d440cc4024
This commit modifies the JusticeDescriptor to support creation of justice transactions spending from anchor commitments. Rather than the unencumbered p2wkh scripts from before, the tower will now use the to-remote-confirmed that includes the additional CSV delay of 1. This also requires setting the sequence number appropriately on the to-remote input.
367 lines
11 KiB
Go
367 lines
11 KiB
Go
package lookout_test
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import (
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"testing"
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"time"
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"github.com/btcsuite/btcd/blockchain"
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"github.com/btcsuite/btcd/btcec"
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"github.com/btcsuite/btcd/txscript"
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"github.com/btcsuite/btcd/wire"
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"github.com/btcsuite/btcutil"
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"github.com/btcsuite/btcutil/txsort"
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"github.com/lightningnetwork/lnd/input"
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"github.com/lightningnetwork/lnd/keychain"
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"github.com/lightningnetwork/lnd/lnwire"
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"github.com/lightningnetwork/lnd/watchtower/blob"
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"github.com/lightningnetwork/lnd/watchtower/lookout"
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"github.com/lightningnetwork/lnd/watchtower/wtdb"
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"github.com/lightningnetwork/lnd/watchtower/wtmock"
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"github.com/lightningnetwork/lnd/watchtower/wtpolicy"
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"github.com/stretchr/testify/require"
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)
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const csvDelay uint32 = 144
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var (
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revPrivBytes = []byte{
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0x8f, 0x4b, 0x51, 0x83, 0xa9, 0x34, 0xbd, 0x5f,
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0x74, 0x6c, 0x9d, 0x5c, 0xae, 0x88, 0x2d, 0x31,
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0x06, 0x90, 0xdd, 0x8c, 0x9b, 0x31, 0xbc, 0xd1,
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0x78, 0x91, 0x88, 0x2a, 0xf9, 0x74, 0xa0, 0xef,
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}
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toLocalPrivBytes = []byte{
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0xde, 0x17, 0xc1, 0x2f, 0xdc, 0x1b, 0xc0, 0xc6,
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0x59, 0x5d, 0xf9, 0xc1, 0x3e, 0x89, 0xbc, 0x6f,
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0x01, 0x85, 0x45, 0x76, 0x26, 0xce, 0x9c, 0x55,
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0x3b, 0xc9, 0xec, 0x3d, 0xd8, 0x8b, 0xac, 0xa8,
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}
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toRemotePrivBytes = []byte{
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0x28, 0x59, 0x6f, 0x36, 0xb8, 0x9f, 0x19, 0x5d,
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0xcb, 0x07, 0x48, 0x8a, 0xe5, 0x89, 0x71, 0x74,
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0x70, 0x4c, 0xff, 0x1e, 0x9c, 0x00, 0x93, 0xbe,
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0xe2, 0x2e, 0x68, 0x08, 0x4c, 0xb4, 0x0f, 0x4f,
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}
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rewardCommitType = blob.TypeFromFlags(
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blob.FlagReward, blob.FlagCommitOutputs,
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)
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altruistCommitType = blob.FlagCommitOutputs.Type()
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altruistAnchorCommitType = blob.TypeAltruistAnchorCommit
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)
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// TestJusticeDescriptor asserts that a JusticeDescriptor is able to produce the
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// correct justice transaction for different blob types.
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func TestJusticeDescriptor(t *testing.T) {
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tests := []struct {
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name string
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blobType blob.Type
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}{
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{
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name: "reward and commit type",
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blobType: rewardCommitType,
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},
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{
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name: "altruist and commit type",
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blobType: altruistCommitType,
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},
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{
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name: "altruist anchor commit type",
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blobType: altruistAnchorCommitType,
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},
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}
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for _, test := range tests {
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t.Run(test.name, func(t *testing.T) {
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testJusticeDescriptor(t, test.blobType)
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})
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}
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}
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func testJusticeDescriptor(t *testing.T, blobType blob.Type) {
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isAnchorChannel := blobType.IsAnchorChannel()
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const (
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localAmount = btcutil.Amount(100000)
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remoteAmount = btcutil.Amount(200000)
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totalAmount = localAmount + remoteAmount
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)
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// Parse the key pairs for all keys used in the test.
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revSK, revPK := btcec.PrivKeyFromBytes(
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btcec.S256(), revPrivBytes,
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)
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_, toLocalPK := btcec.PrivKeyFromBytes(
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btcec.S256(), toLocalPrivBytes,
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)
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toRemoteSK, toRemotePK := btcec.PrivKeyFromBytes(
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btcec.S256(), toRemotePrivBytes,
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)
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// Create the signer, and add the revocation and to-remote privkeys.
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signer := wtmock.NewMockSigner()
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var (
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revKeyLoc = signer.AddPrivKey(revSK)
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toRemoteKeyLoc = signer.AddPrivKey(toRemoteSK)
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)
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// Construct the to-local witness script.
