[MagTF] NothingToSee

Challenge by WelloWorld

NothingToSee is an easy-medium steganography task I have wrote in-order to show a method of using visual way to see things.
You get one PNG file, with nothing you can see.
To solve that, you must to look on the alpha channels in the picture, you can see that all the alphas are 0 or 1 so you save it all as a string in case it’s related to binary data.
Then some solvers may think that it’s something with the real binary data but not, you might want to change all the alphas to 255 to see the real picture and then you can see that what is written there is that the height is 5 and the weight is 61.


Then, you have a rule for something but you don’t know how it’s connected to the long binary raw. Like other steganographic CTFs, the alphas somewhere repeated itself. Because it’s 0’s and 1’s you can’t just read it, so either you understand you need (5*61) characters or make a script calculating where it begins to repeat itself.
After get the repeated string you may think that it means something at binary but not, you must place them 61 weight and 5 height shape. Then you can see the answer is STEGGY so you trying MagTF{STEGGY} and it works :)

Sol.py code

Result of the script