Secure and Durable (SEDURA): An Integrated Encryption and Wear-leveling Framework for PCM-based Main Memory

Phase changing memory (PCM) is considered a promising candidate for next-generation main-memory. Despite its advantages of lower power and high density, PCM faces critical security challenges due to its non-volatility: data are still accessible by the attacker even if the device is detached from a power supply. While encryption has been widely adopted as the solution to protect data, it not only creates additional performance and energy overhead during data encryption/decryption, but also hurts PCM lifetime by introducing more writes to PCM cells. In this paper, we propose a framework that integrates encryption and wear-leveling so as to mitigate the adverse impact of encryption on PCM performance and lifetime. Moreover, by randomizing the address space during wear-leveling, an extra level of protection is provided to the data in memory. We propose two algorithms that respectively prioritize data security and memory lifetime, allowing designers to trade-off between these two factors based on their needs. Compared to previous encryption techniques, the proposed SEDURA framework is able to deliver both more randomness to protect data and more balanced PCM writes, thus effectively balancing the three aspects of data security, application performance, and device lifetime.