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lnwallet: move code to transactions files

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This commit is contained in:
Joost Jager 2019-01-27 19:20:41 +01:00
parent 1863dcef1f
commit 667474db75
No known key found for this signature in database
GPG Key ID: A61B9D4C393C59C7
4 changed files with 499 additions and 487 deletions
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190
lnwallet/script_utils.go
View File

@ -3,7 +3,6 @@ package lnwallet
import (
"bytes"
"crypto/sha256"
"encoding/binary"
"fmt"
"math/big"
@ -22,28 +21,6 @@ var (
// SequenceLockTimeSeconds is the 22nd bit which indicates the lock
// time is in seconds.
SequenceLockTimeSeconds = uint32(1 << 22)
// TimelockShift is used to make sure the commitment transaction is
// spendable by setting the locktime with it so that it is larger than
// 500,000,000, thus interpreting it as Unix epoch timestamp and not
// a block height. It is also smaller than the current timestamp which
// has bit (1 << 30) set, so there is no risk of having the commitment
// transaction be rejected. This way we can safely use the lower 24 bits
// of the locktime field for part of the obscured commitment transaction
// number.
TimelockShift = uint32(1 << 29)
)
const (
// StateHintSize is the total number of bytes used between the sequence
// number and locktime of the commitment transaction use to encode a hint
// to the state number of a particular commitment transaction.
StateHintSize = 6
// maxStateHint is the maximum state number we're able to encode using
// StateHintSize bytes amongst the sequence number and locktime fields
// of the commitment transaction.
maxStateHint uint64 = (1 << 48) - 1
)
// WitnessScriptHash generates a pay-to-witness-script-hash public key script
@ -622,108 +599,6 @@ func receiverHtlcSpendTimeout(signer Signer, signDesc *SignDescriptor,
return witnessStack, nil
}
// createHtlcTimeoutTx creates a transaction that spends the HTLC output on the
// commitment transaction of the peer that created an HTLC (the sender). This
// transaction essentially acts as an off-chain covenant as it spends a 2-of-2
// multi-sig output. This output requires a signature from both the sender and
// receiver of the HTLC. By using a distinct transaction, we're able to
// uncouple the timeout and delay clauses of the HTLC contract. This
// transaction is locked with an absolute lock-time so the sender can only
// attempt to claim the output using it after the lock time has passed.
//
// In order to spend the HTLC output, the witness for the passed transaction
// should be:
// * <0> <sender sig> <receiver sig> <0>
//
// NOTE: The passed amount for the HTLC should take into account the required
// fee rate at the time the HTLC was created. The fee should be able to
// entirely pay for this (tiny: 1-in 1-out) transaction.
func createHtlcTimeoutTx(htlcOutput wire.OutPoint, htlcAmt btcutil.Amount,
cltvExpiry, csvDelay uint32,
revocationKey, delayKey *btcec.PublicKey) (*wire.MsgTx, error) {
// Create a version two transaction (as the success version of this
// spends an output with a CSV timeout), and set the lock-time to the
// specified absolute lock-time in blocks.
timeoutTx := wire.NewMsgTx(2)
timeoutTx.LockTime = cltvExpiry
// The input to the transaction is the outpoint that creates the
// original HTLC on the sender's commitment transaction.
timeoutTx.AddTxIn(&wire.TxIn{
PreviousOutPoint: htlcOutput,
})
// Next, we'll generate the script used as the output for all second
// level HTLC which forces a covenant w.r.t what can be done with all
// HTLC outputs.
witnessScript, err := secondLevelHtlcScript(revocationKey, delayKey,
csvDelay)
if err != nil {
return nil, err
}
pkScript, err := WitnessScriptHash(witnessScript)
if err != nil {
return nil, err
}
// Finally, the output is simply the amount of the HTLC (minus the
// required fees), paying to the regular second level HTLC script.
timeoutTx.AddTxOut(&wire.TxOut{
Value: int64(htlcAmt),
PkScript: pkScript,
})
return timeoutTx, nil
}
// createHtlcSuccessTx creates a transaction that spends the output on the
// commitment transaction of the peer that receives an HTLC. This transaction
// essentially acts as an off-chain covenant as it's only permitted to spend
// the designated HTLC output, and also that spend can _only_ be used as a
// state transition to create another output which actually allows redemption
// or revocation of an HTLC.
