使用 bitcoinjs 发送比特币交易

Question

Can someone please explain how I can send a bitcoin transaction using bitcoinjs??? I have setup two wallets using bitcoinjs.

I want to send 100000 satoshis from here: 1G4iprWu7Q8tNbQLA8UBM2GearcnzwFrxM

to here: 1HsrKvboax8J3X1sgsRdWybEwnUNWsDw4Y

In case it's needed here is the last transaction for 1G4iprWu7Q8tNbQLA8UBM2GearcnzwFrxM

The code I am using is from the bitcoinjs.org website:

var tx = new bitcoin.TransactionBuilder()

// Add the input (who is paying):
// [previous transaction hash, index of the output to use]
var txId = 'aa94ab02c182214f090e99a0d57021caffd0f195a81c24602b1028b130b63e31'
tx.addInput(txId, 0)

// Add the output (who to pay to):
// [payee's address, amount in satoshis]
tx.addOutput("1Gokm82v6DmtwKEB8AiVhm82hyFSsEvBDK", 15000)

// Initialize a private key using WIF
var privateKeyWIF = 'L1uyy5qTuGrVXrmrsvHWHgVzW9kKdrp27wBC7Vs6nZDTF2BRUVwy'
var keyPair = bitcoin.ECPair.fromWIF(privateKeyWIF)

// Sign the first input with the new key
tx.sign(0, keyPair)

// Print transaction serialized as hex
console.log(tx.build().toHex())
// => 0100000001313eb630b128102b60241ca895f1d0ffca21 ...

// You could now push the transaction onto the Bitcoin network manually
// (see https://blockchain.info/pushtx)

Now I am assuming var txId is the transaction id from the last transaction here

Is the `tx.addInput`` where I put the fee? If so is 100 enough?

tx.addOutput is obvs so I am okay with that!

Is var privateKeyWIF* where I put the private key from the sending address?

No idea what var keyPair and tx.sign do!

Anyone who can help tell me where the details are suppposed to go would be much appreciated! For this example pretend my private key for the sender address is 5Kb8kLf9zgWQnogidDA76MzPL6TsZZY36hWXMssSzNydYXYB9KF .

Cheers

Answer 1

A Bitcoin transaction typically references previous transaction outputs as new transaction inputs.

First you need to look at your previous transaction. As you can see here or in the snippet above the txId is: 4303caa91ca5a2236396af3bfae26b70a223a2bcee2fe8d23a7b24626c3c4bd2

 { "hash":"4303caa91ca5a2236396af3bfae26b70a223a2bcee2fe8d23a7b24626c3c4bd2", "ver":1, "vin_sz":1, "vout_sz":2, "size":225, "weight":900, "fee":18713, "relayed_by":"0.0.0.0", "lock_time":448506, "tx_index":7399058499716239, "double_spend":false, "time":1484590465, "block_index":448507, "block_height":448507, "inputs":[ { "sequence":4294967294, "witness":"", "script":"47304402204fdab6f26efa32f49c79d8c91b5d42ea39760cff5afc34351f8595453bd3c9d102201ff8e25e4ababe3c3515617e90f97516cda50061ad0c02f215e4a008d580ede4012102e801e52ff6e7d1ad0bb46ef6732d8fcfae1e122a47ea5690e084b9fa4a73d106", "index":0, "prev_out":{ "spent":true, "script":"76a914d7819c081b247a146922b8f90f89181b02a3c66f88ac", "spending_outpoints":[ { "tx_index":7399058499716239, "n":0 } ], "tx_index":356328836300976, "value":469871307, "addr":"1LeVYfpp1LQQUBqsmruVW6cMbYrZtmunPr", "n":1, "type":0 } } ], "out":[ { "type":0, "spent":true, "value":469352594, "spending_outpoints":[ { "tx_index":5608049158171792, "n":0 } ], "n":0, "tx_index":7399058499716239, "script":"76a9147adfb2779ee7710b0dffeff8fb77c82867ed43e588ac", "addr":"1CChR9sShAc61MNLhMoLzy87w5DwP6jRvv" }, { "type":0, "spent":true, "value":500000, "spending_outpoints":[ { "tx_index":8253272257190039, "n":0 } ], "n":1, "tx_index":7399058499716239, "script":"76a914a53e0c670a2836baef1ea93de125f1fdd77370dd88ac", "addr":"1G4iprWu7Q8tNbQLA8UBM2GearcnzwFrxM" } ] }

Your address 1G4iprWu7Q8tNbQLA8UBM2GearcnzwFrxM shows up as the second output ( index 1 ).

