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Fix HNSHK security profile version for two-step PIN/TAN #214

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Fix HNSHK security profile version for two-step PIN/TAN #214

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3 changes: 3 additions & 0 deletions fints/client.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1305,6 +1305,9 @@ def fetch_tan_mechanisms(self):
else:
self.set_tan_mechanism('999')
self._ensure_system_id()
# Bootstrap phase (anonymous dialog with sf=999) is complete.
# Reset so that errors in subsequent authenticated dialogs are properly raised.
self._bootstrap_mode = False
Comment on lines +1308 to +1310

@mt-software-de mt-software-de Oct 18, 2026 •
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Thanks for this, the bootstrap part solves a problem we ran into as well. It doesn't cover clients restored with from_data, which usually don't call fetch_tan_mechanisms() again and so stay in bootstrap mode, swallowing a 9075. I opened #228, which ends the bootstrap mode in __enter__ instead and covers both cases.

For what it's worth, we can also confirm the security profile change with Consorsbank: PIN:1 in HNSHK is rejected with 9010 Ungültiger Signaturaufbau, PIN:2 works.

if self.get_current_tan_mechanism():
# We already got a reply through _ensure_system_id
return self.get_current_tan_mechanism()
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4 changes: 3 additions & 1 deletion fints/security.py
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Original file line number Diff line number Diff line change
Expand Up @@ -99,13 +99,14 @@ def __init__(self, pin):
self.pin = pin
self.pending_signature = None
self.security_function = None
self.security_method_version = 1

def sign_prepare(self, message: FinTSMessage):
_now = datetime.datetime.now()
rand = random.SystemRandom()

self.pending_signature = HNSHK4(
security_profile=SecurityProfile(SecurityMethod.PIN, 1),
security_profile=SecurityProfile(SecurityMethod.PIN, self.security_method_version),
security_function=self.security_function,
security_reference=rand.randint(1000000, 9999999),
security_application_area=SecurityApplicationArea.SHM,
Expand Down Expand Up @@ -178,6 +179,7 @@ def __init__(self, client, security_function, *args, **kwargs):
super().__init__(*args, **kwargs)
self.client = client
self.security_function = security_function
self.security_method_version = 2

def _get_tan(self):
retval = self.client._pending_tan
Expand Down