title: Apple push notifications certificate upload issue with sinch sms verification
body: <p>I have created development and production <code>APNS</code> certificates through keychain access. However, when I try to upload <code>aps.cer</code> and <code>aps-development.cer</code> to the push configuration dashboard at sinch.com, it says:</p>
  
  <blockquote>
    <p>Error: Incorrect file type, or file too big. Must be pkcs12 and less than 10kbyte.</p>
  </blockquote>
  
  <p>I went back to the Apple Developer portal and downloaded the <code>.cer</code> files there and tried again to no avail.</p>