Esempio n. 1
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// validateSigScripts executes the signature script of the tx input with the
// given index, returning an error if it fails.
func validateSigScript(msgtx *wire.MsgTx, idx int, pkScript []byte) error {
	vm, err := txscript.NewEngine(pkScript, msgtx, idx,
		txscript.StandardVerifyFlags, nil)
	if err != nil {
		return newError(ErrTxSigning, "cannot create script engine", err)
	}
	if err = vm.Execute(); err != nil {
		return newError(ErrTxSigning, "cannot validate tx signature", err)
	}
	return nil
}
Esempio n. 2
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// validateMsgTx verifies transaction input scripts for tx.  All previous output
// scripts from outputs redeemed by the transaction, in the same order they are
// spent, must be passed in the prevScripts slice.
func validateMsgTx(tx *wire.MsgTx, prevScripts [][]byte, inputValues []btcutil.Amount) error {
	hashCache := txscript.NewTxSigHashes(tx)
	for i, prevScript := range prevScripts {
		vm, err := txscript.NewEngine(prevScript, tx, i,
			txscript.StandardVerifyFlags, nil, hashCache, int64(inputValues[i]))
		if err != nil {
			return fmt.Errorf("cannot create script engine: %s", err)
		}
		err = vm.Execute()
		if err != nil {
			return fmt.Errorf("cannot validate transaction: %s", err)
		}
	}
	return nil
}
Esempio n. 3
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// handleFundingCounterPartySigs is the final step in the channel reservation
// workflow. During this step, we validate *all* the received signatures for
// inputs to the funding transaction. If any of these are invalid, we bail,
// and forcibly cancel this funding request. Additionally, we ensure that the
// signature we received from the counterparty for our version of the commitment
// transaction allows us to spend from the funding output with the addition of
// our signature.
func (l *LightningWallet) handleFundingCounterPartySigs(msg *addCounterPartySigsMsg) {
	l.limboMtx.RLock()
	res, ok := l.fundingLimbo[msg.pendingFundingID]
	l.limboMtx.RUnlock()
	if !ok {
		msg.err <- fmt.Errorf("attempted to update non-existant funding state")
		return
	}

	// Grab the mutex on the ChannelReservation to ensure thead-safety
	res.Lock()
	defer res.Unlock()

	// Now we can complete the funding transaction by adding their
	// signatures to their inputs.
	res.theirFundingInputScripts = msg.theirFundingInputScripts
	inputScripts := msg.theirFundingInputScripts
	fundingTx := res.fundingTx
	sigIndex := 0
	fundingHashCache := txscript.NewTxSigHashes(fundingTx)
	for i, txin := range fundingTx.TxIn {
		if len(inputScripts) != 0 && len(txin.Witness) == 0 {
			// Attach the input scripts so we can verify it below.
			txin.Witness = inputScripts[sigIndex].Witness
			txin.SignatureScript = inputScripts[sigIndex].ScriptSig

			// Fetch the alleged previous output along with the
			// pkscript referenced by this input.
			prevOut := txin.PreviousOutPoint
			output, err := l.chainIO.GetUtxo(&prevOut.Hash, prevOut.Index)
			if output == nil {
				msg.err <- fmt.Errorf("input to funding tx does not exist: %v", err)
				return
			}

			// Ensure that the witness+sigScript combo is valid.
			vm, err := txscript.NewEngine(output.PkScript,
				fundingTx, i, txscript.StandardVerifyFlags, nil,
				fundingHashCache, output.Value)
			if err != nil {
				// TODO(roasbeef): cancel at this stage if invalid sigs?
				msg.err <- fmt.Errorf("cannot create script engine: %s", err)
				return
			}
			if err = vm.Execute(); err != nil {
				msg.err <- fmt.Errorf("cannot validate transaction: %s", err)
				return
			}

			sigIndex++
		}
	}

	// At this point, we can also record and verify their signature for our
	// commitment transaction.
	res.theirCommitmentSig = msg.theirCommitmentSig
	commitTx := res.partialState.OurCommitTx
	theirKey := res.theirContribution.MultiSigKey

	// Re-generate both the witnessScript and p2sh output. We sign the
	// witnessScript script, but include the p2sh output as the subscript
	// for verification.
	witnessScript := res.partialState.FundingWitnessScript

