Access to our data can no longer hinge on secrets—a string of characters, 10 strings of characters, the answers to 50 questions—that only we’re supposed to know. The Internet doesn’t do secrets. Everyone is a few clicks away from knowing everything. Instead, our new system will need to hinge on who we are and what we do: where we go and when, what we have with us, how we act when we’re there. And each vital account will need to cue off many such pieces of information—not just two, and definitely not just one.