Python Libraries for Bitcoin and Ethereum, PyCon SK 2018

https://ondrej-sika.cz/blog/2018/python-libraries-for-bitcoin-and-ethereum-pycon-sk-2018/

Transcript

1. Python Libraries
   for Bitcoin & Ethereum
   Ondrej Sika
   ondrej@ondrejsika.com
   PyCon SK 2018,
   Bratislava SK, 10. 3. 2018
   

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

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

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5. What is Bitcoin?
   

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

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7. How Bitcoin works?
   

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

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

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11. 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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12. 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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13. HD Wallets
    - Hierarchical deterministic wallets
    - Support in Trezor, Electrum
    

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14. Interact with Bitcoin
    

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

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

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17. In Python
    libraries
    - jsonrpc_requests
    - btcpy
    - python-trezor
    

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18. 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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19. 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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20. 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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21. 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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22. 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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23. 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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24. 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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25. 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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26. You can do almost
    everything with those 3
    libraries.
    

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27. 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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29. What is Ethereum?
    

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

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31. 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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32. Interact with Ethereum
    

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

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

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36. 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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37. 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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38. 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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39. 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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40. 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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41. Summary
    Python is great tool to hacking Bitcoin & Ethereum
    Python libraries:
    - jsonrpc_requests
    - btcpy
    - python-trezor
    - web3.py
    - py-solc
    

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

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