	// Next, create the spending scriptSig, and then verify that the script
	// is complete, allowing us to spend from the funding transaction.
	theirCommitSig := msg.theirCommitmentSig
	channelValue := int64(res.partialState.Capacity)
	hashCache := txscript.NewTxSigHashes(commitTx)
	sigHash, err := txscript.CalcWitnessSigHash(witnessScript, hashCache,
		txscript.SigHashAll, commitTx, 0, channelValue)
	if err != nil {
		msg.err <- fmt.Errorf("counterparty's commitment signature is invalid: %v", err)
		return
	}

	// Verify that we've received a valid signature from the remote party
	// for our version of the commitment transaction.
	sig, err := btcec.ParseSignature(theirCommitSig, btcec.S256())
	if err != nil {
		msg.err <- err
		return
	} else if !sig.Verify(sigHash, theirKey) {
		msg.err <- fmt.Errorf("counterparty's commitment signature is invalid")
		return
	}
	res.partialState.OurCommitSig = theirCommitSig

	// Funding complete, this entry can be removed from limbo.
	l.limboMtx.Lock()
	delete(l.fundingLimbo, res.reservationID)
	l.limboMtx.Unlock()

	walletLog.Infof("Broadcasting funding tx for ChannelPoint(%v): %v",
		res.partialState.FundingOutpoint, spew.Sdump(fundingTx))

	// Broacast the finalized funding transaction to the network.
	if err := l.PublishTransaction(fundingTx); err != nil {
		msg.err <- err
		return
	}

	// Add the complete funding transaction to the DB, in it's open bucket
	// which will be used for the lifetime of this channel.
	// TODO(roasbeef): revisit faul-tolerance of this flow
	nodeAddr := res.nodeAddr
	if err := res.partialState.FullSyncWithAddr(nodeAddr); err != nil {
		msg.err <- err
		return
	}

	// Create a goroutine to watch the chain so we can open the channel once
	// the funding tx has enough confirmations.
	go l.openChannelAfterConfirmations(res)

	msg.err <- nil
}
Esempio n. 4
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// TestHTLCReceiverSpendValidation tests all possible valid+invalid redemption
// paths in the script used within the reciever's commitment transaction for an
// incoming HTLC.
//
// The following cases are exercised by this test:
//  * reciever spends
//     * HTLC redemption w/ invalid preimage size
//     * HTLC redemption w/ invalid sequence
//     * HTLC redemption w/ valid preimage size
//  * sender spends
//     * revoke w/ sig
//     * refund w/ invalid lock time
//     * refund w/ valid lock time
func TestHTLCReceiverSpendValidation(t *testing.T) {
	// We generate a fake output, and the coresponding txin. This output
	// doesn't need to exist, as we'll only be validating spending from the
	// transaction that references this.
	fundingOut := &wire.OutPoint{
		Hash:  testHdSeed,
		Index: 50,
	}
	fakeFundingTxIn := wire.NewTxIn(fundingOut, nil, nil)

	// Generate a payment and revocation pre-image to be used below.
	revokePreimage := testHdSeed[:]
	revokeHash := fastsha256.Sum256(revokePreimage)
	paymentPreimage := revokeHash
	paymentPreimage[0] ^= 1
	paymentHash := fastsha256.Sum256(paymentPreimage[:])

	// We'll also need some tests keys for alice and bob, and meta-data of
	// the HTLC output.
	aliceKeyPriv, aliceKeyPub := btcec.PrivKeyFromBytes(btcec.S256(),
		testWalletPrivKey)
	bobKeyPriv, bobKeyPub := btcec.PrivKeyFromBytes(btcec.S256(),
		bobsPrivKey)
	paymentAmt := btcutil.Amount(1 * 10e8)
	cltvTimeout := uint32(8)
	csvTimeout := uint32(5)

	// Generate the raw HTLC redemption scripts, and its p2wsh counterpart.
	htlcScript, err := receiverHTLCScript(cltvTimeout, csvTimeout,
		aliceKeyPub, bobKeyPub, revokeHash[:], paymentHash[:])
	if err != nil {
		t.Fatalf("unable to create htlc sender script: %v", err)
	}
	htlcWitnessScript, err := witnessScriptHash(htlcScript)
	if err != nil {
		t.Fatalf("unable to create p2wsh htlc script: %v", err)
	}

