Search code examples
imagebinary-datasteganographyexiftool

Extracting binary data with Exiftool

I am doing a steganography challenge. I have a jpeg file, and when I look the metadata of it with Exiftool, I see something interesting.

Red Tone Reproduction Curve     : (Binary data 64 bytes, use -b option to extract)
Green Tone Reproduction Curve   : (Binary data 64 bytes, use -b option to extract)
Blue Tone Reproduction Curve    : (Binary data 64 bytes, use -b option to extract)

So I thought that maybe there is something interesting there, but I am not sure on how to extract that binary data. When I use the following command: exiftool -b -RedTRC nameOfThePicture.jpeg, then I get this message: curv ck ?Q!)2;FQw]kpz|i}0. I think that message can be something but I don't how to extract that binary data and which type of file could it be. Any help?

Solution

  • That "message" is simply the binary data of that tag displayed on the command line. The curv part is the ID value for the TRC (see example code, specifically tagbase.sig = swap((long)0x63757276L); /*’curv’*/).

    To extract that data to a file, you just need to redirect the output.
    exiftool -b -RedTRC nameOfThePicture.jpeg >RedTRC.dat