Raise a nicer error if the IPB isn't present

Author: russss

emv/card.py

@@ -10,7 +10,7 @@
     GetProcessingOptions,
     VerifyCommand,
 )
-from .exc import InvalidPINException, MissingAppException
+from .exc import InvalidPINException, MissingAppException, EMVProtocolError
 from .util import decode_int
 from .cap import get_arqc_req, get_cap_value
 
@@ -174,6 +174,16 @@ def generate_cap_value(self, pin, challenge=None, value=None):
         # of the data passed to the Get Application Cryptogram function.
         app_data = self.get_application_data(opts["AFL"])
 
+        # In some cases the IPB may not be present. EMVCAP uses the IPB:
+        # 0000FFFFFF0000000000000000000020B938
+        # for VISA cards which don't provide their own, but relies on a hard-coded
+        # list of app names to work out which cards are VISA.
+        #
+        # It appears that Belgian cards use their own silliness.
+        # https://github.com/zoobab/EMVCAP/blob/master/EMV-CAP#L512
+        if Tag.IPB not in app_data:
+            raise EMVProtocolError("Issuer Proprietary Bitmap not found in application file")
+
         self.verify_pin(pin)
 
         resp = self.tp.exchange(

emv/exc.py

@@ -1,10 +1,14 @@
+class EMVProtocolError(Exception):
+    pass
+
+
 class InvalidPINException(Exception):
     pass
 
 
-class MissingAppException(Exception):
+class MissingAppException(EMVProtocolError):
     pass
 
 
-class CAPError(Exception):
+class CAPError(EMVProtocolError):
     pass