feat(core): Warn about unverified external inputs.

core/src/apps/bitcoin/sign_tx/approvers.py

@@ -50,6 +50,7 @@ class Approver:
         self.orig_change_out = 0  # sum of original change output amounts
 
         self.amount_unit = tx.amount_unit
+        self.has_unverified_external_input = False
 
     def is_payjoin(self) -> bool:
         # A PayJoin is a replacement transaction which manipulates the external inputs of the
@@ -73,6 +74,7 @@ class Approver:
             self.orig_total_in += txi.amount
 
         if input_is_external_unverified(txi):
+            self.has_unverified_external_input = True
             if safety_checks.is_strict():
                 raise wire.ProcessError("Unverifiable external input.")
         else:
@@ -235,6 +237,9 @@ class BasicApprover(Approver):
     async def approve_tx(self, tx_info: TxInfo, orig_txs: list[OriginalTxInfo]) -> None:
         await super().approve_tx(tx_info, orig_txs)
 
+        if self.has_unverified_external_input:
+            await helpers.confirm_unverified_external_input()
+
         fee = self.total_in - self.total_out
 
         # some coins require negative fees for reward TX

core/src/apps/bitcoin/sign_tx/helpers.py

@@ -180,6 +180,11 @@ class UiConfirmChangeCountOverThreshold(UiConfirm):
         return layout.confirm_change_count_over_threshold(ctx, self.change_count)
 
 
+class UiConfirmUnverifiedExternalInput(UiConfirm):
+    def confirm_dialog(self, ctx: wire.Context) -> Awaitable[Any]:
+        return layout.confirm_unverified_external_input(ctx)
+
+
 class UiConfirmForeignAddress(UiConfirm):
     def __init__(self, address_n: list):
         self.address_n = address_n
@@ -239,6 +244,10 @@ def confirm_change_count_over_threshold(change_count: int) -> Awaitable[Any]:  #
     return (yield UiConfirmChangeCountOverThreshold(change_count))
 
 
+def confirm_unverified_external_input() -> Awaitable[Any]:  # type: ignore [awaitable-is-generator]
+    return (yield UiConfirmUnverifiedExternalInput())
+
+
 def confirm_foreign_address(address_n: list) -> Awaitable[Any]:  # type: ignore [awaitable-is-generator]
     return (yield UiConfirmForeignAddress(address_n))
 

core/src/apps/bitcoin/sign_tx/layout.py

@@ -220,6 +220,16 @@ async def confirm_change_count_over_threshold(
     )
 
 
+async def confirm_unverified_external_input(ctx: wire.Context) -> None:
+    await layouts.confirm_metadata(
+        ctx,
+        "unverified_external_input",
+        "Warning",
+        "The transaction contains unverified external inputs.",
+        br_code=ButtonRequestType.SignTx,
+    )
+
+
 async def confirm_nondefault_locktime(
     ctx: wire.Context, lock_time: int, lock_time_disabled: bool
 ) -> None:

tests/ui_tests/fixtures.json

@@ -898,9 +898,9 @@
 "TT_bitcoin-test_signtx_external.py::test_p2pkh_presigned": "8dd8089941ceb0d82c9425c69d54240f99e3ae7932ef24acd49313d28389b683",
 "TT_bitcoin-test_signtx_external.py::test_p2pkh_with_proof": "c09de07fbbf1e047442180e2facb5482d06a1a428891b875b7dd93c9e4704ae1",
 "TT_bitcoin-test_signtx_external.py::test_p2tr_external_presigned": "c714c4a4ea8b98dfbdd8185925adafbafc62570f415688972d6003a19d7b4d23",
-"TT_bitcoin-test_signtx_external.py::test_p2tr_external_unverified": "9919d854e2702be375ad09c74af4fbaaa92d36cc2ed360cc7cfbd196c21a39a6",
+"TT_bitcoin-test_signtx_external.py::test_p2tr_external_unverified": "b398085c2fa6d4fa1ba97d872f95f3ac2268e9455f5831344f6e34a4badf7a17",
 "TT_bitcoin-test_signtx_external.py::test_p2tr_with_proof": "d6723e2243bc38231ec4eb9ed63afd39610460c0d859b4c576b12db1f7915d02",
-"TT_bitcoin-test_signtx_external.py::test_p2wpkh_external_unverified": "7780f69c321c49c97ee970617ba91a63a7c375dd5ca3d13dec943c28511fb128",
+"TT_bitcoin-test_signtx_external.py::test_p2wpkh_external_unverified": "d178bd3e2cadbe0992904b3d32df963b75e1da801804a471e45a1c5c0a9f2581",
 "TT_bitcoin-test_signtx_external.py::test_p2wpkh_in_p2sh_presigned": "8313bff77e41aef142c3b25818ab58dcc7e9d658d38e2e8fc50629ebbe05869b",
 "TT_bitcoin-test_signtx_external.py::test_p2wpkh_in_p2sh_with_proof": "c09de07fbbf1e047442180e2facb5482d06a1a428891b875b7dd93c9e4704ae1",
 "TT_bitcoin-test_signtx_external.py::test_p2wpkh_presigned": "4608478b1d61415cf0ec93a0ea4397c35d17a91d4b6d25e9c024b77330e398eb",