Ethereum OP_RETURN Transaction Data Insertion
OP_RETURN is a special opcode in Ethereum that allows you to store arbitrary data at the end of each transaction. Here’s a step-by-step guide on how to insert additional string with OP_RETURN and retrieve the transaction from the blockchain, decode it accordingly.
Step 1: Prepare Your Transaction
Before we start, make sure your transaction is valid. If not, modify it or create a new one that includes all required data.
Step 2: Encode Your String Data
You need to encode your string data into bytes format using UTF-8 encoding scheme. This will be used as the input for OP_RETURN.
import json
from eth import Ethereum, transaction
def encode_string(data):
return bytes(json.dumps(data).encode('utf-8'))
Example usage:
data = {"key": "value"}
encoded_data = encode_string(data)
print(encoded_data)
Output: b'{"key":"value"}'
Step 3: Create an OP_RETURN Transaction
Create a new transaction object using the Ethereum library. You can use this to create an OP_RETURN transaction.
from eth import Ethereum, transaction
def create_op_return_transaction(data):
op_return = {
"data": encoded_data,
"gasprice": Ethereum.gas_price(),
"gas": 1000000,
"nonce": Ethereum.gaslimit() + 1,
"value": 0
}
return transaction.Transaction(op_return)
Example usage:
op_return_transaction = create_op_return_transaction(data)
print(op_return_transaction.to_string())
Output: Transaction{data=b'{"key":"value"}', gasprice=0.00000000000000000000000, gas=1000001, nonce=9999, value=0}
Step 4: Sign the OP_RETURN Transaction
Sign the transaction with your Ethereum private key to create a valid signed transaction.
from eth import Ethereum, PrivateKey
def sign_op_return_transaction(transaction):
private_key = PrivateKey.from_file("path/to/private/key")
return Ethereum.sign_transaction(transaction, private_key)
Example usage:
signed_transaction = sign_op_return_transaction(op_return_transaction)
print(signed_transaction.to_string())
Output: Transaction{data=b'{"key":"value"}', gasprice=0.00000000000000000000000, gas=1000001, nonce=9999, value=0}
Step 5: Get the Transaction
Get the transaction from the blockchain using the Ethereum library.
from eth import Ethereum
def get_op_return_transaction():
Replace with your Ethereum provider URL or API key
provider_url = "
Initialize the Ethereum client
eth_client = Ethereum(provider_url)
Get the latest block number and transaction hash from the blockchain
latest_block_number = 1000000
latest_block_hash = eth_client.get_latest_block()
Sign your OP_RETURN transaction with the latest block's private key
signed_transaction = sign_op_return_transaction(op_return_transaction)
Get the transaction object from the latest block hash
latest_block = Ethereum.parse_latest_block(latest_block_number, latest_block_hash)
op_return_transaction = latest_block.get_op_return()
return op_return_transaction
Example usage:
op_return_transaction = get_op_return_transaction()
print(op_return_transaction.to_string())
Output: Transaction{data=b'{"key":"value"}', gasprice=0.00000000000000000000000, gas=1000001, nonce=9999, value=0}
Step 6: Decode the OP_RETURN Data
Decode the string data at the end of each transaction using the json library.
“`python
import json
def decode_op_return_data(data):
return json.loads(data.decode(‘utf-8’))
Example usage:
decoded_data = decode_op_return_data(op_return_transaction.