Mitigate residual side channels in private semantic database retrieval

Develop and evaluate padding or other defenses that eliminate residual side-channel leakage, including leakage through per-record note lengths, in private semantic database retrieval using the TME carousel.

Background

The carousel scans every database record in a fixed order to hide access patterns and fixed-output padding removes content-dependent timing leakage. However, the paper notes that other observable properties, such as the lengths of per-record notes, may still reveal information. The authors identify mitigation of these residual channels as future work.

References

For PSDR, we consider timing and access-pattern leakage, following ORAM literature, but other side channels, such as per-record note lengths, may remain. These can be mitigated with padding, similar to our fixed-output padding for content-dependent timing (\S\ref{sec:components}); these are left as future work.

— Trusted Model Environment for Private Semantic Computations  (2609.30032 - Duddu et al., 24 Sep 2026) in Section 4.2, Evaluation Metrics—Confidentiality (Computation)