I have raw image data that is XOR-encrypted with a fixed-size one-time pad repeated over the length of the image. I know what the format of the image data container is so I can successfully retrieve the first 6 bytes of the key.
But that's it so far, I have no idea how to proceed.. Are there relations between adjacent pixels? Has any research been done on the subject, and if there is, how? I've searched for hours to no avail.
The file is a Windows BMP image (
BM magic number) with a BITMAPINFOHEADER. That's why I can correctly guess the first 6 bytes and a few more bytes in between.
The key is a stream of 337 bytes generated by a PRNG, more specifically, Mersenne Twister. So the key could be considered random for now.
Right now, all I'm left with is, well, XOR difference between two lines in the image. There is a pattern, I just don't know what to make of it exactly.