International Association
for Cryptologic Research

We explore the problem of preventing length leakage in oblivious data access mechanisms with passive persistent adversaries. Designing mechanisms that prevent both access pattern and length leakage requires navigating a three-way tradeoff between storage footprint, bandwidth footprint, and the information leaked to the adversary. We establish powerful lower bounds on achievable storage and bandwidth footprints for a variety of leakage profiles, and present constructions that perfectly or near-perfectly match the lower bounds.