Paper 2019/1317

Reverse Firewalls for Actively Secure MPCs

Suvradip Chakraborty, Stefan Dziembowski, and Jesper Buus Nielsen

Abstract

Reverse firewalls were introduced at Eurocrypt 2015 by Mironov and Stephens-Davidowitz, as a method for protecting cryptographic protocols against attacks on the devices of the honest parties. In a nutshell: a reverse firewall is placed outside of a device and its goal is to ``sanitize'' the messages sent by it, in such a way that a malicious device cannot leak its secrets to the outside world. It is typically assumed that the cryptographic devices are attacked in a ``functionality-preserving way'' (i.e. informally speaking, the functionality of the protocol remains unchanged under this attacks). In their paper, Mironov and Stephens-Davidowitz construct a protocol for passively-secure two-party computations with firewalls, leaving extension of this result to stronger models as an open question. In this paper, we address this problem by constructing a protocol for secure computation with firewalls that has two main advantages over the original protocol from Eurocrypt 2015. Firstly, it is a multiparty computation protocol (i.e. it works for an arbitrary number of the parties, and not just for ). Secondly, it is secure in much stronger corruption settings, namely in the actively corruption model. More precisely: we consider an adversary that can fully corrupt up to parties, while the remaining parties are corrupt in a functionality-preserving way. Our core techniques are: malleable commitments and malleable non-interactive zero-knowledge, which in particular allow us to create a novel protocol for multiparty augmented coin-tossing into the well with reverse firewalls (that is based on a protocol of Lindell from Crypto 2001).

Metadata
Available format(s)
PDF
Category
Cryptographic protocols
Publication info
A minor revision of an IACR publication in CRYPTO 2020
Keywords
Reverse FirewallsMulti-party ComputationCoin-tossingBroadcast
Contact author(s)
suvradip1111 @ gmail com
stefan dziembowski @ gmail com
jbn @ cs au dk
History
2020-08-21: last of 2 revisions
2019-11-17: received
See all versions
Short URL
https://ia.cr/2019/1317
License
Creative Commons Attribution
CC BY

BibTeX

@misc{cryptoeprint:2019/1317,
      author = {Suvradip Chakraborty and Stefan Dziembowski and Jesper Buus Nielsen},
      title = {Reverse Firewalls for Actively Secure {MPCs}},
      howpublished = {Cryptology {ePrint} Archive, Paper 2019/1317},
      year = {2019},
      url = {https://eprint.iacr.org/2019/1317}
}
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