//
// In order to spend the HTLC output, the witness for the passed transaction
// should be:
// * <0> <sender sig> <recvr sig> <preimage>
func createHtlcSuccessTx(htlcOutput wire.OutPoint, htlcAmt btcutil.Amount,
csvDelay uint32,
revocationKey, delayKey *btcec.PublicKey) (*wire.MsgTx, error) {
// Create a version two transaction (as the success version of this
// spends an output with a CSV timeout).
successTx := wire.NewMsgTx(2)
// The input to the transaction is the outpoint that creates the
// original HTLC on the sender's commitment transaction.
successTx.AddTxIn(&wire.TxIn{
PreviousOutPoint: htlcOutput,
})
// Next, we'll generate the script used as the output for all second
// level HTLC which forces a covenant w.r.t what can be done with all
// HTLC outputs.
witnessScript, err := secondLevelHtlcScript(revocationKey, delayKey,
csvDelay)
if err != nil {
return nil, err
}
pkScript, err := WitnessScriptHash(witnessScript)
if err != nil {
return nil, err
}
// Finally, the output is simply the amount of the HTLC (minus the
// required fees), paying to the timeout script.
successTx.AddTxOut(&wire.TxOut{
Value: int64(htlcAmt),
PkScript: pkScript,
})
return successTx, nil
}
// secondLevelHtlcScript is the uniform script that's used as the output for
// the second-level HTLC transactions. The second level transaction act as a
// sort of covenant, ensuring that a 2-of-2 multi-sig output can only be
@ -1235,71 +1110,6 @@ func DeriveRevocationPrivKey(revokeBasePriv *btcec.PrivateKey,
return priv
}
// SetStateNumHint encodes the current state number within the passed
// commitment transaction by re-purposing the locktime and sequence fields in
// the commitment transaction to encode the obfuscated state number. The state
// number is encoded using 48 bits. The lower 24 bits of the lock time are the
// lower 24 bits of the obfuscated state number and the lower 24 bits of the
// sequence field are the higher 24 bits. Finally before encoding, the
// obfuscator is XOR'd against the state number in order to hide the exact
// state number from the PoV of outside parties.
func SetStateNumHint(commitTx *wire.MsgTx, stateNum uint64,
obfuscator [StateHintSize]byte) error {
// With the current schema we are only able to encode state num
// hints up to 2^48. Therefore if the passed height is greater than our
// state hint ceiling, then exit early.
if stateNum > maxStateHint {
return fmt.Errorf("unable to encode state, %v is greater "+
"state num that max of %v", stateNum, maxStateHint)
}
if len(commitTx.TxIn) != 1 {
return fmt.Errorf("commitment tx must have exactly 1 input, "+
"instead has %v", len(commitTx.TxIn))
}
// Convert the obfuscator into a uint64, then XOR that against the
// targeted height in order to obfuscate the state number of the
// commitment transaction in the case that either commitment
// transaction is broadcast directly on chain.
var obfs [8]byte
copy(obfs[2:], obfuscator[:])
xorInt := binary.BigEndian.Uint64(obfs[:])
stateNum = stateNum ^ xorInt
// Set the height bit of the sequence number in order to disable any
// sequence locks semantics.
commitTx.TxIn[0].Sequence = uint32(stateNum>>24) | wire.SequenceLockTimeDisabled
commitTx.LockTime = uint32(stateNum&0xFFFFFF) | TimelockShift
return nil
}
// GetStateNumHint recovers the current state number given a commitment
// transaction which has previously had the state number encoded within it via
// setStateNumHint and a shared obfuscator.
