SafeSeal

🔒 Principle

SafeSeal is a small web service that helps distribute presentations or documents while discouraging copy/paste or reuse.

• You upload a PPTX, DOCX, or PDF (PDFs are faster).
• The app converts Office files to PDF, then flattens pages into images.
• A watermark with your name is added across each page.
• The result is a PDF that looks the same, but where text cannot be copied or extracted easily.

This makes it easier to share teaching material or slides while keeping attribution clear and limiting uncontrolled reuse.

🌍 Try it online

The app is hosted on Render:

⚙️ How it works (for the curious)

If you are interested in the technical side, here’s a short breakdown of how SafeSeal works:

1. Hosting
   The site is deployed on Render, a cloud platform that makes it easy to host web apps with Python.
   Render runs the app in a Docker container, which allows us to install additional software like LibreOffice.

2. Frontend (GUI)
   The interface is written in Streamlit.
   Streamlit is a lightweight framework for building Python-based graphical web apps.
   It handles file uploads, buttons, progress bars, and layout.

3. Backend (Python)
   The core logic is implemented in Python using:
   • PyMuPDF (fitz): renders PDF pages into images and rebuilds watermarked PDFs.
   • Pillow (PIL): image processing and drawing watermarks.
   • subprocess + LibreOffice: converts Office documents (PPTX, DOCX, XLSX…) into PDF in headless mode.

4. Why LibreOffice?
   Converting Office files directly in Python is not reliable. SafeSeal instead uses LibreOffice in headless mode, which Render lets us install inside a Docker image.
   This guarantees consistent conversion results.

5. Pipeline summary
   • If the file is already a PDF → skip conversion.
   • Else → run LibreOffice inside the container to get a PDF.
   • Each page is rendered as an image, watermarked with the user’s name, then recombined into a new flattened PDF.
   • The sealed file is offered for download.

📦 Repository structure

• app.py — main Streamlit app.
• requirements.txt — Python dependencies.
• Dockerfile — enables LibreOffice inside the Render container.
• assets/ — icons and logos.

💡 Why SafeSeal?

The goal is not perfect DRM, but practical protection for educators and professionals:

• Attribution is visible (your name watermarked).
• Copy/paste and text extraction are discouraged.
• The visual fidelity of your slides is preserved.

This helps you share knowledge while keeping your work traceable.