var data = {
    foo:'This is foo!',
    bar:'This is bar!'
  };
  var hash = CryptoJS.HmacSHA512(JSON.stringify(data), 'secret').toString();
  //e2cd7674aaa16afe505a866348cc3f7288fe1a96acf7da6096c84ee9cc1c8269f6b1cc67f95dfb3680dc761155812fd5b284afbd590f8c0b9cb9e711c82b8490

  $.ajax({
    type: 'POST',
    url: '//localhost/api',
    data: {
      data: data,
      hash: hash
    }
  }).always(function(data) {
    console.log(data.responseText);
  });