Secure Validator Rating System Solidity, JavaScript
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Okay, let's craft a Secure Validator Rating System program using Solidity (for the smart contract) and JavaScript (for interacting with the contract and displaying the data).
**Solidity (Smart Contract): `ValidatorRating.sol`**
```solidity
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
contract ValidatorRating {
struct Validator {
string name;
uint256 stake; // Amount staked by the validator
uint256 uptime; // Percentage of time the validator is online (0-100)
uint256 slashedCount; // Number of times validator has been slashed (penalized)
uint256 rating; // Calculated rating
bool exists; // Flag to track validator existance
}
mapping(address => Validator) public validators;
address[] public validatorAddresses; // List of validator addresses
address public owner;
event ValidatorRegistered(address validatorAddress, string name, uint256 stake);
event ValidatorUpdated(address validatorAddress, uint256 stake, uint256 uptime, uint256 slashedCount);
event ValidatorRatingCalculated(address validatorAddress, uint256 rating);
modifier onlyOwner() {
require(msg.sender == owner, "Only the owner can call this function.");
_;
}
constructor() {
owner = msg.sender;
}
function registerValidator(address _validatorAddress, string memory _name, uint256 _stake) public onlyOwner {
require(validators[_validatorAddress].exists == false, "Validator already registered");
validators[_validatorAddress] = Validator({
name: _name,
stake: _stake,
uptime: 100,
slashedCount: 0,
rating: 0,
exists: true
});
validatorAddresses.push(_validatorAddress);
emit ValidatorRegistered(_validatorAddress, _name, _stake);
}
function updateValidator(address _validatorAddress, uint256 _stake, uint256 _uptime, uint256 _slashedCount) public onlyOwner {
require(validators[_validatorAddress].exists == true, "Validator does not exist");
Validator storage validator = validators[_validatorAddress];
validator.stake = _stake;
validator.uptime = _uptime;
validator.slashedCount = _slashedCount;
emit ValidatorUpdated(_validatorAddress, _stake, _uptime, _slashedCount);
calculateRating(_validatorAddress);
}
function calculateRating(address _validatorAddress) private {
require(validators[_validatorAddress].exists == true, "Validator does not exist");
Validator storage validator = validators[_validatorAddress];
// Simple rating algorithm: (stake * uptime) / (slashedCount + 1)
// The +1 in the denominator prevents division by zero and penalizes slashed validators.
uint256 rating = (validator.stake * validator.uptime) / (validator.slashedCount + 1);
validator.rating = rating;
emit ValidatorRatingCalculated(_validatorAddress, rating);
}
function getValidator(address _validatorAddress) public view returns (string memory, uint256, uint256, uint256, uint256) {
require(validators[_validatorAddress].exists == true, "Validator does not exist");
Validator storage validator = validators[_validatorAddress];
return (validator.name, validator.stake, validator.uptime, validator.slashedCount, validator.rating);
}
function getAllValidators() public view returns (address[] memory){
return validatorAddresses;
}
}
```
**Explanation of Solidity Code:**
1. **`pragma solidity ^0.8.0;`**: Specifies the Solidity compiler version to use. Using `^0.8.0` means any version 0.8.0 or higher, but less than 0.9.0.
2. **`contract ValidatorRating`**: Defines the smart contract named `ValidatorRating`.
3. **`struct Validator`**: Defines a data structure to hold information about each validator. It includes:
* `name`: The validator's name.
* `stake`: The amount of cryptocurrency the validator has staked. Higher stake usually means more responsibility.
* `uptime`: Percentage of time validator is online (0-100)
* `slashedCount`: Number of times the validator was penalized for misbehavior.
* `rating`: A calculated rating based on stake, uptime and slashed count.
* `exists`: A boolean flag that tracks if a validator address exists.
4. **`mapping(address => Validator) public validators;`**: A mapping that associates each validator's Ethereum address to its `Validator` struct. The `public` keyword automatically creates a getter function.
