Creating a new Gava checkout via html form

gava.html

<form name="gava" action="http://example.com/checkout?redirect_to_checkout">
  <input type="hidden" name="reference" value="12" />
  <input type="hidden" name="amount" value="1.00" />
  <input type="hidden" name="return_url" value="http://example.com/thankyou" />
  <input type="hidden" name="cancel_url" value="http://example.com/cart" />
  <input type="hidden" name="signature" value="0b4b9b07fa062952d1df68a04382a8d0ce1f5fc23e03e53081a14f86f905f6b6ecd2a1bb2cc60157e4a5492cc382292cc10a0c5809fced9ae11cd6ac35f0bd70" />
  <input type="submit" />
</form>