Ethereum: How do I sign and send a raw transaction using BitcoinJ?

Signing and sending a raw transaction using Bitcoinj

In this article, we will go through the process of creating a raw transaction of the Ethereum blockchain using the Bitcoinj library. We will cover how to sign and send a raw transaction from scratch.

Prerequisites

Before you begin, make sure you have:

Bitcoinj (the official Java performance of the Bitcoin Protocol)

Bitcoin client (optional but shot to fix errors)

Create a raw transaction

The harsh transaction is a simple text string that represents the content of the block. To create one, we must follow the steps of the thesis:

Create a new transaction : We will use the Bitcoinj Transaction class to create a new transaction.

Initialize the list of unspents : We will store all the coins spent on this list.

Code

`Java

Transaction Transaction = New Transaction (Params);

// 遍历未花费列表组装合适的组装合适的 item

Double sum = 0;

String address = null;

List unspents = new arrayist <>);

scredcoins = new hashmap <>);

// …

Params.Geunspent ().

If (unspen.ispunded ()) {

Double quantity = unspen.getamount ();

amount += amount;

Sredcoins.put (new coin (unspen.gethash (), 1), indivisible);

}

});

Double Totalamount = Sum – Scredcoins.Values ().

.Maptodouble (unpens :: tamount) .sum ();

Transaction.Setfromaddress (address);

Transaction.Settoaddress (“0x …”); // Replace with your recipient’s address

Transaction.Adtransctionondails (Totalamount, “Transaction Datesit”);

key points

We repeat the list of immediate and add any coins that are based on our Scredcoins' folder.




We spent the total amount in the raw transaction, removing the sums of all coins from the amount.



We set the sender's address to a fixed value ("0x ...") and add details of the raw transaction, including its total amount.


 Signing of raw transaction

To sign the raw transaction using Bitcoinj, we will create a new copySigner:

Java

Signing signature = new signature (transaction);

We can be this signing to generate a raw transaction signature:

`Java

byte [] Signature = Signer.signrawransction;

Sending the raw transaction

To send the raw transaction, we will create a copy of “Transactionender”:

`Java

TransactionDender Sender = New Transactionender (Transaction, Null); // not a recipient’s address given

We can be this sender to broadcast the raw transaction in Bitcoin Network:

`Java

Sender.broadcast ();

Note that in practice you could probably set the recipient address for the raw transaction when creating it. The example above shows how to do this.

Example use

To send a raw transaction from scratch using Bitcoinj, follow the steps of the thesis:

Create a new Transaction Copy and Initialize the List of Unspens.

Iteration above the list of immediate and add all funded coins to a card.

Calculate the total amount spent in the harsh transaction.

Set the sender’s address and add details about the raw transaction.

Sign the raw transaction using a signature.

Send the signed raw transaction.

This should give you a good starting point for creating raw transactions on the Ethereum blockchain using Bitcoinj. Be sure to replace the replacement addresses with information about your own recipient!

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