And the total amount at this address is 500000 satoshis .

---

So, lets create our transaction

var txb = new bitcoin.TransactionBuilder()
txb.addInput('4303caa91ca5a2236396af3bfae26b70a223a2bcee2fe8d23a7b24626c3c4bd2', 1)

Now we will send 100000 satoshis

txb.addOutput('1cMh228HTCiwS8ZsaakH8A8wze1JR5ZsP', 100000)

We need to send the change to some address you own

txb.addOutput('1cMh228HTCiwS8ZsaakH8A8wze1JR5ZsP', 398130)

What is left is the miner fee. You can use online services to estimate the ideal fee.

(in)500000 Satoshis - (out)100000 - (out)398130 = (fee)1870

Now we need to sign the transaction to confirm that you own the input address

var yourAddressPrivateKeyWIF = 'L1uyy5qTuGrVXrmrsvHWHgVzW9kKdrp27wBC7Vs6nZDTF2BRUVwy'
var yourAddresskeyPair = bitcoin.ECPair.fromWIF(yourAddressPrivateKeyWIF)
txb.sign(0, yourAddresskeyPair)

If you run yourAddresskeyPair.getAdress() the output should be your address 1G4iprWu7Q8tNbQLA8UBM2GearcnzwFrxM

Now you can send your transaction to the network. Get raw transaction in hex format:

txb.build().toHex()

Paste the result here https://blockchain.info/pushtx or check other solutions here: https://github.com/bitcoinjs/bitcoinjs-lib/issues/839

Answer 2

   let bitcoin = require('bitcoinjs-lib');
   const TESTNET = bitcoin.networks.testnet;
   const keyPair = bitcoin.ECPair.makeRandom({ network: TESTNET });
   const { address } = bitcoin.payments.p2pkh({
      pubkey: keyPair.publicKey,
      network: TESTNET,
   });;
   let wif = keyPair.toWIF()
// console.log(address, keyPair.publicKey.toString('hex') , keyPair.privateKey.toString('hex') , wif);

   let fkeyPair = bitcoin.ECPair.fromWIF(fwif , TESTNET);
   const result = await axios.get(`https://testnet.blockchain.info/rawaddr/${fAddress}`);
   let balance = result.data.final_balance;
   let latestTx = result.data.txs[0].hash;
   console.log('testAddress balance:' , balance);
   console.log('latest tx: ', latestTx);
   var txb = new bitcoin.TransactionBuilder(bitcoin.networks.testnet);
   let sendAmount = 15000;
   let fee = 26456;
   let whatIsLeft = balance - fee - sendAmount;
   txb.addInput(latestTx, 1);
   txb.addOutput(f2Address, sendAmount);
   txb.addOutput(f2Address, whatIsLeft);
   txb.sign(0, fkeyPair);
   let body = txb.build().toHex();
   console.log(body);

Answer 3

I am finding a lot of people are confused about that part - "how to post the transaction to the network". In short, you need access to a separate bitcoin core full node. The full nodes include JSON APIs that you post the raw transaction hex to, then the full node basically does the rest of the work for you behind the scenes (broadcasting over the gossip network to the other nodes, which then add the transaction into their own mempools, and then it waits for a miner to process it so it can be added into the blockchain).

There are two main ways to send the transaction to the network (sending it via the JSON RPC APIs in Bitcoin Core, or via the bitcoin-cli):

1. You could add a nodeJS library that allows you socket access to webservers, then invoke it as you would any other REST service from your nodeJS code.
2. For testing it is easier to use the "bitcoin-cli" that comes with the full node. Make sure your full node is running, SSH onto it, then invoke the sendrawtransaction command from within the bitcoin-cli. Specifically, from a UNIX prompt, it is one line:

•  % bitcoin-cli sendrawtransaction 0000000001186f9f....00000000

That big long hex number IS the transaction HEX that your bitcoinjs code will have generated. The unconfirmed transaction should appear in your wallet within seconds. ie validated, but not yet confirmed.

Answer 4

wif

First understand whatwif format is.

inputs

From github we have:

Transaction.prototype.addInput = function (hash, index, sequence, scriptSig)

so you have to pass the hash of the transaction and the index (which output will be your input) you should check what a bitcoin tx is

keypair

Not verified that, but probably keyPair is your Pk and pk.

signatures

Please verify also that because I did not, but logically tx.sign(index, keyPair) should sign the tx (SIGHASH_ALL) for the input index with the private key in keyPair . If you have more than one input of course you must provide a signature for each one. Take a look at mastering bitcoin