This post is a mixture of AppSec, vibe coding and cryptography. SPOILER ALERT: This post describes how to complete the Capture-The-Flag exercise “Encrypted Pastebin” (Hard) on Hacker101. Over the last few days I have had a lot of fun with a padding oracle. But let’s take a step back: I have been looking at Hacker101 CTF exercises. The premise is simple: You’re given a website The website has flags hidden.