5. **`address[] public validatorAddresses;`**: An array that stores all validator addresses. Used to iterate through all validators.
6. **`address public owner;`**: Address of the contract owner.
7. **`event ValidatorRegistered(...)`**: An event that is emitted when a new validator is registered. Events are useful for logging and off-chain monitoring.
8. **`event ValidatorUpdated(...)`**: An event that is emitted when a validator's information is updated.
9. **`event ValidatorRatingCalculated(...)`**: An event emitted when the rating of a validator is calculated.
10. **`modifier onlyOwner()`**: A modifier that restricts access to functions to the contract owner only.
11. **`constructor()`**: Sets the owner of the contract to the deployer.
12. **`registerValidator(address _validatorAddress, string memory _name, uint256 _stake)`**: Allows the owner to register a new validator with a given name and stake. Requires that the address is not already registered.
13. **`updateValidator(address _validatorAddress, uint256 _stake, uint256 _uptime, uint256 _slashedCount)`**: Allows the owner to update a validator's stake, uptime, and slashed count. After updating, it calls the `calculateRating` function.
14. **`calculateRating(address _validatorAddress)`**: A private function to calculate the rating based on the validator's stake, uptime and slashed count.
15. **`getValidator(address _validatorAddress)`**: A public view function that returns the validator's information (name, stake, uptime, slashedCount, rating). The `view` keyword means this function doesn't modify the contract's state.
16. **`getAllValidators()`**: Public view function that returns all validator addresses.
**JavaScript (Interaction and Display): `app.js`**
```javascript
const Web3 = require('web3');
const contractABI = /* Paste your contract ABI here */; // Get this from your Solidity compilation
const contractAddress = '/* Your contract address here */'; // Replace with your deployed contract address
let web3;
let validatorRatingContract;
async function init() {
// Modern dapp browsers...
if (window.ethereum) {
web3 = new Web3(window.ethereum);
try {
// Request account access if needed
await window.ethereum.enable();
} catch (error) {
console.error("User denied account access");
}
}
// Legacy dapp browsers...
else if (window.web3) {
web3 = new Web3(window.web3.currentProvider);
console.log("Legacy web3 detected.");
}
// If no injected web3 instance is detected, fall back to Ganache/local node
else {
web3 = new Web3(new Web3.providers.HttpProvider('http://localhost:7545')); // Or your Ganache/local node URL
console.log("No web3 instance injected, using Local web3.");
}
validatorRatingContract = new web3.eth.Contract(contractABI, contractAddress);
await displayValidators();
// Event Listener for new validators being added
validatorRatingContract.events.ValidatorRegistered({
fromBlock: 'latest' // Start listening from the latest block
}, async (error, event) => {
if (error) {
console.error("Error with ValidatorRegistered event:", error);
} else {
console.log("New Validator Registered:", event.returnValues);
await displayValidators();
}
});
// Event Listener for validator updates
validatorRatingContract.events.ValidatorUpdated({
fromBlock: 'latest'
}, async (error, event) => {
if (error) {
console.error("Error with ValidatorUpdated event:", error);
} else {
console.log("Validator Updated:", event.returnValues);
await displayValidators();
}
});
validatorRatingContract.events.ValidatorRatingCalculated({
fromBlock: 'latest'
}, async (error, event) => {
if (error) {
console.error("Error with ValidatorRatingCalculated event:", error);
} else {
console.log("Validator Rating Calculated:", event.returnValues);
await displayValidators();
}
});
}
async function registerValidator(name, stake) {
const accounts = await web3.eth.getAccounts();
const ownerAddress = accounts[0];
await validatorRatingContract.methods.registerValidator(accounts[1], name, stake).send({ from: ownerAddress });
}
