There is no such thing as a truly secure password; there are only more secure or less secure passwords. Passwords are currently the most convenient and effective way to control access to your accounts. But passwords are a mess. We have too many; sometimes they are all the same, which makes it easier for a hacker; many passwords are “123456” and easy to crack; and there are numerous ways that a criminal can spy on us to log our keystrokes.
http://robertsiciliano.com/blog/2013/11/20/passwords-fingerprint-heartbeat-or-brainwaves/