Building a high-performance, programmable secure coprocessor

Secure coprocessors enable secure distributed applications by providing safe havens where an application program can execute (and accumulate state), free of observation and interference by an adversary with direct physical access to the device. However, for these coprocessors to be effective, participants in such applications must be able to verify that they are interacting with an authentic program on an authentic, untampered device. Furthermore, secure coprocessors that support general-purpose computation and will be manufactured and distributed as commercial products must provide these core sanctuary and authentication properties while also meeting many additional challenges, including: the applications, operating system, and underlying security management may all come from different, mutually suspicious authorities; configuration and maintenance must occur in a hostile environment, while minimizing disruption of operations; the device must be able to recover from the vulnerabilities that inevitably emerge in complex software; hardware constraints dictate that support for advanced cryptography depends on reloadable software; and physical security dictates that the device itself can never be opened and examined. This paper summarizes the hardware, software, and cryptographic architecture we developed to address these problems. Furthermore, with our colleagues, we have implemented this solution, now available as a commercial product.