Recover Public key from transaction hash

recover.py

#!/usr/bin/python3
# https://www.reddit.com/r/ethdev/comments/poqlb4/recover_a_public_key_from_a_transaction/
from hexbytes import HexBytes
from coincurve import PublicKey as CCPublicKey
from eth_account._utils.signing import to_standard_v
from eth_account._utils.legacy_transactions import serializable_unsigned_transaction_from_dict
from eth_keys.datatypes import Signature
from eth_rlp import HashableRLP
from web3 import Web3


INFURA_URL_MAINNET = "..."
INFURA_URL_TESTNET = "..."


def pub_key_from_tx_eth(txid, chain):
    """Obtain the public key from an Ethereum transaction
    """
    w3test = Web3(Web3.HTTPProvider(INFURA_URL_TESTNET))
    transaction = w3test.eth.get_transaction(txid)
    vrs = (to_standard_v(transaction['v']),
           int.from_bytes(transaction['r'], "big"),
           int.from_bytes(transaction['s'], "big"))
    signature = Signature(vrs=vrs)    
    tx_dict = {'nonce': transaction.nonce,
               'gasPrice': transaction.gasPrice,
               'gas': transaction.gas,
               'to': transaction.to,
               'value': transaction.value
    }
    if chain == "ETH":
        tx_dict['chainId'] = "0x01"
    elif chain == "tETH":
        tx_dict['chainId'] = "0x03"
    if 'input' in transaction:
        tx_dict['data'] = transaction['input']
    serialized_tx = serializable_unsigned_transaction_from_dict(tx_dict)
    rec_pub = signature.recover_public_key_from_msg_hash(serialized_tx.hash())
    if rec_pub.to_checksum_address() != transaction['from']:
        raise ValueError("Unable to obtain public key from transaction: " +
                         f"{txid}")
    return(rec_pub)