Seeds of SEED: Efficient Access Pattern Obfuscation for Untrusted Hybrid Memory System

The emerging non-volatile memory (NVM) is considered a well-qualified candidate for main memory due to its competitive performance, high density, and near-zero idle power. However, the low write endurance hinders NVM from being widely used as the main memory. So hybrid memory architecture (HMA), composed of DRAM and NVM, is used to mitigate this limitation by storing frequently written data in DRAM. Meanwhile, the HMA still has security vulnerabilities, such as side-channel attacks, through memory access patterns. Oblivious RAM (ORAM) can eliminate access patterns leakage to prevent such attacks. However, with massive extra write operations for obfuscation, even in HMA, ORAM can significantly reduce the lifetime of NVM. Providing access pattern protection is still a challenge for a system with NVM. This work aims to propose an efficient access pattern obfuscation framework for a hybrid NVM memory system. We use a lightweight data shuffling scheme to obfuscate NVM’s access pattern. We propose a two-level structure to store the data in NVM while the shuffled mapping information is stored in the DRAM with Path ORAM structure to ensure security. The experimental results show that we improve performance 1.67× compared to Path ORAM, and reduce 96% extra writes that can mitigate the endurance problem of NVM.