Our result Clause Samples

Our result. In this paper, we show that a baiting strategy, that one can implement with these undeniable proofs-of-fraud, is necessary and sufficient to devise a consensus protocol that is robust to a coalition of up to k rational players and t Byzantine players, a problem we call the rational agreement problem. This result holds under the assumption of partial synchrony, where there is an unknown bound on the delay of messages [14]. First, we introduce the notion of baiting strategy as a particular case of pun- ishment strategy and show that it is impossible to solve the rational agreement problem without a baiting strategy: A (k, f, m)-baiting strategy is a (k − m, f )- punishment strategy such that 0 < m ≤ k, and the m rational players that do not collude would lower their utility by not playing the baiting strategy and deviating with the rest of the players of the coalition. Second, we present a solution to the rational agreement problem that relies on a baiting strategy. To this end, we devise the Huntsman protocol for the partially synchronous model that extends an existing consensus protocol that is t-accountable for t < n/3 to become ǫ-(k, t)-robust when n > max( 3 k +3t, 2(k + t)). The key idea is to reward a single player if it exposes the coalition to which it belongs. If the reward is larger than the individual return that a rational gains from causing a disagreement, then rational players in a coalition can find that the strategy to form a coalition and cause a disagreement is strictly dominated by the strategy to betray the coalition in the sequential game. The solution thus finds relevance in the context of a distributed ledger where a disagreement can allow a player to steal digital assets but where requiring play- ers to deposit some of their assets can be used to threaten them. In particular, our protocol pre-decides decisions from a t-accountable consensus protocol that it extends with the Byzantine Fault Tolerant Commit-Reveal protocol (BFTCR) that consists of two reliable broadcasts and one additional broadcast. BFTCR ensures the existence of a baiting strategy (baiting-dominance) and that the protocol still solves agreement even after playing the baiting strategy (baiting- agreement). We also add an additional property outside the problem definition, lossfree-reward, which states that the increase in utility for baiting rational play- ers comes at no cost to non-deviating players. For this purpose, we introduce a deposit per player and reward to ...