//
// See setStateNumHint for further details w.r.t exactly how the state-hints
// are encoded.
func GetStateNumHint(commitTx *wire.MsgTx, obfuscator [StateHintSize]byte) uint64 {
// Convert the obfuscator into a uint64, this will be used to
// de-obfuscate the final recovered state number.
var obfs [8]byte
copy(obfs[2:], obfuscator[:])
xorInt := binary.BigEndian.Uint64(obfs[:])
// Retrieve the state hint from the sequence number and locktime
// of the transaction.
stateNumXor := uint64(commitTx.TxIn[0].Sequence&0xFFFFFF) << 24
stateNumXor |= uint64(commitTx.LockTime & 0xFFFFFF)
// Finally, to obtain the final state number, we XOR by the obfuscator
// value to de-obfuscate the state number.
return stateNumXor ^ xorInt
}
// ComputeCommitmentPoint generates a commitment point given a commitment
// secret. The commitment point for each state is used to randomize each key in
// the key-ring and also to used as a tweak to derive new public+private keys

297
lnwallet/script_utils_test.go
View File

@ -6,7 +6,6 @@ import (
"encoding/hex"
"fmt"
"testing"
"time"
"github.com/btcsuite/btcd/btcec"
"github.com/btcsuite/btcd/chaincfg/chainhash"
@ -16,211 +15,6 @@ import (
"github.com/lightningnetwork/lnd/keychain"
)
// 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) {
t.Parallel()
// 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.
txid, err := chainhash.NewHash(testHdSeed.CloneBytes())
if err != nil {
t.Fatalf("unable to create txid: %v", err)
}
fundingOut := &wire.OutPoint{
Hash: *txid,
Index: 50,
}
fakeFundingTxIn := wire.NewTxIn(fundingOut, nil, nil)
const channelBalance = btcutil.Amount(1 * 10e8)
const csvTimeout = uint32(5)
// 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)
revocationPreimage := testHdSeed.CloneBytes()
commitSecret, commitPoint := btcec.PrivKeyFromBytes(btcec.S256(),
revocationPreimage)
revokePubKey := DeriveRevocationPubkey(bobKeyPub, commitPoint)
aliceDelayKey := TweakPubKey(aliceKeyPub, commitPoint)
bobPayKey := TweakPubKey(bobKeyPub, commitPoint)
aliceCommitTweak := SingleTweakBytes(commitPoint, aliceKeyPub)
bobCommitTweak := SingleTweakBytes(commitPoint, bobKeyPub)
aliceSelfOutputSigner := &mockSigner{
privkeys: []*btcec.PrivateKey{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.
keyRing := &CommitmentKeyRing{
DelayKey: aliceDelayKey,
RevocationKey: revokePubKey,
NoDelayKey: bobPayKey,
}
commitmentTx, err := CreateCommitTx(*fakeFundingTxIn, keyRing, csvTimeout,
channelBalance, channelBalance, DefaultDustLimit())
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", err)
}
sweepTx := wire.NewMsgTx(2)
sweepTx.AddTxIn(wire.NewTxIn(&wire.OutPoint{
Hash: commitmentTx.TxHash(),
Index: 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, aliceDelayKey,
revokePubKey)
if err != nil {
t.Fatalf("unable to generate alice delay script: %v", err)
}
sweepTx.TxIn[0].Sequence = lockTimeToSequence(false, csvTimeout)
signDesc := &SignDescriptor{
WitnessScript: delayScript,
KeyDesc: keychain.KeyDescriptor{
PubKey: aliceKeyPub,
},
SingleTweak: aliceCommitTweak,
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", err)
}
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)
}
bobSigner := &mockSigner{privkeys: []*btcec.PrivateKey{bobKeyPriv}}
// Next, we'll test bob spending with the derived revocation key to
// simulate the scenario when Alice broadcasts this commitment
// transaction after it's been revoked.
