Remove exploit code from php file

So this is exploit code

if you decode the string you get
https://gist.github.com/samccone/8f4ea806880704933ee8

then by echoing the result of this mask operation you get
https://gist.github.com/samccone/bc7f3c8d04bead01480b

which is where I stopped, but this is no good at all.