Ivan Krstic´, 21

Ivan Krstic takes extracurricular activities to the extreme. Born in Croatia, he received a scholarship to attend a Michigan high school when he was 13. While there, he wrote software to interpret data for a neuroscientist at the University of Michigan. He also spent two summers in Croatia, building a patient-management computer system for Zagreb Children's Hospital. He enrolled at Harvard in 2004 but then took a year's leave to return to Croatia and reëngineer the Zagreb hospital's IT system--after a month-long detour to Silicon Valley to help scale up Facebook's software architecture.

Krstic returned to Harvard in 2005 to work on a degree in computer science and theoretical math, but he took another leave last spring to become director of security architecture for the One Laptop per Child (OLPC) program, which is building inexpensive laptops for Third World children. His mandate was to create a secure system that children could use, and that wouldn't need the tech support and continual updates that current anti­virus programs require.

So he set about making such software obsolete, building into OLPC's Linux-based operating system a ­security platform called Bitfrost, named after Bifröst, a bridge in Norse ­mythology that reaches from Earth to heaven and that intruders can't cross. Instead of blocking specific viruses, the system sequesters every program on the computer in a separate virtual operating system, preventing any program from damaging the computer, stealing files, or spying on the user. Viruses are left isolated and impotent, unable to execute their code. "This defeats the entire purpose of writing a virus," says Krstic.

Some in the Linux community are so impressed with this novel approach to fighting malicious code that they have proposed making it part of the Linux standard. But since Bitfrost will allow only programs that are aware of it to run, it would make Linux incompatible with existing applications. The solution is for programmers to create "wrappers," small programs tacked onto existing applications to enable them to communicate with Bitfrost. After OLPC's computer ships late this year, Krstic plans to return to Harvard--and to help write those wrappers. It's just one more ­extracurricular activity to take on.

--Richard L. Brandt