Python in Blockchain

PyCon.LT 2018

Jaro Šatkevič - @chompomonim

About Me

Agenda

What is Blockchain (main building blocks)
Which blockchains actually works.
Intro into Bitcoin and Ethereum.
What are main problem domains to solve in blockchain world.
Ideas where python is good choice.
Actual projects made in pythons (where to join) and list of libraries/tools for those who wanna start own project.

Which of them actually works?

Rest are mostly experiments or tokens

EOS - ERC20 token
Cardano - still in early beta
IOTA - early beta
Tron - ERC20 token
...

What is blockchain?

Consensus

Cryptography is a king

Is Python good for Blockchain?

Isn't C++, Go, Rust or Java mostly used for blockchain creation?

Yes and No

Main parts of Bitcoin

Full node

Mining

Wallet

Bitcoin core

https://github.com/bitcoin/bitcoin

Full node

Ledger of transactions

Mining

creation of blocks with tx

Wallet

view balances, create & sign tx

UTXO > balance

Python libs and tools

Usage example

> from cryptos import *
> c = Bitcoin(testnet=True)
> priv = sha256('a big long brainwallet password')
> priv
'89d8d898b95addf569b458fbbd25620e9c9b19c9f730d5d60102abbabcb72678'
> pub = c.privtopub(priv)
> pub
'041f763d81010db8ba3026fef4ac3dc1ad7ccc2543148041c61a
29e883ee4499dc724ab2737afd66e4aacdc0e4f48550cd783c1a73
edb3dbd0750e1bd0cb03764f'
> addr = c.pubtoaddr(pub)
> addr
'mwJUQbdhamwemrsR17oy7z9upFh4JtNxm1'

Lightning network

In one minute

It knows only what it was told about

Online
Service

User

Service

Python libs and tools

Smart contract

beneficiary: public(address)
auction_start: public(timestamp)
auction_end: public(timestamp)

highest_bidder: public(address)
highest_bid: public(wei_value)

ended: public(bool)

@public
def __init__(_beneficiary: address, _bidding_time: timedelta):
    self.beneficiary = _beneficiary
    self.auction_start = block.timestamp
    self.auction_end = self.auction_start + _bidding_time

@public
@payable
def bid():
    assert block.timestamp < self.auction_end
    assert msg.value > self.highest_bid
    if not self.highest_bid == 0:
        send(self.highest_bidder,self.highest_bid)
    self.highest_bidder = msg.sender
    self.highest_bid = msg.value

@public
def end_auction():
    assert block.timestamp >= self.auction_end

    self.ended = True

    send(self.beneficiary, self.highest_bid)

Oracle

import json
import web3

from web3 import Web3, TestRPCProvider
from solc import compile_source
from web3.contract import ConciseContract

w3 = Web3(TestRPCProvider())

contract = w3.eth.contract(abi=abi)
contract_address = '0x85aC27E4124863492DB18EAFBb358102Cad8fc96'
contract_instance = w3.eth.contract(
                        abi=abi, 
                        address=contract_address, 
                        ContractFactoryClass=ConciseContract)


contract_instance.bid(transact={'from': w3.eth.accounts[0], 'value': 10000})
print('Highest bid: {}'.format(contract_instance.highest_bid()))

Blockchain ecosystem needs you

Full nodes
Mining software
Wallets of all kind
Blockchain explorers
Blockchain monitoring
Payment processors
Exchanges
Smart-contracts
Oracles
Lightning network
Side chains
Splitting coins
Deployment scripts
...

Let's discuss

Jaro Šatkevič - @chompomonim - me@jarocoin.com