diff --git a/app/__init__.py b/app/__init__.py
index 72cc1cb726..a1edfbd7bb 100644
--- a/app/__init__.py
+++ b/app/__init__.py
@@ -17,15 +17,17 @@ from flask import current_app, g, request
 from flask import Flask
 from flask import abort, flash, has_request_context, jsonify
 from flask import render_template
-from flask.json import JSONEncoder
-from flask.logging import default_handler
-from flask_sqlalchemy import SQLAlchemy
-from flask_migrate import Migrate
+from flask_bootstrap import Bootstrap
+from flask_caching import Cache
+from flask_cas import CAS
 from flask_login import LoginManager, current_user
 from flask_mail import Mail
-from flask_bootstrap import Bootstrap
+from flask_migrate import Migrate
 from flask_moment import Moment
-from flask_caching import Cache
+from flask_sqlalchemy import SQLAlchemy
+from flask.json import JSONEncoder
+from flask.logging import default_handler
+
 from jinja2 import select_autoescape
 import sqlalchemy
 
@@ -132,7 +134,7 @@ class ScoDocJSONEncoder(JSONEncoder):
 
 def render_raw_html(template_filename: str, **args) -> str:
     """Load and render an HTML file _without_ using Flask
-    Necessary for 503 error mesage, when DB is down and Flask may be broken.
+    Necessary for 503 error message, when DB is down and Flask may be broken.
     """
     template_path = os.path.join(
         current_app.config["SCODOC_DIR"],
@@ -226,6 +228,7 @@ class ReverseProxied(object):
 
 def create_app(config_class=DevConfig):
     app = Flask(__name__, static_url_path="/ScoDoc/static", static_folder="static")
+    CAS(app, url_prefix="/cas")
     app.wsgi_app = ReverseProxied(app.wsgi_app)
     app.json_encoder = ScoDocJSONEncoder
     app.logger.setLevel(logging.INFO)
@@ -378,6 +381,11 @@ def create_app(config_class=DevConfig):
 
         sco_bulletins_generator.register_bulletin_class(BulletinGeneratorExample)
 
+    from app.auth.cas import set_cas_configuration
+
+    with app.app_context():
+        set_cas_configuration(app)
+
     return app
 
 
diff --git a/app/auth/__init__.py b/app/auth/__init__.py
index 4fb9575d9a..7dcff2b3e1 100644
--- a/app/auth/__init__.py
+++ b/app/auth/__init__.py
@@ -6,3 +6,4 @@ from flask import Blueprint
 bp = Blueprint("auth", __name__)
 
 from app.auth import routes
+from app.auth import cas
diff --git a/app/auth/cas.py b/app/auth/cas.py
new file mode 100644
index 0000000000..067ea3506a
--- /dev/null
+++ b/app/auth/cas.py
@@ -0,0 +1,71 @@
+# -*- coding: UTF-8 -*
+"""
+auth.cas.py
+"""
+import datetime
+
+import flask
+from flask import current_app, flash, url_for
+from flask_login import login_user
+
+from app.auth import bp
+from app.auth.models import User
+from app.models.config import ScoDocSiteConfig
+
+# after_cas_login/after_cas_logout : routes appelées par redirect depuis le serveur CAS.
+
+
+@bp.route("/after_cas_login")
+def after_cas_login():
+    "Called by CAS after CAS authentication"
+    # Ici on a les infos dans flask.session["CAS_ATTRIBUTES"]
+    if ScoDocSiteConfig.is_cas_enabled() and ("CAS_ATTRIBUTES" in flask.session):
+        # Lookup user:
+        cas_id = flask.session["CAS_ATTRIBUTES"].get(
+            "cas:" + ScoDocSiteConfig.get("cas_attribute_id")
+        )
+        if cas_id is not None:
+            user = User.query.filter_by(cas_id=cas_id).first()
+            if user and user.active:
+                if user.cas_allow_login:
+                    current_app.logger.info(f"CAS: login {user.user_name}")
+                    if login_user(user):
+                        flask.session[
+                            "scodoc_cas_login_date"
+                        ] = datetime.datetime.now().isoformat()
+                        return flask.redirect(url_for("scodoc.index"))
+                else:
+                    current_app.logger.info(
+                        f"CAS login denied for {user.user_name} (not allowed to use CAS)"
+                    )
+            else:
+                current_app.logger.info(
+                    f"""CAS login denied for {user.user_name if user else ""} cas_id={cas_id} (unknown or inactive)"""
+                )
+
+    # Echec:
+    flash("échec de l'authentification")
+    return flask.redirect(url_for("auth.login"))
+
+
+@bp.route("/after_cas_logout")
+def after_cas_logout():
+    "Called by CAS after CAS logout"
+    flash("Vous êtes déconnecté")
+    current_app.logger.info("after_cas_logout")
+    return flask.redirect(url_for("scodoc.index"))
+
+
+def set_cas_configuration(app: flask.app.Flask):
+    """Force la configuration du module flask_cas à partir des paramètres de
+    la config de ScoDoc.
+    Appelé au démarrage et à chaque modif des paramètres.
+    """
+    if ScoDocSiteConfig.is_cas_enabled():
+        app.config["CAS_SERVER"] = ScoDocSiteConfig.get("cas_server")
+        app.config["CAS_AFTER_LOGIN"] = "auth.after_cas_login"
+        app.config["CAS_AFTER_LOGOUT"] = "auth.after_cas_logout"
+    else:
+        app.config.pop("CAS_SERVER", None)
+        app.config.pop("CAS_AFTER_LOGIN", None)
+        app.config.pop("CAS_AFTER_LOGOUT", None)
diff --git a/app/auth/logic.py b/app/auth/logic.py
index ba3f73a42d..a1737a3b40 100644
--- a/app/auth/logic.py
+++ b/app/auth/logic.py
@@ -8,9 +8,10 @@ import flask
 from flask import g, redirect, request, url_for
 from flask_httpauth import HTTPBasicAuth, HTTPTokenAuth
 import flask_login
+
 from app import login
-from app.scodoc.sco_utils import json_error
 from app.auth.models import User
+from app.scodoc.sco_utils import json_error
 
 basic_auth = HTTPBasicAuth()
 token_auth = HTTPTokenAuth()
diff --git a/app/auth/models.py b/app/auth/models.py
index 274be8e7a2..866f08ff82 100644
--- a/app/auth/models.py
+++ b/app/auth/models.py
@@ -53,12 +53,28 @@ class User(UserMixin, db.Model):
 
