In the $\mathcal{F}_{\mathsf{SyX}}$-hybrid model, the two parties load $\mathcal{F}_{\mathsf{SyX}}$ with some input, and following this, either party can trigger $\mathcal{F}_{\mathsf{SyX}}$ with a suitable ``witness'' at a later time to receive the output from $\mathcal{F}_{\mathsf{SyX}}$. Crucially the other party also receives output from $\mathcal{F}_{\mathsf{SyX}}$ when $\mathcal{F}_{\mathsf{SyX}}$ is triggered. The trigger witnesses allow us to synchronize the trigger phases of multiple instances of $\mathcal{F}_{\mathsf{SyX}}$, thereby aiding in the design of fair multiparty protocols. Additionally, a pair of parties may reuse a single a priori loaded instance of $\mathcal{F}_{\mathsf{SyX}}$ in any number of multiparty protocols (possibly involving different sets of parties).
Category / Keywords: cryptographic protocols / secure multiparty computation, fair exchange, completeness, preprocessing Date: received 11 Aug 2020, last revised 7 Oct 2020 Contact author: rakumare at visa com,srraghur@visa com,asealfon@berkeley edu Available format(s): PDF | BibTeX Citation Version: 20201007:203231 (All versions of this report) Short URL: ia.cr/2020/976