much.