DocuChain: Blockchain Certificate Verification System 🔗📄

DocuChain is a secure, modern web application built to issue and publicly verify digital documents and certificates using cryptographic blockchain principles.

Designed with an Apple-inspired minimalist aesthetic, DocuChain eliminates the possibility of document forgery by permanently anchoring document hashes on an immutable distributed ledger.

🌐 Live Demo: docuchain.onrender.com

✨ Features

• Immutable Proof of Existence: Documents are cryptographically hashed (SHA-256) and stored in a transparent, tamper-proof blockchain.
• Instant Verification: Anyone can upload a document to mathematically verify if it matches the originally issued file.
• Role-Based Dashboards: Issuers can approve/reject verification requests; Holders can track issued documents and request verification.
• Cloudinary Integration: Documents and profile photos are securely stored on Cloudinary with content-addressed naming.
• QR Code Generation: Each verified document gets a scannable QR code containing full metadata.
• Immutable Profile Photos: Users can set a profile photo that anchors to future verifications, with a 60-day cooldown between changes.
• Premium Apple-Inspired UI: Fully responsive glassmorphic design with SF Pro/Inter typography, soft shadows, and elegant spacing.
• Native Dark Mode: Intelligent dark mode that transitions seamlessly between light and dark themes based on system preference.
• Privacy Protection: Unauthenticated users see censored issuer names and timestamps on the public blockchain explorer.

🛠️ Technology Stack

Layer	Technology
Backend	Python 3, Flask, Werkzeug Security (Scrypt password hashing)
Database	MongoDB Atlas (cloud-hosted NoSQL)
File Storage	Cloudinary (documents, photos, profile images)
Frontend	HTML5, CSS3, Bootstrap 5 (Customized Apple-Aesthetic)
Blockchain	Custom immutable ledger using Python hashlib (SHA-256)
Deployment	Render (Gunicorn WSGI server)

🚀 Getting Started Locally

Prerequisites

• Python 3.9+
• pip (Python package manager)
• A MongoDB Atlas account (free tier works)
• A Cloudinary account (free tier works)

Installation

1. Clone the repository:

   git clone https://github.com/realraunakgupta/DocuChain.git
   cd DocuChain

2. Install dependencies:

   pip install -r requirements.txt

3. Create a .env file in the project root (see Environment Variables below).

4. Run the application:

   python app.py

5. Open your browser and navigate to: http://localhost:5000

🔑 Environment Variables

Create a .env file in the project root with the following variables:

Variable	Description	Where to find it
MONGO_URI	MongoDB Atlas connection string	MongoDB Atlas → Connect → Drivers
CLOUDINARY_URL	Cloudinary API environment variable	Cloudinary Dashboard → Account Details
SECRET_KEY	Flask session secret key (any strong random string)	Generate your own

Note: The .env file is included in .gitignore and will never be committed to the repository.

📁 Project Structure

DocuChain/
├── app.py                        # Main Flask application and URL routing
├── blockchain.py                 # Core cryptographic blockchain ledger logic
├── db.py                         # MongoDB connection and collection setup
├── requirements.txt              # Python package dependencies
├── Procfile                      # Render/Gunicorn deployment config
├── .env                          # Environment variables (not committed)
├── .gitignore                    # Git ignore rules
├── templates/                    # HTML interfaces (Jinja2)
│   ├── base.html                 # Global layout, navbar, footer, dark mode
│   ├── index.html                # Landing page
│   ├── dashboard.html            # Role-based dashboard (Issuer/Holder)
│   ├── issue.html                # Document issuance form
│   ├── verify.html               # Public verification portal
│   ├── chain.html                # Live blockchain explorer
│   ├── document.html             # Individual document detail + QR code
│   ├── request_verification.html # Holder verification request form
│   ├── profile.html              # User profile + immutable photo upload
│   ├── login.html                # Secure authentication
│   ├── register.html             # New user registration
│   ├── privacy.html              # Privacy policy
│   └── terms.html                # Terms of service
├── static/                       # CSS and assets
│   ├── style.css                 # Custom design tokens & dark mode
│   ├── favicon.svg               # Site favicon
│   └── bootstrap.min.css         # Bootstrap 5 stylesheet
└── demo_files/                   # Sample certificates & scripts for testing

🔐 Security Considerations

• Passwords are securely hashed using werkzeug.security with scrypt:32768:8:1 configurations.
• Accessing the dashboard, issue, or profile routes requires authenticated sessions.
• Documents are never uploaded to permanent storage during the verify phase — they are hashed in-memory, checked against the blockchain, and immediately discarded.
• Environment secrets (database credentials, API keys) are loaded from .env and never committed to version control.

📄 License

This project is licensed under the MIT License - see the LICENSE file for details.