# CSCamp CTF Quals 2k13: Steganography - PNG

# file enc.png
enc.png: data
# cat png.py 
#!/usr/bin/python

png = 0x89504e470d0a
enc = 0xf1601c2c3e73

key = str(hex(png^enc))[2:].decode("hex")
print key

encfd = open("enc.png","rb")
data = encfd.read()
encfd.close()
size = len(data)

decfd=open("dec.png","wb")
j = 0

for i in data:
    decfd.write(chr(ord(i)^ord(key[j%6])))
    j+=1

decfd.close()
# ./png.py
x0Rk3y
# file dec.png
dec.png: PNG image data, 640 x 400, 8-bit/color RGBA, non-interlaced