H2O2RAM - A High-Performance Hierarchical Doubly Oblivious RAM

Learn about H2O2RAM, a novel high-performance hierarchical doubly oblivious RAM construction presented at USENIX Security '25. Explore how this 15-minute conference talk addresses the challenges of combining Oblivious RAM (ORAM) with Trusted Execution Environments (TEE) to create doubly oblivious RAM (O2RAM) that ensures memory accesses are oblivious both inside and outside TEEs. Discover the innovative hierarchical framework approach that distinguishes H2O2RAM from existing tree-based doubly oblivious designs, offering superior data locality and parallelization capabilities. Understand how the researchers from City University of Hong Kong and ByteDance Inc. overcame the conflict between FutORAMa's relaxed assumption of sublinear-sized client-side private memory and the doubly oblivious requirement by introducing new efficient oblivious components. Examine the impressive performance improvements demonstrated through implementation and evaluation, including execution time reductions of up to 10³ times and memory usage savings by factors of 5-44 compared to state-of-the-art solutions, making this research particularly valuable for applications requiring protection against memory access pattern attacks in TEE environments.