QR & Barcodes
QR and barcode challenges appear in many CTFs — sometimes as direct image puzzles, hidden data within files, or partial fragments embedded in binaries or spectrograms. Your task is usually to reconstruct the complete code, decode it accurately, and extract a hidden message or flag.
Common scenarios include:
- Damaged or cropped QR codes (split across multiple images)
- Barcode identification and scanning
| Task | Command / Tool |
|---|---|
| Decode standard QR | zbarimg code.png |
| Decode multiple QR at once | zbarimg *.png |
| Decode barcodes (EAN / Code128 / PDF417) | zxing code.jpg |
| Capture code from camera | zbarcam /dev/video0 |
| Reconstruct pieces | Use ImageMagick, GIMP, or ffmpeg grid assembling |
| Tool | Purpose |
|---|---|
| ZBar | CLI tool for decoding QR and various barcodes from images |
| ZXing | Cross‑platform barcode library with GUI & CLI decoders |
| QRazyBox | Online QR code analysis, reconstruction, and error‑level editing |
| ImageMagick | Merge or enhance partial code segments |
| GIMP / Photoshop | Manual alignment of code fragments |