Assertion failed error.

[0xharsha]

I need a singing input transaction hash to sign from an external wallet in bitcoin. I'm getting an assertion failed error in walletCore.TransactionCompiler.preImageHashes method for some reason.

Below is the code I have used to generate the preimage hash.

export const generatePreSignTxHash = async (txObject: any) => {
    const {
        version,
        utxos,
        outputs,
        lockTime,
        fromAddress,
        forFeeAmount,
        feeRate,
        outputAmmount,
        toAddress
    } = txObject;

    const walletCore = await initWasm();

    const utxo = utxos.map(
        (utxo: { txid: any; vout: any; value: any; satoshis: number }) => {
            return TW.Bitcoin.Proto.UnspentTransaction.create({
                outPoint: {
                    hash: utxo.txid,
                    index: utxo.vout,
                    sequence: 4294967295 // default sequence
                },
                amount: new Long(utxo.satoshis),
                script: walletCore.BitcoinScript.lockScriptForAddress(
                    fromAddress,
                    walletCore.CoinType.bitcoin
                ).data()
            });
        }
    );

    const txInput = TW.Bitcoin.Proto.SigningInput.create({
        hashType: walletCore.BitcoinSigHashType.all.value,
        coinType: walletCore.CoinType.bitcoin.value,
        amount: new Long(outputAmmount),
        toAddress: toAddress,
        lockTime: lockTime,
        plan: {
            amount: new Long(outputAmmount),
            fee: new Long(feeRate),
            change: new Long(0),
            utxos: [utxo]
        }
    });

    const inputEncoded = TW.Bitcoin.Proto.SigningInput.encode(txInput).finish();

    const preimageOutputData = walletCore.TransactionCompiler.preImageHashes(
        walletCore.CoinType.bitcoin,
        inputEncoded
    );

    const preimageOutput =
        TW.TxCompiler.Proto.PreSigningOutput.decode(preimageOutputData);

    const inputDataHashHex = walletCore.HexCoding.encode(preimageOutput.dataHash);

    return inputDataHashHex;
};

[satoshiotomakan]

Hi @harshavnaik, please make sure you provided exactly 32 bytes prev out hash, i.e utxo.txid

[0xharsha]

Hi @satoshiotomakan, This is my unspent transaction object. utxo.txid length going in 32 bytes.

this is the prev out hash 338a1898dc83a9987c85b14e9f55ebfb48cf07a5ac8133371603536b1ab1251c

[0xharsha]

@satoshiotomakan updated the code as you suggested, the same error persists after making this update.

const txInput = TW.Bitcoin.Proto.SigningInput.create({
        hashType: walletCore.BitcoinSigHashType.all.value,
        coinType: walletCore.CoinType.bitcoin.value,
        amount: new Long(outputAmmount),
        toAddress: toAddress,
        lockTime: lockTime,
        changeAddress: fromAddress,
        utxo: [utxo]
    });

[satoshiotomakan]

I have a doubt const utxo = utxos.map(...) works as expected.
Please try to create the UTXO without using the map:

    const utxo1 = TW.Bitcoin.Proto.UnspentTransaction.create({
                outPoint: {
                    hash: utxo.txid,
                    index: utxo.vout,
                    sequence: 4294967295 // default sequence
                },
                amount: new Long(utxo.satoshis),
                script: walletCore.BitcoinScript.lockScriptForAddress(
                    fromAddress,
                    walletCore.CoinType.bitcoin
                ).data()
            });

  const txInput = TW.Bitcoin.Proto.SigningInput.create({
    utxo: [utxo1]
  });

[0xharsha]

@satoshiotomakan, here are my input data. Could you please confirm if they are valid?

const utxos = [{
    "txid": "338a1898dc83a9987c85b14e9f55ebfb48cf07a5ac8133371603536b1ab1251c",
    "vout": 0,
    "satoshis": 16717,
    "scriptPk": "0014edf6c1e13ac188fedc396572c8d8319ab62f4d73",
    "addressType": 1,
    "inscriptions": [],
    "atomicals": [],
    "runes": [],
    "pubkey": "",
    "height": 2817006
}];

const fromAddress = "tb1qahmvrcf6cxy0ahpev4ev3kp3n2mz7ntn7ffmae";

const toAddress = "tb1qxptltm2n7mkkuc05lvmmlct7x3thpdvqnqurrx";

const lockTime = 0;

const outputAmount. = "100000000";  // in satoshis

const utxo = utxos[0];

const utxo1 = TW.Bitcoin.Proto.UnspentTransaction.create({
    outPoint: {
        hash: Buffer.from(utxo.txid, 'hex'),
        index: utxo.vout,
        sequence: 4294967295 // default sequence
    },
    amount: new Long(utxo.satoshis),
    script: walletCore.BitcoinScript.lockScriptForAddress(
        fromAddress,
        walletCore.CoinType.bitcoin
    ).data()
});

const txInput = TW.Bitcoin.Proto.SigningInput.create({
    hashType: walletCore.BitcoinSigHashType.all.value,
    coinType: walletCore.CoinType.bitcoin.value,
    amount: new Long(outputAmmount),
    toAddress: toAddress,
    lockTime: lockTime,
    changeAddress: fromAddress,
    utxo: [utxo1]
});

const inputEncoded = TW.Bitcoin.Proto.SigningInput.encode(txInput).finish();

const preimageOutputData = walletCore.TransactionCompiler.preImageHashes(
    walletCore.CoinType.bitcoin,
    inputEncoded
);

const preimageOutput =
    TW.TxCompiler.Proto.PreSigningOutput.decode(preimageOutputData);

const inputDataHashHex = walletCore.HexCoding.encode(preimageOutput.dataHash);

I made the changes as mentioned, but I'm still getting the same error.

[0xharsha]

@satoshiotomakan thank you for reviewing my code. after buffer reverse (i.e, Buffer.from(utxo.txid, 'hex').reverse()) it's working fine for me.

const utxo1 = TW.Bitcoin.Proto.UnspentTransaction.create({
    outPoint: {
        hash: Buffer.from(utxo.txid, 'hex').reverse(), // after reverse it's working fine. 
        index: utxo.vout,
        sequence: 4294967295 // default sequence
    },
    amount: new Long(utxo.satoshis),
    script: walletCore.BitcoinScript.lockScriptForAddress(
        fromAddress,
        walletCore.CoinType.bitcoin
    ).data()
});

[satoshiotomakan]

@harshavnaik I'm glad you managed to fix it!

[Doferesouleymane]

Cool oui que puisse pour vous