Techniques for protecting software in a computing device are provided. A method according to these techniques includes receiving a request from a non-secure software module to execute an instruction of a secure software module comprising encrypted program code, determining whether the instruction comprises an instruction associated with a controlled point of entry to the secure software module accessible outside of the secure software module, executing one or more instructions of the secure software module responsive to the instruction comprising an instruction associated with the controlled point of entry to the secure software module, and controlling exit from the secure software module to return execution to the non-secure software module.