Decentralizing Inner-Product Functional Encryption

Michel Abdalla, Fabrice Benhamouda, Markulf Kohlweiss, Hendrik Waldner

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Multi-client functional encryption (MCFE) is a more flexible variant of functional encryption whose functional decryption involves multiple ciphertexts from different parties. Each party holds a different secret key and can independently and adaptively be corrupted by the adversary. We present two compilers for MCFE schemes for the inner-product functionality, both of which support encryption labels. Our first compiler transforms any scheme with a special key-derivation property into a decentralized scheme, as defined by Chotard et al. (ASIACRYPT 2018), thus allowing for a simple distributed way of generating functional decryption keys without a trusted party. Our second compiler allows to lift an unnatural restriction present in existing (decentralized) MCFE schemes, which requires the adversary to ask for a ciphertext from each party. We apply our compilers to the works of Abdalla et al. (CRYPTO 2018) and Chotard et al. (ASIACRYPT 2018) to obtain schemes with hitherto unachieved properties. From Abdalla et al., we obtain instantiations of DMCFE schemes in the standard model (from DDH, Paillier, or LWE) but without labels. From Chotard et al., we obtain a DMCFE scheme with labels still in the random oracle model, but without pairings.
Original languageEnglish
Title of host publicationPublic-Key Cryptography - PKC 2019 - 22nd IACR International Conference on Practice and Theory of Public-Key Cryptography, Beijing, China, April 14-17, 2019, Proceedings, Part II
PublisherSpringer, Cham
Pages128-157
Number of pages30
ISBN (Electronic)978-3-030-17259-6
ISBN (Print)978-3-030-17258-9
DOIs
Publication statusE-pub ahead of print - 6 Apr 2019
Event22nd edition of the International Conference on Practice and Theory of Public Key Cryptography - Beijing Friendship Hotel, Beijing, China
Duration: 14 Apr 201917 Apr 2019
Conference number: 22
https://pkc.iacr.org/2019/

Publication series

NameLecture Notes in Computer Science (LNCS)
PublisherSpringer, Cham
Volume11443
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349
NameSecurity and Cryptology
Volume11443

Conference

Conference22nd edition of the International Conference on Practice and Theory of Public Key Cryptography
Abbreviated titlePKC 2019
CountryChina
CityBeijing
Period14/04/1917/04/19
Internet address

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