Optimize

x/btcbridge/keeper/keeper_withdraw.go

@@ -70,8 +70,10 @@ func (k Keeper) NewSigningRequest(ctx sdk.Context, sender string, coin sdk.Coin,
 	k.LockUTXOs(ctx, selectedUTXOs)
 
 	// save the change utxo and mark minted
-	k.saveUTXO(ctx, changeUTXO)
-	k.addToMintHistory(ctx, psbt.UnsignedTx.TxHash().String())
+	if changeUTXO != nil {
+		k.saveUTXO(ctx, changeUTXO)
+		k.addToMintHistory(ctx, psbt.UnsignedTx.TxHash().String())
+	}
 
 	signingRequest := &types.BitcoinSigningRequest{
 		Address:      sender,

x/btcbridge/keeper/msg_server.go

@@ -170,6 +170,11 @@ func (m msgServer) SubmitWithdrawSignatures(goCtx context.Context, msg *types.Ms
 	if err != nil {
 		return nil, err
 	}
+
+	if packet.UnsignedTx.TxHash().String() != msg.Txid {
+		return nil, types.ErrInvalidSignatures
+	}
+
 	if err = packet.SanityCheck(); err != nil {
 		return nil, err
 	}