	// This will be Bob's commitment transaction. In this scenario Alice
	// is sending an HTLC to a node she has a a path to (could be Bob,
	// could be multiple hops down, it doesn't really matter).
	recieverCommitTx := wire.NewMsgTx()
	recieverCommitTx.AddTxIn(fakeFundingTxIn)
	recieverCommitTx.AddTxOut(&wire.TxOut{
		Value:    int64(paymentAmt),
		PkScript: htlcWitnessScript,
	})

	prevOut := &wire.OutPoint{
		Hash:  recieverCommitTx.TxSha(),
		Index: 0,
	}

	sweepTx := wire.NewMsgTx()
	sweepTx.AddTxIn(wire.NewTxIn(prevOut, nil, nil))
	sweepTx.AddTxOut(
		&wire.TxOut{
			PkScript: []byte("doesn't matter"),
			Value:    1 * 10e8,
		},
	)

	testCases := []struct {
		witness func() wire.TxWitness
		valid   bool
	}{
		{
			// HTLC redemption w/ invalid preimage size
			makeWitnessTestCase(t, func() (wire.TxWitness, error) {
				return receiverHtlcSpendRedeem(htlcScript,
					paymentAmt, bobKeyPriv, sweepTx,
					bytes.Repeat([]byte{1}, 45), csvTimeout,
				)
			}),
			false,
		},
		{
			// HTLC redemption w/ invalid sequence
			makeWitnessTestCase(t, func() (wire.TxWitness, error) {
				return receiverHtlcSpendRedeem(htlcScript,
					paymentAmt, bobKeyPriv, sweepTx,
					paymentPreimage[:], csvTimeout-2,
				)
			}),
			false,
		},
		{
			// HTLC redemption w/ valid preimage size
			makeWitnessTestCase(t, func() (wire.TxWitness, error) {
				return receiverHtlcSpendRedeem(htlcScript,
					paymentAmt, bobKeyPriv, sweepTx,
					paymentPreimage[:], csvTimeout,
				)
			}),
			true,
		},
		{
			// revoke w/ sig
			makeWitnessTestCase(t, func() (wire.TxWitness, error) {
				return receiverHtlcSpendRevoke(htlcScript, paymentAmt,
					aliceKeyPriv, sweepTx, revokePreimage[:],
				)
			}),
			true,
		},
		{
			// refund w/ invalid lock time
			makeWitnessTestCase(t, func() (wire.TxWitness, error) {
				return receiverHtlcSpendTimeout(htlcScript, paymentAmt,
					aliceKeyPriv, sweepTx, cltvTimeout-2)
			}),
			false,
		},
		{
			// refund w/ valid lock time
			makeWitnessTestCase(t, func() (wire.TxWitness, error) {
				return receiverHtlcSpendTimeout(htlcScript, paymentAmt,
					aliceKeyPriv, sweepTx, cltvTimeout)
			}),
			true,
		},
	}

	for i, testCase := range testCases {
		sweepTx.TxIn[0].Witness = testCase.witness()

		vm, err := txscript.NewEngine(htlcWitnessScript,
			sweepTx, 0, txscript.StandardVerifyFlags, nil,
			nil, int64(paymentAmt))
		if err != nil {
			t.Fatalf("unable to create engine: %v", err)
		}

		// This buffer will trace execution of the Script, only dumping
		// out to stdout in the case that a test fails.
		var debugBuf bytes.Buffer

		done := false
		for !done {
			dis, err := vm.DisasmPC()
			if err != nil {
				t.Fatalf("stepping (%v)\n", err)
			}
			debugBuf.WriteString(fmt.Sprintf("stepping %v\n", dis))

			done, err = vm.Step()
			if err != nil && testCase.valid {
				fmt.Println(debugBuf.String())
				t.Fatalf("spend test case #%v failed, spend should be valid: %v", i, err)
			} else if err == nil && !testCase.valid && done {
				fmt.Println(debugBuf.String())
				t.Fatalf("spend test case #%v succeed, spend should be invalid: %v", i, err)
			}

