Accessing Api data using HMAC Authentication

 have api_key, secret and I have to hash the signature to sha256. The signature = api_key+secret+utctimestamp. I am using Crypto.Js for hashing. I am getting following error

XMLHttpRequest cannot load "HOST LINK". No
'Access-Control-Allow-Origin' header is present on the requested resource. Origin localhost is therefore not allowed access

Following is my code

<script>
var app = (function($){

var baseURL = 'http://xyz.herokuapp.com/api/v1';
var apiSecretKey = 'ABC';
var apiKey = '123';
var init = function(){


$('#login').on('click', function(e){
    e.preventDefault();
    login();
});




};

var login = function() {

var u = encodeURIComponent($('#username').val());
var p = encodeURIComponent($('#password').val());

$.ajax({
    type: "POST",
    url: baseURL + "/login",
    contentType: "application/json; charset=utf-8",
    dataType: "json",
    data: JSON.stringify({email: u, password: p}),      
    beforeSend: function (request) {
        request.setRequestHeader('Access-Control-Allow-Origin', 'http://localhost');
        request.setRequestHeader('X-HASH', getHMAC(apiKey, timestamp));
    },
    success: function (data) {

    $('.loggedIn').show();
    console.log(data);
    $('.loggedIn .name').text("Hello ");
    },
    error: function (errorMessage) {
    alert('Error logging in');
    }
});
};


 timestamp = new Date().getTime() / 1000;;



var getHMAC = function(key, timestamp) {
    var hash = CryptoJS.SHA256(key+timestamp+apiSecretKey);
    return hash.toString();
};


return {
init:init
};
})(jQuery);

app.init();

Is the error due to wrong hashing or CORS problem. This is the first time I am using HMAC authentication, I don't know if I am doing it right or wrong.

Google developer tools give me this information![enter image description here][1]

REQUEST Method: OPTION Status Code: 200 Ok

Request Header Access-Control-Request-Headers:access-control-allow-origin, accept, content-type, x-hash Access-Control-Request-Method:POST

Response Header Allow:DELETE, POST, OPTIONS Connection:keep-alive Content-Length:0 Content-Type:text/html; charset=utf-8 Date:Mon, 04 Aug 2014 21:30:06 GMT Server:gunicorn/18.0 Via:1.1 vegur