diff --git a/bot/Bot.php b/bot/Bot.php
index b42b944..e7f2ad4 100644
--- a/bot/Bot.php
+++ b/bot/Bot.php
@@ -15,16 +15,18 @@ class Bot
         return $masters[array_rand($masters)];
     }
 
-    public function __construct(array $config = [])
+    public function __construct(Request $request, array $config = [])
     {
+        $this->request = $request;
         $this->config = $config;
     }
 
-    // TODO
-    public function isValid(Request $request): bool
+    public function isRequestValid(): bool
     {
-        $this->request = $request;
-        return $this->config['token'] === $request->getToken();
+        return hash_equals(
+            hash_hmac('sha256', $this->request->nc_random . $this->request->body, $this->config['secret']),
+            strtolower($this->request->nc_signature)
+        );
     }
 
     /**
diff --git a/bot/Commands/Help.php b/bot/Commands/Help.php
index 605472c..f541912 100644
--- a/bot/Commands/Help.php
+++ b/bot/Commands/Help.php
@@ -9,18 +9,21 @@ class Help implements Icommands
 
     public static function getMessage(Bot $bot, array $data): void
     {
-        $message = 'Voici la liste de mes commandes : '."\n";
+        $bot->replyPolitely('Voici la liste de mes commandes');
+
+        $message = '|Nom|Description|Pattern|'."\n";
+        $message .= '|---|---|---|'."\n";
         foreach ($bot->listCommands() as $command) {
             $message .= sprintf(
-                '%s : %s (%s)%s',
-                $command,
+                '|%s|%s|`%s`|%s',
+                end(explode('\\', $command)),
                 call_user_func([$command, 'getDescription']),
-                call_user_func([$command, 'getPattern']),
+                str_replace('|', '\|', call_user_func([$command, 'getPattern'])),
                 "\n"
             );
         }
 
-        $bot->replyPolitely($message);
+        $bot->reply($message);
     }
 
     public static function getDescription(): string
diff --git a/bot/Request.php b/bot/Request.php
index 8838baf..a97339a 100644
--- a/bot/Request.php
+++ b/bot/Request.php
@@ -2,7 +2,54 @@
 
 namespace Shikiryu\Bot;
 
+use JsonException;
+
 class Request
 {
+    public string $nc_signature;
+    public string $nc_random;
+    public string $nc_server;
+    public string $delivery;
+    public string $event;
+    public string $signature;
+    public string $body;
 
+    public function __construct()
+    {
+        $this->nc_signature = $_SERVER['HTTP_X_NEXTCLOUD_TALK_SIGNATURE'] ?? '';
+        $this->nc_random = $_SERVER['HTTP_X_NEXTCLOUD_TALK_RANDOM'] ?? '';
+        $this->nc_server = $_SERVER['HTTP_X_NEXTCLOUD_TALK_BACKEND'] ?? '';
+
+        $this->delivery = $_SERVER['HTTP_X_H1_DELIVERY'] ?? '';
+        $this->event = $_SERVER['HTTP_X_H1_EVENT'] ?? '';
+        $this->signature = $_SERVER['HTTP_X_H1_SIGNATURE'] ?? '';
+        $this->body = file_get_contents('php://input');
+    }
+
+    public function getJSONBody(): array
+    {
+        try {
+            return json_decode($this->body, true, 512, JSON_THROW_ON_ERROR);
+        } catch (JsonException $e) {
+            return [];
+        }
+    }
+
+    public function isMessage(): bool
+    {
+        $data = $this->getJSONBody();
+        return $data['type'] === 'Create' &&
+            $data['object']['name'] === 'message' &&
+            !empty($data['object']['content']);
+    }
+
+    public function getMessage(): string
+    {
+        try {
+            $data = $this->getJSONBody();
+            return json_decode($data['object']['content'], true, 512, JSON_THROW_ON_ERROR)['message'];
+        } catch (JsonException $e) {
+            return '';
+        }
+    }
 }
\ No newline at end of file
diff --git a/nextcloud.php b/nextcloud.php
index d026ccf..3b65d38 100644
--- a/nextcloud.php
+++ b/nextcloud.php
@@ -1,24 +1,22 @@
 <?php
 
 use Shikiryu\Bot\Bot;
-
+use Shikiryu\Bot\Request;
 
 require 'vendor/autoload.php';
 
 error_reporting(E_ALL);
 ini_set('log_errors', 1);
 
-$config = include 'config.php';
+$config = include __DIR__.'/config.php';
 
-$bot = new Bot($config);
+$request = new Request();
+$bot = new Bot($request, $config);
 
-$signature = $_SERVER['HTTP_X_NEXTCLOUD_TALK_SIGNATURE'] ?? '';
-$random = $_SERVER['HTTP_X_NEXTCLOUD_TALK_RANDOM'] ?? '';
-$server = $_SERVER['HTTP_X_NEXTCLOUD_TALK_BACKEND'] ?? '';
-
-$delivery = $_SERVER['HTTP_X_H1_DELIVERY'] ?? '';
-$event = $_SERVER['HTTP_X_H1_EVENT'] ?? '';
-$signature = $_SERVER['HTTP_X_H1_SIGNATURE'] ?? '';
+if (!$bot->isRequestValid()) {
+    $bot->reply('I received an invalid request');
+    exit;
+}
 
 // Give the bot something to listen for.
 foreach ($bot->listCommands() as $command) {
@@ -29,22 +27,11 @@ $bot->hears('(hello|hi|bonjour|salut)', function (Bot $bot) {
     $bot->replyPolitely('Bonjour');
 });
 
-$body = file_get_contents('php://input');
-try {
-    $data = json_decode($body, true, 512, JSON_THROW_ON_ERROR);
-} catch (JsonException $e) {
-    $data = [];
-}
-
 // Only on message, not on event or whatever
-if ($data['type'] !== 'Create' || $data['object']['name'] !== 'message') {
+if (!$request->isMessage()) {
     return ;
 }
 
-try {
-    $message = json_decode($data['object']['content'], true, 512, JSON_THROW_ON_ERROR)['message'];
-} catch (JsonException $e) {
-    return;
-}
+$message = $request->getMessage();
 
 $bot->listen($message);