Make Issuer Authentication Flags a named tag

Author: russss

emv/card.py

@@ -184,7 +184,7 @@ def generate_cap_value(self, pin, challenge=None, value=None):
         psn = None
 
         # If the third bit of Issuer Authentication Flags is set then use the PAN Sequence Number
-        if app_data[(0x9F, 0x55)][0] & 0x40:
+        if Tag.IAF in app_data and app_data[Tag.IAF][0] & 0x40:
             psn = app_data[Tag.PAN_SN]
 
         return get_cap_value(resp, app_data[Tag.IPB], psn)

emv/protocol/data_elements.py

@@ -166,7 +166,7 @@ class Parse(Enum):
     ((0x9F, 0x4D), "Log Entry", Parse.BYTES, None),
     ((0x9F, 0x4E), "Merchant Name and Location", Parse.BYTES, None),
     ((0x9F, 0x4F), "Log Format", Parse.BYTES, None),
-    ((0x9F, 0x55), "Issuer Authentication Flags", Parse.BYTES, None),
+    ((0x9F, 0x55), "Issuer Authentication Flags", Parse.BYTES, "IAF"),
     ((0x9F, 0x56), "Issuer Proprietary Bitmap", Parse.BYTES, "IPB"),
     (
         (0x9F, 0x5C),