AWS Signed Cookie from Signed URL cross domain

aws-signed-cookie-from-signed-url.js

/**
 * aws-signed-cookie-from-signed-url.js
 * Include this file in the landing page of the CloudFront assets where a signed url (from another domain) would direct users to
 * If the url is signed (i.e. has Policy, Signature and Key-Pair-Id params) it will create cookies for those attributes based on AWS rules
 * This will allow the internal navigation of CloudFront assets without the need of signed urls for each asset
 */

/**
 *
 */
function getUrlVars() {
	var vars = {};
	var parts = window.location.href.replace(/[?&]+([^=&]+)=([^&]*)/gi, function(m,key,value) {
		vars[key] = value;
	});
	return vars;
}

/**
 *
 * @param parameter
 * @param defaultvalue
 * @returns {*}
 */
function getUrlParam(parameter, defaultvalue){
	var urlparameter = defaultvalue;
	if(window.location.href.indexOf(parameter) > -1){
		urlparameter = getUrlVars()[parameter];
	}
	return urlparameter;
}

/**
 *
 * @param cname
 * @param cvalue
 * @param exdays
 */
function setCookie(cname, cvalue, exdays) {
	var d = new Date();
	d.setTime(d.getTime() + (exdays*24*60*60*1000));
	var expires = "expires="+ d.toUTCString();
	document.cookie = cname + "=" + cvalue + ";" + expires + ";path=/";
}

var Policy = getUrlParam('Policy', '');
var Signature = getUrlParam('Signature', '');
var KeyPairId = getUrlParam('Key-Pair-Id', '');

if (Policy != '' && Signature != '' && KeyPairId != '') {
	//delete cookie first
	setCookie('CloudFront-Policy', '', 0);
	setCookie('CloudFront-Signature', '', 0);
	setCookie('CloudFront-Key-Pair-Id', '', 0);

	//set the cookie
	setCookie('CloudFront-Policy', Policy, 1);
	setCookie('CloudFront-Signature', Signature, 1);
	setCookie('CloudFront-Key-Pair-Id', KeyPairId, 1);
}

@darbelaez Thank you for the info. Did the setup but it seems the script expects a signed URL with a custom policy. Is this a requirement or can this work with a canned policy too?

Thanks, got it working with the signed URL with custom policy. After doing it, it became clear how the custom policy is used by the signed cookies.

Thanks, got it working with the signed URL with custom policy. After doing it, it became clear how the custom policy is used by the signed cookies.

Yes! forgot to mention that - i was using a Custom policy - did not try it with a Canned policy but i'm it can be made to work with one with some minor modification. Glad to hear it's working for you.

How does this work for SPA applications?