this isn't really a Photoshop tutorial you can do this with any version of Photoshop or other graphics program.
the text isn't really random but looks random*accept for the first lines of text these are just normal words*

lets get started then:
first you need the have a picture of something the size of this picture will have effect on the size of the text.
I open up Photoshop and rendered some blue to red clouds.

then save this file to a jpg format.

then open up notepad and open the jpg file you just saved(you need to set is to all file types)

and if done right you will have now you string with random numbers letters and figures*the first line may contain something like Photoshop, time, date collar-profile*
you can now copy this and paste it in your Photoshop file and there you are.
my advise is to rasterize it as fast as you can cause all that text is heavy on you machine.

just ask if you don't understand everthing