After unzipping the given zip file with `unzip challenge.zip`, we can see two images.

* ciphered_message.png
* secret.png

I checked the images with [strings](https://linux.die.net/man/1/strings), [exiftool](https://github.com/exiftool/exiftool) and [hexdump](https://man7.org/linux/man-pages/man1/hexdump.1.html) tools.But, there's nothing interesting in them.

Then, I read the **description** carefully again.

"A fun **VISUAL CRYPTOGRAPHY** tool will amaze your kids!"

I thought `visual cryptography` must be a thing.So, I searched `visual cryptography` online and found this [github repo](https://github.com/ageron/visual_crypto).


### In Usage Section


So, we have to *overlay* these two images and adjust the *transparency* to get the *original* image back.

I used this [online overlay tool](https://www.imgonline.com.ua/eng/impose-picture-on-another-picture.php) to do that.I didn't change anything in *setting*.


Then, I clicked `OK` button.

After a few seconds, the process is completed and I opened the *processed* image.

At first, I couldn't see anything.

But then, I zoomed in the image and found the flag!


*flag*: `TMUCTF{W3_h0p3_y0u_3nj0y_7h15_c0mp371710n_4nd_7h4nk_y0u!}`

Original writeup (https://github.com/MikelAcker/CTF_WRITEUPS_2021/blob/main/TMUCTF_2021_Writeup/Welcome/Warmup/README.md).