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toLocalScript, err := input.CommitScriptToSelf(
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csvDelay, toLocalPK, revPK,
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)
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require.Nil(t, err)
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// Compute the to-local witness script hash.
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toLocalScriptHash, err := input.WitnessScriptHash(toLocalScript)
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require.Nil(t, err)
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// Compute the to-remote redeem script, witness script hash, and
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// sequence numbers.
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//
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// NOTE: This is pretty subtle.
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//
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// The actual redeem script for a p2wkh output is just the pubkey, but
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// the witness sighash calculation injects the classic p2kh script:
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// OP_DUP OP_HASH160 <pubkey-hash160> OP_EQUALVERIFY OP_CHECKSIG. When
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// signing for p2wkh we don't pass the raw pubkey as the witness script
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// to the sign descriptor (since that's also not a valid script).
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// Instead we give it the _pkscript_ of the form OP_0 <pubkey-hash160>
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// from which pubkey-hash160 is extracted during sighash calculation.
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//
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// On the other hand, signing for the anchor p2wsh to-remote outputs
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// requires the sign descriptor to contain the redeem script ver batim.
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// This difference in behavior forces us to use a distinct
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// toRemoteSigningScript to handle both cases.
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var (
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toRemoteSequence uint32
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toRemoteRedeemScript []byte
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toRemoteScriptHash []byte
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toRemoteSigningScript []byte
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)
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if isAnchorChannel {
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toRemoteSequence = 1
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toRemoteRedeemScript, err = input.CommitScriptToRemoteConfirmed(
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toRemotePK,
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)
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require.Nil(t, err)
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toRemoteScriptHash, err = input.WitnessScriptHash(
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toRemoteRedeemScript,
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)
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require.Nil(t, err)
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// As it should be.
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toRemoteSigningScript = toRemoteRedeemScript
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} else {
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toRemoteRedeemScript = toRemotePK.SerializeCompressed()
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toRemoteScriptHash, err = input.CommitScriptUnencumbered(
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toRemotePK,
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)
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require.Nil(t, err)
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// NOTE: This is the _pkscript_.
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toRemoteSigningScript = toRemoteScriptHash
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}
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// Construct the breaching commitment txn, containing the to-local and
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// to-remote outputs. We don't need any inputs for this test.
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breachTxn := &wire.MsgTx{
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Version: 2,
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TxIn: []*wire.TxIn{},
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TxOut: []*wire.TxOut{
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{
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Value: int64(localAmount),
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PkScript: toLocalScriptHash,
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},
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{
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Value: int64(remoteAmount),
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PkScript: toRemoteScriptHash,
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},
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},
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}
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breachTxID := breachTxn.TxHash()
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// Compute the weight estimate for our justice transaction.
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var weightEstimate input.TxWeightEstimator
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// An older ToLocalPenaltyWitnessSize constant used to underestimate the
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// size by one byte. The diferrence in weight can cause different output
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// values on the sweep transaction, so we mimic the original bug and
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// create signatures using the original weight estimate.
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weightEstimate.AddWitnessInput(input.ToLocalPenaltyWitnessSize - 1)
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if isAnchorChannel {
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weightEstimate.AddWitnessInput(input.ToRemoteConfirmedWitnessSize)
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} else {
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weightEstimate.AddWitnessInput(input.P2WKHWitnessSize)
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}
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weightEstimate.AddP2WKHOutput()
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if blobType.Has(blob.FlagReward) {
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weightEstimate.AddP2WKHOutput()
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}
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txWeight := weightEstimate.Weight()
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// Create a session info so that simulate agreement of the sweep
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// parameters that should be used in constructing the justice
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// transaction.
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policy := wtpolicy.Policy{
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TxPolicy: wtpolicy.TxPolicy{
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BlobType: blobType,
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SweepFeeRate: 2000,
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RewardRate: 900000,
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},
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}
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sessionInfo := &wtdb.SessionInfo{
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Policy: policy,
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RewardAddress: makeAddrSlice(22),
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}
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// Begin to assemble the justice kit, starting with the sweep address,
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// pubkeys, and csv delay.
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justiceKit := &blob.JusticeKit{
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BlobType: blobType,
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SweepAddress: makeAddrSlice(22),
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CSVDelay: csvDelay,
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}
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copy(justiceKit.RevocationPubKey[:], revPK.SerializeCompressed())
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copy(justiceKit.LocalDelayPubKey[:], toLocalPK.SerializeCompressed())
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copy(justiceKit.CommitToRemotePubKey[:], toRemotePK.SerializeCompressed())
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// Create a transaction spending from the outputs of the breach
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// transaction created earlier. The inputs are always ordered w/
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// to-local and then to-remote. The outputs are always added as the
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// sweep address then reward address.
