tapdb: fix bug by ensuring that we write the full keydesc to disk

This fixes a bug that would cause a spend of a supply commitment output
to fail. We weren't storing the full key desc, so lnd wasn't able to
sign the PSBT, as the bip32 information didn't match up (derived wrong
key).

Author: Roasbeef

tapdb/supply_commit.go

@@ -855,7 +855,7 @@ func (s *SupplyCommitMachine) InsertSignedCommitTx(ctx context.Context,
 	groupKeyBytes := groupKey.SerializeCompressed()
 
 	commitTx := commitDetails.Txn
-	internalKey := commitDetails.InternalKey
+	internalKeyDesc := commitDetails.InternalKey
 	outputKey := commitDetails.OutputKey
 	outputIndex := commitDetails.OutputIndex
 
@@ -897,15 +897,17 @@ func (s *SupplyCommitMachine) InsertSignedCommitTx(ctx context.Context,
 				"%w", err)
 		}
 
-		// Upsert the internal key to get its ID. We assume key family
-		// and index 0 for now, as this key is likely externally.
+		// Upsert the internal key to get its ID, preserving the full
+		// key derivation information for proper PSBT signing later.
 		internalKeyID, err := db.UpsertInternalKey(ctx, InternalKey{
-			RawKey: internalKey.SerializeCompressed(),
+			RawKey:    internalKeyDesc.PubKey.SerializeCompressed(),
+			KeyFamily: int32(internalKeyDesc.Family),
+			KeyIndex:  int32(internalKeyDesc.Index),
 		})
 		if err != nil {
 			return fmt.Errorf("failed to upsert internal key %x: "+
 				"%w",
-				internalKey.SerializeCompressed(), err)
+				internalKeyDesc.PubKey.SerializeCompressed(), err)
 		}
 
 		// Insert the new commitment record. Chain details (block

tapdb/supply_commit_test.go

@@ -20,6 +20,7 @@ import (
 	"github.com/lightninglabs/taproot-assets/tapdb/sqlc"
 	"github.com/lightninglabs/taproot-assets/universe/supplycommit"
 	lfn "github.com/lightningnetwork/lnd/fn/v2"
+	"github.com/lightningnetwork/lnd/keychain"
 	"github.com/lightningnetwork/lnd/lnutils"
 	"github.com/stretchr/testify/require"
 )
@@ -126,8 +127,8 @@ func (h *supplyCommitTestHarness) addTestMintingBatch() ([]byte, int64,
 		Txid:  mintTxID[:],
 		RawTx: mintTxBytes,
 	})
-	require.NoError(h.t, err)
 
+	require.NoError(h.t, err)
 	genesisPointBytes, err := encodeOutpoint(genesisPoint)
 	require.NoError(h.t, err)
 	err = db.AnchorGenesisPoint(ctx, sqlc.AnchorGenesisPointParams{
@@ -158,7 +159,7 @@ func (h *supplyCommitTestHarness) addTestMintingBatch() ([]byte, int64,
 // transition performed by performSingleTransition.
 type stateTransitionOutput struct {
 	appliedUpdates []supplycommit.SupplyUpdateEvent
-	internalKey    *btcec.PublicKey
+	internalKey    keychain.KeyDescriptor
 	outputKey      *btcec.PublicKey
 	commitTx       *wire.MsgTx
 	chainProof     supplycommit.ChainProof
@@ -720,6 +721,7 @@ func (h *supplyCommitTestHarness) performSingleTransition(
 	// Next, we'll generate a new "fake" commitment transaction along with
 	// sample internal and output keys.
 	commitTx := randTx(h.t, 1)
+
 	// Add inputs to the transaction that spend the pre-commitment outputs.
 	for _, outpoint := range preCommitOutpoints {
 		commitTx.TxIn = append(commitTx.TxIn, &wire.TxIn{
@@ -735,7 +737,7 @@ func (h *supplyCommitTestHarness) performSingleTransition(
 	// and commit that.
 	commitDetails := supplycommit.SupplyCommitTxn{
 		Txn:         commitTx,
-		InternalKey: internalKey.PubKey,
+		InternalKey: internalKey,
 		OutputKey:   outputKey,
 		OutputIndex: 1,
 	}
@@ -810,7 +812,7 @@ func (h *supplyCommitTestHarness) performSingleTransition(
 
