sign.go

package main

import (
	"github.com/bcext/cashutil"
	"github.com/bcext/gcash/txscript"
	"github.com/bcext/gcash/wire"
)

func sign(tx *wire.MsgTx, inputValueSlice []int64, pkScript []byte, wif *cashutil.WIF) (*wire.MsgTx, error) {
	for idx, _ := range tx.TxIn {
		sig, err := txscript.RawTxInSignature(tx, idx, pkScript, cashutil.Amount(inputValueSlice[idx]),
			txscript.SigHashAll|txscript.SigHashForkID, wif.PrivKey)
		if err != nil {
			return nil, err
		}
		sig, err = txscript.NewScriptBuilder().AddData(sig).Script()
		if err != nil {
			return nil, err
		}
		pk, err := txscript.NewScriptBuilder().AddData(wif.PrivKey.PubKey().SerializeCompressed()).Script()
		if err != nil {
			return nil, err
		}
		sig = append(sig, pk...)
		tx.TxIn[idx].SignatureScript = sig

		engine, err := txscript.NewEngine(pkScript, tx, idx, txscript.StandardVerifyFlags,
			nil, nil, inputValueSlice[idx])
		if err != nil {
			return nil, err
		}

		// verify the signature
		err = engine.Execute()
		if err != nil {
			return nil, err
		}
	}

	return tx, nil
}