Backend Implementation for Bitcoin-like Server Project

.gitignore

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README.md

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-# request-for-code
+# Bitcoin-like Server Project
 
-This repository contains a bunch of interesting requests for people to code. These are things I've always wanted to build but don't get the time to get to them. 
+## Overview
+
+This project implements a simplified Bitcoin-like server, designed to simulate key aspects of the Bitcoin network. The project consists of a central WebSocket server and multiple miner servers. Each miner maintains its own transaction pool, mines blocks at regular intervals, and interacts with the central server to receive new transactions.
+
+## Architecture
+
+The project consists of the following components:
+
+1. **Central Server** (`centralServer.js`)
+   - Acts as the central hub for broadcasting transactions to all connected miners.
+   - Manages WebSocket connections and ensures that all miners receive the latest transactions.
+   - Facilitates decentralized block mining by keeping miners in sync with the transaction pool.
+
+2. **Miner Server** (`minerServer.js`)
+   - Each miner operates independently, maintaining its own transaction pool.
+   - Mines blocks at a fixed interval (e.g., every 30 seconds).
+   - Interacts with the central server to receive new transactions and broadcast mined blocks.
+
+3. **Blockchain Utilities** (`blockchainUtils.js`)
+   - Contains utility functions for blockchain operations, including block creation, transaction handling, and validation.
+   - Ensures consistent and reliable blockchain functionality across all servers.
+
+## Usage
+
+Use the `fund-wallets.txt` file to view the initial accounts created to send transactions.
+
+### API Endpoints
+
+The following APIs are exposed via an Express server:
+
+- **Send Transaction**: Allows sending transactions to a recipient.
+  - **Endpoint**: `POST /sendTransaction`
+  - **Request Body**:
+    - `recipient` (string): The recipient's address (40 characters).
+    - `amount` (number): The amount to send (must be greater than 0).
+    - `privateKey` (string): The private key for signing the transaction (64 characters).
+  - **Response**: `Transaction processed` if successful, with error messages for invalid inputs.
+
+- **Get Balances**: Retrieves the balance of all accounts.
+  - **Endpoint**: `GET /getBalances`
+  - **Response**: A JSON object containing all account balances.
+
+- **Get Block Height**: Retrieves the current block height of the blockchain.
+  - **Endpoint**: `GET /getBlockHeight`
+  - **Response**: A JSON object with the current block height.
+
+- **Get Balance**: Retrieves the balance of a specific address.
+  - **Endpoint**: `GET /getBalance/:address`
+  - **Response**: A JSON object with the balance of the specified address.
+
+### Running the Servers
+
+To run the project, follow these steps:
+
+1. **Start the Central Server**:
+   ```bash
+   node centralServer.js
+
+2. **Start the Miner Servers**:
+   ```bash
+   node minerServer.js
+   ```
+
+3. **Access the API Endpoints**:
+    - Send transactions to the central server using the provided APIs.
+    - View the balances of all accounts using the `/getBalances` endpoint.
+    - Monitor the block height using the `/getBlockHeight` endpoint.

blockchainUtils.js

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+// blockchainUtils.js
+const crypto = require('crypto');
+const EC = require('elliptic').ec;
+const ec = new EC('secp256k1');
+
+function generateBlockHash(block) {
+    return crypto.createHash('sha256')
+        .update(block.previousHash + JSON.stringify(block.transactions) + block.nonce + block.timestamp + block.index)
+        .digest('hex');
+}
+
+function publicKeyToAddress(publicKey) {
+    const sha256 = crypto.createHash('sha256').update(publicKey, 'hex').digest();
+    const ripemd160 = crypto.createHash('ripemd160').update(sha256).digest('hex');
+    return ripemd160;
+}
+
+function createTransaction(publicKey, senderAddress, recipient, amount, privateKey) {
+    const key = ec.keyFromPrivate(privateKey, 'hex');
+
+    const transaction = {
+        publicKey,
+        senderAddress,
+        recipient,
+        amount,
+        timestamp: Date.now(),
+    };
+
+    const transactionData = publicKey + senderAddress + recipient + amount + transaction.timestamp;
+    const transactionHash = crypto.createHash('sha256').update(transactionData).digest('hex');
+    const signature = key.sign(crypto.createHash('sha256').update(transactionData).digest()).toDER('hex');
+
+    transaction.hash = transactionHash;
+    transaction.signature = signature;
+    return transaction;
+}
+
+function validateTransaction(transaction, balances) {
+    const { publicKey, senderAddress , recipient, amount, timestamp, signature } = transaction;
+    const key = ec.keyFromPublic(publicKey, 'hex');
+    const isValid = key.verify(crypto.createHash('sha256').update(publicKey + senderAddress + recipient + amount + timestamp).digest(), signature);
+
+
+    if (balances[senderAddress] === undefined || balances[senderAddress] < amount) {
+        return false;
+    }
+    return isValid;
+}
+
+function validateBlock(block, difficulty) {
+    const hash = generateBlockHash(block);
+    return hash.substring(0, difficulty) === '0'.repeat(difficulty);
+}
+
+module.exports = {
+    generateBlockHash,
+    publicKeyToAddress,
+    createTransaction,
+    validateTransaction,
+    validateBlock,
+};