apps.common: add protect_by_passphrase

src/apps/common/request_passphrase.py

@@ -2,8 +2,9 @@ from trezor import ui, wire
 
 
 async def request_passphrase(session_id):
+    from trezor.messages.FailureType import ActionCancelled
     from trezor.messages.PassphraseRequest import PassphraseRequest
-    from trezor.messages.wire_types import PassphraseAck
+    from trezor.messages.wire_types import PassphraseAck, Cancel
     from trezor.ui.text import Text
 
     ui.display.clear()
@@ -11,5 +12,17 @@ async def request_passphrase(session_id):
                 'Please enter passphrase', 'on your computer.')
     text.render()
 
-    ack = await wire.call(session_id, PassphraseRequest(), PassphraseAck)
+    ack = await wire.call(session_id, PassphraseRequest(), PassphraseAck, Cancel)
+    if ack.MESSAGE_WIRE_TYPE == Cancel:
+        raise wire.FailureError(ActionCancelled, 'Passphrase cancelled')
+
     return ack.passphrase
+
+
+async def protect_by_passphrase(session_id):
+    from apps.common import storage
+
+    if storage.is_protected_by_passphrase():
+        return await request_passphrase(session_id)
+    else:
+        return ''

src/apps/common/seed.py

@@ -22,7 +22,7 @@ async def get_seed(session_id: int) -> bytes:
 
 async def compute_seed(session_id: int) -> bytes:
     from trezor.messages.FailureType import Other
-    from .request_passphrase import request_passphrase
+    from .request_passphrase import protect_by_passphrase
     from .request_pin import protect_by_pin
     from . import storage
 
@@ -31,8 +31,5 @@ async def compute_seed(session_id: int) -> bytes:
 
     await protect_by_pin(session_id)
 
-    if storage.is_protected_by_passphrase():
-        passphrase = await request_passphrase(session_id)
-    else:
-        passphrase = ''
+    passphrase = await protect_by_passphrase(session_id)
     return bip39.seed(storage.get_mnemonic(), passphrase)