Sign Google Maps for Business requests with the privateKey using Node.js

sign_request.js

var crypto = require('crypto'),
    url = require('url'),
    URLSafeBase64 = require('urlsafe-base64');

function GenerateSignature(privateKey, query) {
    var u = url.parse(query);
    var urlToSign = u.path;
    var decodedKey = URLSafeBase64.decode(privateKey);
    var signature = crypto.createHmac('sha1', decodedKey).update(urlToSign);
    var encodedSignature = URLSafeBase64.encode(signature.digest());

    return "http://maps.googleapis.com" + u.pathname + "?" + u.query + "&signature=" + encodedSignature;
}