hesela.devOblivious RAM
Oblivious RAM hides logical storage access patterns by making physical accesses for equal-length request sequences computationally indistinguishable.
Scope: The trusted client protects its state while the storage server observes physical accesses. The standard definition compares equal-length sequences; request timing and frequency are excluded from the Path ORAM model. Integrity and freshness require additional protection. [1]
Cost: Read/write traffic that waits for a requested block is online bandwidth. Overall bandwidth also includes maintenance such as eviction and reshuffling. Ring ORAM separates these costs; its constant online transfer variant requires server-side XOR computation, not just a passive store. [2]
Relations
Citations
- Stefanov et al. Path ORAM: An Extremely Simple Oblivious RAM Protocol. JACM 65(4), 2018, sections 2-4 and 6.4. DOI 10.1145/3177872.
- Ren et al. Constants Count: Practical Improvements to Oblivious RAM. USENIX Security 2015, sections 1.3, 3 and 5.
Further reading
Sources & caveats
- Reviewed the author-hosted JACM 2018 and USENIX Security 2015 papers. This is a definition of their models, not a claim that a deployed service hides all metadata.