wallet: change init_lightning to sometimes create deterministic LN keys

electrum/gui/kivy/main_window.py

@@ -1421,23 +1421,26 @@ class ElectrumWindow(App, Logger):
                             "This means that you must save a backup of your wallet everytime you create a new channel.\n\n"
                             "If you want to have recoverable channels, you must create a new wallet with an Electrum seed")
                 self.show_info(msg)
-        else:
-            if self.wallet.can_have_lightning():
-                root.dismiss()
+        elif self.wallet.can_have_lightning():
+            root.dismiss()
+            if self.wallet.can_have_deterministic_lightning():
+                msg = messages.MSG_LIGHTNING_SCB_WARNING + "\n" + _("Create lightning keys?")
+            else:
                 msg = _(
                     "Warning: this wallet type does not support channel recovery from seed. "
                     "You will need to backup your wallet everytime you create a new wallet. "
                     "Create lightning keys?")
-                d = Question(msg, self._enable_lightning, title=_('Enable Lightning?'))
-                d.open()
-            else:
-                pass
+            d = Question(msg, self._enable_lightning, title=_('Enable Lightning?'))
+            d.open()
 
     def _enable_lightning(self, b):
         if not b:
             return
+        self.protected(_("Create lightning keys?"), self.__enable_lightning, ())
+
+    def __enable_lightning(self, password):
         wallet_path = self.get_wallet_path()
-        self.wallet.init_lightning()
+        self.wallet.init_lightning(password=password)
         self.show_info(_('Lightning keys have been initialized.'))
         self.stop_wallet()
         self.load_wallet_by_name(wallet_path)

electrum/gui/qt/main_window.py

@@ -2386,12 +2386,21 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger):
             self.set_contact(line2.text(), line1.text())
 
     def init_lightning_dialog(self):
-        if self.question(_(
+        assert not self.wallet.has_lightning()
+        if self.wallet.can_have_deterministic_lightning():
+            msg = messages.MSG_LIGHTNING_SCB_WARNING + "\n" + _("Create lightning keys?")
+        else:
+            msg = _(
                 "Warning: this wallet type does not support channel recovery from seed. "
                 "You will need to backup your wallet everytime you create a new wallet. "
-                "Create lightning keys?")):
-            self.wallet.init_lightning()
-            self.show_message("Lightning keys created. Please restart Electrum")
+                "Create lightning keys?")
+        if self.question(msg):
+            self._init_lightning_dialog()
+
+    @protected
+    def _init_lightning_dialog(self, *, password):
+        self.wallet.init_lightning(password=password)
+        self.show_message("Lightning keys created. Please restart Electrum")
 
     def show_wallet_info(self):
         dialog = WindowModalDialog(self, _("Wallet Information"))

electrum/wallet.py

@@ -333,24 +333,34 @@ class Abstract_Wallet(AddressSynchronizer, ABC):
         new_db.write(new_storage)
         return new_path
 
-    def has_lightning(self):
+    def has_lightning(self) -> bool:
         return bool(self.lnworker)
 
-    def can_have_lightning(self):
+    def can_have_lightning(self) -> bool:
         # we want static_remotekey to be a wallet address
         return self.txin_type == 'p2wpkh'
 
-    def init_lightning(self):
+    def can_have_deterministic_lightning(self) -> bool:
+        if not self.can_have_lightning():
+            return False
+        if not self.keystore:
+            return False
+        return self.keystore.can_have_deterministic_lightning_xprv()
+
+    def init_lightning(self, *, password) -> None:
         assert self.can_have_lightning()
         assert self.db.get('lightning_xprv') is None
-        if self.db.get('lightning_privkey2'):
-            return
-        # TODO derive this deterministically from wallet.keystore at keystore generation time
-        # probably along a hardened path ( lnd-equivalent would be m/1017'/coinType'/ )
-        seed = os.urandom(32)
-        node = BIP32Node.from_rootseed(seed, xtype='standard')
-        ln_xprv = node.to_xprv()
-        self.db.put('lightning_privkey2', ln_xprv)
+        assert self.db.get('lightning_privkey2') is None
+
+        if self.can_have_deterministic_lightning():
+            ks = self.keystore
+            assert isinstance(ks, keystore.BIP32_KeyStore)
+            self.db.put('lightning_xprv', ks.get_lightning_xprv(password))
+        else:
+            seed = os.urandom(32)
+            node = BIP32Node.from_rootseed(seed, xtype='standard')
+            ln_xprv = node.to_xprv()
+            self.db.put('lightning_privkey2', ln_xprv)
 
     async def stop(self):
         """Stop all networking and save DB to disk."""