Cryptology ePrint Archive: Report 2022/398

Auditable, Available and Resilient Private Computation on the Blockchain via MPC

Christopher Cordi and Michael P. Frank and Kasimir Gabert and Carollan Helinski and Ryan C. Kao and Vladimir Kolesnikov and Abrahim Ladha and Nicholas Pattengale

Abstract: Simple but mission-critical internet-based applications that require extremely high reliability, availability, and verifiability (e.g., auditability) could benefit from running on robust public programmable blockchain platforms such as Ethereum. Unfortunately, program code running on such blockchains is normally publicly viewable, rendering these platforms unsuitable for applications requiring strict privacy of application code, data, and results. In this work, we investigate using MPC techniques to protect the privacy of a blockchain computation. While our main goal is to hide both the data and the computed function itself, we also consider the standard MPC setting where the function is public. We describe GABLE (Garbled Autonomous Bots Leveraging Ethereum), a blockchain MPC architecture and system. The GABLE architecture specifies the roles and capabilities of the players. GABLE includes two approaches for implementing MPC over blockchain: Garbled Circuits (GC), evaluating universal circuits, and Garbled Finite State Automata (GFSA). We formally model and prove the security of GABLE implemented over garbling schemes, a popular abstraction of GC and GFSA from (Bellare et al, CCS 2012). We analyze in detail the performance (including Ethereum gas costs) of both approaches and discuss the trade-offs. We implement a simple prototype of GABLE and report on the implementation issues and experience.

Category / Keywords: cryptographic protocols / MPC, garbled circuits, blockchain, garbled FSA

Original Publication (with major differences): 6th International Symposium on Cyber Security, Cryptology and Machine Learning (CSCML 2022)

Date: received 27 Mar 2022

Contact author: mpfrank at sandia gov, vlad kolesnikov at gmail com

Available format(s): PDF | BibTeX Citation

Note: To be published at CSCML 2022.

Version: 20220328:144554 (All versions of this report)

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