Allow to configure length of ticket secret

src/pretix/api/serializers/event.py

@@ -694,6 +694,7 @@ class EventSettingsSerializer(SettingsSerializer):
         'ticket_download_nonadm',
         'ticket_download_pending',
         'ticket_download_require_validated_email',
+        'ticket_secret_length',
         'mail_prefix',
         'mail_from',
         'mail_from_name',

src/pretix/base/secrets.py

@@ -29,7 +29,6 @@ from cryptography.hazmat.primitives.serialization import (
     Encoding, NoEncryption, PrivateFormat, PublicFormat, load_pem_private_key,
     load_pem_public_key,
 )
-from django.conf import settings
 from django.dispatch import receiver
 from django.utils.crypto import get_random_string
 from django.utils.translation import gettext_lazy as _
@@ -111,7 +110,7 @@ class RandomTicketSecretGenerator(BaseTicketSecretGenerator):
         if current_secret and not force_invalidate:
             return current_secret
         return get_random_string(
-            length=settings.ENTROPY['ticket_secret'],
+            length=self.event.settings.ticket_secret_length,
             # Exclude o,0,1,i,l to avoid confusion with bad fonts/printers
             allowed_chars='abcdefghjkmnpqrstuvwxyz23456789'
         )

src/pretix/base/settings.py

@@ -461,6 +461,32 @@ DEFAULTS = {
         'default': 'random',
         'type': str,
     },
+    'ticket_secret_length': {
+        'default': settings.ENTROPY['ticket_secret'],
+        'type': int,
+        'form_class': forms.IntegerField,
+        'serializer_class': serializers.IntegerField,
+        'serializer_kwargs': dict(
+            validators=[
+                MinValueValidator(12),
+                MaxValueValidator(64),
+            ]
+        ),
+        'form_kwargs': dict(
+            label=_('Length of ticket codes'),
+            validators=[
+                MinValueValidator(12),
+                MaxValueValidator(64),
+            ],
+            widget=forms.NumberInput(
+                attrs={
+                    'min': '12',
+                    'max': '64',
+                    'data-display-dependency': 'input[name=ticket_secret_generator][value=random]',
+                },
+            ),
+        )
+    },
     'reservation_time': {
         'default': '30',
         'type': int,

src/pretix/control/forms/event.py

@@ -1083,6 +1083,7 @@ class TicketSettingsForm(SettingsForm):
         'ticket_download_nonadm',
         'ticket_download_pending',
         'ticket_download_require_validated_email',
+        'ticket_secret_length',
     ]
     ticket_secret_generator = forms.ChoiceField(
         label=_("Ticket code generator"),

src/pretix/control/templates/pretixcontrol/event/tickets.html

@@ -65,6 +65,7 @@
             <fieldset>
                 <legend>{% trans "Ticket codes" %}</legend>
                 {% bootstrap_field form.ticket_secret_generator layout="control" %}
+                {% bootstrap_field form.ticket_secret_length layout="control" %}
             </fieldset>
         </div>
         <div class="form-group submit-group">