CAMSCTF CCTF 2015: Python 2 (Programming) Write-up

Description:

1.) Take the RGB value of every pixel in one image.(Start at (0,0). Move down to (0,299). Go to (1,0). Move to (1,299). And so on. Read the files in numerical order.)
2.) Add all of the R values, G values, and B values in each image. (Have one R sum, one B sum, one G sum for every image.)
3.) Take these sums and convert them into strings. Take the MD5 hash of each string.
4.) Concatenate these MD5 hashes into one string.
5.) Take the MD5 hash of the new string.
6.) Do this for every image and concatenate the final MD5 hashes into one string. (Image 1 final hash + Image 2 final hash + ...)
7.) Take the MD5 of this string to get the flag.
PIL.zip

Solution: 

	#!/usr/bin/python
	# Author: Kitwipat Towattana (@icheernoom)
	import hashlib
	from PIL import Image
	md5 = []
	width = 300
	height = 300
	for i in range(0,10):
	img_file = "pixels{0}.png".format(i)
	img = Image.open(img_file)
	rgb_img = img.convert('RGB')
	xr = 0
	xg = 0
	xb = 0
	for x in range(0,width):
	for y in range(0,height):
	r, g, b = rgb_img.getpixel((x,y))
	xr += r
	xg += g
	xb += b
	r = hashlib.md5("{0}".format(xr)).hexdigest()
	g = hashlib.md5("{0}".format(xg)).hexdigest()
	b = hashlib.md5("{0}".format(xb)).hexdigest()
	sum_md5 = "{0}{1}{2}".format(r,g,b)
	concate = hashlib.md5("{0}".format(sum_md5)).hexdigest()
	print "[*] MD5 of {0}: {1}".format(img_file,concate)
	md5.append(concate)
	print "[*] Flag:",hashlib.md5("".join(md5)).hexdigest()
	'''
	root@ubuntu:/PIL# ls
	pixels0.png pixels2.png pixels4.png pixels6.png pixels8.png prog250.py
	pixels1.png pixels3.png pixels5.png pixels7.png pixels9.png Thumbs.db
	root@ubuntu:/PIL# python prog250.py
	[*] MD5 of pixels0.png: e767124634834f12a7152104d4713074
	[*] MD5 of pixels1.png: a88372d92bcc6e8f5f569bc3c00fab23
	[*] MD5 of pixels2.png: 345265539e1b9078323b7051346892de
	[*] MD5 of pixels3.png: 92ae219f8b8403e04b550eb831a017bf
	[*] MD5 of pixels4.png: a4bd4eb96fe9cc779c2e81864c81b674
	[*] MD5 of pixels5.png: 4723f098c933b160d00678b7be3421c4
	[*] MD5 of pixels6.png: 3a4c3cb7b2fd704c4e7717547f7db4d9
	[*] MD5 of pixels7.png: bc1f5bc7b30eaac677d6daa37eed5e4c
	[*] MD5 of pixels8.png: a4edf81b7f2915c4c1b72d8367c5016a
	[*] MD5 of pixels9.png: 864ae043e67a693d7672986487a87813
	[*] Flag: 2d98c27f040ce429b35dd84124397f65
	root@ubuntu:/PIL#
	'''

view raw prog250.py hosted with ❤ by GitHub

Flag: 2d98c27f040ce429b35dd84124397f65