Consistency for Functional Encryption

Christian Badertscher, Aggelos Kiayias, Markulf Kohlweiss, Hendrik Waldner

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

Abstract

In functional encryption (FE) a sender, Alice, encrypts plaintexts for which a receiver, Bob, can obtain functional evaluations, while Charlie is responsible for initializing the encryption keys and issuing the decryption keys. Standard notions of security for FE deal with a malicious Bob and guarantee the confidentiality of Alice’s messages despite the leakage that occurs due to the functional keys that are revealed to the adversary via various forms of indistinguishability experiments that correspond to IND-CPA, IND-CCA and simulation-based security.

In this work we provide a complete and systematic investigation of Consistency, a natural security property for FE, that deals with attacks that can be mounted by Alice, Charlie or a collusion of the two against Bob. We develop three main types of consistency notions according to which set of parties is corrupted and investigate their relation to the standard security properties of FE. To validate our different consistency types, we extend the universally composable framework for FE by Matt and Maurer (CSF 2015) and we show that our consistency notions naturally complement FE security by proving how they imply (and are implied by) UC security depending on which set of parties is corrupted; in this way we demonstrate a complete characterization of consistency for FE. Finally, we provide explicit constructions that achieve consistency efficiently either directly via a construction based on MDDH for specific function classes of inner products over a modulo group or generically for all the consistency types via compilers using standard cryptographic tools.
Original languageEnglish
Title of host publication2021 IEEE 34th Computer Security Foundations Symposium (CSF)
PublisherIEEE
Pages1-16
Number of pages47
ISBN (Electronic)978-1-7281-7607-9
ISBN (Print)978-1-7281-7608-6
DOIs
Publication statusPublished - 10 Aug 2021
Event34th IEEE Computer Security Foundations Symposium -
Duration: 21 Jun 202125 Jun 2021
https://www.ieee-security.org/TC/CSF2021/accepted.html

Publication series

Name
ISSN (Print)1940-1434
ISSN (Electronic)2374-8303

Symposium

Symposium34th IEEE Computer Security Foundations Symposium
Abbreviated titleCSF 2021
Period21/06/2125/06/21
Internet address

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