The Cobalt Blindspot

#Solution — The Cobalt Blindspot

The challenge is a three-part forensic extraction. The final flag is not stored directly; recover the three components, concatenate them in discovery order, and wrap the result in rvcectf{...}.

#1. Extract Part 1 from the image

The note's clue "deep azure wavelengths" points toward the blue channel. Extract the least-significant bit of each blue pixel in row-major order:

python3 -c "from PIL import Image;i=Image.open('specimen_9.png').convert('RGB');b=[p[2]&1 for p in i.getdata()];print(bytes(sum(b[i+j]<<(7-j) for j in range(8)) for i in range(0,len(b)-7,8))[:7].decode())"

Output:

cobalt_

So:

PART 1 = cobalt_