I've been working on a steganography CTF challenge generator and wanted to share it with the community. It's completely free and runs 100% client-side.

Link: https://8gwifi.org/ctf/stego-ctf-generator.jsp

The problem it solves: Creating stego challenges for CTF events or training is tedious. You have to manually encode a flag through multiple steps, embed it, document the solution, and write hints. This tool automates the entire process.

How it works:

1. Enter your flag (e.g., flag{hidden_in_plain_sight})
2. Pick a difficulty level (7 options from easy LSB to multi-layer encrypted pipelines)
3. Optionally upload your own cover image or audio file
4. Click Generate

The engine selects a random pipeline of transforms from 34 available steps (base64, Caesar, Vigenere, AES-256, tar/zip wrapping, etc.), applies them to your flag, then embeds the result using LSB steganography into an image or audio file.

Output: A JSON bundle containing the challenge file (base64), complete solution (flag, pipeline, keys, SHA-256 hash), and progressive hints for solvers.

Key technical details:

• LSB embedding with variable bit depth (0-7)
• Key-based scatter embedding (pseudo-random pixel placement using seeded PRNG)
• Spectrogram encoding (hide data in audio frequencies)
• Container wrapping (TAR, ZIP, strings-hide)
• Inner embed (image-inside-image)
• Reed-Solomon error correction option
• Web Crypto API for AES-256-GCM encryption
• Reproducible output via seed parameter

No server, no signup: Everything happens in the browser. The JavaScript engine handles all encoding, encryption, and embedding locally.

Feedback welcome — especially from CTF organizers on what additional features would be useful.