loop: Loop In MuSig2 support

client_test.go

@@ -13,7 +13,6 @@ import (
 	"github.com/lightninglabs/loop/loopdb"
 	"github.com/lightninglabs/loop/swap"
 	"github.com/lightninglabs/loop/test"
-	"github.com/lightningnetwork/lnd/input"
 	"github.com/lightningnetwork/lnd/lnrpc"
 	"github.com/lightningnetwork/lnd/lntypes"
 	"github.com/stretchr/testify/require"
@@ -240,8 +239,12 @@ func testLoopOutResume(t *testing.T, confs uint32, expired, preimageRevealed,
 				Preimage:        preimage,
 				AmountRequested: amt,
 				CltvExpiry:      744,
-				ReceiverKey:     receiverKey,
-				SenderKey:       senderKey,
+				HtlcKeys: loopdb.HtlcKeys{
+					SenderScriptKey:        senderKey,
+					SenderInternalPubKey:   senderKey,
+					ReceiverScriptKey:      receiverKey,
+					ReceiverInternalPubKey: receiverKey,
+				},
 				MaxSwapFee:      60000,
 				MaxMinerFee:     50000,
 				ProtocolVersion: protocolVersion,
@@ -273,30 +276,13 @@ func testLoopOutResume(t *testing.T, confs uint32, expired, preimageRevealed,
 	// Expect client to register for our expected number of confirmations.
 	confIntent := ctx.AssertRegisterConf(preimageRevealed, int32(confs))
 
-	// Assert that the loopout htlc equals to the expected one.
-	scriptVersion := GetHtlcScriptVersion(protocolVersion)
-	var htlc *swap.Htlc
-
-	switch scriptVersion {
-	case swap.HtlcV2:
-		htlc, err = swap.NewHtlcV2(
-			pendingSwap.Contract.CltvExpiry, senderKey,
-			receiverKey, hash, &chaincfg.TestNet3Params,
-		)
-
-	case swap.HtlcV3:
-		htlc, err = swap.NewHtlcV3(
-			input.MuSig2Version040,
-			pendingSwap.Contract.CltvExpiry, senderKey,
-			receiverKey, senderKey, receiverKey, hash,
-			&chaincfg.TestNet3Params,
-		)
-
-	default:
-		t.Fatalf(swap.ErrInvalidScriptVersion.Error())
-	}
-
+	htlc, err := GetHtlc(
+		hash, &pendingSwap.Contract.SwapContract,
+		&chaincfg.TestNet3Params,
+	)
 	require.NoError(t, err)
+
+	// Assert that the loopout htlc equals to the expected one.
 	require.Equal(t, htlc.PkScript, confIntent.PkScript)
 
 	signalSwapPaymentResult(nil)
@@ -315,7 +301,7 @@ func testLoopOutResume(t *testing.T, confs uint32, expired, preimageRevealed,
 		func(r error) {},
 		func(r error) {},
 		preimageRevealed,
-		confIntent, scriptVersion,
+		confIntent, GetHtlcScriptVersion(protocolVersion),
 	)
 }
 

loopdb/loop.go

@@ -10,6 +10,31 @@ import (
 	"github.com/lightningnetwork/lnd/lntypes"
 )
 
+// HtlcKeys is a holder of all keys used when constructing the swap HTLC. Since
+// it's used for both loop in and loop out swaps it may hold partial information
+// about the sender or receiver depending on the swap type.
+type HtlcKeys struct {
+	// SenderScriptKey is the sender's public key that is used in the HTLC,
+	// specifically when constructing the script spend scripts.
+	SenderScriptKey [33]byte
+
+	// SenderInternalPubKey is the sender's internal pubkey that is used in
+	// taproot HTLCs as part of the aggregate internal key.
+	SenderInternalPubKey [33]byte
+
+	// ReceiverScriptKey is the receiver's public key that is used in the
+	// HTLC, specifically when constructing the script spend scripts.
+	ReceiverScriptKey [33]byte
+
+	// ReceiverInternalPubKey is the sender's internal pubkey that is used
+	// in taproot HTLCs as part of the aggregate internal key.
+	ReceiverInternalPubKey [33]byte
+
+	// ClientScriptKeyLocator is the client's key locator for the key used
+	// in the HTLC script spend scripts.
+	ClientScriptKeyLocator keychain.KeyLocator
+}
+
 // SwapContract contains the base data that is serialized to persistent storage
 // for pending swaps.
 type SwapContract struct {
@@ -19,18 +44,8 @@ type SwapContract struct {
 	// AmountRequested is the total amount of the swap.
 	AmountRequested btcutil.Amount
 
