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Vape Nation
Challenge
Go Green!
Solution
The hint makes us suspect that we need to look at the green channel, manual inspection show it contains mostly even values, but some uneven ones, so we try outputting where the uneven ones are
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from PIL import Image
img = Image.open('vape_nation.png').convert('RGB')
pixels_orig = img.load()
(w,h)=img.size
outimg = Image.new( 'RGB', (w,h), "white")
pixels_out = outimg.load()
for i in range(0,h):
for j in range(0,w):
(r,g,b) = pixels_orig[i,j]
if g%2 != 0:
pixels_out[i,j] = (0,0,0)
outimg.save("vape_nation_out.png","png")
which outputs the following image containing our flag:
Flag
IceCTF{420_CuR35_c4NCEr}