async function updateValidator(validatorAddress, stake, uptime, slashedCount) {
const accounts = await web3.eth.getAccounts();
const ownerAddress = accounts[0];
await validatorRatingContract.methods.updateValidator(validatorAddress, stake, uptime, slashedCount).send({ from: ownerAddress });
}
async function displayValidators() {
const allValidatorAddresses = await validatorRatingContract.methods.getAllValidators().call();
const validatorListElement = document.getElementById('validatorList');
validatorListElement.innerHTML = ''; // Clear existing list
for (const validatorAddress of allValidatorAddresses) {
const validatorData = await validatorRatingContract.methods.getValidator(validatorAddress).call();
const validatorElement = document.createElement('div');
validatorElement.innerHTML = `
<strong>Address:</strong> ${validatorAddress}<br>
<strong>Name:</strong> ${validatorData[0]}<br>
<strong>Stake:</strong> ${validatorData[1]}<br>
<strong>Uptime:</strong> ${validatorData[2]}<br>
<strong>Slashed Count:</strong> ${validatorData[3]}<br>
<strong>Rating:</strong> ${validatorData[4]}<br><br>
`;
validatorListElement.appendChild(validatorElement);
}
}
// Example usage (call these functions from your HTML/UI)
window.onload = async () => {
await init();
//Example Calls
//await registerValidator("Validator 1", 100);
//await updateValidator("0x...", 150, 95, 1); // Replace "0x..." with a validator's address
};
// Make functions accessible from the HTML
window.registerValidator = registerValidator;
window.updateValidator = updateValidator;
```
**Explanation of JavaScript Code:**
1. **`const Web3 = require('web3');`**: Imports the Web3.js library.
2. **`const contractABI = /* Paste your contract ABI here */;`**: This is *crucial*. After you compile your Solidity contract (e.g., using Remix or Truffle), you get an Application Binary Interface (ABI). This ABI describes the contract's functions and data types. *Replace the comment with your actual ABI.*
3. **`const contractAddress = '/* Your contract address here */';`**: Replace this with the address where you deployed your `ValidatorRating` contract on the blockchain.
4. **`let web3;`**: Declares a variable to hold the Web3 instance.
5. **`let validatorRatingContract;`**: Declares a variable to hold the contract instance.
6. **`async function init()`**: An asynchronous function that initializes Web3 and the contract.
* **Web3 Provider Detection**: It checks for a Web3 provider (like MetaMask) and uses it if available. If not, it falls back to a local Ganache/Hardhat node. This is important for interacting with the blockchain.
* **Contract Instantiation**: Creates a `validatorRatingContract` instance using the ABI and contract address.
* **Event Listeners**: Listens for `ValidatorRegistered`, `ValidatorUpdated` and `ValidatorRatingCalculated` events. This is how the UI can update dynamically when the contract state changes. When an event is received, it calls `displayValidators()` to refresh the displayed list.
7. **`async function registerValidator(name, stake)`**: Calls the `registerValidator` function in the smart contract. It needs the name and stake as parameters. It sends the transaction from the account provided by metamask.
8. **`async function updateValidator(validatorAddress, stake, uptime, slashedCount)`**: Calls the `updateValidator` function in the smart contract. Needs the validator address, stake, uptime, and slashed count as parameters.
9. **`async function displayValidators()`**: Fetches the list of validators from the contract and displays them in the `validatorList` element in your HTML. It iterates through the validators and creates HTML elements to display their data.
10. **`window.onload = async () => { ... }`**: Executes the `init` function when the page loads and provides example calls that are commented out. You can uncomment these to test the functions.
11. **`window.registerValidator = registerValidator;`**, **`window.updateValidator = updateValidator;`**: Exposes the JavaScript functions to the HTML so you can call them from buttons or forms.
