ShieldNVM

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Data encryption and authentication are essential for secure non-volatile memory (NVM). However, the introduced security metadata needs to be atomically written back to NVM along with data, so as to provide crash consistency, which unfortunately incurs high overhead. To support fine-grained data protection and fast recovery for a secure NVM system without compromising the performance, we propose ShieldNVM. It first proposes an epoch-based mechanism to aggressively cache the security metadata in the metadata cache while retaining the consistency of them in NVM. Deferred spreading is also introduced to reduce the calculating overhead for data authentication. Leveraging the ability of data hash message authentication codes, we can always recover the consistent but old security metadata to its newest version. By recording a limited number of dirty addresses of the security metadata, ShieldNVM achieves fast recovering the secure NVM system after crashes. Compared to Osiris, a state-of-the-art secure NVM, ShieldNVM reduces system runtime by 39.1% and hash message authentication code computation overhead by 80.5% on average over NVM workloads. When system crashes happen, ShieldNVM’s recovery time is orders of magnitude faster than Osiris. In addition, ShieldNVM also recovers faster than AGIT, which is the Osiris-based state-of-the-art mechanism addressing the recovery time of the secure NVM system. Once the recovery process fails, instead of dropping all data due to malicious attacks, ShieldNVM is able to detect and locate the area of the tampered data with the help of the tracked addresses.