IACR News item: 25 March 2015
Baodong Qin, Shengli Liu
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\\item We introduce the Refined Subgroup Indistinguishability (RSI) assumption, which is a subclass of subgroup indistinguishability assumptions, including many standard number-theoretical assumptions, like the quadratic residuosity assumption, the decisional composite residuosity assumption and the subgroup decision assumption over a group of known order defined by Boneh et al.
\\item We show that universal hash proof (UHP) system and one-time lossy filter (OT-LF) can be simply and efficiently constructed from the RSI assumption. Applying Qin and Liu\'s paradigm gives simple and efficient PKE schemes under the RSI assumption.
\\item With the RSI assumption over a specific group (free of pairing), public parameters of UHP and OT-LF can be chosen in a flexible way, resulting in a leakage-flexible CCA-secure PKE scheme. More specifically, we get the first CCA-secure PKE with leakage rate of $1-o(1)$ without pairing.
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