LYKNCTF 2026 Crack Writeup: 9 Reverse Engineering Challenges (ARX VMs, Self-Hash Anti-Tamper, ChaCha20 Layers, Brainfuck Esolang)
LYKNCTF 2026’s crack track (reverse engineering) was built around a repeating pattern: build a small cipher out of well-known cryptographic primitives, wrap it in obfuscation that looks harder than it is, then bake a .text-derived self-hash into the state so that any patch or debugger attach silently produces wrong output without changing the error message. Nine challenges, nine variations on that theme, from a simple string-import inspection in a Tauri desktop app all the way to a four-layer keygen whose master key mixes account name, license key, SHA-256(.text), and an anti-debug byte. ...