Existing Protocols for Asynchronous Byzantine Agreement Sample Clauses

Existing Protocols for Asynchronous Byzantine Agreement. The literate of existing protocols for ABA is very rich. We focus on the binary case and restrict our discussion to solutions which handle the maximal corruption bound of n corrupted parties and require a polynomial amount of running time. Also, we focus on solutions which do not require set up beyond the assumption of a trusted dealer who distributes public keys to the parties before the protocol. The problem of XXXX was first solved independently by Xxx-Xx and Xxxxx [6, 33] (albeit, not with optimal resilience). To circumvent the well-known impossibility for deterministic solutions to the BABA problem by Xxxxxxx et al. [27], they were the first to harness the power of randomness in the form of a common coin, that is available to all parties, but is not predictable for the adversary. Most subsequent solutions to the BABA problem use the abstraction of a common coin. The first (polynomial time) protocol to implement a common coin without any set-up as- sumptions is the beautiful work by Xxxxxxx and Xxxxx [14]. However, their protocol uses an expensive variant of asynchronous verifiable secret sharing (AVSS) which renders their protocol completely impractical. Their common coin construction was subsequently improved by Abra- ham et al. [2] and Xxxxxxxxx et al. [32]. However, their solutions are still far beyond the scope of practicality. Xxxxxx et al. [11] gave the first efficient solution to the BABA problem which has a commu- nication complexity of O(n2l), where l denotes the size of an RSA signature. Their protocol is based on a threshold signature scheme and thus achieves security only against a bounded adversary, whereas the protocols in [14, 2, 32] can tolerate even unbounded adversaries, given that private channels are available for free. As already pointed out earlier, another difference of [11] to the aforementioned protocols is that the latter tolerates only static corruptions. The protocol’s weakness against adaptive corruptions is inherited from their common coin protocol, which tolerates only static corruptions. Most recently, Most´efaoui et al. [29] gave an improvement over the protocol of [11], which reduces the communication complexity to O(n2) when using the common coin from [11]. In theory, their protocol could also be instantiated with the AVSS-based common coin protocols which would improve its security to the adaptive case. We use this observation and instantiate the common coin in their protocol with an efficient protocol that attains ...