signDesc = &SignDescriptor{
KeyDesc: keychain.KeyDescriptor{
PubKey: bobKeyPub,
},
DoubleTweak: commitSecret,
WitnessScript: delayScript,
SigHashes: txscript.NewTxSigHashes(sweepTx),
Output: &wire.TxOut{
Value: int64(channelBalance),
},
HashType: txscript.SigHashAll,
InputIndex: 0,
}
bobWitnessSpend, err := CommitSpendRevoke(bobSigner, signDesc,
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)
}
// In order to test the final scenario, we modify the TxIn of the sweep
// transaction to instead point to the regular output (non delay)
// within the commitment transaction.
sweepTx.TxIn[0] = &wire.TxIn{
PreviousOutPoint: wire.OutPoint{
Hash: commitmentTx.TxHash(),
Index: 1,
},
}
// Finally, we test bob sweeping his output as normal in the case that
// Alice broadcasts this commitment transaction.
bobScriptP2WKH, err := CommitScriptUnencumbered(bobPayKey)
if err != nil {
t.Fatalf("unable to create bob p2wkh script: %v", err)
}
signDesc = &SignDescriptor{
KeyDesc: keychain.KeyDescriptor{
PubKey: bobKeyPub,
},
SingleTweak: bobCommitTweak,
WitnessScript: bobScriptP2WKH,
SigHashes: txscript.NewTxSigHashes(sweepTx),
Output: &wire.TxOut{
Value: int64(channelBalance),
PkScript: bobScriptP2WKH,
},
HashType: txscript.SigHashAll,
InputIndex: 0,
}
bobRegularSpend, err := CommitSpendNoDelay(bobSigner, signDesc,
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.
@ -1053,97 +847,6 @@ func TestSecondLevelHtlcSpends(t *testing.T) {
}
}
func TestCommitTxStateHint(t *testing.T) {
t.Parallel()
stateHintTests := []struct {
name string
from uint64
to uint64
inputs int
shouldFail bool
}{
{
name: "states 0 to 1000",
from: 0,
to: 1000,
inputs: 1,
shouldFail: false,
},
{
name: "states 'maxStateHint-1000' to 'maxStateHint'",
from: maxStateHint - 1000,
to: maxStateHint,
inputs: 1,
shouldFail: false,
},
{
name: "state 'maxStateHint+1'",
from: maxStateHint + 1,
to: maxStateHint + 10,
inputs: 1,
shouldFail: true,
},
{
name: "commit transaction with two inputs",
inputs: 2,
shouldFail: true,
},
}
var obfuscator [StateHintSize]byte
copy(obfuscator[:], testHdSeed[:StateHintSize])
timeYesterday := uint32(time.Now().Unix() - 24*60*60)
for _, test := range stateHintTests {
commitTx := wire.NewMsgTx(2)
// Add supplied number of inputs to the commitment transaction.
for i := 0; i < test.inputs; i++ {
commitTx.AddTxIn(&wire.TxIn{})
}
for i := test.from; i <= test.to; i++ {
stateNum := uint64(i)
err := SetStateNumHint(commitTx, stateNum, obfuscator)
if err != nil && !test.shouldFail {
t.Fatalf("unable to set state num %v: %v", i, err)
} else if err == nil && test.shouldFail {
t.Fatalf("Failed(%v): test should fail but did not", test.name)
}
locktime := commitTx.LockTime
sequence := commitTx.TxIn[0].Sequence
// Locktime should not be less than 500,000,000 and not larger
// than the time 24 hours ago. One day should provide a good
// enough buffer for the tests.
