The XO laptop (previously known as the $100 laptop) is poised to create a computing monoculture, and it’s Ivan Krstic's job to make sure it's a monoculture of impossible targets. As director of security architecture at the nonprofit OLPC, Krstic created Bitfrost, an architecture-level specification that provides a comprehensive overview of the XO’s security model, covering everything from use of passwords, hard-drive encryption, machine authentication, security updates and data-loss prevention. If Bitfrost proves itself on the XO, it will influence anti-malware security on mainstream operating systems.