Blockchain-Based Voting System

Introduction
Blockchain technology provides transparency, immutability, and security, making it an ideal solution for voting systems. This tutorial will guide you through creating a simple voting system on Ethereum using Solidity.

Step 1: Define the Voting Requirements
A basic blockchain voting system should:

• Allow only authorized voters to cast their votes.
• Restrict each voter to one vote.
• Store votes transparently and immutably.
• Display real-time results.

Step 2: Writing the Voting Smart Contract
Create a file named Voting.sol and add the following code:

// SPDX-License-Identifier: MIT  
pragma solidity ^0.8.0;  

contract Voting {  
    address public admin;  
    mapping(address => bool) public hasVoted;  
    mapping(string => uint256) public votes;  
    string[] public candidates;  

    event Voted(address voter, string candidate);  

    modifier onlyAdmin() {  
        require(msg.sender == admin, "Only admin can perform this action");  
        _;  
    }  

    constructor(string[] memory _candidates) {  
        admin = msg.sender;  
        candidates = _candidates;  
    }  

    function vote(string memory candidate) public {  
        require(!hasVoted[msg.sender], "You have already voted");  
        bool validCandidate = false;  
        for (uint256 i = 0; i < candidates.length; i++) {  
            if (keccak256(abi.encodePacked(candidates[i])) == keccak256(abi.encodePacked(candidate))) {  
                validCandidate = true;  
                break;  
            }  
        }  
        require(validCandidate, "Invalid candidate");  
        hasVoted[msg.sender] = true;  
        votes[candidate] += 1;  
        emit Voted(msg.sender, candidate);  
    }  

    function getVotes(string memory candidate) public view returns (uint256) {  
        return votes[candidate];  
    }  
}  

Step 3: Deploying the Contract
Deploy the contract on a testnet such as Goerli. Pass an array of candidate names (e.g., ["Alice", "Bob", "Charlie"]) as a parameter during deployment.

Step 4: Interacting with the Voting System
Voters can call the vote function using their wallets (e.g., MetaMask). Admins and users can view real-time results using the getVotes function.

Step 5: Enhancing the Voting System
For added security and functionality:

• Implement a whitelist to authorize voters.
• Integrate a frontend using Web3.js for user-friendly voting.
• Use zk-SNARKs for private voting.

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