			debugBuf.WriteString(fmt.Sprintf("Stack: ", vm.GetStack()))
			debugBuf.WriteString(fmt.Sprintf("AltStack: ", vm.GetAltStack()))
		}
	}
}
Esempio n. 5
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// TestCommitmentSpendValidation test the spendability of both outputs within
// the commitment transaction.
//
// The following spending cases are covered by this test:
//   * Alice's spend from the delayed output on her commitment transaction.
//   * Bob's spend from Alice's delayed output when she broadcasts a revoked
//     commitment transaction.
//   * Bob's spend from his unencumbered output within Alice's commitment
//     transaction.
func TestCommitmentSpendValidation(t *testing.T) {
	// We generate a fake output, and the corresponding txin. This output
	// doesn't need to exist, as we'll only be validating spending from the
	// transaction that references this.
	fundingOut := &wire.OutPoint{
		Hash:  testHdSeed,
		Index: 50,
	}
	fakeFundingTxIn := wire.NewTxIn(fundingOut, nil, nil)

	// We also set up set some resources for the commitment transaction.
	// Each side currently has 1 BTC within the channel, with a total
	// channel capacity of 2BTC.
	aliceKeyPriv, aliceKeyPub := btcec.PrivKeyFromBytes(btcec.S256(),
		testWalletPrivKey)
	bobKeyPriv, bobKeyPub := btcec.PrivKeyFromBytes(btcec.S256(),
		bobsPrivKey)
	channelBalance := btcutil.Amount(1 * 10e8)
	csvTimeout := uint32(5)
	revocationPreimage := testHdSeed[:]
	revokePubKey := DeriveRevocationPubkey(bobKeyPub, revocationPreimage)

	aliceSelfOutputSigner := &mockSigner{aliceKeyPriv}

	// With all the test data set up, we create the commitment transaction.
	// We only focus on a single party's transactions, as the scripts are
	// identical with the roles reversed.
	//
	// This is Alice's commitment transaction, so she must wait a CSV delay
	// of 5 blocks before sweeping the output, while bob can spend
	// immediately with either the revocation key, or his regular key.
	commitmentTx, err := CreateCommitTx(fakeFundingTxIn, aliceKeyPub,
		bobKeyPub, revokePubKey, csvTimeout, channelBalance, channelBalance)
	if err != nil {
		t.Fatalf("unable to create commitment transaction: %v", nil)
	}

	delayOutput := commitmentTx.TxOut[0]
	regularOutput := commitmentTx.TxOut[1]

	// We're testing an uncooperative close, output sweep, so construct a
	// transaction which sweeps the funds to a random address.
	targetOutput, err := commitScriptUnencumbered(aliceKeyPub)
	if err != nil {
		t.Fatalf("unable to create target output: %v")
	}
	sweepTx := wire.NewMsgTx()
	sweepTx.Version = 2
	sweepTx.AddTxIn(wire.NewTxIn(&wire.OutPoint{commitmentTx.TxSha(), 0}, nil, nil))
	sweepTx.AddTxOut(&wire.TxOut{
		PkScript: targetOutput,
		Value:    0.5 * 10e8,
	})

	// First, we'll test spending with Alice's key after the timeout.
	delayScript, err := commitScriptToSelf(csvTimeout, aliceKeyPub, revokePubKey)
	if err != nil {
		t.Fatalf("unable to generate alice delay script: %v")
	}
	sweepTx.TxIn[0].Sequence = lockTimeToSequence(false, csvTimeout)
	signDesc := &SignDescriptor{
		WitnessScript: delayScript,
		SigHashes:     txscript.NewTxSigHashes(sweepTx),
		Output: &wire.TxOut{
			Value: int64(channelBalance),
		},
		HashType:   txscript.SigHashAll,
		InputIndex: 0,
	}
	aliceWitnessSpend, err := CommitSpendTimeout(aliceSelfOutputSigner,
		signDesc, sweepTx)
	if err != nil {
		t.Fatalf("unable to generate delay commit spend witness :%v")
	}
	sweepTx.TxIn[0].Witness = aliceWitnessSpend
	vm, err := txscript.NewEngine(delayOutput.PkScript,
		sweepTx, 0, txscript.StandardVerifyFlags, nil,
		nil, int64(channelBalance))
	if err != nil {
		t.Fatalf("unable to create engine: %v", err)
	}
	if err := vm.Execute(); err != nil {
		t.Fatalf("spend from delay output is invalid: %v", err)
	}