if locktime < 5e8 || locktime > timeYesterday {
if !test.shouldFail {
t.Fatalf("The value of locktime (%v) may cause the commitment "+
"transaction to be unspendable", locktime)
}
}
if sequence&wire.SequenceLockTimeDisabled == 0 {
if !test.shouldFail {
t.Fatalf("Sequence locktime is NOT disabled when it should be")
}
}
extractedStateNum := GetStateNumHint(commitTx, obfuscator)
if extractedStateNum != stateNum && !test.shouldFail {
t.Fatalf("state number mismatched, expected %v, got %v",
stateNum, extractedStateNum)
} else if extractedStateNum == stateNum && test.shouldFail {
t.Fatalf("Failed(%v): test should fail but did not", test.name)
}
}
t.Logf("Passed: %v", test.name)
}
}
// TestSpecificationKeyDerivation implements the test vectors provided in
// BOLT-03, Appendix E.
func TestSpecificationKeyDerivation(t *testing.T) {

201
lnwallet/transactions.go Normal file
View File

@ -0,0 +1,201 @@
package lnwallet
import (
"encoding/binary"
"fmt"
"github.com/btcsuite/btcd/btcec"
"github.com/btcsuite/btcd/wire"
"github.com/btcsuite/btcutil"
)
const (
// StateHintSize is the total number of bytes used between the sequence
// number and locktime of the commitment transaction use to encode a hint
// to the state number of a particular commitment transaction.
StateHintSize = 6
// MaxStateHint is the maximum state number we're able to encode using
// StateHintSize bytes amongst the sequence number and locktime fields
// of the commitment transaction.
maxStateHint uint64 = (1 << 48) - 1
)
var (
// TimelockShift is used to make sure the commitment transaction is
// spendable by setting the locktime with it so that it is larger than
// 500,000,000, thus interpreting it as Unix epoch timestamp and not
// a block height. It is also smaller than the current timestamp which
// has bit (1 << 30) set, so there is no risk of having the commitment
// transaction be rejected. This way we can safely use the lower 24 bits
// of the locktime field for part of the obscured commitment transaction
// number.
TimelockShift = uint32(1 << 29)
)
// createHtlcSuccessTx creates a transaction that spends the output on the
// commitment transaction of the peer that receives an HTLC. This transaction
// essentially acts as an off-chain covenant as it's only permitted to spend
// the designated HTLC output, and also that spend can _only_ be used as a
// state transition to create another output which actually allows redemption
// or revocation of an HTLC.
//
// In order to spend the HTLC output, the witness for the passed transaction
// should be:
// * <0> <sender sig> <recvr sig> <preimage>
func createHtlcSuccessTx(htlcOutput wire.OutPoint, htlcAmt btcutil.Amount,
csvDelay uint32,
revocationKey, delayKey *btcec.PublicKey) (*wire.MsgTx, error) {
// Create a version two transaction (as the success version of this
// spends an output with a CSV timeout).
successTx := wire.NewMsgTx(2)
// The input to the transaction is the outpoint that creates the
// original HTLC on the sender's commitment transaction.
successTx.AddTxIn(&wire.TxIn{
PreviousOutPoint: htlcOutput,
})
// Next, we'll generate the script used as the output for all second
// level HTLC which forces a covenant w.r.t what can be done with all
// HTLC outputs.
witnessScript, err := secondLevelHtlcScript(revocationKey, delayKey,
csvDelay)
if err != nil {
return nil, err
}
pkScript, err := WitnessScriptHash(witnessScript)
if err != nil {
return nil, err
}
// Finally, the output is simply the amount of the HTLC (minus the
// required fees), paying to the timeout script.
successTx.AddTxOut(&wire.TxOut{
Value: int64(htlcAmt),
PkScript: pkScript,
})
return successTx, nil
}
// createHtlcTimeoutTx creates a transaction that spends the HTLC output on the
// commitment transaction of the peer that created an HTLC (the sender). This
// transaction essentially acts as an off-chain covenant as it spends a 2-of-2
// multi-sig output. This output requires a signature from both the sender and
// receiver of the HTLC. By using a distinct transaction, we're able to
// uncouple the timeout and delay clauses of the HTLC contract. This
// transaction is locked with an absolute lock-time so the sender can only
// attempt to claim the output using it after the lock time has passed.
