CTF杂项之图片隐写、crypto

用linux下的信息提取工具Binwalk看一下：

root@kali:~/Desktop# binwalk 图片名
 
DECIMAL       HEXADECIMAL     DESCRIPTION
--------------------------------------------------------------------------------
0             0x0             PNG image, 1000 x 562, 8-bit/color RGBA, non-interlaced
91            0x5B            Zlib compressed data, compressed
3526          0xDC6           Zlib compressed data, best compression
1421307       0x15AFFB        Zlib compressed data, default 

compression后面是Zlib压缩的数据，写个脚本解压一下：

python提取脚本

from PIL import Image
from zlib import *
 
data = open(‘图片名‘,‘rb‘).read()[0x15AFFB:]
data = decompress(data)
 
img = Image.new(‘1‘, (25,25))
d = img.load()
 
for n,i in enumerate(data):
d[(n%25,n/25)] = int(i)*255
 
f = open(‘flag.png‘,‘wb‘)
img.save(f)