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 $n$ of the parties, and not just for $2$). 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 $n-1$ 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).
Category / Keywords: cryptographic protocols / Reverse Firewalls, Multi-party Computation, Coin-tossing, Broadcast Original Publication (with minor differences): IACR-CRYPTO-2020 Date: received 13 Nov 2019, last revised 20 Aug 2020 Contact author: suvradip1111 at gmail com, stefan dziembowski at gmail com, jbn at cs au dk Available format(s): PDF | BibTeX Citation Version: 20200821:012316 (All versions of this report) Short URL: ia.cr/2019/1317