//
// In order to spend the HTLC output, the witness for the passed transaction
// should be:
// * <0> <sender sig> <receiver sig> <0>
//
// NOTE: The passed amount for the HTLC should take into account the required
// fee rate at the time the HTLC was created. The fee should be able to
// entirely pay for this (tiny: 1-in 1-out) transaction.
func createHtlcTimeoutTx(htlcOutput wire.OutPoint, htlcAmt btcutil.Amount,
cltvExpiry, csvDelay uint32,
revocationKey, delayKey *btcec.PublicKey) (*wire.MsgTx, error) {
// Create a version two transaction (as the success version of this
// spends an output with a CSV timeout), and set the lock-time to the
// specified absolute lock-time in blocks.
timeoutTx := wire.NewMsgTx(2)
timeoutTx.LockTime = cltvExpiry
// The input to the transaction is the outpoint that creates the
// original HTLC on the sender's commitment transaction.
timeoutTx.AddTxIn(&wire.TxIn{
PreviousOutPoint: htlcOutput,
})
// Next, we'll generate the script used as the output for all second
// level HTLC which forces a covenant w.r.t what can be done with all
// HTLC outputs.
witnessScript, err := secondLevelHtlcScript(revocationKey, delayKey,
csvDelay)
if err != nil {
return nil, err
}
pkScript, err := WitnessScriptHash(witnessScript)
if err != nil {
return nil, err
}
// Finally, the output is simply the amount of the HTLC (minus the
// required fees), paying to the regular second level HTLC script.
timeoutTx.AddTxOut(&wire.TxOut{
Value: int64(htlcAmt),
PkScript: pkScript,
})
return timeoutTx, nil
}
// SetStateNumHint encodes the current state number within the passed
// commitment transaction by re-purposing the locktime and sequence fields in
// the commitment transaction to encode the obfuscated state number. The state
// number is encoded using 48 bits. The lower 24 bits of the lock time are the
// lower 24 bits of the obfuscated state number and the lower 24 bits of the
// sequence field are the higher 24 bits. Finally before encoding, the
// obfuscator is XOR'd against the state number in order to hide the exact
// state number from the PoV of outside parties.
func SetStateNumHint(commitTx *wire.MsgTx, stateNum uint64,
obfuscator [StateHintSize]byte) error {
// With the current schema we are only able to encode state num
// hints up to 2^48. Therefore if the passed height is greater than our
// state hint ceiling, then exit early.
if stateNum > maxStateHint {
return fmt.Errorf("unable to encode state, %v is greater "+
"state num that max of %v", stateNum, maxStateHint)
}
if len(commitTx.TxIn) != 1 {
return fmt.Errorf("commitment tx must have exactly 1 input, "+
"instead has %v", len(commitTx.TxIn))
}
// Convert the obfuscator into a uint64, then XOR that against the
// targeted height in order to obfuscate the state number of the
// commitment transaction in the case that either commitment
// transaction is broadcast directly on chain.
var obfs [8]byte
copy(obfs[2:], obfuscator[:])
xorInt := binary.BigEndian.Uint64(obfs[:])
stateNum = stateNum ^ xorInt
// Set the height bit of the sequence number in order to disable any
// sequence locks semantics.
commitTx.TxIn[0].Sequence = uint32(stateNum>>24) | wire.SequenceLockTimeDisabled
commitTx.LockTime = uint32(stateNum&0xFFFFFF) | TimelockShift
return nil
}
// GetStateNumHint recovers the current state number given a commitment
// transaction which has previously had the state number encoded within it via
// setStateNumHint and a shared obfuscator.
