Blockchain for a Cryptocurrency

A blockchain implementation in Java for a cryptocurrency. The blockchain is modeled after Bitcoin.

Date

Late October of 2020. 10th grade.

How does it work?

It is a command line interface over the blockchain to:

• Be either a miner or just a listening node (pulling the blockchain real time, but not mining)
• Mine the pending transactions into a block
• Make a transaction
• View blockchain
• View your balance

Tech Stack

• Java Programming Language & OOP (inheritance)
• Gradle

Specs

I tried to make this cryptocurrency as robust to my abilities. This included signing transactions, validating blocks in a chain, and a basic P2P network.

Keys

• secp256k1 key cryptography
• SHA256withECDSA transaction signature algorithm

Blockchain

• Blocks are stored in an ArrayList
• Blocks hashed with SHA256 algorithm
• Blocks mined like in Bitcoin (specified number of zeros at the beginning of hash)

Peer to peer network

• Only on LAN (localhost)
• Can connect and listen to other peers, assigning you a port
• Miners can broadcast newly mined blocks to other nodes (only full nodes, not other miners, for now)

How to run

./gradlew run --console plain

Useful links

Useful links that helped guide me:

• Bitcoin repository
• Simple Blockcain in JS
• Java P2P demonstration