Forensics 200: now you don’t

Challenge

We heard that there is something hidden in this picture. Can you find it?

Solution

We extract the LSB of each of the colour channels using this script

and find the flag in the red channel:

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$ python3 extractlsb.py -i nowYouDont.png

This script outputs 3 black-and-white images, each signifying the least significant bit of each of the 3 RGB channels.

the outputfile for the red channel, nowYouDont_lsb_r.png, contained the flag:

Flag