//
// See setStateNumHint for further details w.r.t exactly how the state-hints
// are encoded.
func GetStateNumHint(commitTx *wire.MsgTx, obfuscator [StateHintSize]byte) uint64 {
// Convert the obfuscator into a uint64, this will be used to
// de-obfuscate the final recovered state number.
var obfs [8]byte
copy(obfs[2:], obfuscator[:])
xorInt := binary.BigEndian.Uint64(obfs[:])
// Retrieve the state hint from the sequence number and locktime
// of the transaction.
stateNumXor := uint64(commitTx.TxIn[0].Sequence&0xFFFFFF) << 24
stateNumXor |= uint64(commitTx.LockTime & 0xFFFFFF)
// Finally, to obtain the final state number, we XOR by the obfuscator
// value to de-obfuscate the state number.
return stateNumXor ^ xorInt
}

298
lnwallet/transactions_test.go
View File

@ -5,10 +5,12 @@ import (
"encoding/hex"
"fmt"
"testing"
"time"
"github.com/btcsuite/btcd/btcec"
"github.com/btcsuite/btcd/chaincfg"
"github.com/btcsuite/btcd/chaincfg/chainhash"
"github.com/btcsuite/btcd/txscript"
"github.com/btcsuite/btcd/wire"
"github.com/btcsuite/btcutil"
"github.com/davecgh/go-spew/spew"
@ -910,3 +912,299 @@ func htlcViewFromHTLCs(htlcs []channeldb.HTLC) *htlcView {
}
return &theHTLCView
}
func TestCommitTxStateHint(t *testing.T) {
t.Parallel()
stateHintTests := []struct {
name string
from uint64
to uint64
inputs int
shouldFail bool
}{
{
name: "states 0 to 1000",
from: 0,
to: 1000,
inputs: 1,
shouldFail: false,
},
{
name: "states 'maxStateHint-1000' to 'maxStateHint'",
from: maxStateHint - 1000,
to: maxStateHint,
inputs: 1,
shouldFail: false,
},
{
name: "state 'maxStateHint+1'",
from: maxStateHint + 1,
to: maxStateHint + 10,
inputs: 1,
shouldFail: true,
},
{
name: "commit transaction with two inputs",
inputs: 2,
shouldFail: true,
},
}
var obfuscator [StateHintSize]byte
copy(obfuscator[:], testHdSeed[:StateHintSize])
timeYesterday := uint32(time.Now().Unix() - 24*60*60)
for _, test := range stateHintTests {
commitTx := wire.NewMsgTx(2)
// Add supplied number of inputs to the commitment transaction.
for i := 0; i < test.inputs; i++ {
commitTx.AddTxIn(&wire.TxIn{})
}
for i := test.from; i <= test.to; i++ {
stateNum := uint64(i)
err := SetStateNumHint(commitTx, stateNum, obfuscator)
if err != nil && !test.shouldFail {
t.Fatalf("unable to set state num %v: %v", i, err)
} else if err == nil && test.shouldFail {
t.Fatalf("Failed(%v): test should fail but did not", test.name)
}
locktime := commitTx.LockTime
sequence := commitTx.TxIn[0].Sequence
// Locktime should not be less than 500,000,000 and not larger
// than the time 24 hours ago. One day should provide a good
// enough buffer for the tests.
if locktime < 5e8 || locktime > timeYesterday {
if !test.shouldFail {
t.Fatalf("The value of locktime (%v) may cause the commitment "+
"transaction to be unspendable", locktime)
}
}
if sequence&wire.SequenceLockTimeDisabled == 0 {
if !test.shouldFail {
t.Fatalf("Sequence locktime is NOT disabled when it should be")
}
}
extractedStateNum := GetStateNumHint(commitTx, obfuscator)
if extractedStateNum != stateNum && !test.shouldFail {
t.Fatalf("state number mismatched, expected %v, got %v",
stateNum, extractedStateNum)
} else if extractedStateNum == stateNum && test.shouldFail {
t.Fatalf("Failed(%v): test should fail but did not", test.name)
}
}
t.Logf("Passed: %v", test.name)
}
}
// 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) {
t.Parallel()
// 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.
