Soteria: Towards Resilient Integrity-Protected and Encrypted Non-Volatile Memories

Although emerging Non-Volatile Memories (NVMs) are expected to be adopted in future memory and storage systems, their nonvolatility brings complications in designing processors wherein security is an essential requirement. One of these complications is maintaining the correctness of the security metadata for encryption and integrity verification. Due to the accommodation of security metadata in the NVMs, they are susceptible to reliability threats posed by the underlying memory technology. This is undesirable because the secure operation of the system highly depends on the correctness of the security metadata stored in the memory. We observe that the error sensitivity of security metadata is higher than general data and requires special attention. A single uncorrectable error in a top Merkle tree node can leave a large portion of memory data unverifiable. To solve this, we propose Soteria, a scheme that provides higher error-tolerance of security metadata by lazily duplicating them. Soteria decouples existing memory reliability from the security metadata reliability and achieves security, performance, and high reliability within the same system with only minor memory controller changes. Our proposed scheme improves the reliability of the improved security NVM system significantly while causing only about 1% system slowdown on average.