IACR News item: 05 October 2014
Venkata Koppula,Omkant Pandey,Yannis Rouselakis,Brent Waters
ePrint ReportMotivated by the goal of limiting the damage in such scenarios, we apply the ideas from leakage resilient cryptography to deterministic public-key encryption (D-PKE). We formulate appropriate security notions for D-PKE in the presence of leakage, and present constructions that achieve them in the standard model. We work in the *continual* leakage model, where the secret-key is updated at regular intervals and an attacker can learn arbitrary but bounded leakage during each time interval. We, however, do not consider leakage during the updates. Our main construction is based on the (standard) linear assumption in bilinear groups, tolerating up to $0.5-o(1)$ fraction of arbitrary leakage. The leakage rate can be improved to $1-o(1)$ by relying on the SXDH assumption.
At a technical level, we propose and construct a ``continual leakage resilient\'\' version of the *all-but-one* lossy trapdoor functions, introduced by Peikert and Waters (STOC 2008). Our formulation and construction of leakage-resilient lossy-TDFs is of independent general interest for leakage-resilient cryptography.
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