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justiceTxn := &wire.MsgTx{
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Version: 2,
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TxIn: []*wire.TxIn{
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{
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PreviousOutPoint: wire.OutPoint{
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Hash: breachTxID,
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Index: 0,
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},
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},
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{
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PreviousOutPoint: wire.OutPoint{
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Hash: breachTxID,
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Index: 1,
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},
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Sequence: toRemoteSequence,
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},
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},
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}
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outputs, err := policy.ComputeJusticeTxOuts(
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totalAmount, int64(txWeight), justiceKit.SweepAddress,
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sessionInfo.RewardAddress,
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)
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require.Nil(t, err)
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// Attach the txouts and BIP69 sort the resulting transaction.
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justiceTxn.TxOut = outputs
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txsort.InPlaceSort(justiceTxn)
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hashCache := txscript.NewTxSigHashes(justiceTxn)
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// Create the sign descriptor used to sign for the to-local input.
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toLocalSignDesc := &input.SignDescriptor{
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KeyDesc: keychain.KeyDescriptor{
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KeyLocator: revKeyLoc,
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},
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WitnessScript: toLocalScript,
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Output: breachTxn.TxOut[0],
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SigHashes: hashCache,
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InputIndex: 0,
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HashType: txscript.SigHashAll,
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}
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// Create the sign descriptor used to sign for the to-remote input.
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toRemoteSignDesc := &input.SignDescriptor{
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KeyDesc: keychain.KeyDescriptor{
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KeyLocator: toRemoteKeyLoc,
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PubKey: toRemotePK,
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},
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WitnessScript: toRemoteSigningScript,
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Output: breachTxn.TxOut[1],
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SigHashes: hashCache,
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InputIndex: 1,
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HashType: txscript.SigHashAll,
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}
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// Verify that our test justice transaction is sane.
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btx := btcutil.NewTx(justiceTxn)
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err = blockchain.CheckTransactionSanity(btx)
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require.Nil(t, err)
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// Compute a DER-encoded signature for the to-local input.
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toLocalSigRaw, err := signer.SignOutputRaw(justiceTxn, toLocalSignDesc)
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require.Nil(t, err)
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// Compute the witness for the to-remote input. The first element is a
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// DER-encoded signature under the to-remote pubkey. The sighash flag is
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// also present, so we trim it.
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toRemoteSigRaw, err := signer.SignOutputRaw(justiceTxn, toRemoteSignDesc)
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require.Nil(t, err)
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// Convert the DER to-local sig into a fixed-size signature.
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toLocalSig, err := lnwire.NewSigFromSignature(toLocalSigRaw)
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require.Nil(t, err)
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// Convert the DER to-remote sig into a fixed-size signature.
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toRemoteSig, err := lnwire.NewSigFromSignature(toRemoteSigRaw)
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require.Nil(t, err)
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// Complete our justice kit by copying the signatures into the payload.
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copy(justiceKit.CommitToLocalSig[:], toLocalSig[:])
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copy(justiceKit.CommitToRemoteSig[:], toRemoteSig[:])
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justiceDesc := &lookout.JusticeDescriptor{
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BreachedCommitTx: breachTxn,
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SessionInfo: sessionInfo,
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JusticeKit: justiceKit,
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}
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// Construct a breach punisher that will feed published transactions
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// over the buffered channel.
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publications := make(chan *wire.MsgTx, 1)
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punisher := lookout.NewBreachPunisher(&lookout.PunisherConfig{
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PublishTx: func(tx *wire.MsgTx, _ string) error {
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publications <- tx
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return nil
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},
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})
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// Exact retribution on the offender. If no error is returned, we expect
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// the justice transaction to be published via the channel.
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err = punisher.Punish(justiceDesc, nil)
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require.Nil(t, err)
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// Retrieve the published justice transaction.
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var wtJusticeTxn *wire.MsgTx
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select {
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case wtJusticeTxn = <-publications:
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case <-time.After(50 * time.Millisecond):
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t.Fatalf("punisher did not publish justice txn")
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}
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// Construct the test's to-local witness.
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justiceTxn.TxIn[0].Witness = make([][]byte, 3)
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justiceTxn.TxIn[0].Witness[0] = append(toLocalSigRaw.Serialize(),
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byte(txscript.SigHashAll))
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justiceTxn.TxIn[0].Witness[1] = []byte{1}
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justiceTxn.TxIn[0].Witness[2] = toLocalScript
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// Construct the test's to-remote witness.
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justiceTxn.TxIn[1].Witness = make([][]byte, 2)
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justiceTxn.TxIn[1].Witness[0] = append(toRemoteSigRaw.Serialize(),
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byte(txscript.SigHashAll))
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justiceTxn.TxIn[1].Witness[1] = toRemoteRedeemScript
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// Assert that the watchtower derives the same justice txn.
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require.Equal(t, justiceTxn, wtJusticeTxn)
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}
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