His work focuses on finding vulnerabilities in insecure systems, and building secure systems. In 2003 he was part of the team that conducted the first security review of the Diebold electronic voting machine software, and he also conducted the first public experimental security analysis of a modern implantable cardiac device (2008) and a complete automobile (2010 and 2011). His group also framed a networked printer for copyright infringement, with the printer receiving a DMCA takedown notice for illegally downloading Iron Man. Prior to academia, Kohno worked as a cryptographer and security consultant at Counterpane Systems and Cigital. Kohno is the co-author of Cryptography Engineering, with Niels Ferguson and Bruce Schneier, and is chairing the 2012 USENIX Security Symposium.