HER FINALIST PROJECT: Figuring out what an odd perfect number would look like

What led to the project: As a student at the Bronx High School of Science, Susan Landau excelled at math. Born to immigrant parents who never went to college, Landau was already taking linear algebra at Lehman College when she was a high school senior. When it came time to choose a project for the annual Westinghouse Science Talent Search, Landau decided to work on the number theory problem of what an odd perfect number would have to look like. It was a bit of a hypothetical problem, because all the known perfect numbers are even (that is, divisible by 2).

A perfect number is a number that is equal to the sum of the numbers that can be divided into it neatly except itself. For instance, 6 is the sum of 1, 2 and 3; 28 is the sum of 1, 2, 4, 7 and 14. She didn't actually find an odd perfect number (in fact, no one has), but she came up with some intriguing ideas about the minimum number of prime factors that perfect number would have to have. "They weren't theorems that would have astounded an established number theorist," she says, but they were good enough to earn her a finalist nod in the 1972 Westinghouse Science Talent Search.

The effect on her career: Landau studied math at Princeton as an undergraduate, but soon became interested in theoretical computer science. She ultimately wound up earning a PhD from the Massachusetts Institute of Technology in this area, working on problems related to Galois theory, which involves breaking down certain equations into their roots.

Landau started out in academia, working at Wesleyan, and the University of Massachusetts Amherst. Her research made advances in symbolic computation and algebraic algorithms, including ideas that can be used in cryptography.

She enjoyed the work. However, her husband was also an academic computer scientist, and for years they faced what academic families ruefully call "the two body problem." Finding one tenure track job is tough. Finding two tenure-track jobs in similar fields in the same geographic area is even tougher, as Landau has described. Branching out to industry promised to alleviate the problem a bit, and eventually, Sun Microsystems "made me an offer I couldn't refuse," Landau says. In 1999 she started working for Sun from home.

What she's doing now: As a distinguished engineer at Sun, Landau has worked on Sun's principles for digital rights management, and on how to share a user's information efficiently while respecting privacy. She's best known, though, for her work on security and public policy.

The rub? Governments want the ability to do surveillance on communications to fight crime—and have asked communications companies to build surveillance capability into their devices—but wiretapping is, at its more fundamental level, a security breach. "Grant the [National Security Administration] what it wants, and within 10 years the United States will be vulnerable to attacks from hackers across the globe, as well as the militaries of China, Russia and other nations,” she wrote last year in the Washington Post.  Her main point is that any openings left for government agencies to monitor communications will ultimately be available to terrorists and others with less savory motives. It's as if the police wanted houses built with faulty basement doors so they could get in more quickly in emergencies. You'd have a lot of burglaries on your hands.

She's since spoken on this topic to many audiences, and given Congressional briefings. That, in part, led the Anita Borg Institute (which advances the cause of women in technology) to honor her with one of three 2008 Women of Vision awards.  "The tech work she's done has had a huge social impact on security policy," notes Telle Whitney, the Anita Borg CEO. "She's a phenomenal role model."