postpone Restore Saved MicroSD card reading

(cherry picked from commit 56e26d051e)

releases/ChangeLog.md

@@ -4,6 +4,9 @@
 - Enhancement: Add current temporary seed to Seed Vault from within Seed Vault menu.
   If current active temporary seed is not saved yet, `Add current tmp` menu item is 
   present in Seed Vault menu.
+- Enhancement: `Restore Saved` passphrases: MicroSD card data reading postponed after 
+  user chooses the menu option, not on access to `Passphrase` menu as before.
+  This speeds up opening `Passphrase` menu when MicroSD card is available.
 - Reorg: `12 Words` menu option preferred on the top of the menu in all the seed menus
 
 ## 5.2.0 - 2023-10-10

shared/pwsave.py

@@ -2,7 +2,7 @@
 #
 # pwsave.py - Save bip39 passphrases into encrypted file on MicroSD (if desired)
 #
-import sys, stash, ujson, os, ngu, pyb
+import stash, ujson, ngu, pyb
 from files import CardSlot, CardMissingError, needs_microsd
 from ux import ux_dramatic_pause, ux_confirm, ux_show_story
 from utils import xfp2str
@@ -13,6 +13,8 @@ class PassphraseSaver:
     # to a file on MicroSD card. Order is preserved.
     # AES-256 CTR with key=SHA256(SHA256(salt + derived key off master + salt))
     # where: salt=sha256(microSD serial # details)
+    def __init__(self):
+        self.key = None
 
     def filename(self, card):
         # Construct actual filename to use.
@@ -21,17 +23,14 @@ class PassphraseSaver:
 
     def _calc_key(self, card, force=False):
         # calculate the key to be used.
-        if not force and getattr(self, 'key', None):
+        if not force and self.key:
             return
 
-        try:
-            salt = card.get_id_hash()
+        salt = card.get_id_hash()
 
-            with stash.SensitiveValues(bypass_tmp=True) as sv:
-                self.key = bytearray(sv.encryption_key(salt))
+        with stash.SensitiveValues(bypass_tmp=True) as sv:
+            self.key = bytearray(sv.encryption_key(salt))
 
-        except:
-            self.key = None
 
     def _read(self, card):
         # Return a list of saved passphrases, or empty list if fail.
@@ -44,9 +43,6 @@ class PassphraseSaver:
             txt = decrypt.cipher(msg)
 
             return ujson.loads(txt)
-        except OSError:
-            #print('missing? ' + fname)
-            return []
         except:
             return []
 
@@ -88,25 +84,16 @@ class PassphraseSaver:
         from ux import ux_show_story
         from seed import set_bip39_passphrase
 
-        # Very quick check for card not present case.
-        if not pyb.SDCard().present():
-            return None
-
         # Read file, decrypt and make a menu to show; OR return None
         # if any error hit.
-        try:
-            with CardSlot() as card:
+        with CardSlot() as card:
 
-                self._calc_key(card)
-                if not self.key: return None
+            self._calc_key(card)
+            if not self.key: return None
 
-                data = self._read(card)
+            data = self._read(card)
 
-                if not data: return None
-
-        except CardMissingError:
-            # not an error: they just aren't using feature
-            return None
+            if not data: return None
 
         # We have a list of xfp+pw fields. Make a menu.
 

shared/seed.py

@@ -10,20 +10,21 @@
 #    - 'abandon' * 17 + 'agent'
 #    - 'abandon' * 11 + 'about'
 #
+import ngu, uctypes, bip39, random, stash, pyb
 from menu import MenuItem, MenuSystem
-from utils import xfp2str, parse_extended_key, swab32, pad_raw_secret
-import ngu, uctypes, bip39, random, version, stash, chains
+from utils import xfp2str, parse_extended_key, swab32, pad_raw_secret, problem_file_line
 from uhashlib import sha256
 from ux import ux_show_story, the_ux, ux_dramatic_pause, ux_confirm
 from ux import PressRelease, ux_input_numbers, ux_input_text, show_qr_code
 from actions import goto_top_menu
 from stash import SecretStash
 from ubinascii import hexlify as b2a_hex
-from ubinascii import unhexlify as a2b_hex
 from pwsave import PassphraseSaver
 from glob import settings, dis
 from pincodes import pa
 from nvstore import SettingsObject
+from files import CardMissingError, needs_microsd, CardSlot
+
 
 # seed words lengths we support: 24=>256 bits, and recommended
 VALID_LENGTHS = (24, 18, 12)
@@ -1069,7 +1070,7 @@ class PassphraseMenu(MenuSystem):
     # singleton (cls level) vars
     done_cb = None
 
-    def __init__(self, done_cb=None, items=None):
+    def __init__(self):
         global pp_sofar
         pp_sofar = ''
 
@@ -1082,17 +1083,37 @@ class PassphraseMenu(MenuSystem):
             MenuItem('APPLY', f=self.done_apply),
             MenuItem('CANCEL', f=self.done_cancel),
         ]
+        # quick SD card check
+        if pyb.SDCard().present():
+            try:
+                with CardSlot() as card:
+                    # check if passphrases file exists on SD
+                    # if yes add menu item
+                    if card.exists(PassphraseSaver().filename(card)):
+                        items.insert(0, MenuItem('Restore Saved', menu=self.restore_saved))
 
-        try:
-            saved = PassphraseSaver().make_menu()
-            if saved:
-                items.insert(0, MenuItem('Restore Saved', menu=saved))
-        except:
-            # don't want bugs/corrupt files to make rest of menu inaccessible
-            pass
+            except: pass
 
         super(PassphraseMenu, self).__init__(items)
 
+    @staticmethod
+    async def restore_saved(*a):
+        dis.fullscreen("Decrypting...")
+        try:
+            menu = PassphraseSaver().make_menu()
+        except CardMissingError:
+            await needs_microsd()
+            return
+        except Exception as e:
+            await ux_show_story(title="Failure", msg=str(e) + problem_file_line(e))
+            return
+
+        if not menu:
+            await ux_show_story("Nothing found")
+            return
+
+        return menu
+
     def on_cancel(self):
         # zip to cancel item when they fail to exit via X button
         self.goto_idx(self.count - 1)