diff --git a/backend/app/config/checkFormat.config.js b/backend/app/config/checkFormat.config.js
new file mode 100644
index 0000000..6b74fe0
--- /dev/null
+++ b/backend/app/config/checkFormat.config.js
@@ -0,0 +1,9 @@
+const {sendError} = require ("./response.config");
+
+function checkFormat(req, res){
+  if(req.get('Content-Type') !== 'application/json') {
+    return sendError(res, 401, -1, "Invalid header format (please use JSON)");
+  }
+  return true; // Is valid
+}
+module.exports = checkFormat
diff --git a/backend/app/config/response.config.js b/backend/app/config/response.config.js
index 625a6cc..dcf5145 100644
--- a/backend/app/config/response.config.js
+++ b/backend/app/config/response.config.js
@@ -1,9 +1,9 @@
 function sendMessage (res, successCode, data) {
-  return res.status(200).json({ status: 'success', successCode: successCode, data: data });
+  res.status(200).json({ status: 'success', successCode: successCode, data: data });
 }
 
 function sendError (res, statusCode, errorCode, reason) {
-  return res.status(statusCode).json({ status: 'error', errorCode: errorCode, reason: reason });
+  res.status(statusCode).json({ status: 'error', errorCode: errorCode, reason: reason });
 }
 
 module.exports = { sendMessage, sendError };
diff --git a/backend/app/config/sessionJWT.config.js b/backend/app/config/sessionJWT.config.js
index 5f525b5..0a50b10 100644
--- a/backend/app/config/sessionJWT.config.js
+++ b/backend/app/config/sessionJWT.config.js
@@ -1,6 +1,6 @@
 const sessionJWTConfig = require ('jsonwebtoken');
 require('dotenv').config({ path: './app/.env' });
-const {sendError, sendMessage} = require ("./response.config");
+const {sendError} = require ("./response.config");
 
 if(process.env.JWTRS256_PRIVATE_KEY === undefined || process.env.JWTRS256_PUBLIC_KEY === undefined){
   console.log('Error Env Variables');
@@ -8,8 +8,9 @@ if(process.env.JWTRS256_PRIVATE_KEY === undefined || process.env.JWTRS256_PUBLIC
 }
 
 console.log('Env variables received');
-const JWTRS256_PRIVATE_KEY = Buffer.from(process.env.JWTRS256_PRIVATE_KEY, 'base64');
-const JWTRS256_PUBLIC_KEY = Buffer.from(process.env.JWTRS256_PUBLIC_KEY, 'base64');
+const JWTRS256_PRIVATE_KEY = Buffer.from(process.env.JWTRS256_PRIVATE_KEY, 'base64').toString('utf-8');
+const JWTRS256_PUBLIC_KEY = Buffer.from(process.env.JWTRS256_PUBLIC_KEY, 'base64').toString('utf-8');
+
 
 function createSessionJWT (mail) {
   return sessionJWTConfig.sign(
@@ -37,31 +38,50 @@ function createSessionCookie(req, res, payload) {
   }
   res.cookie('SESSIONID', jwtToken, {httpOnly:true, secure:false});
 }
-module.exports.createSessionCookie = createSessionCookie;
 
-function decodeSessionCookie(sessionid, res) {
+function decodeSessionCookie(sessionid) {
   if (typeof sessionid === 'undefined') {
-    return { mail: -1 };
+    return {mail: -1};
   }
   try {
     const token = sessionJWTConfig.verify(
       sessionid,
       JWTRS256_PUBLIC_KEY,
       {algorithms: ['RS256']});
-    return sendMessage(res,1,{token: token});
+    return {token: token};
   }
   catch (err) {
-    return sendError(res,-1,{mail: -1});
+    return {mail: -1};
   }
 }
-module.exports.decodeSessionCookie = decodeSessionCookie;
 
-function getSession (sessionid, res) {
-  return decodeSessionCookie(sessionid, res);
+function getSession(sessionid) {
+  return decodeSessionCookie(sessionid);
 }
-module.exports.getSession = getSession;
+module.exports.getSession = getSession
 
 function setSessionCookie (req, res, session) {
   createSessionCookie(req, res, session);
 }
 module.exports.setSessionCookie = setSessionCookie;
+
+function getMail(session) {
+  if (typeof session === 'undefined' || typeof session.token === 'undefined') return -1;
+  return session.token;
+}
+module.exports.getMail = getMail;
+
+function checkLogin(req, res){
+  if(typeof req.cookies !== 'undefined'){
+    const session = getSession(req.cookies.SESSIONID);
+    const token = getMail(session);
+    if(token.mail === 'undefined' || token.mail === -1){
+      return sendError(res, 500, -1, "User not authenticated.");
+    } else{
+      return token;
+    }
+  } else {
+    return sendError(res, 500, -1, "Cookies don't exist.");
+  }
+}
+module.exports.checkLogin = checkLogin;
diff --git a/backend/app/controllers/user.controller.js b/backend/app/controllers/user.controller.js
index b0cc4cf..9659cef 100644
--- a/backend/app/controllers/user.controller.js
+++ b/backend/app/controllers/user.controller.js
@@ -1,11 +1,13 @@
 const db = require("../models/mongodb.model");
 const {sendError, sendMessage} = require ("../config/response.config");
+const checkFormat = require("../config/checkFormat.config");
 const sessionJWT = require('../config/sessionJWT.config');
+const {checkLogin} = require("../config/sessionJWT.config");
 const User = db.users;
 
