Information#
Version#
| By | Version | Comment |
|---|---|---|
| noraj | 1.0 | Creation |
CTF#
- Name : VolgaCTF 2017 Quals
- Website : quals.2017.volgactf.ru
- Type : Online
- Format : Jeopardy
- CTF Time : link
Description#
There are files A.png and B.png. But where's the flag?
A.png:
B.png:
Solution#
If you know OTP you must know this famous attack on pad reused.
You can also see some black lines on image B. Now let's XOR image A and B (with ImageMagick):
1 | $ convert A.png B.png -fx "(((255*u)&(255*(1-v)))|((255*(1-u))&(255*v)))/255" out.png |
And now we get the result:
Flag is: VolgaCTF{Classic_secret_sharing_scheme}.
Note: VC is for Visual Cryptography