Spoiler if you google what you need to decrypt, the first thing you will find is this reddit thread: https://www.reddit.com/r/encryption/comments/4c1o6j/encrypted_riddle/ .
Oh hey, I'm there! I found that thread when looking for the answer string you get for the mission. Yeah, that puts a damper on things, but I guess it can't be helped. Like having the choice between finding it yourself or looking at a walkthrough, it goes the same way: Avoid the reddit post in order to not be spoiled :/
