lnd.xprv/lnwallet/script_utils_test.go
Olaoluwa Osuntokun e22734f9cf
lnwallet: update HTLC+commitment scripts
This commit updates the previous HTLC and commitment scripts to their
current latest evolution.

The HTLC scripts have been optimized for space savings, the
functionality itself has remained relatively unchanged. A trade off was
made to add additional bytes into the sigScript in order to avoid
extraneous CHECKSIG’s. The rationale is that an extra 1-2 bytes in the
sigScript to guide execution, are worthwhile since they’re in the
witness, and witness data may be pruned in the near future.

The primary change is within the commitment transaction itself. Instead
of using revocation hashes, we now use signature based revocation. This
saves space in the Script, and optimizes away an extra hashing
operation. Elkrem/shachain is still used but, we now use the pre-images
to homomorphically derive a public key which the other party will be
able to sign with, once we disclose the pre-image itself.

Finally, we have switched to using SHA-256 everywhere uniformly for
both revocation hashes, and payment hashes. The rationale is that the
output of ripemd160 is too small for modern security margins, and that
other coins/chains are more likely to have SHA-256 implemented, than
ripemd160.

A set of tests has also been included which contain (mostly) exhaustive
tests of all possible redemption paths for both commitment and HTLC.
2016-06-27 11:35:32 -07:00

513 lines
15 KiB
Go

package lnwallet
import (
"bytes"
"fmt"
"testing"
"github.com/btcsuite/fastsha256"
"github.com/roasbeef/btcd/btcec"
"github.com/roasbeef/btcd/txscript"
"github.com/roasbeef/btcd/wire"
"github.com/roasbeef/btcutil"
)
// 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 transaciton.
// * 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 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)
// 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)
revocationHash := testHdSeed[:]
// 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, revocationHash, 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.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.
revokePubKey := deriveRevocationPubkey(bobKeyPub, revocationHash)
delayScript, err := commitScriptToSelf(csvTimeout, aliceKeyPub, revokePubKey)
if err != nil {
t.Fatalf("unable to generate alice delay script: %v")
}
aliceWitnessSpend, err := commitSpendTimeout(delayScript, channelBalance,
csvTimeout, aliceKeyPriv, 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, revocationHash)
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)
}
}
// TestRevocationKeyDerivation tests that given a public key, and a revocation
// hash, the homomorphic revocation public and private key derivation work
// properly.
func TestRevocationKeyDerivation(t *testing.T) {
revocationPreimage := testHdSeed[:]
priv, pub := btcec.PrivKeyFromBytes(btcec.S256(), testWalletPrivKey)
revocationPub := deriveRevocationPubkey(pub, revocationPreimage)
revocationPriv := deriveRevocationPrivKey(priv, revocationPreimage)
x, y := btcec.S256().ScalarBaseMult(revocationPriv.D.Bytes())
derivedRevPub := &btcec.PublicKey{
Curve: btcec.S256(),
X: x,
Y: y,
}
// The the revocation public key derived from the original public key,
// and the one derived from the private key should be identical.
if !revocationPub.IsEqual(derivedRevPub) {
t.Fatalf("derived public keys don't match!")
}
}
func makeWitnessTestCase(t *testing.T, f func() (wire.TxWitness, error)) func() wire.TxWitness {
return func() wire.TxWitness {
witness, err := f()
if err != nil {
t.Fatalf("unable to create witness test case: %v", err)
}
return witness
}
}
// TestHTLCSenderSpendValidation tests all possible valid+invalid redemption
// paths in the script used within the sender's commitment transaction for an
// outgoing HTLC.
//
// The following cases are exercised by this test:
// sender script:
// * reciever spends
// * revoke w/ sig
// * HTLC with invalid pre-image size
// * HTLC with valid pre-image size + sig
// * sender spends
// * invalid lock-time for CLTV
// * invalid sequence for CSV
// * valid lock-time+sequence, valid sig
func TestHTLCSenderSpendValidation(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)
revokePreimage := testHdSeed[:]
revokeHash := fastsha256.Sum256(revokePreimage)
paymentPreimage := revokeHash
paymentPreimage[0] ^= 1
paymentHash := fastsha256.Sum256(paymentPreimage[:])
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)
htlcScript, err := senderHTLCScript(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 Alice'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).
senderCommitTx := wire.NewMsgTx()
senderCommitTx.AddTxIn(fakeFundingTxIn)
senderCommitTx.AddTxOut(&wire.TxOut{
Value: int64(paymentAmt),
PkScript: htlcWitnessScript,
})
prevOut := &wire.OutPoint{
Hash: senderCommitTx.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
}{
{
// revoke w/ sig
// TODO(roasbeef): test invalid revoke
makeWitnessTestCase(t, func() (wire.TxWitness, error) {
return senderHtlcSpendRevoke(htlcScript, paymentAmt,
bobKeyPriv, sweepTx,
revokePreimage)
}),
true,
},
{
// HTLC with invalid pre-image size
makeWitnessTestCase(t, func() (wire.TxWitness, error) {
return senderHtlcSpendRedeem(htlcScript, paymentAmt,
bobKeyPriv, sweepTx,
// Invalid pre-image length
bytes.Repeat([]byte{1}, 45))
}),
false,
},
{
// HTLC with valid pre-image size + sig
// TODO(roabeef): invalid pre-image
makeWitnessTestCase(t, func() (wire.TxWitness, error) {
return senderHtlcSpendRedeem(htlcScript, paymentAmt,
bobKeyPriv, sweepTx,
paymentPreimage[:])
}),
true,
},
{
// invalid lock-time for CLTV
makeWitnessTestCase(t, func() (wire.TxWitness, error) {
return senderHtlcSpendTimeout(htlcScript, paymentAmt,
aliceKeyPriv, sweepTx, cltvTimeout-2, csvTimeout)
}),
false,
},
{
// invalid sequence for CSV
makeWitnessTestCase(t, func() (wire.TxWitness, error) {
return senderHtlcSpendTimeout(htlcScript, paymentAmt,
aliceKeyPriv, sweepTx, cltvTimeout, csvTimeout-2)
}),
false,
},
{
// valid lock-time+sequence, valid sig
makeWitnessTestCase(t, func() (wire.TxWitness, error) {
return senderHtlcSpendTimeout(htlcScript, paymentAmt,
aliceKeyPriv, sweepTx, cltvTimeout, csvTimeout)
}),
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)
}
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()))
}
}
}
// 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)
revokePreimage := testHdSeed[:]
revokeHash := fastsha256.Sum256(revokePreimage)
paymentPreimage := revokeHash
paymentPreimage[0] ^= 1
paymentHash := fastsha256.Sum256(paymentPreimage[:])
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)
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)
}
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()))
}
}
}