Add test with unspendable taproot keypath during wallet registration

tests/test_register_wallet.py

@@ -24,7 +24,8 @@ def run_register_test(navigator: Navigator, client: RaggerClient, speculos_globa
  assert wallet_policy_id == wallet_policy.id
 
  assert hmac.compare_digest(
- hmac.new(speculos_globals.wallet_registration_key, wallet_policy_id, sha256).digest(),
+ hmac.new(speculos_globals.wallet_registration_key,
+ wallet_policy_id, sha256).digest(),
  wallet_hmac,
  )
 
@@ -105,7 +106,8 @@ def test_register_wallet_reject_header(navigator: Navigator, firmware: Firmware,
 
  with pytest.raises(ExceptionRAPDU) as e:
  client.register_wallet(wallet, navigator,
- instructions=register_wallet_instruction_reject(firmware),
+ instructions=register_wallet_instruction_reject(
+ firmware),
  testname=test_name)
 
  assert DeviceException.exc.get(e.value.status) == DenyError
@@ -224,7 +226,8 @@ def test_register_miniscript_long_policy(navigator: Navigator, firmware: Firmwar
  assert wallet_id == wallet.id
 
  assert hmac.compare_digest(
- hmac.new(speculos_globals.wallet_registration_key, wallet_id, sha256).digest(),
+ hmac.new(speculos_globals.wallet_registration_key,
+ wallet_id, sha256).digest(),
  wallet_hmac,
  )
 
@@ -381,6 +384,25 @@ def test_register_wallet_tr_script_pk(navigator: Navigator, firmware: Firmware,
  test_name=test_name)
 
 
+def test_register_wallet_tr_with_nums_keypath(navigator: Navigator, firmware: Firmware, client:
+ RaggerClient, test_name: str, speculos_globals):
+ # The taproot keypath is unspendable; the UX must explicitly mark it as a 'dummy' key.
+ # The tpub for @0 is obtained by using the NUMS (Nothing-Up-My-Sleeve) key defined in BIP-0341,
+ # and using 32 zero bytes as the chaincode.
+ # It is important that the app can detect and clearly communicate to the user that the key is
+ # a dummy one, therefore unusable for spending.
+ run_register_test(navigator, client, speculos_globals, WalletPolicy(
+ name="Taproot unspendable keypath",
+ descriptor_template="tr(@0/**,pk(@1/**))",
+ keys_info=[
+ "tpubD6NzVbkrYhZ4WLczPJWReQycCJdd6YVWXubbVUFnJ5KgU5MDQrD998ZJLSmaB7GVcCnJSDWprxmrGkJ6SvgQC6QAffVpqSvonXmeizXcrkN",
+ "[f5acc2fd/48'/1'/0'/2']tpubDFAqEGNyad35aBCKUAXbQGDjdVhNueno5ZZVEn3sQbW5ci457gLR7HyTmHBg93oourBssgUxuWz1jX5uhc1qaqFo9VsybY1J5FuedLfm4dK",
+ ],
+ ),
+ instructions=register_wallet_instruction_approve(firmware),
+ test_name=test_name)
+
+
 def test_register_wallet_tr_script_sortedmulti(navigator: Navigator, firmware: Firmware, client:
  RaggerClient, test_name: str, speculos_globals):
  run_register_test(navigator, client, speculos_globals, WalletPolicy(