How do you make this?

If you take a look at the attached image, you’ll see it’s one of those secret message graphics where something written in cyan is covered with a random pattern of red, such that if you look at the image through a red filter, you see the secret message.

I want to make one of these graphics myself, but I don’t know how to make the red portion which seems to be a random red pattern.

As always, thanks for the help.