---

⚠️ For education purposes only. This is by no means a complete implementation and it is by no means secure!

Features

• Simple proof-of-work algorithm
• Verify blockchain (to prevent tampering)
• Generate wallet (private/public key)
• Sign transactions

Installation

yarn;

Usage

Balance on this demo is 1000 coins, and every transactions take 10 coins.

It takes a two optional parameters which are

• the difficulty of the mining process. Default is 4.
• the number of blocks to mine. Default is 10.

yarn start [difficulty = 4] [numberOfBlocks = 10]
yarn start 4 10

Generate a keypair

To make transactions on this blockchain you need a keypair. The public key becomes your wallet address and the private key is used to sign transactions.

const EC = require('elliptic').ec;
const ec = new EC('secp256k1');

const myKey = ec.genKeyPair();

The myKey object now contains your public & private key:

console.log('Public key:', myKey.getPublic('hex'));
console.log('Private key:', myKey.getPrivate('hex'));

Create a blockchain instance

Now you can create a new instance of a Blockchain:

import { Blockchain } from './blockchain';
import { Transaction } from './transaction';

const myChain = new Blockchain();

Adding transactions

// Transfer 100 coins from my wallet to "toAddress"
const tx = new Transaction(myKey.getPublic('hex'), 'toAddress', 100);
tx.signTransaction(myKey);

myChain.addTransaction(tx);

To finalize this transaction, we have to mine a new block. We give this method our wallet address because we will receive a mining reward:

myChain.minePendingTransactions(myKey.getPublic('hex'));

---