In one embodiment, a system includes a non-volatile memory that may serve as both the main memory system and the backing store (or persistent storage). In some embodiments, the non-volatile memory is divided into a main memory portion and a persistent portion. Data in the main memory operation may be encrypted using one or more first keys, and data in the persistent portion may be encrypted using one or more second keys, in an embodiment. The volatile behavior of main memory may be implemented by discarding the one or more first keys in a power down event or other event that indicates a loss of main memory data, while the one or more second keys may be retained. In one embodiment, the physical address space of the non-volatile memory may be a mapping from a second physical address space that is used within the system.