This research develops Code White, a hardware-implemented trusted execution mechanism for the Symbian mobile operating system. Code White combines a signed whitelist approach with the execute never bit in the ARM architecture. It prevents all untrusted code from executing while minimally impacting the user experience, as shown via validation and performance testing. Smartphones have proven to be invaluable to military, civic, and business users due in a large part to their ability to execute code just like any desktop computer can. While many useful applications have been developed for these users, numerous malicious programs have also surfaced. And while smartphones have desktop-like capabilities to execute software, they do not have the same resources to scan for malware. More efficient means which minimize resource usage are needed.