🎓 Blockchain-Based Online Examination System

A decentralized, secure, and transparent solution for conducting online exams using Ethereum, IPFS, and Smart Contracts.

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📖 Table of Contents

• 📌 Introduction
• 🔍 Project Overview
• ⚙️ How Does It Work?
• 🧠 Architecture Flow (Mermaid Diagram)
• 🧩 Technologies Used
• 🧪 Example Workflow
• 👥 Roles & Responsibilities
• 🚀 Getting Started
• 🎯 Hackathon Goal
• 📷 Screenshots
• 📜 License

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📌 Introduction

This project aims to eliminate security issues, manipulation, and central authority in online examination systems by leveraging blockchain technology. The system ensures:

• Tamper-proof question & answer storage
• Fair evaluation and transparent results
• Immutable logs of all exam-related actions

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🔍 Project Overview

In recent times, major examination systems have suffered from issues like paper leaks and manipulated result data. Our blockchain-based exam portal provides:

• ✅ Decentralization — IPFS for question/answer storage
• ✅ Transparency — Immutable records on Ethereum
• ✅ Security — Role-restricted smart contract logic
• ✅ Automation — Streamlined exam lifecycle

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⚙️ How Does It Work?

📌 1. Exam Creation (Admin Role)

• Admin uploads questions as a JSON file to IPFS
• Receives a CID (Content Identifier)
• CID is stored in ExamContract.sol on Ethereum
• Students can view, not edit

📌 2. Student Submission (Student Role)

• Student answers questions offline
• Uploads answer JSON to IPFS
• CID is stored in SubmissionContract.sol on Ethereum

📌 3. Evaluation (Teacher/Admin Role)

• Teacher fetches answer using CID from IPFS
• Evaluates, uploads result to IPFS
• Stores result CID in EvaluationContract.sol

📌 4. Result Viewing (Student Role)

• Students fetch result CID from Ethereum
• View results and feedback from IPFS

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🧠 Architecture Flow (Mermaid Diagram)

Use the VS Code Markdown Preview Mermaid Support extension or GitHub preview to view this chart.

flowchart TD
    A[Admin Uploads Exam JSON to IPFS] --> B[Get CID of Exam JSON]
    B --> C[Store CID in ExamContract on Ethereum]
    C --> D[Student Views Exam Using CID]
    D --> E[Student Submits Answer JSON to IPFS]
    E --> F[Get CID of Answer]
    F --> G[Store CID in SubmissionContract on Ethereum]
    G --> H[Teacher Fetches Answer CID from Blockchain]
    H --> I[Retrieve Answer JSON from IPFS]
    I --> J[Evaluate, Upload Result to IPFS]
    J --> K[Store Result CID in EvaluationContract]
    K --> L[Student Fetches Result from Blockchain and IPFS]

    subgraph Blockchain
        C
        G
        K
    end

    subgraph IPFS
        A
        E
        J
    end

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🧩 Technologies Used

Component	Technology
Frontend	React.js + Ethers.js
Backend	Golang + Geth
Blockchain	Ethereum (Sepolia Testnet)
Smart Contracts	Solidity
Storage	IPFS
Authentication	MetaMask Wallet

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🧪 Example Workflow (Step-by-Step)

1. ✅ Admin uploads exam (JSON) → IPFS → stores CID on Ethereum
2. 🧑‍🎓 Student submits answers (JSON) → IPFS → stores CID on Ethereum
3. 🧑‍🏫 Teacher/Admin fetches answers → evaluates → uploads evaluated JSON to IPFS → stores result CID
4. 🔍 Student retrieves result CID → fetches score from IPFS → reads feedback

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👥 Roles & Responsibilities

Team Member	Role & Responsibilities
UI/UX Designer	Design clean, intuitive frontend. Collaborate on MetaMask flows and result display UI.
Frontend Developer	Build React interface, integrate Ethers.js, handle wallet connection via MetaMask.
Smart Contract Dev	Write & deploy Solidity contracts (Exam, Submission, Evaluation). Secure access.
Backend Developer	Build Go backend, connect to Geth, manage API calls and IPFS file management.
Security Specialist	Audit smart contracts, optimize gas, test vulnerabilities (via Remix/Hardhat).

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🚀 Getting Started

✅ Prerequisites

• Node.js, npm
• Go installed
• MetaMask browser extension
• IPFS CLI installed
• Sepolia ETH in MetaMask

🔧 Installation

# Clone the repository
git clone https://github.com/your-repo/blockchain-exam-system.git
cd blockchain-exam-system

# Install frontend dependencies
npm install

⚒️ Smart Contract Deployment

• Use Remix or Hardhat to deploy:

  • ExamContract.sol
  • SubmissionContract.sol
  • EvaluationContract.sol

• Add contract addresses to .env or config files

▶️ Run the Project

# Start React frontend
npm start

# Start Go backend (assuming main.go exists)
go run main.go

📷 Screenshots

📜 License

This project is licensed under the MIT License. Feel free to fork, use, or contribute.

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🛠 Built with 💙 at Hack 5.0 🧑‍💻 Team: Paradox