Passwords establish the identity of a user, and they are an
essential component of modern information technology. In this
article, I describe one-time passwords: passwords that you use
once and then never again. Because they’re used only once, you
don’t have to remember them. I describe how to implement one-
time passwords with a Texas Instruments (TI) eZ430-Chronos
wireless development tool in a watch and how to use them to log
in to existing web services such as Google Gmail (see Photo 1).
Photo 1—The Texas Instruments eZ430 Chronos watch displays a
unique code that enables logging into Google Gmail. The code is
derived from the current time and a secret value embedded in the
watch. To help me get around on the Internet, I use a list of
about 80 passwords (at the latest count). Almost any online
service I use requires a password: reading e-mail, banking,
shopping, checking reservations, and so on. Many of these
Internet-based services have Draconian password rules. For
example, some sites require a password