     id = db.Column(db.Integer, primary_key=True)
     user_name = db.Column(db.String(64), index=True, unique=True)
+    "le login"
     email = db.Column(db.String(120))
 
     nom = db.Column(db.String(64))
     prenom = db.Column(db.String(64))
     dept = db.Column(db.String(SHORT_STR_LEN), index=True)
+    "acronyme du département de l'utilisateur"
     active = db.Column(db.Boolean, default=True, index=True)
+    "si faux, compte utilisateur désactivé"
+    cas_id = db.Column(db.Text(), index=True, unique=True, nullable=True)
+    "uid sur le CAS (mail ou autre attribut, selon config.cas_attribute_id)"
+    cas_allow_login = db.Column(
+        db.Boolean, default=False, server_default="false", nullable=False
+    )
+    "Peut-on se logguer via le CAS ?"
+    cas_allow_scodoc_login = db.Column(
+        db.Boolean, default=True, server_default="false", nullable=False
+    )
+    """(not yet implemented XXX)
+    si CAS activé, peut-on se logguer sur ScoDoc directement ?
+    (le rôle ScoSuperAdmin peut toujours)
+    """
 
     password_hash = db.Column(db.String(128))
     password_scodoc7 = db.Column(db.String(42))
@@ -184,6 +200,9 @@ class User(UserMixin, db.Model):
             "dept": self.dept,
             "id": self.id,
             "active": self.active,
+            "cas_id": self.cas_id,
+            "cas_allow_login": self.cas_allow_login,
+            "cas_allow_scodoc_login": self.cas_allow_scodoc_login,
             "status_txt": "actif" if self.active else "fermé",
             "last_seen": self.last_seen.isoformat() + "Z" if self.last_seen else None,
             "nom": (self.nom or ""),  # sco8
@@ -206,7 +225,17 @@ class User(UserMixin, db.Model):
         """Set users' attributes from given dict values.
         Roles must be encoded as "roles_string", like "Ens_RT, Secr_CJ"
         """
-        for field in ["nom", "prenom", "dept", "active", "email", "date_expiration"]:
+        for field in [
+            "nom",
+            "prenom",
+            "dept",
+            "active",
+            "email",
+            "date_expiration",
+            "cas_id",
+            "cas_allow_login",
+            "cas_allow_scodoc_login",
+        ]:
             if field in data:
                 setattr(self, field, data[field] or None)
         if new_user:
diff --git a/app/auth/routes.py b/app/auth/routes.py
index 2c1594bc84..b6a0df9a7c 100644
--- a/app/auth/routes.py
+++ b/app/auth/routes.py
@@ -3,6 +3,7 @@
 auth.routes.py
 """
 
+import flask
 from flask import current_app, flash, render_template
 from flask import redirect, url_for, request
 from flask_login import login_user, logout_user, current_user
@@ -20,6 +21,7 @@ from app.auth.models import Role
 from app.auth.models import User
 from app.auth.email import send_password_reset_email
 from app.decorators import admin_required
+from app.models.config import ScoDocSiteConfig
 
 _ = lambda x: x  # sans babel
 _l = _
@@ -30,6 +32,7 @@ def login():
     "ScoDoc Login form"
     if current_user.is_authenticated:
         return redirect(url_for("scodoc.index"))
+
     form = LoginForm()
     if form.validate_on_submit():
         user = User.query.filter_by(user_name=form.user_name.data).first()
@@ -42,14 +45,22 @@ def login():
         return form.redirect("scodoc.index")
     message = request.args.get("message", "")
     return render_template(
-        "auth/login.j2", title=_("Sign In"), form=form, message=message
+        "auth/login.j2",
+        title=_("Sign In"),
+        form=form,
+        message=message,
+        is_cas_enabled=ScoDocSiteConfig.is_cas_enabled(),
     )
 
 
 @bp.route("/logout")
-def logout():
-    "Logout current user and redirect to home page"
+def logout() -> flask.Response:
+    "Logout a scodoc user. If CAS session, logout from CAS. Redirect."
+    current_app.logger.info(f"logout user {current_user.user_name}")
     logout_user()
+    if ScoDocSiteConfig.is_cas_enabled() and flask.session.get("scodoc_cas_login_date"):
+        flask.session.pop("scodoc_cas_login_date", None)
+        return redirect(url_for("cas.logout"))
     return redirect(url_for("scodoc.index"))
 
 
diff --git a/app/forms/main/config_cas.py b/app/forms/main/config_cas.py
new file mode 100644
index 0000000000..663e487b51
--- /dev/null
+++ b/app/forms/main/config_cas.py
@@ -0,0 +1,53 @@
+# -*- mode: python -*-
+# -*- coding: utf-8 -*-
+
+##############################################################################
+#
+# ScoDoc
+#
+# Copyright (c) 1999 - 2023 Emmanuel Viennet.  All rights reserved.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+#
+#   Emmanuel Viennet      emmanuel.viennet@viennet.net
+#
+##############################################################################
+
+"""
+Formulaires configuration Exports Apogée (codes)
+"""
+
+from flask_wtf import FlaskForm
+from wtforms import BooleanField, SubmitField
+from wtforms.fields.simple import StringField
+
+
+class ConfigCASForm(FlaskForm):
+    "Formulaire paramétrage CAS"
+    cas_enable = BooleanField("activer le CAS")
+
+    cas_server = StringField(
+        label="URL du serveur CAS",
+        description="""url complète. Commence en général par <tt>https://</tt>.""",
+    )
+
+    cas_attribute_id = StringField(
+        label="Attribut CAS utilisé comme id",
+        description="""Le champs CAS qui sera considéré comme l'id unique des 
+        comptes utilisateurs.""",
+    )
+
+    submit = SubmitField("Valider")
+    cancel = SubmitField("Annuler", render_kw={"formnovalidate": True})
diff --git a/app/models/config.py b/app/models/config.py
index f4f09cc329..bbe0c0ae75 100644
--- a/app/models/config.py
+++ b/app/models/config.py
@@ -87,6 +87,10 @@ class ScoDocSiteConfig(db.Model):
         "enable_entreprises": bool,
         "month_debut_annee_scolaire": int,
         "month_debut_periode2": int,
+        # CAS
+        "cas_enable": bool,
+        "cas_server": str,
+        "cas_attribute_id": str,
     }
 
     def __init__(self, name, value):
@@ -170,7 +174,7 @@ class ScoDocSiteConfig(db.Model):
         (starting with empty string to represent "no bonus function").
         """
         d = bonus_spo.get_bonus_class_dict()
-        class_list = [(name, d[name].displayed_name) for name in d.keys()]
+        class_list = [(name, d[name].displayed_name) for name in d]
         class_list.sort(key=lambda x: x[1].replace(" du ", " de "))
         return [("", "")] + class_list
 
