OCR is Cool | Google CTF 2018

Google CTF 2018

OCR is Cool

Caesar once said, don’t stab me… but taking a screenshot of an image sure feels like being stabbed. You connected to a VNC server on the Foobanizer 9000, it was view only. This screenshot is all that was present but it’s gibberish. Can you recover the original text?

You can find my all CTF solution in here

You can download attachment in here:

I unzip the attachment and it is a picture of mail.

Question of title is the OCR is Cool so that, I use the OCR and this OCR must be tesseract 🙂 You can download tesseract use the

sudo apt install tesseract

But first I scale up the image because of the OCR may not conver to small character

convert image.png -scale %300

You can use above command for the scale up

After OCR txt file is like above.

In the question ceaser keywords past, caesar is one of the encyropter app in linux. You can download ;

sudo apt install bsdgames

In Linux, I don’t know why rot32 and Caesar don’t work so that I switch Ubuntu. When I looking up the text file VMY{blablabla} looks like the answer

I decrypted this text and I pretty sure the this is my answer.


But OCR did not work perfect, I write the code manually and 7. text is correct !! 🙂


Leave a Reply

Your email address will not be published. Required fields are marked *