Applebaum, B and Ishai, Y and Karni, O and Patra, A (2022) Quadratic Multiparty Randomized Encodings Beyond Honest Majority and Their Applications. In: 42nd Annual International Cryptology Conference, CRYPTO 2022, 15 August 2022 - 18 August 2022, Barbara, pp. 453-482.
Full text not available from this repository.Abstract
Multiparty randomized encodings (Applebaum, Brakerski, and Tsabary, SICOMP 2021) reduce the task of securely computing a complicated multiparty functionality f to the task of securely computing a simpler functionality g. The reduction is non-interactive and preserves information-theoretic security against a passive (semi-honest) adversary, also referred to as privacy. The special case of a degree-2 encoding g (2MPRE) has recently found several applications to secure multiparty computation (MPC) with either information-theoretic security or making black-box access to cryptographic primitives. Unfortunately, as all known constructions are based on information-theoretic MPC protocols in the plain model, they can only be private with an honest majority. In this paper, we break the honest-majority barrier and present the first construction of general 2MPRE that remains secure in the presence of a dishonest majority. Our construction encodes every n-party functionality f by a 2MPRE that tolerates at most t= ⌊ 2 n/ 3 ⌋ passive corruptions. We derive several applications including: (1) The first non-interactive client-server MPC protocol with perfect privacy against any coalition of a minority of the servers and up to t of the n clients; (2) Completeness of 3-party functionalities under non-interactive t-private reductions; and (3) A single-round t-private reduction from general-MPC to an ideal oblivious transfer (OT). These positive results partially resolve open questions that were posed in several previous works. We also show that t-private 2MPREs are necessary for solving (2) and (3), thus establishing new equivalence theorems between these three notions. Finally, we present a new approach for constructing fully-private 2MPREs based on multi-round protocols in the OT-hybrid model that achieve perfect privacy against active attacks. Moreover, by slightly restricting the power of the active adversary, we derive an equivalence between these notions. This forms a surprising, and quite unique, connection between a non-interactive passively-private primitive to an interactive actively-private primitive.
| Item Type: | Conference Paper |
|---|---|
| Publication: | Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) |
| Publisher: | Springer Science and Business Media Deutschland GmbH |
| Additional Information: | The copyright for this article belongs to Springer Science and Business Media Deutschland GmbH |
| Keywords: | Computation theory; Cryptography, reductions; Black boxes; Cryptographic primitives; Encodings; Information- theoretic securities; Multi-party computation protocols; Oblivious transfer; Secure multi-party computation; Semi-honest adversaries; Simple++, Encoding (symbols) |
| Department/Centre: | Division of Electrical Sciences > Computer Science & Automation |
| Date Deposited: | 13 Dec 2022 05:46 |
| Last Modified: | 13 Dec 2022 05:46 |
| URI: | https://eprints.iisc.ac.in/id/eprint/78723 |
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