diff --git a/api/templates/api/third_party/auth.jinja b/api/templates/api/third_party/auth.jinja
new file mode 100644
index 00000000..e4e9e4f6
--- /dev/null
+++ b/api/templates/api/third_party/auth.jinja
@@ -0,0 +1,32 @@
+{% extends "core/base.jinja" %}
+
+{% block content %}
+  <form method="post">
+    {% csrf_token %}
+    <h3>{% trans %}Confidentiality{% endtrans %}</h3>
+    <p>
+      {% trans trimmed app=third_party_app %}
+        By ticking this box and clicking on the send button, you
+        acknowledge and agree to provide {{ app }} with your
+        first name, last name, nickname and any other information
+        that was the third party app was explicitly authorized to fetch
+        and that it must have acknowledged to you, in a complete and accurate manner.
+      {% endtrans %}
+    </p>
+    <p class="margin-bottom">
+      {% trans trimmed app=third_party_app, cgu_link=third_party_cgu, sith_cgu_link=sith_cgu %}
+        The privacy policies of <a href="{{ cgu_link }}">{{ app }}</a>
+        and of <a href="{{ sith_cgu_link }}">the Students' Association</a>
+        applies as soon as the form is submitted.
+      {% endtrans %}
+    </p>
+    <div class="row">{{ form.cgu_accepted }} {{ form.cgu_accepted.label_tag() }}</div>
+    <br>
+    <h3 class="margin-bottom">{% trans %}Confirmation of identity{% endtrans %}</h3>
+    <div class="row margin-bottom">
+      {{ form.is_username_valid }} {{ form.is_username_valid.label_tag() }}
+    </div>
+    {% for field in form.hidden_fields() %}{{ field }}{% endfor %}
+    <input type="submit" class="btn btn-blue">
+  </form>
+{% endblock %}
\ No newline at end of file
diff --git a/core/utils.py b/core/utils.py
index 30c0116d..1adf50ec 100644
--- a/core/utils.py
+++ b/core/utils.py
@@ -12,12 +12,15 @@
 # OR WITHIN THE LOCAL FILE "LICENSE"
 #
 #
+from __future__ import annotations
 
+import hmac
 from datetime import date, timedelta
 
 # Image utils
 from io import BytesIO
 from typing import TYPE_CHECKING, Final
+from urllib.parse import urlencode
 
 import PIL
 from django.conf import settings
@@ -25,6 +28,15 @@ from django.core.files.base import ContentFile
 from django.utils.timezone import localdate
 from PIL.Image import Image, Resampling
 
+if TYPE_CHECKING:
+    from _hashlib import HASH
+    from collections.abc import Buffer, Mapping, Sequence
+    from typing import Any, Callable, Final
+
+    from django.core.files.uploadedfile import UploadedFile
+    from django.http import HttpRequest
+
+
 if TYPE_CHECKING:
     from django.core.files.uploadedfile import UploadedFile
     from django.http import HttpRequest
@@ -190,3 +202,30 @@ def get_client_ip(request: HttpRequest) -> str | None:
             return ip
 
     return None
+
+
+def hmac_hexdigest(
+    key: str | bytes,
+    data: Mapping[str, Any] | Sequence[tuple[str, Any]],
+    digest: str | Callable[[Buffer], HASH] = "sha256",
+) -> str:
+    """Return the hexdigest of the signature of the given data.
+
+    Args:
+        key: the HMAC key used for the signature
+        data: the data to sign
+        digest: a PEP247 hashing algorithm
+
+    Examples:
+        ```python
+        data = {
+            "foo": 5,
+            "bar": "somevalue",
+        }
+        hmac_key = secrets.token_hex(64)
+        signature = hmac_hexdigest(hmac_key, data, "sha512")
+        ```
+    """
+    if isinstance(key, str):
+        key = key.encode()
+    return hmac.digest(key, urlencode(data).encode(), digest).hex()