In this article, we introduce a single-chip secure processor called Aegis. In addition to supporting mechanisms to authenticate the platform and software, our processor incorporates mechanisms to protect the integrity and privacy of applications from physical attacks as well as software attacks. Therefore, physically secure systems can be built using this processor. Two key primitives, physical unclonable functions (PUFs) and off-chip memory protection, enable the physical security of our system. These primitives can also be easily applied to other secure computing systems to enhance their security.