txid, err := chainhash.NewHash(testHdSeed.CloneBytes())
if err != nil {
t.Fatalf("unable to create txid: %v", err)
}
fundingOut := &wire.OutPoint{
Hash: *txid,
Index: 50,
}
fakeFundingTxIn := wire.NewTxIn(fundingOut, nil, nil)
const channelBalance = btcutil.Amount(1 * 10e8)
const csvTimeout = uint32(5)
// 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)
revocationPreimage := testHdSeed.CloneBytes()
commitSecret, commitPoint := btcec.PrivKeyFromBytes(btcec.S256(),
revocationPreimage)
revokePubKey := DeriveRevocationPubkey(bobKeyPub, commitPoint)
aliceDelayKey := TweakPubKey(aliceKeyPub, commitPoint)
bobPayKey := TweakPubKey(bobKeyPub, commitPoint)
aliceCommitTweak := SingleTweakBytes(commitPoint, aliceKeyPub)
bobCommitTweak := SingleTweakBytes(commitPoint, bobKeyPub)
aliceSelfOutputSigner := &mockSigner{
privkeys: []*btcec.PrivateKey{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.
keyRing := &CommitmentKeyRing{
DelayKey: aliceDelayKey,
RevocationKey: revokePubKey,
NoDelayKey: bobPayKey,
}
commitmentTx, err := CreateCommitTx(*fakeFundingTxIn, keyRing, csvTimeout,
channelBalance, channelBalance, DefaultDustLimit())
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", err)
}
sweepTx := wire.NewMsgTx(2)
sweepTx.AddTxIn(wire.NewTxIn(&wire.OutPoint{
Hash: commitmentTx.TxHash(),
Index: 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, aliceDelayKey,
revokePubKey)
if err != nil {
t.Fatalf("unable to generate alice delay script: %v", err)
}
sweepTx.TxIn[0].Sequence = lockTimeToSequence(false, csvTimeout)
signDesc := &SignDescriptor{
WitnessScript: delayScript,
KeyDesc: keychain.KeyDescriptor{
PubKey: aliceKeyPub,
},
SingleTweak: aliceCommitTweak,
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", err)
}
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)
}
bobSigner := &mockSigner{privkeys: []*btcec.PrivateKey{bobKeyPriv}}
// Next, we'll test bob spending with the derived revocation key to
// simulate the scenario when Alice broadcasts this commitment
// transaction after it's been revoked.
signDesc = &SignDescriptor{
KeyDesc: keychain.KeyDescriptor{
PubKey: bobKeyPub,
},
DoubleTweak: commitSecret,
WitnessScript: delayScript,
SigHashes: txscript.NewTxSigHashes(sweepTx),
Output: &wire.TxOut{
Value: int64(channelBalance),
},
HashType: txscript.SigHashAll,
InputIndex: 0,
}
bobWitnessSpend, err := CommitSpendRevoke(bobSigner, signDesc,
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)
}
// In order to test the final scenario, we modify the TxIn of the sweep
// transaction to instead point to the regular output (non delay)
// within the commitment transaction.
sweepTx.TxIn[0] = &wire.TxIn{
PreviousOutPoint: wire.OutPoint{
Hash: commitmentTx.TxHash(),
Index: 1,
},
}
// Finally, we test bob sweeping his output as normal in the case that
// Alice broadcasts this commitment transaction.
bobScriptP2WKH, err := CommitScriptUnencumbered(bobPayKey)
if err != nil {
t.Fatalf("unable to create bob p2wkh script: %v", err)
}
signDesc = &SignDescriptor{
KeyDesc: keychain.KeyDescriptor{
PubKey: bobKeyPub,
},
SingleTweak: bobCommitTweak,
WitnessScript: bobScriptP2WKH,
SigHashes: txscript.NewTxSigHashes(sweepTx),
Output: &wire.TxOut{
Value: int64(channelBalance),
PkScript: bobScriptP2WKH,
},
HashType: txscript.SigHashAll,
InputIndex: 0,
}
bobRegularSpend, err := CommitSpendNoDelay(bobSigner, signDesc,
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)
}
}