	// Next, we'll test bob spending with the derived revocation key to
	// simulate the scenario when alice broadcasts this commitmen
	// transaction after it's been revoked.
	revokePrivKey := DeriveRevocationPrivKey(bobKeyPriv, revocationPreimage)
	bobWitnessSpend, err := commitSpendRevoke(delayScript, channelBalance,
		revokePrivKey, sweepTx)
	if err != nil {
		t.Fatalf("unable to generate revocation witness: %v", err)
	}
	sweepTx.TxIn[0].Witness = bobWitnessSpend
	vm, err = txscript.NewEngine(delayOutput.PkScript,
		sweepTx, 0, txscript.StandardVerifyFlags, nil,
		nil, int64(channelBalance))
	if err != nil {
		t.Fatalf("unable to create engine: %v", err)
	}
	if err := vm.Execute(); err != nil {
		t.Fatalf("revocation spend is invalid: %v", err)
	}

	// Finally, we test bob sweeping his output as normal in the case that
	// alice broadcasts this commitment transaction.
	bobScriptp2wkh, err := commitScriptUnencumbered(bobKeyPub)
	if err != nil {
		t.Fatalf("unable to create bob p2wkh script: %v", err)
	}
	bobRegularSpend, err := commitSpendNoDelay(bobScriptp2wkh,
		channelBalance, bobKeyPriv, sweepTx)
	if err != nil {
		t.Fatalf("unable to create bob regular spend: %v", err)
	}
	sweepTx.TxIn[0].Witness = bobRegularSpend
	vm, err = txscript.NewEngine(regularOutput.PkScript,
		sweepTx, 0, txscript.StandardVerifyFlags, nil,
		nil, int64(channelBalance))
	if err != nil {
		t.Fatalf("unable to create engine: %v", err)
	}
	if err := vm.Execute(); err != nil {
		t.Fatalf("bob p2wkh spend is invalid: %v", err)
	}
}
Esempio n. 6
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// validateHandler consumes items to validate from the internal validate channel
// and returns the result of the validation on the internal result channel. It
// must be run as a goroutine.
func (v *txValidator) validateHandler() {
out:
	for {
		select {
		case txVI := <-v.validateChan:
			// Ensure the referenced input transaction is available.
			txIn := txVI.txIn
			originTxHash := &txIn.PreviousOutPoint.Hash
			originTxIndex := txIn.PreviousOutPoint.Index
			txEntry := v.utxoView.LookupEntry(originTxHash)
			if txEntry == nil {
				str := fmt.Sprintf("unable to find input "+
					"transaction %v referenced from "+
					"transaction %v", originTxHash,
					txVI.tx.Hash())
				err := ruleError(ErrMissingTx, str)
				v.sendResult(err)
				break out
			}

			// Ensure the referenced input transaction public key
			// script is available.
			pkScript := txEntry.PkScriptByIndex(originTxIndex)
			if pkScript == nil {
				str := fmt.Sprintf("unable to find unspent "+
					"output %v script referenced from "+
					"transaction %s:%d",
					txIn.PreviousOutPoint, txVI.tx.Hash(),
					txVI.txInIndex)
				err := ruleError(ErrBadTxInput, str)
				v.sendResult(err)
				break out
			}

			// Create a new script engine for the script pair.
			sigScript := txIn.SignatureScript
			witness := txIn.Witness
			inputAmount := txEntry.AmountByIndex(originTxIndex)
			vm, err := txscript.NewEngine(pkScript, txVI.tx.MsgTx(),
				txVI.txInIndex, v.flags, v.sigCache, txVI.sigHashes,
				inputAmount)
			if err != nil {
				str := fmt.Sprintf("failed to parse input "+
					"%s:%d which references output %s:%d - "+
					"%v (input witness %v, input script "+
					"bytes %x, prev output script bytes %x)",
					txVI.tx.Hash(), txVI.txInIndex, originTxHash,
					originTxIndex, err, witness, sigScript,
					pkScript)
				err := ruleError(ErrScriptMalformed, str)
				v.sendResult(err)
				break out
			}

			// Execute the script pair.
			if err := vm.Execute(); err != nil {
				str := fmt.Sprintf("failed to validate input "+
					"%s:%d which references output %s:%d - "+
					"%v (input witness %v, input script "+
					"bytes %x, prev output script bytes %x)",
					txVI.tx.Hash(), txVI.txInIndex,
					originTxHash, originTxIndex, err,
					witness, sigScript, pkScript)
				err := ruleError(ErrScriptValidation, str)
				v.sendResult(err)
				break out
			}

