Practical Garbled RAM: GRAM with $O(log^2 n)$ Overhead

David Heath

Abstract:

Garbled RAM (GRAM) is a powerful technique that equips Garbled Circuit (GC) with a sublinear cost RAM without adding rounds of interaction. While GRAM constructions are known, none are suitable for practice, due to costs that have high constants and poor scaling.

In this talk, I will present the first GRAM suitable for practice. For computational security parameter $\kappa$ and for a size-n RAM that stores blocks of size $w = \Omega(log^2 n)$ bits, our GRAM incurs only amortized $O(w log^2 n \kappa)$ communication and computation per access. We evaluated the concrete cost of our GRAM; our approach outperforms trivial linear-scan-based RAM for as few as 512 128-bit elements.

Time and Place

Tuesday, November 16, 2:00pm
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