-
 // Authenticate an User
 exports.auth = (req, res) => {
+  checkFormat(req, res);
   // Validate request
   if (!req.body.mail || !req.body.hashPass) {
     sendError(res, 400,-1,"Content can not be empty ! (mail and hashPass needed)");
@@ -19,7 +21,7 @@ exports.auth = (req, res) => {
           return sendMessage(res, 1, true);
         } else {
           sessionJWT.setSessionCookie(req, res, { mail: -1 });
-          return sendError(res, -1, "Invalid mail or password.");
+          return sendError(res, 500, -1, "Invalid mail or password.");
         }
       })
       .catch(err => {
@@ -28,8 +30,19 @@ exports.auth = (req, res) => {
   }
 };
 
+// Disconnect an User
+exports.disconnect = (req, res) => {
+  let token;
+  if(checkFormat(req, res) && (token = checkLogin(req, res))) {
+    console.log(token);
+    sessionJWT.setSessionCookie(req, res, {mail: -1});
+    return sendMessage(res, 1, {message: "User disconnected"});
+  }
+};
+
 // Create and Save a new User
 exports.create = (req, res) => {
+    checkFormat(req, res);
   // Validate request
   if (!req.body.login || !req.body.hashPass || !req.body.mail || !req.body.role) {
     sendError(res, 400,-1,"Content can not be empty ! (login, hashPass,  mail and role needed");
@@ -67,20 +80,25 @@ exports.create = (req, res) => {
 
 // Retrieve all Users from the database.
 exports.findAll = (req, res) => {
-  const login = req.query.login;
-  let condition = login ? { login: { $regex: new RegExp(login), $options: "i" } } : {};
+  let token;
+  if(checkFormat(req, res) && (token = checkLogin(req, res))){
+    console.log(token);
+    const login = req.query.login;
+    let condition = login ? { login: { $regex: new RegExp(login), $options: "i" } } : {};
 
-  User.find(condition, {hashPass: false})
-    .then(data => {
-      sendMessage(res, 1, data)
-    })
-    .catch(err => {
-      sendError(res,500,-1,err.message || "Some error occurred while retrieving users.");
-    });
+    User.find(condition, {hashPass: false})
+      .then(data => {
+        sendMessage(res, 1, data)
+      })
+      .catch(err => {
+        sendError(res,500,-1,err.message || "Some error occurred while retrieving users.");
+      });
+  }
 };
 
 // Find a single User with an id
 exports.findOne = (req, res) => {
+  checkFormat(req, res);
   const id = req.params.id;
 
   User.findById(id, {hashPass: false})
@@ -98,6 +116,7 @@ exports.findOne = (req, res) => {
 
 // Update a User by the id in the request
 exports.update = (req, res) => {
+  checkFormat(req, res);
   if (!req.body) {
     sendError(res,400,-1,"Data to update can not be empty!");
   } else{
@@ -119,6 +138,7 @@ exports.update = (req, res) => {
 
 // Delete a User with the specified id in the request
 exports.delete = (req, res) => {
+  checkFormat(req, res);
   const id = req.params.id;
 
   User.findByIdAndRemove(id)
@@ -136,6 +156,7 @@ exports.delete = (req, res) => {
 
 // Delete all Users from the database.
 exports.deleteAll = (req, res) => {
+  checkFormat(req, res);
   User.deleteMany({})
     .then(data => {
       sendMessage(res, 1,{
diff --git a/backend/app/models/user.model.js b/backend/app/models/user.model.js
index bf8a5c8..fe29d74 100644
--- a/backend/app/models/user.model.js
+++ b/backend/app/models/user.model.js
@@ -14,5 +14,5 @@ module.exports = mongoose => {
     return object;
   });
 
-  return User = mongoose.model("user", schema);
+  return mongoose.model("user", schema);
 };
diff --git a/backend/app/routes/user.routes.js b/backend/app/routes/user.routes.js
index 7eee3e1..b3ba76f 100644
--- a/backend/app/routes/user.routes.js
+++ b/backend/app/routes/user.routes.js
@@ -23,5 +23,8 @@ module.exports = app => {
   // Authenticate a User
   router.post("/auth", users.auth);
 
+  // Disconnect a User
+  router.delete("/auth/disconnect", users.disconnect);
+
   app.use('/api/users', router);
 };
diff --git a/backend/package.json b/backend/package.json
index 1316b91..15a6c33 100644
--- a/backend/package.json
+++ b/backend/package.json
@@ -16,5 +16,6 @@
     "express": "^4.17.1",
     "jsonwebtoken": "^8.5.1",
     "mongoose": "^6.0.12"
-  }
+  },
+  "devDependencies": {}
 }