input: ensure sessionOpts is properly threaded through

lnwallet/musig_session.go

@@ -2,15 +2,12 @@ package lnwallet
 
 import (
 	"bytes"
-	"crypto/hmac"
-	"crypto/sha256"
 	"fmt"
 	"io"
 
 	"github.com/btcsuite/btcd/btcec/v2"
 	"github.com/btcsuite/btcd/btcec/v2/schnorr"
 	"github.com/btcsuite/btcd/btcec/v2/schnorr/musig2"
-	"github.com/btcsuite/btcd/chaincfg/chainhash"
 	"github.com/btcsuite/btcd/txscript"
 	"github.com/btcsuite/btcd/wire"
 	"github.com/lightningnetwork/lnd/input"
@@ -575,41 +572,3 @@ func NewMusigPairSession(cfg *MusigSessionCfg) *MusigPairSession {
 		signer:        cfg.Signer,
 	}
 }
-
-var (
-	// taprootRevRootKey is the key used to derive the revocation root for
-	// the taproot nonces. This is done via HMAC of the existing revocation
-	// root.
-	taprootRevRootKey = []byte("taproot-rev-root")
-)
-
-// deriveMusig2Shachain derives a shachain producer for the taproot channel
-// from normal shachain revocation root.
-func deriveMusig2Shachain(revRoot shachain.Producer) (shachain.Producer, error) {
-	// In order to obtain the revocation root hash to create the taproot
-	// revocation, we'll encode the producer into a buffer, then use that
-	// to derive the shachain root needed.
-	var rootHashBuf bytes.Buffer
-	if err := revRoot.Encode(&rootHashBuf); err != nil {
-		return nil, fmt.Errorf("unable to encode producer: %v", err)
-	}
-
-	revRootHash := chainhash.HashH(rootHashBuf.Bytes())
-
-	// For taproot channel types, we'll also generate a distinct shachain
-	// root using the same seed information. We'll use this to generate
-	// verification nonces for the channel. We'll bind with this a simple
-	// hmac.
-	taprootRevHmac := hmac.New(sha256.New, taprootRevRootKey)
-	if _, err := taprootRevHmac.Write(revRootHash[:]); err != nil {
-		return nil, err
-	}
-
-	taprootRevRoot := taprootRevHmac.Sum(nil)
-
-	// Once we have the root, we can then generate our shachain producer
-	// and from that generate the per-commitment point.
-	return shachain.NewRevocationProducerFromBytes(
-		taprootRevRoot,
-	)
-}