Blockchain

A "naive blockchain" implementation in Elixir inspired by this JS implementation This is an umbrella project that provides the blockchain core and a REST API built with Phoenix. It provides peer-to-peer communications, naive blockchain logic and a rudimentary Proof of Work.

Usage

Setting up a 3 nodes blockchain locally:

• node 1: iex -S mix phx.server (defaults: PORT=4000 P2P_PORT=5000)
• node 2: PORT=4001 P2P_PORT=5001 iex -S mix phx.server
• node 3: PORT=4002 P2P_PORT=5002 iex -S mix phx.server

Then connect the nodes using the REST API, for example:

curl -H 'Content-Type: application/json' localhost:4001/api/peers -X POST -d '{ "uri": "localhost:5000"}'  # connect node2 to node1

curl -H 'Content-Type: application/json' localhost:4002/api/peers -X POST -d '{ "uri": "localhost:5001"}'  # connect node3 to node2

or directly in the iex console:

$node2> Blockchain.connect("localhost:5000") # connect node2 to node1

$node3> Blockchain.connect("localhost:5001") # connect node3 to node2

You can then mine blocks using the REST API or directly in the iex console.

iex

Interaction with the blockchain in the iex console:

Blockchain.connect("host:port") # connect to a peer
Blockchain.list_peers() # list direct peers
Blockchain.mine("some data") # add a block to the blockchain
Blockchain.blocks() # get all blocks in the chain

REST API

Interaction with the blockchain with the REST API:

# create a block
curl -H 'Content-Type: application/json' localhost:4000/api/blocks -X POST -d '{"data": "block data"}'

# show the blockchain
curl -H 'Content-Type: application/json' localhost:4000/api/blocks

# show connected peers
curl -H 'Content-Type: application/json' localhost:4000/api/peers

# connect to a peer
curl -H 'Content-Type: application/json' localhost:4002/api/peers -X POST -d '{ "uri": "localhost:5001"}'

Motivations / next steps

The goal of this project is to understand basic mechanisms behind the blockchain and to use Elixir and OTP. It has been designed to be modular and extensible. Some ideas to make it more complete :

• web UI to control the node
• build more blockchain features to make it a less "naive" blockchain

Issues and pull requests are very welcome 😊

Resources

• naive blockchain and its medium post
• legion blockchain
• proof of work

For future improvements:

• minimum viable blockchain
• minimum viable blockchain Go implementation