Thomas Dullien, the security researcher widely known as Halvar Flake, has joined OpenAI to work on cybersecurity and computing efficiency. He announced on X on August 4 that he would start the following Monday. OpenAI and Dullien have not published a formal job title.
Dullien is best known for reverse-engineering and software-security research. He founded zynamics, whose BinDiff tool became an industry standard for comparing executable programs, and joined Google when it acquired the company. He later worked on Google's Project Zero security team, where his research included helping demonstrate how the Rowhammer hardware flaw could be exploited.
More recently, Dullien co-founded Optimyze to measure and reduce wasted computing across large cloud fleets. After Elastic acquired the company, he continued that work as a distinguished engineer—experience that connects the two parts of his new remit at OpenAI.