Touching and finger-swiping are the dominant method of navigating on hundreds of millions of smartphones and tablet computers. The same touch might soon confirm your identity, too.

A new device dispatches a few bits of data, representing a password, from a special ring on your finger and sends the data as tiny voltage bursts through your skin for capture by the screen of the phone, so that your touch alone identifies you by the code from the ring.

Depending on the application, this could allow rapid switching between settings of people who share the same device, allow a game to distinguish between multiple players using the same screen, replace passwords, or provide an additional layer of protection atop passwords (see "Study Reveals a Confused View of Mobile Phone Privacy and Security").