Cryptology ePrint Archive: Report 2019/512

Tight Leakage-Resilient CCA-Security from Quasi-Adaptive Hash Proof System

Shuai Han and Shengli Liu and Lin Lyu and Dawu Gu

Abstract: We propose the concept of quasi-adaptive hash proof system (QAHPS), where the projection key is allowed to depend on the specific language for which hash values are computed. We formalize leakage-resilient(LR)-ardency for QAHPS by defining two statistical properties, including LR-<L_0,L_1>-universal and LR-<L_0,L_1>-key-switching.

We provide a generic approach to tightly leakage-resilient CCA (LR-CCA) secure public-key encryption (PKE) from LR-ardent QAHPS. Our approach is reminiscent of the seminal work of Cramer and Shoup (Eurocrypt'02), and employ three QAHPS schemes, one for generating a uniform string to hide the plaintext, and the other two for proving the well-formedness of the ciphertext. The LR-ardency of QAHPS makes possible the tight LR-CCA security. We give instantiations based on the standard k-Linear (k-LIN) assumptions over asymmetric and symmetric pairing groups, respectively, and obtain fully compact PKE with tight LR-CCA security. The security loss is O(log Q_e) where Q_e denotes the number of encryption queries. Specifically, our tightly LR-CCA secure PKE instantiation from SXDH has only 4 group elements in the public key and 7 group elements in the ciphertext, thus is the most efficient one.

Category / Keywords: public-key cryptography / public-key encryption, leakage-resilience, CCA security, tight security reduction, hash proof system

Original Publication (with major differences): IACR-CRYPTO-2019

Date: received 16 May 2019, last revised 22 May 2019

Contact author: dalen17 at sjtu edu cn, slliu@sjtu edu cn, lvlin@sjtu edu cn, dwgu@sjtu edu cn

Available format(s): PDF | BibTeX Citation

Note: Minor changes for descriptions.

Version: 20190523:022833 (All versions of this report)

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