Round and Communication Balanced Protocols for Oblivious Evaluation of Finite State Machines

Rafael Dowsley; Caleb Horst; Anderson C A Nascimento

Paper 2021/375

Round and Communication Balanced Protocols for Oblivious Evaluation of Finite State Machines

Rafael Dowsley, Caleb Horst, and Anderson C A Nascimento

Abstract

We propose protocols for obliviously evaluating finite-state machines, i.e., the evaluation is shared between the provider of the finite-state machine and the provider of the input string in such a manner that neither party learns the other's input, and the states being visited are hidden from both. For alphabet size $|\Sigma|$, number of states $|Q|$, and input length $n$, previous solutions have either required a number of rounds linear in $n$ or communication $\Omega(n|\Sigma||Q|\log|Q|)$. Our solutions require 2 rounds with communication $O(n(|\Sigma|+|Q|\log|Q|))$. We present two different solutions to this problem, a two-party one and a setting with an untrusted but non-colluding helper.

Metadata

Available format(s): PDF
Category: Cryptographic protocols
Publication info: Preprint. MINOR revision.
Contact author(s): rafael dowsley @ monash edu
calebjh @ uw edu
andclay @ uw edu
History: 2022-01-06: revised; 2021-03-22: received; See all versions
Short URL: https://ia.cr/2021/375
License: CC BY

BibTeX

@misc{cryptoeprint:2021/375,
      author = {Rafael Dowsley and Caleb Horst and Anderson C A Nascimento},
      title = {Round and Communication Balanced Protocols for Oblivious Evaluation of Finite State Machines},
      howpublished = {Cryptology ePrint Archive, Paper 2021/375},
      year = {2021},
      note = {\url{https://eprint.iacr.org/2021/375}},
      url = {https://eprint.iacr.org/2021/375}
}