core: implement auto-lock after a configurable timeout (fixes #75)

core/src/apps/base.py

@@ -187,3 +187,5 @@ def boot() -> None:
     wire.register(MessageType.Cancel, handle_Cancel)
     wire.register(MessageType.LockDevice, handle_LockDevice)
     wire.register(MessageType.Ping, handle_Ping)
+
+    workflow.idle_timer.set(storage.device.get_autolock_delay_ms(), lock_device)

core/src/apps/management/apply_settings.py

@@ -1,19 +1,24 @@
 import storage.device
-from trezor import ui, wire
+from trezor import ui, wire, workflow
 from trezor.messages import ButtonRequestType
 from trezor.messages.Success import Success
 from trezor.ui.text import Text
 
+from apps.base import lock_device
 from apps.common.confirm import require_confirm
 
+if False:
+    from trezor.messages.ApplySettings import ApplySettings
 
-async def apply_settings(ctx, msg):
+
+async def apply_settings(ctx: wire.Context, msg: ApplySettings):
     if (
         msg.homescreen is None
         and msg.label is None
         and msg.use_passphrase is None
         and msg.passphrase_always_on_device is None
         and msg.display_rotation is None
+        and msg.auto_lock_delay_ms is None
     ):
         raise wire.ProcessError("No setting provided")
 
@@ -36,17 +41,27 @@ async def apply_settings(ctx, msg):
     if msg.display_rotation is not None:
         await require_confirm_change_display_rotation(ctx, msg.display_rotation)
 
+    if msg.auto_lock_delay_ms is not None:
+        msg.auto_lock_delay_ms = max(
+            msg.auto_lock_delay_ms, storage.device.AUTOLOCK_DELAY_MINIMUM
+        )
+        await require_confirm_change_autolock_delay(ctx, msg.auto_lock_delay_ms)
+
     storage.device.load_settings(
         label=msg.label,
         use_passphrase=msg.use_passphrase,
         homescreen=msg.homescreen,
         passphrase_always_on_device=msg.passphrase_always_on_device,
         display_rotation=msg.display_rotation,
+        autolock_delay_ms=msg.auto_lock_delay_ms,
     )
 
     if msg.display_rotation is not None:
         ui.display.orientation(storage.device.get_rotation())
 
+    # use the value that was stored, not the one that was supplied by the user
+    workflow.idle_timer.set(storage.device.get_autolock_delay_ms(), lock_device)
+
     return Success(message="Settings applied")
 
 
@@ -98,3 +113,10 @@ async def require_confirm_change_display_rotation(ctx, rotation):
     text.normal("to")
     text.bold("%s?" % label)
     await require_confirm(ctx, text, ButtonRequestType.ProtectCall)
+
+
+async def require_confirm_change_autolock_delay(ctx, delay_ms):
+    text = Text("Auto-lock delay", ui.ICON_CONFIG, new_lines=False)
+    text.normal("Do you really want to", "auto-lock your device", "after")
+    text.bold("{} seconds?".format(delay_ms // 1000))
+    await require_confirm(ctx, text, ButtonRequestType.ProtectCall)

core/src/storage/device.py

@@ -38,6 +38,8 @@ _DEFAULT_BACKUP_TYPE       = BackupType.Bip39
 # fmt: on
 
 HOMESCREEN_MAXSIZE = 16384
+AUTOLOCK_DELAY_MINIMUM = 10 * 1000  # 10 seconds
+AUTOLOCK_DELAY_DEFAULT = 10 * 60 * 1000  # 10 minutes
 
 # Length of SD salt auth tag.
 # Other SD-salt-related constants are in sd_salt.py
@@ -159,6 +161,7 @@ def load_settings(
     homescreen: bytes = None,
     passphrase_always_on_device: bool = None,
     display_rotation: int = None,
+    autolock_delay_ms: int = None,
 ) -> None:
     if use_passphrase is False:
         passphrase_always_on_device = False
@@ -185,6 +188,8 @@ def load_settings(
             common.set(
                 _NAMESPACE, _ROTATION, display_rotation.to_bytes(2, "big"), True
             )  # public
+    if autolock_delay_ms is not None:
+        set_autolock_delay_ms(autolock_delay_ms)
 
 
 def get_flags() -> int:
@@ -209,14 +214,13 @@ def set_flags(flags: int) -> None:
 def get_autolock_delay_ms() -> int:
     b = common.get(_NAMESPACE, _AUTOLOCK_DELAY_MS)
     if b is None:
-        return 10 * 60 * 1000
+        return AUTOLOCK_DELAY_DEFAULT
     else:
         return int.from_bytes(b, "big")
 
 
 def set_autolock_delay_ms(delay_ms: int) -> None:
-    if delay_ms < 60 * 1000:
+    delay_ms = max(delay_ms, AUTOLOCK_DELAY_MINIMUM)
-        delay_ms = 60 * 1000
     common.set(_NAMESPACE, _AUTOLOCK_DELAY_MS, delay_ms.to_bytes(4, "big"))