Sample of the Transaction API:

    var utxo = txWithUTXO.outputs[0]; 
    var outpoint = TransactionOutpoint(txWithUTXO.id, 0, utxo.satoshis, utxo.script);
    var signer = TransactionSigner(SighashType.SIGHASH_FORKID.value | SighashType.SIGHASH_ALL.value, privateKey);

    var unlocker = P2PKHUnlockBuilder(privateKey.publicKey);
    
    var transaction = TransactionBuilder()
        .spendFromOutpointWithSigner(signer, outpoint, TransactionInput.MAX_SEQ_NUMBER, unlocker)
        .spendToPKH(recipientAddress, BigInt.from(50000000)) //spend half of a bitcoin 
        .sendChangeToPKH(changeAddress) // spend change to a different address
        .withFeePerKb(50) //set a fee of 50 satoshis per kilobyte
        .build(false); //build the transaction, disabling checks

    //at this point you have a fully signed transaction ready to be broadcast

    try {
      transaction.verify(); //perform a pre-broadcast sanity check on the transaction
    } on VerificationException catch (ex){
      print("Transaction failed verification - ${ex.cause}");  
    }

Installation

This library was built using version 3.0.7 of the Dart SDK( https://dart.dev/tools/sdk ).
As of Version 1.0.0 this library supports Dart Null Safety. Current minimum Dart SDK version required is version 2.17.0.

Navigate to the root folder of this project, and pull the required supported Dart libraries using the pub package manager.

> pub get

Running the Tests

In the root folder of this project, run the command:

> pub run test

Acknowledgement

A debt of gratitude is owed to the developers acknowledged in the LICENSE file. Without the hard work of individuals working on earlier library and node implementations like Bitcoin Core, Bitcoin Cash, MoneyButton/BSV, BitcoinJ and many more, this library would likely not have come to fruition. Thank you.

Contact

You can reach the author at :

• @twostack_org on Twitter
• [email protected] (PayMail to buy me a beer)
• [email protected] (drop me an email. GPG supported. )