Implementing a Simple Decentralized P2P Network for Blockchain in Go Using go-libp2p

Background Knowledge

In a true P2P architecture no centralized service maintains the blockchain state; each node holds a full copy and updates it when transactions occur, achieving consensus when >50% of nodes agree.

Implementation Overview

The tutorial builds on a previous 200‑line Go blockchain implementation and adds a P2P layer using the go‑libp2p library.

Installation

Install the library and its dependencies:

go get -d github.com/libp2p/go-libp2p/…

cd go-libp2p

make

make deps

Create an example directory and a main.go file:

mkdir ./examples/p2p

Key Components

Define global variables for the blockchain (blocks store BPM values), a mutex, and helper functions such as isBlockValid , calculateHash , and generateBlock .

Implement makeBasicHost to create a libp2p host with a listening port, optional secio encryption, and optional random seed.

Set up stream handling with a ReadWriter , launching a goroutine that continuously reads incoming JSON blocks, validates length, and updates the local chain, while another goroutine periodically broadcasts the latest chain.

Running the Network

Start three terminals as independent nodes:

go run main.go -l 10000 -secio

go run main.go -l 10001 -d <address> -secio

go run main.go -l 10002 -d <address> -secio

Enter BPM values (e.g., 70, 80) in any node; the new block is propagated to all peers, demonstrating decentralized synchronization without any central server.

Next Steps

Potential improvements include handling data‑race bugs in go‑libp2p, integrating consensus algorithms (PoW/PoS), adding persistent storage, testing with many nodes, and exploring node discovery mechanisms.