๋ณ ๋ค๋ฅธ ํํธ๊ฐ ์๊ธฐ ๋๋ฌธ์
์ผ๋จ hidden.jpg ๋ฅผ ๋ค์ด๋ฐ์๋ค
์ฒซ๋ฒ์งธ๋ก ์์ฑ์ ํ์ธ
์์ธํ ํญ ๋ ํ์ธํ์ผ๋ ๋ณ๋ค๋ฅธ ์ด๋์ด ์์๋ค
๋๋ฒ์งธ๋ ํ๋ฉด์ด ์ฌํ ๋ณด์ด์ง ์๊ธฐ ๋๋ฌธ์
์ด๋ฏธ์ง ์คํ ๊ฐ๋ ธ๊ทธ๋ํผ๋ฅผ ์ด์ฉํ ๋ฌธ์ ๋ผ๊ณ ์๊ฐํ์ฌ
์๋ ์ฌ์ดํธ๋ฅผ ์ด์ฉํ๋ค
https://incoherency.co.uk/image-steganography/#unhide
Image Steganography
Each channel (red, green, blue) of each pixel in an image is represented by an 8-bit value. To hide the secret image inside the cover image, we replace the n least significant bits of the cover pixel value with the same number of most significant bits from
incoherency.co.uk
ํ์ผ ์ ํ์ผ๋ก jpg์ ์ฐ ๋ค์
Hidden bits ๋ฅผ ์กฐ์ ํด์ฃผ๋ฉด ๊ฐ์ด ์์ํ ๋์จ๋ค
(๋๋ต 3, 4์์ ์ ๋ณด์ธ๋ค)
์ด๋ ๊ฒ Download Full-size Image ๋ฒํผ์ ๋๋ฌ ์ฌ์ง์ ํฌ๊ฒ ํ์ธํ ์๋ ์๋ค
๊ทธ๋ฌ๋ฉด ๋ต์ tjctf{th3_f0x_jump3d_0v3r_m3} ์ด๋ผ๊ณ ๋์จ๋ค
'๋ณด์ > CTF' ์นดํ ๊ณ ๋ฆฌ์ ๋ค๋ฅธ ๊ธ
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