How to Obfuscate MPC Inputs

Ian McQuoid; Mike Rosulek; Jiayu Xu

Paper 2022/1463

How to Obfuscate MPC Inputs

Ian McQuoid, Oregon State University

Mike Rosulek, Oregon State University

Jiayu Xu, Oregon State University

Abstract

We introduce the idea of input obfuscation for secure two-party computation ($\textsf{io2PC}$). Suppose Alice holds a private value $x$ and wants to allow clients to learn $f(x,y_i)$, for their choice of $y_i$, via a secure computation protocol. The goal of $\textsf{io2PC}$ is for Alice to encode $x$ so that an adversary who compromises her storage gets only oracle access to the function $f(x,\cdot)$. At the same time, there must be a 2PC protocol for computing $f(x,y)$ that takes only this encoding (and not the plaintext $x$) as input. We show how to achieve $\textsf{io2PC}$ for functions that have virtual black-box (VBB) obfuscation in either the random oracle model or generic group model. For functions that can be VBB-obfuscated in the random oracle model, we provide an $\textsf{io2PC}$ protocol by replacing the random oracle with an oblivious PRF. For functions that can be VBB-obfuscated in the generic group model, we show how Alice can instantiate a "personalized" generic group. A personalized generic group is one where only Alice can perform the algebraic operations of the group, but where she can let others perform operations in that group via an oblivious interactive protocol.

Note: Full version of an IACR publication in TCC 2022

Metadata

Available format(s): PDF
Category: Cryptographic protocols
Publication info: A major revision of an IACR publication in TCC 2022
Keywords: Secure Multiparty Computation Obfuscation Virtual Black Box
Contact author(s): mcquoidi @ oregonstate edu
rosulekm @ eecs oregonstate edu
xujiay @ oregonstate edu
History: 2022-10-26: approved; 2022-10-26: received; See all versions
Short URL: https://ia.cr/2022/1463
License: CC BY

BibTeX

@misc{cryptoeprint:2022/1463,
      author = {Ian McQuoid and Mike Rosulek and Jiayu Xu},
      title = {How to Obfuscate {MPC} Inputs},
      howpublished = {Cryptology {ePrint} Archive, Paper 2022/1463},
      year = {2022},
      url = {https://eprint.iacr.org/2022/1463}
}