A Simple Blockchain-based Voting System

A simple blockchain-based voting system application built from scratch by Python. It's available for running with multipeer.

How it looks

How to use

• Mine : mine unconfirmed transaction
• Resync : Reload front-end
• Update Chaincode : Load smart contract from chaincode.py in vosy_app to blockchain transaction
• Pending Transaction : List unconfirmed transaction
• List Node : List node in the network

!!! Note. If you want to use chaincode, you need to click to Update Chaincode to load chaincode.py to blockchain transaction and mine it to confirm this chaincode. After that. you can create new survey ( I writed a simple chaincode count_down_opening_time to auto close survey after a period of time ). You can write your own contract and use it by create new execution transaction like this ( You need to Update Chaincode and Mine it before use ) :

[
{
"content": {
"author": "192.168.1.38:5000", 
"contract": "count_down_opening_time",
"argument": [opening_time, author, questionid, CONNECTED_NODE_ADDRESS],
"timestamp": 1544369155.5413423
}, 
"timestamp": 1544369155.5453415, 
"type": "execute"
}
]

Instructions to run

To understand, read system architecture This project can run separately by python or use docker-compose

Running by Docker-compose

NOTE!!! It can only be used in linux, or maybe window. I have some problem with macOS. I use remote_addr to identify user. But every request from outside of docker having the same remote address is 172.18.0.1. It cause network_mode: "bridge" is default in Docker. If you have any problem with request ip address, try to uncomment network_mode: "host" in docker-compose.yml. It just works in Linux. Docker in macOS have some limited and I cannot find any good solution. If you have any idea, please report to me. Thank you.

Prerequisites

You need to install docker and docker-compose before

Running

In first machine

Follow this command:

docker-compose build
docker-compose up

You can run in background:

docker-compose up -d

You can stop this application:

docker-compose stop

Or down ( delete container ):

docker-compose down

In second machine

You have to provide IP address of machine 1 in .env file.

ORDERER_IP=192.168.43.162
CA_IP=192.168.43.162
PEER_IP=192.168.43.162

Then run command

docker-compose -f docker-compose-peer-only.yml build
docker-compose -f docker-compose-peer-only.yml up

Running by Python command

Prerequisites

It needs python, pip to run. Install requirements

pip install -r requirements.txt

Running

In first machine

You need to run 4 app orderer.py certificate_authority.py peer.py vosy.py ( if you don't need front-end in this machine, you don't need to run vosy.py) . You can run each app on different machines but need to provide ip address for it.

python bcb_server/orderer.py

Certificate authority need to know aleast 1 orderer. so if is not default value 0.0.0.0, you need to pass orderer ip address to certificate_authority by argument --orderer

python bcb_server/certificate_authority.py

Peer need to know aleast 1 orderer and 1 certificate_authority so you need to pass orderer ip address and ca ip address to peer by argument --orderer and --ca

python bcb_server/peer.py

Vosy need to know aleast 1 peer so you need to pass peer ip address to vosy app by argument --host

python vosy_app/vosy.py

for example, with window users, ip address 0.0.0.0 is not avalible, so you need to run in localhost, so you have to follow this command in 4 cmd:

python bcb_server/orderer.py

python bcb_server/certificate_authority.py --orderer 127.0.0.1

python bcb_server/peer.py --orderer 127.0.0.1 --ca 127.0.0.1

python vosy_app/vosy.py --host 127.0.0.1

In second machine

You just need to run peer.py and vosy.py but you need to provide Lan IP address orderer.py and certificate_authority.py run in machine 1. In my case, it is 192.168.43.162

python bcb_server/peer.py --orderer 192.168.43.162 --ca 192.168.43.162

python vosy_app/vosy.py

this vosy will auto connect to local peer in address 0.0.0.0:5000

Tutorial

It is simple architecture of my network

Certificate Authority

It can validate connection when a node ask to join to network and Set permission for each node and validate transaction

Orderer

It can hold a list of peers and broadcast to all peer when receive a request broadcast new block or new transaction. It also have consensus method, which can return the longest blockchain in the network

Peer

It hold all data about blockchain, it have some method like mine, validate_transaction, return chain, open surveys, ...

Vosy

A blockchain-based application for voting system