Misc and esoteric languages
The category you cannot prepare for by learning a technique - so prepare the triage instead, and learn to identify a dozen shapes on sight.
By the end you can
- Identify Brainfuck, Whitespace, Ook!, JSFuck and Piet from their character sets alone
- Use a distinct-character count as a first-pass identifier for any unknown text
- Recognise the recurring misc shapes: encoding chains, damaged codes, audio, text steganography
- Read a file in hex before concluding it is empty or plain
- Recognise when a challenge is a joke and automate rather than repeat
1. Read
2. Use the tools
In the order they come up while solving. Each opens the workspace tab that runs it.
Brainfuck and esolang decoder
Run Brainfuck, Ook!, Befunge, Whitespace, Deadfish, and friends. Esolangs are a recognition problem more than an execution problem.
Cipher identifier and automatic decoder
Paste anything and find out what it is. ctfpal runs every decoder and rotation, including multi-pass cascades, and ranks results by English-likeness and flag patterns.
Zero-width character and text steganography decoder
Reveal messages hidden in zero-width Unicode characters, trailing whitespace, and homoglyph substitution - text steganography that survives copy-paste.
QR code decoder
Decode QR codes from any image, including inverted, low-contrast, and partially damaged codes. Nothing is uploaded.
Audio spectrogram and SSTV decoder
View a WAV as a spectrogram to find text drawn in frequency space, decode Morse and SSTV, and extract LSB data from audio samples.
3. Try one now
Generated in your browser and checked in your browser. No account, nothing to download, and a fresh one whenever you want another.
4. Practise on the real thing
Real picoCTF challenges that use these techniques, easiest first. 10 match in total - see the full index.
Checkpoint
Given five unlabelled artifacts, identify what each one is and name the tool that opens it, without solving any of them.
Teaching note
Resist the urge to teach how Brainfuck works. The transferable skill is identification, and an hour spent on tape semantics is an hour not spent seeing ten different shapes.