I need help signing transaction

[jerempjerem]

I'm new to bitcoin and I need some help to build my transaction, I just want to send btc from a P2SH address (3...) to another P2SH address (3...)

here is my code :

func getPayToAddressScript(address_ string, network *chaincfg.Params) ([]byte, error) {
	address, err := btcutil.DecodeAddress(address_, network)
	if err != nil {
		return nil, err
	}

	pkScript, err := txscript.PayToAddrScript(address)
	if err != nil {
		return nil, err
	}

	return pkScript, nil
}

func main() {
	// Define the sender's address, receiver's address, and the amount to send
	const (
		fromAddressPrivateKey = "L....." // WIF private key
		fromAddress           = "3Lo9e23FBMsHpi8Pn274x9eLDenAjTjTP5"
		toAddress             = "3H7DkHLvjtdZ9n386Vi3qirducguyLdLSG"
	)

	var sentAmountBtc float64 = 0.0005
	var sentAmount int64 = int64(sentAmountBtc * 1e8)
	var network *chaincfg.Params = &chaincfg.MainNetParams
	var feeRate int = 10                  // in Satoshi unit
	var fees int64 = int64(feeRate * 250) // TODO: calculate the size of the transaction

	// Get the UTXOs for the sender's address
	utxos, err := getUtxo(fromAddress)
	if err != nil {
		fmt.Println(err)
		return
	}

	// Create a new transaction
	var txMsg *wire.MsgTx = wire.NewMsgTx(2)

	var totalInputAmount int64
	for _, utxo := range utxos {
		// Create the outpoint for the UTXO
		chainHash, _ := chainhash.NewHashFromStr(utxo.Txid)
		outpoint := wire.NewOutPoint(chainHash, uint32(utxo.Vout))

		// Create a new transaction input and add it to the transaction
		txIn := wire.NewTxIn(outpoint, nil, nil)
		txIn.Sequence = 0xFFFFFFFD
		txMsg.AddTxIn(txIn)

		// Add the UTXO's value to the total input
		totalInputAmount += utxo.Value

		// If the total input is enough to cover the total amount, stop adding inputs
		if totalInputAmount >= sentAmount+fees {
			break
		}
	}

	fmt.Println("Total input amount: ", totalInputAmount)
	fmt.Println("Sent amount: ", sentAmount)
	fmt.Println("Fees: ", fees)
	// Check if the total input is enough to cover the total amount
	if totalInputAmount < sentAmount+fees {
		fmt.Println("Not enough funds")
		return
	}

	// Add the transaction output for the receiver
	toAddressScript, _ := getPayToAddressScript(toAddress, network)
	txMsg.AddTxOut(wire.NewTxOut(sentAmount, toAddressScript))

	// Calculate the change amount
	changeAmount := totalInputAmount - sentAmount - fees

	// Add the transaction output for the change
	fromAddressScript, _ := getPayToAddressScript(fromAddress, network)
	txMsg.AddTxOut(wire.NewTxOut(changeAmount, fromAddressScript))

	// Decode the sender's WIF private key
	wif, err := btcutil.DecodeWIF(fromAddressPrivateKey)
	if err != nil {
		fmt.Println(err)
		return
	}

	// Sign the transaction
	for i, v := range txMsg.TxIn {
		sigScript, _ := txscript.SignatureScript(txMsg, i, fromAddressScript, txscript.SigHashAll, wif.PrivKey, false)
		v.SignatureScript = sigScript
	}

	var buf bytes.Buffer
	txMsg.Serialize(&buf)

	fmt.Printf("Signed transaction: %x\n", buf.Bytes())

}

[guggero]

Is this a nested segwit (np2wkh) address? Then you need to pass in the correct subscript into the txscript.SignatureScript. See https://github.com/lightningnetwork/lnd/blob/1a2d50d3850080de6b0fa4dcb5ac3317c347d9b0/lnwallet/btcwallet/psbt.go#L434 for an example.

[jerempjerem]

Hi,

no I just did the same transaction but manually to analyse the hex data and see the difference between them, and everything looks good except the asm and hex field in the script input field, tried a lot of thing but can't figured out what's wrong

here is the correct hex data of the manual transaction:

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

[guggero]

Ah, I see the difference... My fault, can you try this instead:

	// Get the subscript
	witnessScript, err := txscript.PayToAddrScript(addressWitnessPubKeyHash)
	if err != nil {
		fmt.Println(err)
		return
	}

	subScript, err := txscript.NewScriptBuilder().AddData(witnessScript).Script()
	if err != nil {
		fmt.Println(err)
		return
	}

[jerempjerem]

it's better I think, the script input field looks correct and I don't have the error "bas-witness-nonstandard" anymore when trying to broadcast, but now I have this error : "Code: -26, Error: non-mandatory-script-verify-flag (Signature must be zero for failed CHECK(MULTI)SIG operation)"

here is the hex data of of the transaction :

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

Thank you again for your help 🙏

[guggero]

Okay, I think you need to both use the witnessScript and the subScript differently now. Use the witnessScript for the call to RawTxInWitnessSignature and the subScript is what's assigned to txIn.SignatureScript. Does that work?

[jerempjerem]

https://www.blockchain.com/explorer/transactions/btc/6d09088c03c67be4977f177f5bca9f11755fb7eeee54ee1e8f691e514eaf69c0

❤️ thank you very much for your help

[guggero]

Cool! You're welcome.