From f00e832d4ac1a3e391b348565391c42225ed6d09 Mon Sep 17 00:00:00 2001
From: Jonathan Weth <git@jonathanweth.de>
Date: Sat, 17 Jun 2023 17:17:14 +0200
Subject: [PATCH] Fix bugs in SDM implementation
---
aleksis/apps/kort/models/sdm.py | 19 ++++++++++++-------
1 file changed, 12 insertions(+), 7 deletions(-)
diff --git a/aleksis/apps/kort/models/sdm.py b/aleksis/apps/kort/models/sdm.py
index 19de0e7..55aed0f 100644
--- a/aleksis/apps/kort/models/sdm.py
+++ b/aleksis/apps/kort/models/sdm.py
@@ -1,10 +1,10 @@
from binascii import unhexlify
from django.core.exceptions import BadRequest
-from django.core.http import Request
+from django.http import HttpRequest
from libsdm import EncMode, InvalidMessage, decrypt_sun_message
-from libsdm.derive import derive_undiversified_key, derive_tag_key
+from libsdm.derive import derive_tag_key, derive_undiversified_key
from libsdm.util import parse_parameters
from aleksis.core.mixins import ExtensibleModel, ObjectAuthenticator
@@ -15,13 +15,18 @@ from .cards import Card
class NfcSdmAuthenticator(ObjectAuthenticator):
"""Object authenticator using NFC SDM."""
+
name = "nfc_sdm"
require_lrp = False
- def authenticate(self, request: Request, obj: ExtensibleModel):
+ def authenticate(self, request: HttpRequest, obj: ExtensibleModel):
"""SUN decrypting authenticator"""
- master_key = unhexlify(get_site_preferences()["nfc__sdm_master_key"])
- param_mode, picc_enc_data, enc_file_data, sdmmac = parse_parameters(request.GET)
+ master_key = unhexlify(get_site_preferences()["kort__sdm_master_key"])
+ try:
+ param_mode, picc_enc_data, enc_file_data, sdmmac = parse_parameters(request.GET)
+ except ValueError as e:
+ raise BadRequest(**e.args)
+
try:
res = decrypt_sun_message(
param_mode=param_mode,
@@ -40,13 +45,13 @@ class NfcSdmAuthenticator(ObjectAuthenticator):
try:
card = Card.objects.get(chip_number__iexact=res["uid"].hex())
- except Card.DoesNotExact:
+ except Card.DoesNotExist:
return False
if card.person != obj:
raise BadRequest("Card is not linked to identified object")
- if card.last_read_counter <= res["read_ctr"]:
+ if card.last_read_counter >= res["read_ctr"]:
raise BadRequest("Read counter went backwards, possible replay attack")
card.last_read_counter = res["read_ctr"]
card.save()
--
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