added check to see if browser is gcm compliant

frontend/src/upload.js

@@ -1,10 +1,18 @@
 const FileSender = require('./fileSender');
-const { notify } = require('./utils');
+const { notify, gcmCompliant } = require('./utils');
 const $ = require('jquery');
 
 const Raven = window.Raven;
 
 $(document).ready(function() {
+
+  // added as a print statement for now, eventually move init stuff
+  // into here and display an error page if it's not compliant
+  gcmCompliant().catch(err => {
+    $('#page-one').hide();
+    $('#compliance-error').show();
+  })
+
   // reset copy button
   const $copyBtn = $('#copy-btn');
   $copyBtn.attr('disabled', false);
@@ -15,6 +23,7 @@ $(document).ready(function() {
   $('#upload-progress').hide();
   $('#share-link').hide();
   $('#upload-error').hide();
+  $('#compliance-error').hide();
 
   if (localStorage.length === 0) {
     toggleHeader();

frontend/src/utils.js

@@ -32,8 +32,42 @@ function notify(str) {
   }
 }
 
+function gcmCompliant() {
+  try {
+    return window.crypto.subtle.generateKey(
+      {
+        name: 'AES-GCM',
+        length: 128
+      },
+      true,
+      ['encrypt', 'decrypt']
+    ).then(key => {
+      return window.crypto.subtle.encrypt(
+        {
+          name: 'AES-GCM',
+          iv: window.crypto.getRandomValues(new Uint8Array(12)),
+          additionalData: window.crypto.getRandomValues(new Uint8Array(6))
+        },
+        key,
+        new ArrayBuffer(8)
+      )
+      .then(() => {
+        return Promise.resolve()
+      })
+      .catch(err => {
+        return Promise.reject()
+      })
+    }).catch(err => {
+      return Promise.reject();
+    })
+  } catch(err) {
+    return Promise.reject();
+  }
+}
+
 module.exports = {
   arrayToHex,
   hexToArray,
-  notify
+  notify,
+  gcmCompliant
 };

views/index.handlebars

@@ -100,6 +100,16 @@
       </div>
     </div>
 
+    <div id="compliance-error">
+      <div class="title">
+        Encryption error<br>
+        Your browser does not support gcm encryption.
+      </div>
+      <div class="send-new">
+        Send another file
+      </div>
+    </div>
+
   </div>
 
 </body>