H2O2RAM: A High-Performance Hierarchical Doubly Oblivious RAM
Leqian Zheng
34th USENIX Security Symposium (USENIX Security '25) · Day 3 · Crypto 5: HE, MPC, Oblivious Computation
In the realm of modern computing, particularly within cloud environments leveraging **Trusted Execution Environments (TEEs)**, the confidentiality of data is paramount. However, traditional security measures often fall short in protecting against a subtle yet potent class of attacks: those that infer sensitive information by observing a program's **access patterns**. While encryption secures data at rest and in transit, the sequence and location of memory accesses during computation can still leak critical insights, such as inferring a secret value by observing which accounts are accessed in a transaction. This talk introduces **Oblivious RAM (ORAM)** as a fundamental primitive designed to mitigate such leakage, ensuring that memory access patterns provide no meaningful information beyond the total length of the input data.
AI review
Solid systems-crypto research that actually moves the needle on a long-standing practical barrier. A 1,000x speedup over prior ORAM state-of-the-art is a real number that demands attention, and the engineering behind it — adaptive hash scheme selection, stashless cuckoo construction, numerical parameter optimization — reflects genuine depth rather than asymptotic hand-waving.