ArenaNet has announced that, effective immediately, Guild Wars 2 players can take part in the new beta of a two-factor authentication system. Players can download and install an authenticator program for a desktop PC or Mac and/or Android and iPhone mobile platforms. The new authentication system is designed to protect player accounts from hackers.
Mobile two-factor authentication is an alternative means of securing your Guild Wars 2account, and like e-mail authentication, is optional but strongly encouraged. Rather than sending you an e-mail when unauthorized login attempts occur, the game (or any of our online web sites) will prompt you for a six-digit number any time you log in to a Mobile Authenticator-protected account. Using a freely available app on three major smartphone platforms – iOS, Android, and Windows Phone – you can obtain the correct six-digit number unique to your account. These numbers change every 30 seconds and can only be used once; this ensures that without your mobile device, an attacker would not be able to compromise your Guild Wars 2 account.
Read more on the Guild Wars 2 site.