Python Libraries for Bitcoin and Ethereum, PyCon SK 2018

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Python Libraries for Bitcoin & Ethereum Ondrej Sika [email protected] PyCon SK 2018, Bratislava SK, 10. 3. 2018

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Agenda - What is Bitcoin - What is Ethereum - RPC, Web3 - Bitcoin libraries - Ethereum libraries

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Ondrej Sika - Software engineer at Slush Pool (mining) - Bitcoin, Zcash, Ethereum mining backends - Pythoner since 2011 - Bitcoiner since 2013

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What is Bitcoin?

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What is Bitcoin? - Peer to Peer payment network - Decentralized currency - Digital gold - Money of internet - Internet of money

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How Bitcoin works?

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- Wallet is a pair of private and public keys - Public key (hash) is your address for receiving money - Private key is for sending your money - Wallets can be mobile apps (eg. Mycelium), desktop apps (eg. Electrum) or hardware wallets (eg. Trezor) Wallet

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Transaction - Transaction is signed payment order - Signed by sender's private key - To receiver address (public key (hash))

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Blockchain - Blockchain is distributed ledger which stores all transactions in chronological order - Transactions in blockchain are stored in blocks

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Block - Block is a 1MB list of transactions - In block header are some meta informations and POW - It is very hard to create block

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Proof of Work (POW) - Piece of data which is hard to find (time-consuming and costly) - Producing this proof is mining - Way how to slow down block generation - DDOS protection

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HD Wallets - Hierarchical deterministic wallets - Support in Trezor, Electrum

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Interact with Bitcoin

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Bitcoind Bitcoin daemon - Full Bitcoin node - Require Blockchain (160 GB) - JSON RPC API (HTTP) - CLI

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Bitcoind CLI bitcoin-cli getnewaddress 3Kyvxpx3B55q6Hx7JYJahLNi16cEfFajZ5 bitcoin-cli dumpprivkey 3Ky..jZ5 L1XxeiQ3Y4LpeWCSEZonew7oBZoEgxWuDFK6cH9rmjfM Y5FbhZfn

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In Python libraries - jsonrpc_requests - btcpy - python-trezor

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jsonrpc_requests - Just JSON RPC wrapper for Python - Require running bitcoind for every operation - Everything is stored on bitcoind (wallets, …) - https://github.com/gciotta/jsonrpc-requests pip install jsonrpc_requests

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jsonrpc_requests example from jsonrpc_requests import Server bitcoind = Server('http://chains.bo:8332', auth=('btcrpc', 'btc')) address = bitcoind.getnewaddress() privkey = bitcoind.dumpprivkey(address) print(address) print(privkey)

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btcpy - Maintained bitcoin library - Support segwit addresses (new format) - Implement Wallets, Transactions (doesn't require bitcoind) - https://github.com/chainside/btcpy pip install chainside-btcpy

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btcpy - Wallets from btcpy.setup import setup setup('mainnet') from btcpy.structs.crypto import PrivateKey privkey = PrivateKey.from_wif('L1Xx..Zfn') pubkey = privkey.pub() print(pubkey.to_address()) print(pubkey.to_segwit_address())

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btcpy - HD Wallets from btcpy.setup import setup setup('mainnet') from btcpy.structs.hd import ExtendedPrivateKey xprv = ExtendedPrivateKey.decode('xprv9s2..X73') print(xprv.key.pub().to_address()) print(xprv.key.pub().to_segwit_address())

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python-trezor - Communicate with Trezor HW - Support all trezor API - Wallets, Transactions - Trezor management (eg. pin change) - https://github.com/trezor/python-trezor sudo apt-get install python3-dev git \ cython3 libusb-1.0-0-dev libudev-dev \ pip install trezor

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python-trezor from trezorlib.client import TrezorClient from trezorlib.transport import get_transport client = TrezorClient(get_transport()) bip32_path = client.expand_path("44'/0'/0'/0/0") address = client.get_address('Bitcoin', bip32_path) print(address) bip32_path = client.expand_path("44'/0'/0'/0/1") address = client.get_address('Bitcoin', bip32_path) print(address)

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Trezor XPUB with btcpy from btcpy.setup import setup setup('mainnet') from btcpy.structs.hd import ExtendedPublicKey xpub = ExtendedPublicKey.decode('xpub6Cn..QfL') print(xpub.derive('./0/0').key.to_address()) print(xpub.derive('./0/1').key.to_address())

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You can do almost everything with those 3 libraries.

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You can do ... - Access Bitcoind - Use wallets - Work with transactions - Block parsing You can't do: - mining - you need a special mining HW

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What is Ethereum?

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What is Ethereum? - Also currency, network, … - Decentralized computer - Smart contract platform

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What is a smart contract? Smart contrat are scripts which can hold any informations, run any code (supported by Turing-complete EVM - ethereum virtual machine). Smart contract are commanded by users and also by other smart contracts. You can use smart contract for: - Crowdfundings - Property registries - Company shares

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Interact with Ethereum

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jsonrpc_requests You can also use requests, because Ethereum has JSON RPC interface.

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jsonrpc_requests example from jsonrpc_requests import Server eth = Server('http://eth.xsika.cz:8545') print(eth.eth_blockNumber()) print(eth.personal_newAccount(''))

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web3.py Web3.py is Python implementation of Ethereum JavaScript API. - https://github.com/ethereum/web3.py pip install web3

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web3.py example from web3 import Web3, HTTPProvider w3 = Web3(HTTPProvider('http://eth.xsika.cz:8545')) print(w3.eth.blockNumber) print(w3.personal.newAccount('x'))

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py-solc Python wrapper around solc - solidity compiler. - https://github.com/ethereum/py-solc - http://solidity.readthedocs.io/en/latest/installing-solidit y.html - How to install solc pip install py-solc

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greeter.sol pragma solidity ^0.4.0; contract Greeter { string public greeting; function Greeter() { greeting = 'Hello'; } function setGreeting(string _greeting) public { greeting = _greeting; } function greet() constant returns (string) { return greeting; } }

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py-solc example from web3 import Web3, HTTPProvider from solc import compile_source with open('greeter.sol', 'r') as f: src = f.read() compiled_sol = compile_source(src) contract_interface = compiled_sol[':Greeter'] w3 = Web3(HTTPProvider('http://eth.xsika.cz:8545')) con = w3.eth.contract(abi=contract_interface['abi'], bytecode=contract_interface['bin']) tx_id = con.deploy()

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Interact with contract ... print('Contract value: {}'.format(con.greet()) # Prints: Contract value: Hello cont.setGreeting('Nihao') print('Contract value:{}'.format(con.greet())) # Prints: Contract value: Nihao

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Summary Python is great tool to hacking Bitcoin & Ethereum Python libraries: - jsonrpc_requests - btcpy - python-trezor - web3.py - py-solc

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Thank you & Questions Ondrej Sika email: [email protected] web: ondrej-sika.cz twitter: @ondrejsika linkedin: /in/ondrejsika/ Slides: https://sika.link/pyconsk2018