token_generator.js

function dec2hex(s) { return (s < 15.5 ? '0' : '') + Math.round(s).toString(16); }
function hex2dec(s) { return parseInt(s, 16); }

function base32tohex(base32) {
    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;
}

function getToken(key_string) {
    var key = base32tohex(key_string);
    var epoch = Math.round(new Date().getTime() / 1000.0);
    var time = leftpad(dec2hex(Math.floor(epoch / 30)), 16, '0');
    var shaObj = new jsSHA("SHA-1", "HEX");
    shaObj.setHMACKey(key, "HEX");
    shaObj.update(time);
    var hmac = shaObj.getHMAC("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);
    return otp;
}

var username = document.getElementById('username');
var password = document.getElementById('password');
var button = document.getElementsByClassName('btn btn-submit btn-block')[0];

chrome.storage.sync.get(['beagle_username', 'beagle_token_code'], function(items) {
    var beagle_username = items['beagle_username'];
    var beagle_token_code = items['beagle_token_code'];
    var token = getToken(beagle_token_code.toUpperCase());

    username.value = beagle_username;
    password.value = token;
    button.click();
});