Cryptology ePrint Archive: Report 2019/487

From Single-Input to Multi-Client Inner-Product Functional Encryption

Michel Abdalla and Fabrice Benhamouda and Romain Gay

Abstract: We present a new generic construction of multi-client functional encryption (MCFE) for inner products from single-input functional inner-product encryption and standard pseudorandom functions. In spite of its simplicity, the new construction supports labels, achieves security in the standard model under adaptive corruptions, and can be instantiated from the plain DDH, LWE, and Paillier assumptions. Prior to our work, the only known constructions required discrete-log-based assumptions and the random-oracle model. Since our new scheme is not compatible with the compiler from Abdalla et al. (PKC 2019) that decentralizes the generation of the functional decryption keys, we also show how to modify the latter transformation to obtain a decentralized version of our scheme with similar features.

Category / Keywords: cryptographic protocols / Decentralized, multi-client functional encryption, inner products

Original Publication (with minor differences): IACR-ASIACRYPT-2019

Date: received 13 May 2019, last revised 16 Feb 2020

Contact author: romain rgay at gmail com,michel abdalla@ens fr,fabrice benhamouda@normalesup org

Available format(s): PDF | BibTeX Citation

Note: update on Section5: Decentralized Multi-Client Functional Encryption

Version: 20200216:234216 (All versions of this report)

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