each person's DNA is unique to that person. What we need is a small device made by Microsoft and each time a password code is needed we just spit at the device
I'll do ya one better. A device you strap to your arm that will only activate if the devices stored DNA profile matches the profile of the person it is strapped to.
Then when a request comes through, it just verifies the DNA by doing a skin-prick or whatever and then automagically approving the request.
Sure your arm may look like you are a junkie after a while, but it is more convenient than making up and remembering a long, easy for you to remember password and then having to type it in all the time.
Who cares if you have blood dripping off of your arm all the time... you can just like it off and get the nutrients back, right?