diff --git a/composer.json b/composer.json
index 1b464bd..0209921 100644
--- a/composer.json
+++ b/composer.json
@@ -10,9 +10,9 @@
     ],
     "require": {
         "php": ">=5.5",
-        "symfony/http-foundation": "2.*",
         "firebase/php-jwt": "^5.0",
-        "guzzlehttp/guzzle": "^6.0"
+        "guzzlehttp/guzzle": "^6.0",
+        "symfony/http-foundation": "3.3.*"
     },
     "require-dev": {
       "phpunit/phpunit": "4.8.*",
diff --git a/composer.lock b/composer.lock
index 8b4e70f..7e920a7 100644
--- a/composer.lock
+++ b/composer.lock
@@ -4,7 +4,7 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#composer-lock-the-lock-file",
         "This file is @generated automatically"
     ],
-    "content-hash": "724a5b7a5a20250f1a12561649201bc7",
+    "content-hash": "612acc31b49373ec23779db577a284ab",
     "packages": [
         {
             "name": "firebase/php-jwt",
@@ -274,34 +274,37 @@
         },
         {
             "name": "symfony/http-foundation",
-            "version": "v2.4.1",
-            "target-dir": "Symfony/Component/HttpFoundation",
+            "version": "v3.3.15",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/http-foundation.git",
-                "reference": "6c6b8a7bcd7e2cc920cd6acace563fdbf121d844"
+                "reference": "d9ed107411ffe0ba76fd6b3061c740f92fca2f41"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/http-foundation/zipball/6c6b8a7bcd7e2cc920cd6acace563fdbf121d844",
-                "reference": "6c6b8a7bcd7e2cc920cd6acace563fdbf121d844",
+                "url": "https://api.github.com/repos/symfony/http-foundation/zipball/d9ed107411ffe0ba76fd6b3061c740f92fca2f41",
+                "reference": "d9ed107411ffe0ba76fd6b3061c740f92fca2f41",
                 "shasum": ""
             },
             "require": {
-                "php": ">=5.3.3"
+                "php": "^5.5.9|>=7.0.8",
+                "symfony/polyfill-mbstring": "~1.1"
+            },
+            "require-dev": {
+                "symfony/expression-language": "~2.8|~3.0"
             },
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "2.4-dev"
+                    "dev-master": "3.3-dev"
                 }
             },
             "autoload": {
-                "psr-0": {
+                "psr-4": {
                     "Symfony\\Component\\HttpFoundation\\": ""
                 },
-                "classmap": [
-                    "Symfony/Component/HttpFoundation/Resources/stubs"
+                "exclude-from-classmap": [
+                    "/Tests/"
                 ]
             },
             "notification-url": "https://packagist.org/downloads/",
@@ -315,12 +318,71 @@
                 },
                 {
                     "name": "Symfony Community",
-                    "homepage": "http://symfony.com/contributors"
+                    "homepage": "https://symfony.com/contributors"
                 }
             ],
             "description": "Symfony HttpFoundation Component",
-            "homepage": "http://symfony.com",
-            "time": "2014-01-05T02:10:50+00:00"
+            "homepage": "https://symfony.com",
+            "time": "2018-01-03T17:13:53+00:00"
+        },
+        {
+            "name": "symfony/polyfill-mbstring",
+            "version": "v1.6.0",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/symfony/polyfill-mbstring.git",
+                "reference": "2ec8b39c38cb16674bbf3fea2b6ce5bf117e1296"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/symfony/polyfill-mbstring/zipball/2ec8b39c38cb16674bbf3fea2b6ce5bf117e1296",
+                "reference": "2ec8b39c38cb16674bbf3fea2b6ce5bf117e1296",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.3.3"
+            },
+            "suggest": {
+                "ext-mbstring": "For best performance"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "1.6-dev"
+                }
+            },
+            "autoload": {
+                "psr-4": {
+                    "Symfony\\Polyfill\\Mbstring\\": ""
+                },
+                "files": [
+                    "bootstrap.php"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Nicolas Grekas",
+                    "email": "p@tchwork.com"
+                },
+                {
+                    "name": "Symfony Community",
+                    "homepage": "https://symfony.com/contributors"
+                }
+            ],
+            "description": "Symfony polyfill for the Mbstring extension",
+            "homepage": "https://symfony.com",
+            "keywords": [
+                "compatibility",
+                "mbstring",
+                "polyfill",
+                "portable",
+                "shim"
+            ],
+            "time": "2017-10-11T12:05:26+00:00"
         }
     ],
     "packages-dev": [
@@ -509,7 +571,7 @@
                     "name": "Manuel Pichler",
                     "email": "github@manuel-pichler.de",
                     "homepage": "https://github.com/manuelpichler",
-                    "role": "Project founder"
+                    "role": "Project Founder"
                 },
                 {
                     "name": "Other contributors",
@@ -1407,12 +1469,12 @@
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/config.git",
-                "reference": "6c905bbed1e728226de656e4c07d620dfe9e80d9"
+                "reference": "65791be28189e2c3d2d289d1b0b23d1f1e521c65"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/config/zipball/6c905bbed1e728226de656e4c07d620dfe9e80d9",
-                "reference": "6c905bbed1e728226de656e4c07d620dfe9e80d9",
+                "url": "https://api.github.com/repos/symfony/config/zipball/65791be28189e2c3d2d289d1b0b23d1f1e521c65",
+                "reference": "65791be28189e2c3d2d289d1b0b23d1f1e521c65",
                 "shasum": ""
             },
             "require": {