diff --git a/.github/workflows/pull-request.yaml b/.github/workflows/pull-request.yaml
index 85c83d9..ff7931d 100644
--- a/.github/workflows/pull-request.yaml
+++ b/.github/workflows/pull-request.yaml
@@ -20,7 +20,7 @@ jobs:
         run: |
           python -m pip install --upgrade pip
           pip install -r requirements.txt
-          pip install pylint==3.0.3 pylint-django==2.5.5 black==23.1.0
+          pip install pylint==3.0.3 pylint-django==2.5.5 black==24.4.2
 
       - name: Run pylint and black
         run: |
diff --git a/LedenAdministratie/api.py b/LedenAdministratie/api.py
index 34b2ac1..4e982d0 100644
--- a/LedenAdministratie/api.py
+++ b/LedenAdministratie/api.py
@@ -1,6 +1,12 @@
+import hashlib
+import hmac
+import imghdr
+
+from django.conf import settings
 from django.db.models import Q
 from django.http import HttpResponse, JsonResponse, HttpResponseForbidden
 from django.utils import timezone
+from django.views import View
 from oauth2_provider.views import ProtectedResourceView, ScopedProtectedResourceView
 
 from LedenAdministratie.models import Member
@@ -10,19 +16,20 @@
 
 class ApiV1Smoelenboek(ProtectedResourceView):
     def get(self, request, *args, **kwargs):
-        large = request.GET.get("large", "0") == "1"
+        large = request.GET.get("large", "0")
         members = Member.objects.filter(
             Q(afmeld_datum__gt=timezone.now()) | Q(afmeld_datum=None)
         ).order_by("first_name")
 
         response = []
+        expiry = int((timezone.now() + timezone.timedelta(days=1)).timestamp())
         for member in members:
-            if large:
-                photo = member.foto
-            else:
-                photo = member.thumbnail
-                if photo is None:
-                    photo = member.foto
+            # Generate a signed URL for the image
+            url = request.build_absolute_uri(f"{member.id}/{expiry}/?large={large}")
+            signature = hmac.new(
+                settings.SECRET_KEY.encode(), url.encode(), hashlib.sha256
+            ).hexdigest()
+            url += f"&signature={signature}"
 
             memberdict = {
                 "id": member.id,
@@ -30,13 +37,34 @@ def get(self, request, *args, **kwargs):
                 "first_name": member.first_name,
                 "last_name": member.last_name,
                 "types": ",".join([tmptype.slug for tmptype in member.types.all()]),
-                "photo": img2base64(photo),
+                "photo": url,
             }
             response.append(memberdict)
 
         return JsonResponse(data=response, safe=False)
 
 
+class ApiV1SmoelenboekSigned(View):
+    def get(self, request, *args, **kwargs):
+        # Validate signature and expiry datetime
+        signature = request.GET.get("signature", "")
+        url = request.build_absolute_uri().replace(f"&signature={signature}", "")
+        new_signature = hmac.new(
+            settings.SECRET_KEY.encode(), url.encode(), hashlib.sha256
+        ).hexdigest()
+        if new_signature != signature:
+            return HttpResponseForbidden()
+        if timezone.now().timestamp() > kwargs.get("expiry", 0):
+            return HttpResponseForbidden()
+
+        # Return the image if all is OK
+        large = request.GET.get("large", "0") == "1"
+        member = Member.objects.get(id=kwargs.get("pk"))
+        photo = member.foto if large else member.thumbnail
+        content_type = imghdr.what(None, photo)
+        return HttpResponse(photo, content_type=f"image/{content_type}")
+
+
 class ApiV1SmoelenboekUser(ProtectedResourceView):
     def get(self, request, *args, **kwargs):
         large = request.GET.get("large", "0") == "1"
diff --git a/LedenAdministratie/oidc.py b/LedenAdministratie/oidc.py
index 61ecc86..40a901b 100644
--- a/LedenAdministratie/oidc.py
+++ b/LedenAdministratie/oidc.py
@@ -27,12 +27,14 @@ def get_additional_claims(self) -> dict:
             "media": lambda request: True,
             "account_type": lambda request: request.user.member.idp_types(),
             "days": lambda request: request.user.member.days,
-            "stripcard": lambda request: {
-                "count": request.user.member.active_stripcard.count,
-                "used": request.user.member.active_stripcard.used,
-            }
-            if request.user.member.active_stripcard
-            else None,
+            "stripcard": lambda request: (
+                {
+                    "count": request.user.member.active_stripcard.count,
+                    "used": request.user.member.active_stripcard.used,
+                }
+                if request.user.member.active_stripcard
+                else None
+            ),
         }
 
     def validate_user(
diff --git a/LedenAdministratie/urls.py b/LedenAdministratie/urls.py
index 0b9e863..1895443 100644
--- a/LedenAdministratie/urls.py
+++ b/LedenAdministratie/urls.py
@@ -13,6 +13,7 @@
     1. Add an import:  from blog import urls as blog_urls
     2. Add a URL to urlpatterns:  url(r'^blog/', include(blog_urls))
 """
+
 from django.contrib import admin
 from django.urls import path, include
 from two_factor.urls import urlpatterns as tf_urls
@@ -98,6 +99,11 @@
     path("email/log/", views.EmailLogView.as_view(), name="email_log"),
     path("settings/", views.SettingsView.as_view(), name="settings"),
     path("api/v1/smoelenboek/", api.ApiV1Smoelenboek.as_view()),
+    path(
+        "api/v1/smoelenboek/<int:pk>/<int:expiry>/",
+        api.ApiV1SmoelenboekSigned.as_view(),
+        name="smoelenboek_signed",
+    ),
     path("api/v1/smoelenboek/<int:pk>/", api.ApiV1SmoelenboekUser.as_view()),
     path("api/v1/member/details", api.ApiV1UserDetails.as_view()),
     path("o/", include("oauth2_provider.urls", namespace="oauth2_provider")),
diff --git a/LedenAdministratie/views.py b/LedenAdministratie/views.py
index f1c17d4..5c970be 100644
--- a/LedenAdministratie/views.py
+++ b/LedenAdministratie/views.py
@@ -233,9 +233,9 @@ def get_context_data(self, **kwargs):
         if self.kwargs.get("member_id"):
             context["member"] = Member.objects.get(pk=self.kwargs["member_id"])
         else:
-            context["form"].fields[
-                "members"
-            ].queryset = InvoiceTool.get_members_invoice_type(self.invoice_type)
+            context["form"].fields["members"].queryset = (
+                InvoiceTool.get_members_invoice_type(self.invoice_type)
+            )
 
         self.lines = self.LinesFormSet(
             initial=InvoiceTool.get_defaults_for_invoice_type(