Our contribution is three-fold. First, we put forth a new formal model of secure MPC with compensation and we show how the introduction of suitable ledger and synchronization functionalities makes it possible to express completely such protocols using standard interactive Turing machines (ITM) circumventing the need for the use of extra features that are outside the standard model as in previous works. Second, our model, is expressed in the universal composition setting with global setup and is equipped with a composition theorem that enables the design of protocols that compose safely with each other and within larger environments where other protocols with compensation take place; a composition theorem for MPC protocols with compensation was not known before. Third, we introduce the first robust MPC protocol with compensation, i.e., an MPC protocol where not only fairness is guaranteed (via compensation) but additionally the protocol is guaranteed to deliver output to the parties that get engaged and therefore the adversary, after an initial round of deposits, is not even able to mount a denial of service attack without having to suffer a monetary penalty. Importantly, our robust MPC protocol requires only a {\em constant } number of (coin-transfer and communication) rounds.
Category / Keywords: cryptographic protocols / Date: received 10 Jun 2015, last revised 29 Oct 2015 Contact author: aggelos at di uoa gr; hszhou@vcu edu; vzikas@inf ethz ch Available format(s): PDF | BibTeX Citation Version: 20151029:193742 (All versions of this report) Short URL: ia.cr/2015/574 Discussion forum: Show discussion | Start new discussion