passman/js/app/directives/otp.js

'use strict';

/**
 * @ngdoc directive
 * @name passmanApp.directive:passwordGen
 * @description
 * # passwordGen
 */
angular.module('passmanApp')
	.directive('otpGenerator', ['$compile', '$timeout',
		function ($compile, $timeout) {
			function dec2hex(s) { return (s < 15.5 ? '0' : '') + Math.round(s).toString(16); }
			function hex2dec(s) { return parseInt(s, 16); }

			function base32tohex(base32) {
				if(!base32){
					return;
				}
				var base32chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567";
				var bits = "";
				var hex = "";

				for (var i = 0; i < base32.length; i++) {
					var val = base32chars.indexOf(base32.charAt(i).toUpperCase());
					bits += leftpad(val.toString(2), 5, '0');
				}

				for (var i = 0; i+4 <= bits.length; i+=4) {
					var chunk = bits.substr(i, 4);
					hex = hex + parseInt(chunk, 2).toString(16) ;
				}
				return hex;

			}

			function leftpad(str, len, pad) {
				if (len + 1 >= str.length) {
					str = Array(len + 1 - str.length).join(pad) + str;
				}
				return str;
			}
			return {
				restrict: 'A',
				template: '<span class="otp_generator"><span credential-field value="otp" secret="\'true\'"></span> <span ng-bind="timeleft"></span></span>',
				transclude: false,
				scope: {
					secret: '='
				},
				replace: true,
				link: function (scope, element) {
					scope.otp = null;
					scope.timeleft = null;
					scope.timer = null;
					var updateOtp = function () {
						if (!scope.secret) {
							return;
						}
						var key = base32tohex(scope.secret);
						var epoch = Math.round(new Date().getTime() / 1000.0);
						var time = leftpad(dec2hex(Math.floor(epoch / 30)), 16, '0');
						var hmacObj = new jsSHA(time, 'HEX');
						var hmac = hmacObj.getHMAC(key, 'HEX', 'SHA-1', "HEX");
						var offset = hex2dec(hmac.substring(hmac.length - 1));
						var otp = (hex2dec(hmac.substr(offset * 2, 8)) & hex2dec('7fffffff')) + '';
						otp = (otp).substr(otp.length - 6, 6);
						scope.otp = otp;

					};

					var timer = function () {
						var epoch = Math.round(new Date().getTime() / 1000.0);
						var countDown = 30 - (epoch % 30);
						if (epoch % 30 == 0) updateOtp();
						scope.timeleft = countDown;
						scope.timer = $timeout(timer, 1000);

					};
					scope.$watch("secret", function (n) {
						if (n) {
							$timeout.cancel(scope.timer);
							updateOtp();
							timer();
						} else {
							$timeout.cancel(scope.timer);
						}
					}, true);
					scope.$on(
						"$destroy",
						function (event) {
							$timeout.cancel(scope.timer);
						}
					);
				}
			}
		}
	]);