@@ -204,13 +208,31 @@ class ScoDocSiteConfig(db.Model):
             db.session.add(cfg)
             db.session.commit()
 
+    @classmethod
+    def is_cas_enabled(cls) -> bool:
+        """True si on utilise le CAS"""
+        cfg = ScoDocSiteConfig.query.filter_by(name="cas_enable").first()
+        return cfg is not None and cfg.value
+
+    @classmethod
+    def cas_enable(cls, enabled=True) -> bool:
+        """Active (ou déactive) le CAS. True si changement."""
+        if enabled != ScoDocSiteConfig.is_cas_enabled():
+            cfg = ScoDocSiteConfig.query.filter_by(name="cas_enable").first()
+            if cfg is None:
+                cfg = ScoDocSiteConfig(name="cas_enable", value="on" if enabled else "")
+            else:
+                cfg.value = "on" if enabled else ""
+            db.session.add(cfg)
+            db.session.commit()
+            return True
+        return False
+
     @classmethod
     def is_entreprises_enabled(cls) -> bool:
         """True si on doit activer le module entreprise"""
         cfg = ScoDocSiteConfig.query.filter_by(name="enable_entreprises").first()
-        if (cfg is None) or not cfg.value:
-            return False
-        return True
+        return cfg is not None and cfg.value
 
     @classmethod
     def enable_entreprises(cls, enabled=True) -> bool:
@@ -228,6 +250,26 @@ class ScoDocSiteConfig(db.Model):
             return True
         return False
 
+    @classmethod
+    def get(cls, name: str) -> str:
+        "Get configuration param; empty string if unset"
+        cfg = ScoDocSiteConfig.query.filter_by(name=name).first()
+        return (cfg.value or "") if cfg else ""
+
+    @classmethod
+    def set(cls, name: str, value: str) -> bool:
+        "Set parameter, returns True if change. Commit session."
+        if cls.get(name) != (value or ""):
+            cfg = ScoDocSiteConfig.query.filter_by(name=name).first()
+            if cfg is None:
+                cfg = ScoDocSiteConfig(name=name, value=str(value))
+            else:
+                cfg.value = str(value or "")
+            db.session.add(cfg)
+            db.session.commit()
+            return True
+        return False
+
     @classmethod
     def _get_int_field(cls, name: str, default=None) -> int:
         """Valeur d'un champs integer"""
diff --git a/app/scodoc/sco_etud.py b/app/scodoc/sco_etud.py
index 6d9bc49f45..a4240d4be7 100644
--- a/app/scodoc/sco_etud.py
+++ b/app/scodoc/sco_etud.py
@@ -225,6 +225,9 @@ _identiteEditor = ndb.EditableTable(
         "nom",
         "nom_usuel",
         "prenom",
+        "cas_id",
+        "cas_allow_login",
+        "cas_allow_scodoc_login",
         "civilite",  # 'M", "F", or "X"
         "date_naissance",
         "lieu_naissance",
diff --git a/app/scodoc/sco_users.py b/app/scodoc/sco_users.py
index d3db5b8e7e..53a298bb64 100644
--- a/app/scodoc/sco_users.py
+++ b/app/scodoc/sco_users.py
@@ -28,11 +28,10 @@
 """Fonctions sur les utilisateurs
 """
 
-# Anciennement ZScoUsers.py, fonctions de gestion des données réécrite avec flask/SQLAlchemy
+# Anciennement ZScoUsers.py, fonctions de gestion des données réécrites avec flask/SQLAlchemy
 import re
 
 from flask import url_for, g, request
-from flask.templating import render_template
 from flask_login import current_user
 
 
@@ -42,23 +41,11 @@ from app.auth.models import Permission
 from app.auth.models import User
 
 from app.scodoc import html_sco_header
-from app.scodoc import sco_etud
-from app.scodoc import sco_excel
 from app.scodoc import sco_preferences
 from app.scodoc.gen_tables import GenTable
-from app import log, cache
-from app.scodoc.scolog import logdb
-import app.scodoc.sco_utils as scu
+from app import cache
 
-from app.scodoc.sco_exceptions import (
-    AccessDenied,
-    ScoValueError,
-)
-
-
-# ---------------
-
-# ---------------
+from app.scodoc.sco_exceptions import ScoValueError
 
 
 def index_html(all_depts=False, with_inactives=False, format="html"):
@@ -70,19 +57,21 @@ def index_html(all_depts=False, with_inactives=False, format="html"):
 
     if current_user.has_permission(Permission.ScoUsersAdmin, g.scodoc_dept):
         H.append(
-            '<p><a href="{}" class="stdlink">Ajouter un utilisateur</a>'.format(
-                url_for("users.create_user_form", scodoc_dept=g.scodoc_dept)
-            )
+            f"""<p><a href="{url_for("users.create_user_form",
+                scodoc_dept=g.scodoc_dept)
+            }" class="stdlink">Ajouter un utilisateur</a>"""
         )
         if current_user.is_administrator():
             H.append(
-                '&nbsp;&nbsp; <a href="{}" class="stdlink">Importer des utilisateurs</a></p>'.format(
-                    url_for("users.import_users_form", scodoc_dept=g.scodoc_dept)
-                )
+                """&nbsp;&nbsp; <a href="{url_for("users.import_users_form",
+                    scodoc_dept=g.scodoc_dept)
+                }" class="stdlink">Importer des utilisateurs</a></p>"""
             )
+
         else:
             H.append(
-                "&nbsp;&nbsp; Pour importer des utilisateurs en masse (via xlsx file) contactez votre administrateur scodoc."
+                """&nbsp;&nbsp; Pour importer des utilisateurs en masse (via fichier xlsx)
+                contactez votre administrateur scodoc."""
             )
     if all_depts:
         checked = "checked"
@@ -93,11 +82,12 @@ def index_html(all_depts=False, with_inactives=False, format="html"):
     else:
         olds_checked = ""
     H.append(
-        """<p><form name="f" action="%s" method="get">
-    <input type="checkbox" name="all_depts" value="1" onchange="document.f.submit();" %s>Tous les départements</input>
-    <input type="checkbox" name="with_inactives" value="1" onchange="document.f.submit();" %s>Avec anciens utilisateurs</input>
+        f"""<p><form name="f" action="{request.base_url}" method="get">
+    <input type="checkbox" name="all_depts" value="1" onchange="document.f.submit();"
+    {checked}>Tous les départements</input>
+    <input type="checkbox" name="with_inactives" value="1" onchange="document.f.submit();"
+    {olds_checked}>Avec anciens utilisateurs</input>
     </form></p>"""
-        % (request.base_url, checked, olds_checked)
     )
 
