Improving privacy and lifetime of PCM-based main memory

Phase change memory (PCM) is a promising technology for computer memory systems. However, the non-volatile nature of PCM poses serious threats to computer privacy. The low programming endurance of PCM devices also limits the lifetime of PCM-based main memory (PRAM). In this paper, we first adopt counter-mode encryption for privacy protection and show that encryption significantly reduces the effectiveness of some previously proposed wear-leveling techniques for PRAM. To mitigate such adverse impact, we propose simple, yet effective extensions to the encryption scheme. In addition, we propose to reuse the encryption counters as age counters and to dynamically adjust the strength of error correction code (ECC) to extend the lifetime of PRAM. Our experiments show that our mechanisms effectively achieve privacy protection and lifetime extension for PRAM with very low performance overhead.