Blockchain-BTC

A Go-based implementation of a simple blockchain designed for educational purposes. This project showcases the fundamental concepts of blockchain technology, including cryptographic hashing of transactions and blocks, peer-to-peer networking, and transaction handling. Note that this implementation is basic and not feature-complete, thus advanced features such as consensus mechanism for validator election and public ledger are beyond the scope of this project.

Features

• P2P Peer Exchange: Each node broadcasts its peers to all nodes in the network, facilitating decentralized peer discovery.
• P2P Transaction Propagation: Transactions are broadcasted across the network in a decentralized and efficient manner (using Mempool).
• Transaction Handling and Validation: Nodes can create and broadcast transactions to the network, ensuring all transactions are validated before inclusion in a block, preventing double-spending.
• Mempool: A mempool is used for managing transactions before they are included in a block, reducing the overhead of re-broadcasting transactions.
• Block/Tx/UTXO Storages: All blockchain data entities are stored is separate memory stores, which can be easily extended by implementing a custom Store interface.
• Protobuf Definitions: Protocol buffers are used for defining the structure of messages exchanged between nodes.
• gRPC-based Communication: Nodes use gRPC for broadcasting transactions and blocks, enabling efficient and scalable communication.
• Public Key Infrastructure (PKI): Transactions use a public key-based addressing system, enhancing security and traceability. Ed25519 signature algorithm is used for transaction/block signing.
• Multi-node Network Bootstrapping: The system supports a multi-node setup for testing and development, allowing easy network simulations.
• Merkle Tree Calculation: Each block contains a Merkle tree root hash of all transactions, ensuring blockchain data integrity and efficient verification.

Installation

Clone the repository:

git clone https://github.com/oleglegun/blockchain-btc.git

cd blockchain-btc

Install dependencies:

go mod download

Usage

To run the blockchain network with 3 nodes (default):

make run

To run the the network with an arbitrary number of nodes:

make build

./bin/blockchain -nodeCount=4

This will start blockchain network with a single (pre-elected) validator node. Transactions are broadcasted to the network each second.

Project Structure

• cmd/node/main.go: Entry point for the blockchain node.
• internal/cryptography: Contains cryptographic utilities.
  • keys.go: Functions for key generation, signing, and verification.
  • merkletree.go: Implementation of Merkle tree for transaction verification.
• internal/genproto: Generated protobuf files.
  • blockchain.pb.go: Protobuf definitions for blockchain data structures.
  • blockchain_grpc.pb.go: gRPC service definitions for blockchain communication.
• internal/node: Core blockchain logic, including chain management and transaction handling.
  • chain.go: Blockchain chain management.
  • mempool.go: Memory pool for pending transactions.
  • node.go: Node operations and network communication.
  • store.go: Storage for blockchain data.
  • utxo.go: Unspent transaction output (UTXO) management.
• internal/random: Utilities for generating random data.
  • random.go: Functions for generating random hashes and blocks.
• internal/types: Extra behavior for the PB generated data structures (blocks, transactions).
  • block.go: Block data structure and related functions.
  • transaction.go: Transaction data structure and related functions.
• proto/blockchain.proto: Protobuf definitions for blockchain data structures and services.
• Makefile: Build, run, and test commands for the project.
• go.mod: Go module dependencies.
• go.sum: Checksums for module dependencies.

Example output

make run

Running blockchain with 3 nodes
level=DEBUG node=:3001 msg=running... 
level=DEBUG node=:3001 msg="running validation loop" pubKey=a57f266d17767b307a7dda3e27dbccdfeb4545fe13813f13d0a5a201f4602399
level=DEBUG node=:3002 msg=running...
level=DEBUG node=:3002 msg="discovered new peers" peers=[localhost:3001]
level=DEBUG node=:3003 msg=running...
level=DEBUG node=:3003 msg="discovered new peers" peers=[localhost:3002]
level=DEBUG node=:3001 msg="connected nodes" count=1
level=DEBUG node=:3001 msg="new peer connected" peer=:3002
level=DEBUG node=:3002 msg="connected nodes" count=1
level=DEBUG node=:3002 msg="new peer connected" peer=:3001
level=DEBUG node=:3002 msg="connected nodes" count=2
level=DEBUG node=:3002 msg="new peer connected" peer=:3003
level=DEBUG node=:3003 msg="connected nodes" count=1
level=DEBUG node=:3003 msg="new peer connected" peer=:3002
level=DEBUG node=:3003 msg="discovered new peers" peers=[:3001]
level=DEBUG node=:3001 msg="connected nodes" count=2
level=DEBUG node=:3001 msg="new peer connected" peer=:3003
level=DEBUG node=:3003 msg="connected nodes" count=2
level=DEBUG node=:3003 msg="new peer connected" peer=:3001
level=DEBUG node=:3002 msg="received tx" from=[::1]:52277 tx=86a382becd80e93334869574b75079b470c2545321bf7c28ff06223c92d9e7c7
level=DEBUG node=:3001 msg="received tx" from=[::1]:52248 tx=86a382becd80e93334869574b75079b470c2545321bf7c28ff06223c92d9e7c7
level=DEBUG node=:3002 msg="received tx" from=[::1]:52277 tx=132311d3cf73751f49b7435461fface3b046ab5139288d7c126b0a5ceebfa2fd
level=DEBUG node=:3001 msg="received tx" from=[::1]:52248 tx=132311d3cf73751f49b7435461fface3b046ab5139288d7c126b0a5ceebfa2fd
level=DEBUG node=:3003 msg="received tx" from=[::1]:52304 tx=132311d3cf73751f49b7435461fface3b046ab5139288d7c126b0a5ceebfa2fd
level=DEBUG node=:3003 msg="received tx" from=[::1]:52304 tx=86a382becd80e93334869574b75079b470c2545321bf7c28ff06223c92d9e7c7
level=DEBUG node=:3001 msg="creating new block" txs=2
level=DEBUG node=:3002 msg="received tx" from=[::1]:52277 tx=a7d541420f5768b341b70259be2a5db5260641fd7e5383e1c0f953f8d69b49be
level=DEBUG node=:3003 msg="received tx" from=[::1]:52304 tx=a7d541420f5768b341b70259be2a5db5260641fd7e5383e1c0f953f8d69b49be
level=DEBUG node=:3001 msg="received tx" from=[::1]:52248 tx=a7d541420f5768b341b70259be2a5db5260641fd7e5383e1c0f953f8d69b49be
...