**HTML (UI): `index.html`**
```html
<!DOCTYPE html>
<html>
<head>
<title>Validator Rating System</title>
<script src="https://cdn.jsdelivr.net/npm/web3@1.7.0/dist/web3.min.js"></script>
<script src="app.js"></script>
</head>
<body>
<h1>Validator Rating System</h1>
<h2>Register Validator</h2>
<input type="text" id="registerName" placeholder="Validator Name">
<input type="number" id="registerStake" placeholder="Stake">
<button onclick="registerValidator(document.getElementById('registerName').value, parseInt(document.getElementById('registerStake').value))">Register</button>
<h2>Update Validator</h2>
<input type="text" id="updateAddress" placeholder="Validator Address">
<input type="number" id="updateStake" placeholder="Stake">
<input type="number" id="updateUptime" placeholder="Uptime">
<input type="number" id="updateSlashedCount" placeholder="Slashed Count">
<button onclick="updateValidator(
document.getElementById('updateAddress').value,
parseInt(document.getElementById('updateStake').value),
parseInt(document.getElementById('updateUptime').value),
parseInt(document.getElementById('updateSlashedCount').value)
)">Update</button>
<h2>Validators</h2>
<div id="validatorList"></div>
</body>
</html>
```
**Explanation of HTML:**
1. **`<script src="https://cdn.jsdelivr.net/npm/web3@1.7.0/dist/web3.min.js"></script>`**: Includes the Web3.js library. It's best to use a specific version. Check for the latest version on the Web3.js website or a CDN.
2. **`<script src="app.js"></script>`**: Includes your JavaScript file.
3. **UI Elements**:
* Inputs for registering a validator (name, stake).
* Inputs for updating a validator (address, stake, uptime, slashed count).
* Buttons to trigger the `registerValidator` and `updateValidator` functions in your JavaScript.
* A `div` with the ID `validatorList` where the validator information will be displayed.
4. **`onclick="..."`**: The `onclick` attributes on the buttons call the JavaScript functions when the buttons are clicked.
**How to Use This:**
1. **Set up a Development Environment:**
* Install Node.js and npm.
* Install Ganache (a local Ethereum blockchain) or use Hardhat.
* Install MetaMask in your browser.
2. **Compile and Deploy the Smart Contract:**
* Use Remix or Truffle to compile the `ValidatorRating.sol` contract.
* Deploy the contract to your local Ganache/Hardhat network.
* **Get the Contract Address and ABI:** After deployment, you'll get the contract address and the ABI. You *need* these for your JavaScript.
3. **Configure Your JavaScript:**
* Replace `/* Paste your contract ABI here */` in `app.js` with the actual ABI of your contract.
* Replace `/* Your contract address here */` in `app.js` with the contract's address.
* Adjust the Web3 provider URL in `app.js` if you're not using Ganache at `http://localhost:7545`.
4. **Run Your Application:**
* Serve your `index.html` file using a simple web server (e.g., `npx serve .` from the command line in the directory where you saved your files).
* Open the HTML file in your browser.
* Connect MetaMask to your local Ganache network.
* You should now be able to register validators, update their information, and see the dynamically updated ratings.
**Important Considerations:**
* **Security:** This is a simplified example. In a real-world system, you'd need to address security vulnerabilities like:
* **Reentrancy Attacks:** If your contract interacts with other contracts, be careful about reentrancy.
* **Integer Overflow/Underflow:** Use SafeMath libraries (or Solidity 0.8.0+ which has built-in overflow/underflow protection) to prevent integer overflows/underflows.
* **Access Control:** Implement more robust access control mechanisms.
* **Gas Optimization:** Solidity code can be optimized to reduce gas costs.
* **Error Handling:** Add more robust error handling in both your Solidity and JavaScript code.
* **UI/UX:** Improve the user interface and user experience.
* **Rating Algorithm:** The rating algorithm is very basic. You'd likely want a more sophisticated algorithm that considers multiple factors and prevents manipulation.
* **Ownership:** Consider if you really need an owner. If not, make the contract immutable by removing the owner and the onlyOwner modifier.
This example provides a foundation for building a more complex and secure validator rating system. Remember to thoroughly test and audit your code before deploying it to a live blockchain. Good luck!
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