			// Validation succeeded.
			v.sendResult(nil)

		case <-v.quitChan:
			break out
		}
	}
}
Esempio n. 7
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// This example demonstrates manually creating and signing a redeem transaction.
func ExampleSignTxOutput() {
	// Ordinarily the private key would come from whatever storage mechanism
	// is being used, but for this example just hard code it.
	privKeyBytes, err := hex.DecodeString("22a47fa09a223f2aa079edf85a7c2" +
		"d4f8720ee63e502ee2869afab7de234b80c")
	if err != nil {
		fmt.Println(err)
		return
	}
	privKey, pubKey := btcec.PrivKeyFromBytes(btcec.S256(), privKeyBytes)
	pubKeyHash := btcutil.Hash160(pubKey.SerializeCompressed())
	addr, err := btcutil.NewAddressPubKeyHash(pubKeyHash,
		&chaincfg.MainNetParams)
	if err != nil {
		fmt.Println(err)
		return
	}

	// For this example, create a fake transaction that represents what
	// would ordinarily be the real transaction that is being spent.  It
	// contains a single output that pays to address in the amount of 1 BTC.
	originTx := wire.NewMsgTx(wire.TxVersion)
	prevOut := wire.NewOutPoint(&chainhash.Hash{}, ^uint32(0))
	txIn := wire.NewTxIn(prevOut, []byte{txscript.OP_0, txscript.OP_0}, nil)
	originTx.AddTxIn(txIn)
	pkScript, err := txscript.PayToAddrScript(addr)
	if err != nil {
		fmt.Println(err)
		return
	}
	txOut := wire.NewTxOut(100000000, pkScript)
	originTx.AddTxOut(txOut)
	originTxHash := originTx.TxHash()

	// Create the transaction to redeem the fake transaction.
	redeemTx := wire.NewMsgTx(wire.TxVersion)

	// Add the input(s) the redeeming transaction will spend.  There is no
	// signature script at this point since it hasn't been created or signed
	// yet, hence nil is provided for it.
	prevOut = wire.NewOutPoint(&originTxHash, 0)
	txIn = wire.NewTxIn(prevOut, nil, nil)
	redeemTx.AddTxIn(txIn)

	// Ordinarily this would contain that actual destination of the funds,
	// but for this example don't bother.
	txOut = wire.NewTxOut(0, nil)
	redeemTx.AddTxOut(txOut)

	// Sign the redeeming transaction.
	lookupKey := func(a btcutil.Address) (*btcec.PrivateKey, bool, error) {
		// Ordinarily this function would involve looking up the private
		// key for the provided address, but since the only thing being
		// signed in this example uses the address associated with the
		// private key from above, simply return it with the compressed
		// flag set since the address is using the associated compressed
		// public key.
		//
		// NOTE: If you want to prove the code is actually signing the
		// transaction properly, uncomment the following line which
		// intentionally returns an invalid key to sign with, which in
		// turn will result in a failure during the script execution
		// when verifying the signature.
		//
		// privKey.D.SetInt64(12345)
		//
		return privKey, true, nil
	}
	// Notice that the script database parameter is nil here since it isn't
	// used.  It must be specified when pay-to-script-hash transactions are
	// being signed.
	sigScript, err := txscript.SignTxOutput(&chaincfg.MainNetParams,
		redeemTx, 0, originTx.TxOut[0].PkScript, txscript.SigHashAll,
		txscript.KeyClosure(lookupKey), nil, nil)
	if err != nil {
		fmt.Println(err)
		return
	}
	redeemTx.TxIn[0].SignatureScript = sigScript

	// Prove that the transaction has been validly signed by executing the
	// script pair.
	flags := txscript.ScriptBip16 | txscript.ScriptVerifyDERSignatures |
		txscript.ScriptStrictMultiSig |
		txscript.ScriptDiscourageUpgradableNops
	vm, err := txscript.NewEngine(originTx.TxOut[0].PkScript, redeemTx, 0,
		flags, nil, nil, -1)
	if err != nil {
		fmt.Println(err)
		return
	}
	if err := vm.Execute(); err != nil {
		fmt.Println(err)
		return
	}
	fmt.Println("Transaction successfully signed")

	// Output:
	// Transaction successfully signed
}