     L = list_users(
@@ -189,9 +179,8 @@ def list_users(
         },
         caption=title,
         page_title="title",
-        html_title="""<h2>%d utilisateurs %s</h2>
-        <p class="help">Cliquer sur un nom pour changer son mot de passe</p>"""
-        % (len(r), comm),
+        html_title=f"""<h2>{len(r)} utilisateurs {comm}</h2>
+        <p class="help">Cliquer sur un nom pour changer son mot de passe</p>""",
         html_class="table_leftalign list_users",
         html_with_td_classes=True,
         html_sortable=True,
@@ -273,6 +262,9 @@ def user_info(user_name_or_id=None, user: User = None):
         return info
 
 
+MSG_OPT = """<br>Attention: (vous pouvez forcer l'opération en cochant "<em>Ignorer les avertissements</em>" en bas de page)"""
+
+
 def check_modif_user(
     edit,
     enforce_optionals=False,
@@ -281,7 +273,8 @@ def check_modif_user(
     prenom="",
     email="",
     dept="",
-    roles=[],
+    roles: list = None,
+    cas_id: str = None,
 ):
     """Vérifie que cet utilisateur peut être créé (edit=0) ou modifié (edit=1)
     Cherche homonymes.
@@ -290,32 +283,31 @@ def check_modif_user(
             (si ok est faux, l'utilisateur peut quand même forcer la creation)
         - msg: message warning à presenter à l'utilisateur
     """
-    MSG_OPT = """<br>Attention: (vous pouvez forcer l'opération en cochant "<em>Ignorer les avertissements</em>" en bas de page)"""
+    roles = roles or []
     # ce login existe ?
-    user = _user_list(user_name)
+    user = User.query.filter_by(user_name=user_name).first()
     if edit and not user:  # safety net, le user_name ne devrait pas changer
-        return False, "identifiant %s inexistant" % user_name
+        return False, f"identifiant {user_name} inexistant"
     if not edit and user:
-        return False, "identifiant %s déjà utilisé" % user_name
+        return False, f"identifiant {user_name} déjà utilisé"
     if not user_name or not nom or not prenom:
         return False, "champ requis vide"
     if not re.match(r"^[a-zA-Z0-9@\\\-_\\\.]*$", user_name):
         return (
             False,
-            "identifiant '%s' invalide (pas d'accents ni de caractères spéciaux)"
-            % user_name,
+            f"identifiant '{user_name}' invalide (pas d'accents ni de caractères spéciaux)",
         )
     if enforce_optionals and len(user_name) > 64:
-        return False, "identifiant '%s' trop long (64 caractères)" % user_name
+        return False, f"identifiant '{user_name}' trop long (64 caractères)"
     if enforce_optionals and len(nom) > 64:
-        return False, "nom '%s' trop long (64 caractères)" % nom + MSG_OPT
+        return False, f"nom '{nom}' trop long (64 caractères)" + MSG_OPT
     if enforce_optionals and len(prenom) > 64:
-        return False, "prenom '%s' trop long (64 caractères)" % prenom + MSG_OPT
-    # check that tha same user_name has not already been described in this import
+        return False, f"prenom '{prenom}' trop long (64 caractères)" + MSG_OPT
+    # check that same user_name has not already been described in this import
     if not email:
         return False, "vous devriez indiquer le mail de l'utilisateur créé !"
     if len(email) > 120:
-        return False, "email '%s' trop long (120 caractères)" % email
+        return False, f"email '{email}' trop long (120 caractères)"
     if not re.fullmatch(r"\b[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Z|a-z]{2,}\b", email):
         return False, "l'adresse mail semble incorrecte"
     # check département
@@ -324,19 +316,31 @@ def check_modif_user(
         and dept
         and Departement.query.filter_by(acronym=dept).first() is None
     ):
-        return False, "département '%s' inexistant" % dept + MSG_OPT
+        return False, f"département '{dept}' inexistant" + MSG_OPT
     if enforce_optionals and not roles:
         return False, "aucun rôle sélectionné, êtes vous sûr ?" + MSG_OPT
     # Unicité du mail
     users_with_this_mail = User.query.filter_by(email=email).all()
     if edit:  # modification
-        if email != user["email"] and len(users_with_this_mail) > 0:
+        if email != user.email and len(users_with_this_mail) > 0:
             return False, "un autre utilisateur existe déjà avec cette adresse mail"
     else:  # création utilisateur
         if len(users_with_this_mail) > 0:
             return False, "un autre utilisateur existe déjà avec cette adresse mail"
 
-    # ok
+    # Unicité du cas_id
+    if cas_id:
+        cas_users = User.query.filter_by(cas_id=cas_id).all()
+        if edit:
+            if cas_users and (
+                len(cas_users) > 1 or cas_users[0].user_name != user_name
+            ):
+                return (
+                    False,
+                    "un autre utilisateur existe déjà avec cet identifiant CAS",
+                )
+        elif cas_users:
+            return False, "un autre utilisateur existe déjà avec cet identifiant CAS"
     # Des noms/prénoms semblables existent ?
     nom = nom.lower().strip()
     prenom = prenom.lower().strip()
@@ -367,7 +371,7 @@ def user_edit(user_name, vals):
     """Edit the user specified by user_name
     (ported from Zope to SQLAlchemy, hence strange !)
     """
-    u = User.query.filter_by(user_name=user_name).first()
+    u: User = User.query.filter_by(user_name=user_name).first()
     if not u:
         raise ScoValueError("Invalid user_name")
     u.from_dict(vals)
diff --git a/app/templates/auth/login.j2 b/app/templates/auth/login.j2
index 2877f6725c..8f9f4a8cfe 100644
--- a/app/templates/auth/login.j2
+++ b/app/templates/auth/login.j2
@@ -9,6 +9,12 @@
 {% endif %}
 
