Leakage Resilient IBE and IPE under the DLIN Assumption

In this paper, we show identity-based encryption (IBE) and inner product encryption (IPE) schemes which achieve the maximum-possible leakage rate 1 − o(1). These schemes are secure under the decision linear (DLIN) assumption in the standard model. Specifically, even if 1− o(1) fraction of each private key is arbitrarily leaked, the IBE scheme is fully secure and the IPE scheme is selectively secure. (To our knowledge, no leakage resilient IPE scheme has been known so far.) Moreover, their variants with leakage rate 1/2− o(1) enjoy comparable private keys and ciphertexts with the counterparts without leakage resilience in the literature.