-	// SenderKey is the key of the sender that will be used in the on-chain
-	// HTLC.
-	SenderKey [33]byte
-
-	// ReceiverKey is the of the receiver that will be used in the on-chain
-	// HTLC.
-	ReceiverKey [33]byte
-
-	// ClientKeyLocator is the key locator (family and index) for the client
-	// key. It is for the receiver key if this is a loop out contract, or
-	// the sender key if this is a loop in contract.
-	ClientKeyLocator keychain.KeyLocator
+	// HtlcKeys holds all keys used in the swap HTLC construction.
+	HtlcKeys HtlcKeys
 
 	// CltvExpiry is the total absolute CLTV expiry of the swap.
 	CltvExpiry int32

loopdb/loopin.go

@@ -63,15 +63,15 @@ func serializeLoopInContract(swap *LoopInContract) (
 		return nil, err
 	}
 
-	n, err := b.Write(swap.SenderKey[:])
+	n, err := b.Write(swap.HtlcKeys.SenderScriptKey[:])
 	if err != nil {
 		return nil, err
 	}
 	if n != keyLength {
 		return nil, fmt.Errorf("sender key has invalid length")
 	}
 
-	n, err = b.Write(swap.ReceiverKey[:])
+	n, err = b.Write(swap.HtlcKeys.ReceiverScriptKey[:])
 	if err != nil {
 		return nil, err
 	}
@@ -161,15 +161,15 @@ func deserializeLoopInContract(value []byte) (*LoopInContract, error) {
 		return nil, err
 	}
 
-	n, err := r.Read(contract.SenderKey[:])
+	n, err := r.Read(contract.HtlcKeys.SenderScriptKey[:])
 	if err != nil {
 		return nil, err
 	}
 	if n != keyLength {
 		return nil, fmt.Errorf("sender key has invalid length")
 	}
 
-	n, err = r.Read(contract.ReceiverKey[:])
+	n, err = r.Read(contract.HtlcKeys.ReceiverScriptKey[:])
 	if err != nil {
 		return nil, err
 	}

loopdb/loopout.go

@@ -134,15 +134,15 @@ func deserializeLoopOutContract(value []byte, chainParams *chaincfg.Params) (
 		return nil, err
 	}
 
-	n, err := r.Read(contract.SenderKey[:])
+	n, err := r.Read(contract.HtlcKeys.SenderScriptKey[:])
 	if err != nil {
 		return nil, err
 	}
 	if n != keyLength {
 		return nil, fmt.Errorf("sender key has invalid length")
 	}
 
-	n, err = r.Read(contract.ReceiverKey[:])
+	n, err = r.Read(contract.HtlcKeys.ReceiverScriptKey[:])
 	if err != nil {
 		return nil, err
 	}
@@ -229,15 +229,15 @@ func serializeLoopOutContract(swap *LoopOutContract) (
 		return nil, err
 	}
 
-	n, err := b.Write(swap.SenderKey[:])
+	n, err := b.Write(swap.HtlcKeys.SenderScriptKey[:])
 	if err != nil {
 		return nil, err
 	}
 	if n != keyLength {
 		return nil, fmt.Errorf("sender key has invalid length")
 	}
 
-	n, err = b.Write(swap.ReceiverKey[:])
+	n, err = b.Write(swap.HtlcKeys.ReceiverScriptKey[:])
 	if err != nil {
 		return nil, err
 	}

loopdb/protocol_version.go

@@ -55,6 +55,9 @@ const (
 	// HTLC v3 (P2TR) script for swaps.
 	ProtocolVersionHtlcV3 = 10
 
+	// ProtocolVersionMuSig2 will enable MuSig2 signature scheme for loops.
+	ProtocolVersionMuSig2 ProtocolVersion = 11
+
 	// ProtocolVersionUnrecorded is set for swaps were created before we
 	// started saving protocol version with swaps.
 	ProtocolVersionUnrecorded ProtocolVersion = math.MaxUint32
@@ -65,7 +68,7 @@ const (
 
 	// experimentalRPCProtocolVersion defines the RPC protocol version that
 	// includes all currently experimentally released features.
-	experimentalRPCProtocolVersion = looprpc.ProtocolVersion_HTLC_V3
+	experimentalRPCProtocolVersion = looprpc.ProtocolVersion_MUSIG2
 )
 
 var (
@@ -141,6 +144,9 @@ func (p ProtocolVersion) String() string {
 	case ProtocolVersionHtlcV3:
 		return "HTLC V3"
 
+	case ProtocolVersionMuSig2:
+		return "MuSig2"
+
 	default:
 		return "Unknown"
 	}