 <h1>Connexion</h1>
+
+{% if is_cas_enabled %}
+<div class"cas_link">
+<a href="{{ url_for('cas.login') }}" class="stdlink">Se connecter avec CAS</a>
+</div>
+{% endif %}
 <div class="row">
     <div class="col-md-4">
         {{ wtf.quick_form(form) }}
diff --git a/app/templates/auth/user_info_page.j2 b/app/templates/auth/user_info_page.j2
index 23e8c27b21..d5284579af 100644
--- a/app/templates/auth/user_info_page.j2
+++ b/app/templates/auth/user_info_page.j2
@@ -7,6 +7,9 @@
 <h2>Utilisateur: {{user.user_name}} ({{'actif' if user.active else 'fermé'}})</h2>
 <p>
     <b>Login :</b> {{user.user_name}}<br>
+    <b>CAS id:</b> {{user.cas_id or "(aucun)"}}
+    (CAS {{'autorisé' if user.cas_allow_login else 'interdit'}} pour cet utilisateur)
+    <br>
     <b>Nom :</b> {{user.nom or ""}}<br>
     <b>Prénom :</b> {{user.prenom or ""}}<br>
     <b>Mail :</b> {{user.email}}<br>
@@ -48,9 +51,15 @@
 </ul>
 
 {% if current_user.id == user.id %}
-<p><b>Se déconnecter:
-        <a class="stdlink" href="{{url_for('auth.logout')}}">logout</a>
-    </b></p>
+<div class="user_info_session">
+    {% if session_info %}
+    <p><b>CAS session started at </b>{{ session_info }}</p>
+    {% endif %}
+    <p><b>Se déconnecter:
+            <a class="stdlink" href="{{url_for('auth.logout')}}">logout</a>
+        </b>
+    </p>
+</div>
 {% endif %}
 
 {# Liste des permissions #}
diff --git a/app/templates/config_cas.j2 b/app/templates/config_cas.j2
new file mode 100644
index 0000000000..2cccd0de46
--- /dev/null
+++ b/app/templates/config_cas.j2
@@ -0,0 +1,18 @@
+{% extends "base.j2" %}
+{% import 'bootstrap/wtf.html' as wtf %}
+
+{% block app_content %}
+<h1>Configuration du Service d'Authentification Central (CAS)</h1>
+
+
+<div class="help">
+    <p>Le CAS...</p>
+</div>
+<div class="row">
+    <div class="col-md-4">
+        {{ wtf.quick_form(form) }}
+    </div>
+</div>
+
+
+{% endblock %}
\ No newline at end of file
diff --git a/app/templates/configuration.j2 b/app/templates/configuration.j2
index 05567ef3f2..94726c62b9 100644
--- a/app/templates/configuration.j2
+++ b/app/templates/configuration.j2
@@ -53,8 +53,9 @@
     </p>
 </section>
 
-<h2>Utilisateurs</h2>
+<h2>Utilisateurs et CAS</h2>
 <section>
+    <p><a class="stdlink" href="{{url_for('scodoc.config_cas')}}">configuration du service CAS</a>
     <p><a class="stdlink" href="{{url_for('auth.reset_standard_roles_permissions')}}">remettre
             les permissions des rôles standards à leurs valeurs par défaut</a> (efface les modifications apportées)
     </p>
diff --git a/app/views/scodoc.py b/app/views/scodoc.py
index 83055b5048..6a9c5e0228 100644
--- a/app/views/scodoc.py
+++ b/app/views/scodoc.py
@@ -62,6 +62,7 @@ from app.decorators import (
 from app.forms.main import config_logos, config_main
 from app.forms.main.create_dept import CreateDeptForm
 from app.forms.main.config_apo import CodesDecisionsForm
+from app.forms.main.config_cas import ConfigCASForm
 from app import models
 from app.models import Departement, Identite
 from app.models import departements
@@ -134,6 +135,33 @@ def toggle_dept_vis(dept_id):
     return redirect(url_for("scodoc.index"))
 
 
+@bp.route("/ScoDoc/config_cas", methods=["GET", "POST"])
+@admin_required
+def config_cas():
+    """Form config CAS"""
+    form = ConfigCASForm()
+    if request.method == "POST" and form.cancel.data:  # cancel button
+        return redirect(url_for("scodoc.index"))
+    if form.validate_on_submit():
+        if ScoDocSiteConfig.cas_enable(enabled=form.data["cas_enable"]):
+            flash("CAS " + ("activé" if form.data["cas_enable"] else "désactivé"))
+        if ScoDocSiteConfig.set("cas_server", form.data["cas_server"]):
+            flash("Serveur CAS enregistré")
+        if ScoDocSiteConfig.set("cas_attribute_id", form.data["cas_attribute_id"]):
+            flash("Serveur CAS enregistré")
+
+        return redirect(url_for("scodoc.configuration"))
+    elif request.method == "GET":
+        form.cas_enable.data = ScoDocSiteConfig.get("cas_enable")
+        form.cas_server.data = ScoDocSiteConfig.get("cas_server")
+        form.cas_attribute_id.data = ScoDocSiteConfig.get("cas_attribute_id")
+        return render_template(
+            "config_cas.j2",
+            form=form,
+            title="Configuration du Service d'Authentification Central (CAS)",
+        )
+
+
 @bp.route("/ScoDoc/config_codes_decisions", methods=["GET", "POST"])
 @admin_required
 def config_codes_decisions():
diff --git a/app/views/users.py b/app/views/users.py
index f6d0bcc711..7efc08e1ad 100644
--- a/app/views/users.py
+++ b/app/views/users.py
@@ -56,6 +56,7 @@ from app.auth.models import UserRole
 from app.auth.models import is_valid_password
 from app.email import send_email
 from app.models import Departement
+from app.models.config import ScoDocSiteConfig
 
