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Aside from Jsteg of Derek Upham, Outguess of Neils Provos, and F5 (improvement of F3 and F4) of Pfitzmann and Westfeld, What other methods can you use in information hiding in JPEG images?

The methods I mentioned above hide the message in the DCT coefficients of the image before it is compressed. Are there other component in jpeg which can be used to perform steganography? Pixel values can be used for PNG and BMP images but they cannot be used for JPEG since they change after being compressed.

Thank you.

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I am not sure if Jsteg, Outguess or F5 make already use of this, but in theory you could use the APP segment to hide information.

Also the Quantization Table (DQT) could offer some limited space. You will have to study the effects of hiding data in there.

Changing the DCT coefficients seems to be the most sensible thing to do in my opinion.

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  • $\begingroup$ Thank you for the suggestion, I'm still finding out if the algorithms I mentioned modify the app segment. Can you suggest a tutorial or reading on how to modify and read the application segment of jpeg? Thank you again for answering. $\endgroup$ – Frank Smith Feb 3 '12 at 0:51
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If you are encoding the JPEG image, and know exactly which JPEG decoder or decoding algorithm will be used, any change in the pixel values can be determined. Thus it might be possible to encode information in sufficiently spaced pixel values by using an iterative approach to modifying their value (which may involve modifying nearby pixels as well).

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  • $\begingroup$ Thank you for the answer. Can you also help me learn how to do it? Maybe suggesting some tutorials or readings about that will help. Sorry I'm not so familiar with JPEG and I'm still learning on it. My focus is on steganography. Thank you again $\endgroup$ – Frank Smith Feb 3 '12 at 0:48

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