## Cryptology ePrint Archive: Report 2013/654

Leakage-Resilient Chosen-Ciphertext Secure Public-Key Encryption from Hash Proof System and One-Time Lossy Filter

Baodong Qin and Shengli Liu

Abstract: We present a new generic construction of a public-key encryption (PKE) scheme secure against leakage-resilient chosen-ciphertext attacks (LR-CCA), from any Hash Proof System (HPS) and any one-time lossy filter (OT-LF). Efficient constructions of HPSs and OT-LFs from the DDH and DCR assumptions suggest that our construction is a practical approach to LR-CCA security. Most of practical PKEs with LR-CCA security, like variants of Cramer-Shoup scheme, rooted from Hash Proof Systems, but with leakage rates at most $1/4-o(1)$ (defined as the ratio of leakage amount to secret-key size). The instantiations of our construction from the DDH and DCR assumptions result in LR-CCA secure PKEs with leakage rate of $1/2-o(1)$. On the other hand, our construction also creates a new approach for constructing IND-CCA secure (leakage-free) PKE schemes, which may be of independent interest.

Category / Keywords: public-key cryptography / Public-key encryption, leakage-resilience, chosen-ciphertext security, hash proof system

Original Publication (with minor differences): IACR-ASIACRYPT-2013