 from app.decorators import (
     scodoc,
@@ -226,7 +227,7 @@ def create_user_form(user_name=None, edit=0, all_roles=True):
     if edit:
         if not user_name:
             raise ValueError("missing argument: user_name")
-        the_user = User.query.filter_by(user_name=user_name).first()
+        the_user: User = User.query.filter_by(user_name=user_name).first()
         if not the_user:
             raise ScoValueError("utilisateur inexistant")
         initvalues = the_user.to_dict()
@@ -367,6 +368,7 @@ def create_user_form(user_name=None, edit=0, all_roles=True):
                 {"input_type": "hidden", "default": initvalues["user_name"]},
             )
         ]
+    cas_enabled = ScoDocSiteConfig.is_cas_enabled()
     descr += [
         (
             "email",
@@ -376,11 +378,34 @@ def create_user_form(user_name=None, edit=0, all_roles=True):
                 "explanation": "requis, doit fonctionner"
                 if not edit_only_roles
                 else "",
-                "size": 20,
+                "size": 36,
                 "allow_null": False,
                 "readonly": edit_only_roles,
             },
-        )
+        ),
+        (
+            "cas_id",
+            {
+                "title": "Identifiant CAS",
+                "input_type": "text",
+                "explanation": "id du compte utilisateur sur le CAS de l'établissement "
+                + "(service CAS activé)"
+                if cas_enabled
+                else "(service CAS non activé)",
+                "size": 36,
+                "allow_null": True,
+                "readonly": not cas_enabled,
+            },
+        ),
+        (
+            "cas_allow_login",
+            {
+                "title": "Autorise connexion via CAS",
+                "input_type": "boolcheckbox",
+                "explanation": "en test: seul le super-administrateur peut changer ce réglage",
+                "readonly": not current_user.is_administrator(),
+            },
+        ),
     ]
     if not edit:  # options création utilisateur
         descr += [
@@ -438,7 +463,8 @@ def create_user_form(user_name=None, edit=0, all_roles=True):
                     "d",
                     {
                         "input_type": "separator",
-                        "title": f"""L'utilisateur appartient au département {the_user.dept or "(tous)"}""",
+                        "title": f"""L'utilisateur appartient au département {
+                            the_user.dept or "(tous)"}""",
                     },
                 )
             )
@@ -541,7 +567,6 @@ def create_user_form(user_name=None, edit=0, all_roles=True):
         if err_msg:
             H.append(tf_error_message(f"""Erreur: {err_msg}"""))
             return "\n".join(H) + "\n" + tf[1] + F
-
         if not edit_only_roles:
             ok_modif, msg = sco_users.check_modif_user(
                 edit,
@@ -552,6 +577,7 @@ def create_user_form(user_name=None, edit=0, all_roles=True):
                 email=vals["email"],
                 dept=vals.get("dept", auth_dept),
                 roles=vals["roles"],
+                cas_id=vals["cas_id"],
             )
             if not ok_modif:
                 H.append(tf_error_message(msg))
@@ -815,12 +841,17 @@ def user_info_page(user_name=None):
     if not user:
         raise ScoValueError("invalid user_name")
 
+    session_info = None
+    if user.id == current_user.id:
+        session_info = flask.session.get("scodoc_cas_login_date")
+
     return render_template(
         "auth/user_info_page.j2",
         user=user,
         title=f"Utilisateur {user.user_name}",
         Permission=Permission,
         dept=dept,
+        session_info=session_info,
     )
 
 
diff --git a/config.py b/config.py
index 740860a617..584a6843b6 100755
--- a/config.py
+++ b/config.py
@@ -43,6 +43,10 @@ class Config:
     # STATIC_URL_PATH = "/ScoDoc/static"
     # static_folder = "stat"
     # SERVER_NAME = os.environ.get("SERVER_NAME")
+    # XXX temporaire: utiliser SiteConfig
+    CAS_SERVER = os.environ.get("CAS_SERVER")
+    CAS_AFTER_LOGIN = os.environ.get("CAS_AFTER_LOGIN")
+    CAS_AFTER_LOGOUT = os.environ.get("CAS_AFTER_LOGOUT")
 
