Title: Delegation-based conversion from CPA to CCA-secure predicate encryption

Authors: Mridul Nandi; Tapas Pandit

Addresses: Applied Statistics Unit, Indian Statistical Institute Kolkata, India ' Department of Computer Science and Automation, Indian Institute of Science Bangalore, India

Abstract: In 2011, Yamada et al. proposed CPA to CCA-secure conversions for attribute-based encryption (ABE) based on the properties, verifiability and delegation. Later, the verifiability-based conversion was generalised from ABE to predicate encryption (PE) by Yamada et al. (2012) and Nandi et al. (2017). We observe that for bilinear-pairing based PE schemes, the cost of CCA-decryption blows up to the double of the cost of CPA-decryption due to verifiability testing. Therefore, the conversion based on delegation is mostly acceptable whenever a delegation-based conversion is available for the primitive PE scheme. In this paper, we investigate a generic delegation-based conversion from CPA to CCA-secure predicate encryption schemes. Our conversion generalises the delegation-based conversion of Yamada et al. (2011) from ABE to PE. We show that our conversion captures many subclasses of PE, e.g., (hierarchical) inner-product encryption, (doubly-)spatial encryption and functional encryption for regular languages.

Keywords: predicate encryption; delegation; CPA to CCA conversion.

DOI: 10.1504/IJACT.2020.10029197

International Journal of Applied Cryptography, 2020 Vol.4 No.1, pp.16 - 35

Accepted: 30 Dec 2018
Published online: 06 May 2020 *

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