sanitize tapscript proof

Author: keithsue

x/lending/types/dlc.go

@@ -40,11 +40,12 @@ func BuildDLCMeta(borrowerPubKey string, borrowerAuthPubKey string, dcmPubKey st
 
 	liquidationScript, repaymentScript, timeoutRefundScript, _ := GetVaultScripts(borrowerPubKey, borrowerAuthPubKey, dcmPubKey, finalTimeout)
 
-	tapScriptTree := GetTapScriptTree([][]byte{liquidationScript, repaymentScript, timeoutRefundScript})
+	tapscriptTree := GetTapscriptTree([][]byte{liquidationScript, repaymentScript, timeoutRefundScript})
+	sanitizeTapscriptTreeProofs(tapscriptTree)
 
-	liquidationScriptProof := tapScriptTree.LeafMerkleProofs[0]
-	repaymentScriptProof := tapScriptTree.LeafMerkleProofs[1]
-	timeoutRefundScriptProof := tapScriptTree.LeafMerkleProofs[2]
+	liquidationScriptProof := tapscriptTree.LeafMerkleProofs[0]
+	repaymentScriptProof := tapscriptTree.LeafMerkleProofs[1]
+	timeoutRefundScriptProof := tapscriptTree.LeafMerkleProofs[2]
 
 	liquidationScriptControlBlock, err := GetControlBlock(internalKey, liquidationScriptProof)
 	if err != nil {
@@ -628,3 +629,22 @@ func getVaultUtxosFromDepositTx(depositTx *psbt.Packet, vaultPkScript []byte) ([
 
 	return utxos, nil
 }
+
+// sanitizeTapscriptTreeProofs adjusts the merkle proofs of given tapscript tree
+// NOTE: This is a workaround because btcsuite.AssembleTaprootScriptTree overrides the proof if there exist same scripts
+// This method only works for three-leaf script tree
+func sanitizeTapscriptTreeProofs(tree *txscript.IndexedTapScriptTree) {
+	proofTwo := tree.LeafMerkleProofs[1].InclusionProof
+
+	// abnormal proof
+	if len(proofTwo) > 64 {
+		// trim the second proof
+		tree.LeafMerkleProofs[1].InclusionProof = proofTwo[0:64]
+
+		// get the last element
+		lastProofElement := proofTwo[len(proofTwo)-32:]
+
+		// append to the first proof
+		tree.LeafMerkleProofs[0].InclusionProof = append(tree.LeafMerkleProofs[0].InclusionProof, lastProofElement...)
+	}
+}

x/lending/types/taproot.go

@@ -57,8 +57,8 @@ func CreatePubKeyTimeLockScript(pubKey []byte, lockTime int64) ([]byte, error) {
 
 // CreateTaprootAddress creates the taproot address with the given internal key and scripts
 func CreateTaprootAddress(internalKey *secp256k1.PublicKey, scripts [][]byte, params *chaincfg.Params) (string, error) {
-	tapScriptTree := GetTapScriptTree(scripts)
-	scriptRoot := tapScriptTree.RootNode.TapHash()
+	tapscriptTree := GetTapscriptTree(scripts)
+	scriptRoot := tapscriptTree.RootNode.TapHash()
 
 	taprootOutKey := txscript.ComputeTaprootOutputKey(internalKey, scriptRoot[:])
 
@@ -145,7 +145,7 @@ func GetInternalKey(borrowerPubKey []byte, dcmPubKey []byte) *btcec.PublicKey {
 	return btcec.NewPublicKey(&P.X, &P.Y)
 }
 
-func GetTapScriptTree(scripts [][]byte) *txscript.IndexedTapScriptTree {
+func GetTapscriptTree(scripts [][]byte) *txscript.IndexedTapScriptTree {
 	leaves := []txscript.TapLeaf{}
 
 	for _, script := range scripts {