 
 class ProdConfig(Config):
diff --git a/flask_cas/README.md b/flask_cas/README.md
new file mode 100644
index 0000000000..d71e8b507c
--- /dev/null
+++ b/flask_cas/README.md
@@ -0,0 +1,7 @@
+# Flask-CAS
+
+Forked from <https://github.com/MasterRoshan/flask-cas-ng>
+and adapted by Emmanuel Viennet, Feb. 2023.
+
+- logout: clear `_CAS_TOKEN`.
+- Use `url` instead of `service` parameter in logout URL.
diff --git a/flask_cas/__init__.py b/flask_cas/__init__.py
new file mode 100644
index 0000000000..76e02c2524
--- /dev/null
+++ b/flask_cas/__init__.py
@@ -0,0 +1,106 @@
+"""
+flask_cas.__init__
+"""
+
+import flask
+from flask import current_app
+
+# Find the stack on which we want to store the database connection.
+# Starting with Flask 0.9, the _app_ctx_stack is the correct one,
+# before that we need to use the _request_ctx_stack.
+try:
+    from flask import _app_ctx_stack as stack
+except ImportError:
+    from flask import _request_ctx_stack as stack
+
+from . import routing
+
+from functools import wraps
+
+class CAS(object):
+    """
+    Required Configs:
+
+    |Key             |
+    |----------------|
+    |CAS_SERVER      |
+    |CAS_AFTER_LOGIN |
+
+    Optional Configs:
+
+    |Key                        | Default               |
+    |---------------------------|-----------------------|
+    |CAS_TOKEN_SESSION_KEY      | _CAS_TOKEN            |
+    |CAS_USERNAME_SESSION_KEY   | CAS_USERNAME          |
+    |CAS_ATTRIBUTES_SESSION_KEY | CAS_ATTRIBUTES        |
+    |CAS_LOGIN_ROUTE            | '/cas'                |
+    |CAS_LOGOUT_ROUTE           | '/cas/logout'         |
+    |CAS_VALIDATE_ROUTE         | '/cas/serviceValidate'|
+    |CAS_AFTER_LOGOUT           | None                  |
+    """
+
+    def __init__(self, app=None, url_prefix=None):
+        self._app = app
+        if app is not None:
+            self.init_app(app, url_prefix)
+
+    def init_app(self, app, url_prefix=None):
+        # Configuration defaults
+        app.config.setdefault('CAS_TOKEN_SESSION_KEY', '_CAS_TOKEN')
+        app.config.setdefault('CAS_USERNAME_SESSION_KEY', 'CAS_USERNAME')
+        app.config.setdefault('CAS_ATTRIBUTES_SESSION_KEY', 'CAS_ATTRIBUTES')
+        app.config.setdefault('CAS_LOGIN_ROUTE', '/cas')
+        app.config.setdefault('CAS_LOGOUT_ROUTE', '/cas/logout')
+        app.config.setdefault('CAS_VALIDATE_ROUTE', '/cas/serviceValidate')
+        # Requires CAS 2.0
+        app.config.setdefault('CAS_AFTER_LOGOUT', None)
+        # Register Blueprint
+        app.register_blueprint(routing.blueprint, url_prefix=url_prefix)
+
+        # Use the newstyle teardown_appcontext if it's available,
+        # otherwise fall back to the request context
+        if hasattr(app, 'teardown_appcontext'):
+            app.teardown_appcontext(self.teardown)
+        else:
+            app.teardown_request(self.teardown)
+
+    def teardown(self, exception):
+        ctx = stack.top
+    
+    @property
+    def app(self):
+        return self._app or current_app
+
+    @property
+    def username(self):
+        return flask.session.get(
+            self.app.config['CAS_USERNAME_SESSION_KEY'], None)
+
+    @property
+    def attributes(self):
+        return flask.session.get(
+            self.app.config['CAS_ATTRIBUTES_SESSION_KEY'], None)
+
+    @property
+    def token(self):
+        return flask.session.get(
+            self.app.config['CAS_TOKEN_SESSION_KEY'], None)
+
+def login():
+    return flask.redirect(flask.url_for('cas.login', _external=True))
+
+def logout():
+    return flask.redirect(flask.url_for('cas.logout', _external=True))
+
+def login_required(function):
+    @wraps(function)
+    def wrap(*args, **kwargs):
+        if 'CAS_USERNAME' not in flask.session:
+            flask.session['CAS_AFTER_LOGIN_SESSION_URL'] = (
+                flask.request.script_root +
+                flask.request.full_path
+            )
+            return login()
+        else:
+            return function(*args, **kwargs)
+    return wrap
diff --git a/flask_cas/cas_urls.py b/flask_cas/cas_urls.py
new file mode 100644
index 0000000000..276ef89c76
--- /dev/null
+++ b/flask_cas/cas_urls.py
@@ -0,0 +1,125 @@
+"""
+flask_cas.cas_urls
+
+Functions for creating urls to access CAS.
+"""
+
+try:
+    from urllib import quote
+    from urllib import urlencode
+    from urlparse import urljoin
+except ImportError:
+    from urllib.parse import quote
+    from urllib.parse import urljoin
+    from urllib.parse import urlencode
+
+
+def create_url(base, path=None, *query):
+    """Create a url.
+
+    Creates a url by combining base, path, and the query's list of
+    key/value pairs. Escaping is handled automatically. Any
+    key/value pair with a value that is None is ignored.
+
+    Keyword arguments:
+    base -- The left most part of the url (ex. http://localhost:5000).
+    path -- The path after the base (ex. /foo/bar).
+    query -- A list of key value pairs (ex. [('key', 'value')]).
+
+    Example usage:
+    >>> create_url(
+    ...     'http://localhost:5000',
+    ...     'foo/bar',
+    ...     ('key1', 'value'),
+    ...     ('key2', None),     # Will not include None
+    ...     ('url', 'http://example.com'),
+    ... )
+    'http://localhost:5000/foo/bar?key1=value&url=http%3A%2F%2Fexample.com'
+    """
+    url = base
+    # Add the path to the url if it's not None.
+    if path is not None:
+        url = urljoin(url, quote(path))
+    # Remove key/value pairs with None values.
+    query = filter(lambda pair: pair[1] is not None, query)
+    # Add the query string to the url
+    url = urljoin(url, "?{0}".format(urlencode(list(query))))
+    return url
+
+
+def create_cas_login_url(cas_url, cas_route, service, renew=None, gateway=None):
+    """Create a CAS login URL .
+
+    Keyword arguments:
+    cas_url -- The url to the CAS (ex. http://sso.pdx.edu)
+    cas_route -- The route where the CAS lives on server (ex. /cas)
+    service -- (ex.  http://localhost:5000/login)
+    renew -- "true" or "false"
+    gateway -- "true" or "false"
+
+    Example usage:
+    >>> create_cas_login_url(
+    ...     'http://sso.pdx.edu',
+    ...     '/cas',
+    ...     'http://localhost:5000',
+    ... )
+    'http://sso.pdx.edu/cas?service=http%3A%2F%2Flocalhost%3A5000'
+    """
+    return create_url(
+        cas_url,
+        cas_route,
+        ("service", service),
+        ("renew", renew),
+        ("gateway", gateway),
+    )
+
+
+def create_cas_logout_url(cas_url, cas_route, service=None):
+    """Create a CAS logout URL.
+
+    Keyword arguments:
+    cas_url -- The url to the CAS (ex. http://sso.pdx.edu)
+    cas_route -- The route where the CAS lives on server (ex. /cas/logout)
+    url -- (ex.  http://localhost:5000/login)
+
+    Example usage:
+    >>> create_cas_logout_url(
+    ...     'http://sso.pdx.edu',
+    ...     '/cas/logout',
+    ...     'http://localhost:5000',
+    ... )
+    'http://sso.pdx.edu/cas/logout?service=http%3A%2F%2Flocalhost%3A5000'
+    """
+    return create_url(
+        cas_url,
+        cas_route,
+        ("url", service),  # 'url' (and not 'service'): redirect here after CAS logout
+    )
+
+
+def create_cas_validate_url(cas_url, cas_route, service, ticket, renew=None):
+    """Create a CAS validate URL.
+
+    Keyword arguments:
+    cas_url -- The url to the CAS (ex. http://sso.pdx.edu)
+    cas_route -- The route where the CAS lives on server (ex. /cas/serviceValidate)
+    service -- (ex.  http://localhost:5000/login)