 	return stateTransitionOutput{
 		appliedUpdates: updates,
-		internalKey:    internalKey.PubKey,
+		internalKey:    internalKey,
 		outputKey:      outputKey,
 		commitTx:       commitTx,
 		chainProof:     chainProof,
@@ -1017,7 +1019,7 @@ func (h *supplyCommitTestHarness) assertTransitionApplied(
 	// The keys should also be inserted, and the db commitment should match
 	// what we inserted.
 	require.Equal(
-		h.t, internalKey.SerializeCompressed(),
+		h.t, internalKey.PubKey.SerializeCompressed(),
 		h.fetchInternalKeyByID(dbCommitment.InternalKeyID).RawKey,
 		"internalKey mismatch",
 	)
@@ -1161,7 +1163,7 @@ func (h *supplyCommitTestHarness) assertTransitionApplied(
 		"SupplyCommit returned wrong Txn hash",
 	)
 	require.Equal(
-		h.t, output.internalKey.SerializeCompressed(),
+		h.t, output.internalKey.PubKey.SerializeCompressed(),
 		fetchedCommit.InternalKey.PubKey.SerializeCompressed(),
 		"SupplyCommit returned wrong InternalKey",
 	)
@@ -1401,7 +1403,7 @@ func TestSupplyCommitInsertSignedCommitTx(t *testing.T) {
 	commitTxid2 := commitTx2.TxHash()
 
 	// Insert the signed commitment with the updated transaction.
-	internalKey := test.RandPubKey(t)
+	internalKey, _ := test.RandKeyDesc(t)
 	outputKey := test.RandPubKey(t)
 	commitDetails := supplycommit.SupplyCommitTxn{
 		Txn:         commitTx2,
@@ -1440,7 +1442,7 @@ func TestSupplyCommitInsertSignedCommitTx(t *testing.T) {
 	require.NoError(t, err)
 	require.Equal(t, chainTx2Record.TxnID, newDbCommitment.ChainTxnID)
 	require.Equal(t,
-		internalKey.SerializeCompressed(),
+		internalKey.PubKey.SerializeCompressed(),
 		h.fetchInternalKeyByID(newDbCommitment.InternalKeyID).RawKey,
 	)
 	require.Equal(
@@ -1463,7 +1465,7 @@ func TestSupplyCommitInsertSignedCommitTx(t *testing.T) {
 		t, commitTxid2, fetchedTransition.NewCommitment.Txn.TxHash(),
 	)
 	require.Equal(
-		t, internalKey.SerializeCompressed(),
+		t, internalKey.PubKey.SerializeCompressed(),
 		fetchedTransition.NewCommitment.InternalKey.PubKey.SerializeCompressed(), //nolint:lll
 	)
 	require.Equal(
@@ -1577,7 +1579,7 @@ func TestSupplyCommitFetchState(t *testing.T) {
 
 	// Next, we'll insert a signed commitment transaction.
 	commitTx := randTx(t, 1)
-	internalKey := test.RandPubKey(t)
+	internalKey, _ := test.RandKeyDesc(t)
 	outputKey := test.RandPubKey(t)
 
 	commitDetails := supplycommit.SupplyCommitTxn{

universe/supplycommit/env.go

@@ -517,8 +517,9 @@ type SupplyCommitTxn struct {
 	// Txn is the transaction that creates the supply commitment.
 	Txn *wire.MsgTx
 
-	// InternalKey is the internal key used for the commitment output.
-	InternalKey *btcec.PublicKey
+	// InternalKey is the internal key descriptor used for the commitment
+	// output. This preserves the full key derivation information.
+	InternalKey keychain.KeyDescriptor
 
 	// OutputKey is the taproot output key used for the commitment output.
 	OutputKey *btcec.PublicKey

universe/supplycommit/transitions.go

@@ -750,7 +750,7 @@ func (s *CommitTxSignState) ProcessEvent(event Event,
 		newCommit := &stateTransition.NewCommitment
 		commitTxnDetails := SupplyCommitTxn{
 			Txn:         commitTx,
-			InternalKey: newCommit.InternalKey.PubKey,
+			InternalKey: newCommit.InternalKey,
 			OutputKey:   newCommit.OutputKey,
 			OutputIndex: newCommit.TxOutIdx,
 		}