thedenisnikulin/poc_p2p_blockchain_project

Proof-of-Concept Peer-to-Peer Blockchain Network built with sockets

PoC P2P Blockchain Network

I like the idea of bitcoin and blockchain. This is a basic proof-of-concept blockchain that I've built. It is based on a peer-to-peer decentralized TCP network.

Warning! It is working only on Windows for now.

Table of contents

1. Description
2. Features
3. Technologies used
4. How to use

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Description

Class structure

• Blockchain
• Block
• Transaction
• Server
• Client
• SuperPeer
• Peer

The P2P network is based on Client and Server classes.

• Server:

1. waits for client to connect,
2. accepts connection,
3. adds client to list of clients (= list of peers),
4. broadcasts the list to all the clients (lets clients know about new client),
5. listens to client messages

• Client:

1. connects to the server
2. lets user interact with the program logic (i.e. blockchain and networking)
3. listens to server messages

The core logic lies in two concepts: Peer and SuperPeer

Peer - a classic peer, it's just a client
SuperPeer - a super peer, it's both client and server

How it all works together

1. first, program becomes a Peer
2. it tries to connect to the SuperPeer by public address, which is stored in server_tracker.txt
3. if connection is established successfully, it remains Peer
4. if it can't connect to the SuperPeer for some reason (most likely there's no SuperPeer to connect to), it becomes a SuperPeer itself and stores its address in server_tracker.txt for other peers to connect

If something is not clear for you, check out the source code. I tried to write as much comments as possible to make it easier to understand.

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Features

• Self-repairing network. When SuperPeer disables/disconnects, one of peers becomes SuperPeer, which makes it impossible to stop the network.
• Persistent state. Blockchain saves its state across all peers even when SuperPeer disconnects.
• Data broadcasting. All the data is broadcasted between peers.
• CLI interface. A convenient interface built with PyInquirer.
• Blockchain implementation. This blockchain implementation is similar to original Bitcoin's blockchain, but I simplified some stuff.

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Technologies used

• Data serialization - pickle
• CLI interface - PyInquirer
• Parallelism - threading
• Networking - socket
• Hashes - hashlib

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How to use

• Download project

git clone https://github.com/thedenisnikulin/poc_p2p_blockchain_project.git

• Install dependencies

pip install -r ./requirements.txt

• Run

python src/main.py

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