+    ticket -- (ex. 'ST-58274-x839euFek492ou832Eena7ee-cas')
+    renew -- "true" or "false"
+
+    Example usage:
+    >>> create_cas_validate_url(
+    ...     'http://sso.pdx.edu',
+    ...     '/cas/serviceValidate',
+    ...     'http://localhost:5000/login',
+    ...     'ST-58274-x839euFek492ou832Eena7ee-cas'
+    ... )
+    'http://sso.pdx.edu/cas/serviceValidate?service=http%3A%2F%2Flocalhost%3A5000%2Flogin&ticket=ST-58274-x839euFek492ou832Eena7ee-cas'
+    """
+    return create_url(
+        cas_url,
+        cas_route,
+        ("service", service),
+        ("ticket", ticket),
+        ("renew", renew),
+    )
diff --git a/flask_cas/routing.py b/flask_cas/routing.py
new file mode 100644
index 0000000000..e241dfcc23
--- /dev/null
+++ b/flask_cas/routing.py
@@ -0,0 +1,165 @@
+import flask
+from xmltodict import parse
+from flask import current_app
+from .cas_urls import create_cas_login_url
+from .cas_urls import create_cas_logout_url
+from .cas_urls import create_cas_validate_url
+
+
+try:
+    from urllib import urlopen
+except ImportError:
+    from urllib.request import urlopen
+
+blueprint = flask.Blueprint("cas", __name__)
+
+
+@blueprint.route("/login/")
+def login():
+    """
+    This route has two purposes. First, it is used by the user
+    to login. Second, it is used by the CAS to respond with the
+    `ticket` after the user logs in successfully.
+
+    When the user accesses this url, they are redirected to the CAS
+    to login. If the login was successful, the CAS will respond to this
+    route with the ticket in the url. The ticket is then validated.
+    If validation was successful the logged in username is saved in
+    the user's session under the key `CAS_USERNAME_SESSION_KEY` and
+    the user's attributes are saved under the key
+    'CAS_USERNAME_ATTRIBUTE_KEY'
+    """
+
+    cas_token_session_key = current_app.config["CAS_TOKEN_SESSION_KEY"]
+
+    redirect_url = create_cas_login_url(
+        current_app.config["CAS_SERVER"],
+        current_app.config["CAS_LOGIN_ROUTE"],
+        flask.url_for(
+            ".login",
+            origin=flask.session.get("CAS_AFTER_LOGIN_SESSION_URL"),
+            _external=True,
+        ),
+    )
+
+    if "ticket" in flask.request.args:
+        flask.session[cas_token_session_key] = flask.request.args["ticket"]
+
+    if cas_token_session_key in flask.session:
+
+        if validate(flask.session[cas_token_session_key]):
+            if "CAS_AFTER_LOGIN_SESSION_URL" in flask.session:
+                redirect_url = flask.session.pop("CAS_AFTER_LOGIN_SESSION_URL")
+            elif flask.request.args.get("origin"):
+                redirect_url = flask.request.args["origin"]
+            else:
+                redirect_url = flask.url_for(current_app.config["CAS_AFTER_LOGIN"])
+        else:
+            flask.session.pop(cas_token_session_key, None)
+
+    current_app.logger.debug("Redirecting to: {0}".format(redirect_url))
+
+    return flask.redirect(redirect_url)
+
+
+@blueprint.route("/logout/")
+def logout():
+    """
+    When the user accesses this route they are logged out.
+    """
+
+    cas_username_session_key = current_app.config["CAS_USERNAME_SESSION_KEY"]
+    cas_attributes_session_key = current_app.config["CAS_ATTRIBUTES_SESSION_KEY"]
+    cas_token_session_key = current_app.config["CAS_TOKEN_SESSION_KEY"]
+
+    flask.session.pop(cas_username_session_key, None)
+    flask.session.pop(cas_attributes_session_key, None)
+    flask.session.pop(cas_token_session_key, None)  # added by EV
+
+    cas_after_logout = current_app.config["CAS_AFTER_LOGOUT"]
+    if cas_after_logout is not None:
+        # If config starts with http, use it as dest URL.
+        # Else, build Flask URL
+        dest_url = (
+            cas_after_logout
+            if cas_after_logout.startswith("http")
+            else flask.url_for(cas_after_logout, _external=True)
+        )
+        redirect_url = create_cas_logout_url(
+            current_app.config["CAS_SERVER"],
+            current_app.config["CAS_LOGOUT_ROUTE"],
+            dest_url,
+        )
+    else:
+        redirect_url = create_cas_logout_url(
+            current_app.config["CAS_SERVER"], current_app.config["CAS_LOGOUT_ROUTE"]
+        )
+
+    current_app.logger.debug("Redirecting to: {0}".format(redirect_url))
+    return flask.redirect(redirect_url)
+
+
+def validate(ticket):
+    """
+    Will attempt to validate the ticket. If validation fails, then False
+    is returned. If validation is successful, then True is returned
+    and the validated username is saved in the session under the
+    key `CAS_USERNAME_SESSION_KEY` while tha validated attributes dictionary
+    is saved under the key 'CAS_ATTRIBUTES_SESSION_KEY'.
+    """
+
+    cas_username_session_key = current_app.config["CAS_USERNAME_SESSION_KEY"]
+    cas_attributes_session_key = current_app.config["CAS_ATTRIBUTES_SESSION_KEY"]
+
+    current_app.logger.debug("validating token {0}".format(ticket))
+
+    cas_validate_url = create_cas_validate_url(
+        current_app.config["CAS_SERVER"],
+        current_app.config["CAS_VALIDATE_ROUTE"],
+        flask.url_for(
+            ".login",
+            origin=flask.session.get("CAS_AFTER_LOGIN_SESSION_URL"),
+            _external=True,
+        ),
+        ticket,
+    )
+
+    current_app.logger.debug("Making GET request to {0}".format(cas_validate_url))
+
+    xml_from_dict = {}
+    isValid = False
+
+    try:
+        xmldump = urlopen(cas_validate_url).read().strip().decode("utf8", "ignore")
+        xml_from_dict = parse(xmldump)
+        isValid = (
+            True
+            if "cas:authenticationSuccess" in xml_from_dict["cas:serviceResponse"]
+            else False
+        )
+    except ValueError:
+        current_app.logger.error("CAS returned unexpected result")
+
+    if isValid:
+        current_app.logger.debug("valid")
+        xml_from_dict = xml_from_dict["cas:serviceResponse"][
+            "cas:authenticationSuccess"
+        ]
+        username = xml_from_dict["cas:user"]
+        attributes = xml_from_dict.get("cas:attributes", {})
+
+        if attributes and "cas:memberOf" in attributes:
+            if isinstance(attributes["cas:memberOf"], basestring):
+                attributes["cas:memberOf"] = (
+                    attributes["cas:memberOf"].lstrip("[").rstrip("]").split(",")
+                )
+                for group_number in range(0, len(attributes["cas:memberOf"])):
+                    attributes["cas:memberOf"][group_number] = (
+                        attributes["cas:memberOf"][group_number].lstrip(" ").rstrip(" ")
+                    )
+        flask.session[cas_username_session_key] = username
+        flask.session[cas_attributes_session_key] = attributes
+    else:
+        current_app.logger.debug("invalid")
+
+    return isValid
diff --git a/requirements-3.9.txt b/requirements-3.9.txt
index 9032183ad1..99dddf507a 100755
--- a/requirements-3.9.txt
+++ b/requirements-3.9.txt
@@ -85,4 +85,5 @@ visitor==0.1.3
 Werkzeug==2.1.1
 wrapt==1.14.0
 WTForms==3.0.1
+xmltodict==0.13.0
 zipp==3.8.0
diff --git a/sco_version.py b/sco_version.py
index 4a20b3b647..e99111a475 100644
--- a/sco_version.py
+++ b/sco_version.py
@@ -10,6 +10,7 @@ SCONEWS = """
 <ul>
 <li>ScoDoc 9.4</li>
 <ul>
+    <li>Connexion avec service CAS</li>
     <li>Améliorations des tableaux récapitulatifs</li>
     <li>Nouvelle interface de gestions des groupes (S. Lehmann)</li>
     <li>Enrichissement des jurys BUT et des procès-verbaux associés.</li>