Common use of Communication Model Clause in Contracts

Communication Model. We assume a synchronous network, where all parties begin the protocol at the same time, the clocks of the parties progress at the same rate, and all messages are delivered within some known finite time ∆ > 0 (called the network delay) after being sent. In particular, messages of honest parties cannot be dropped from the network and are always delivered. Thus, we can consider protocols that execute in rounds of length ∆ where parties start executing round r at time (r 1)∆. We further assume that ∆ is public information and is known to all parties and the adversary, and any action carried out by any party can depend on ∆. With that in mind, and to avoid notation encumbrance, we omit ∆ from the list of inputs to algorithms and protocols in our definitions. Adversarial Model. The adversary model we consider in the paper is an amalgamation of two common adversaries in the literature. Formally, given two parameters ti ≤ ts < n/2 such that 2ti + ts < n, the adversary A can be described as a tuple A = (A0, A1, A2) such that – 0(Π, r, Trr) = r where r denotes the set of corrupt parties at round r. I.e. 0 is an algorithm that chooses for every round the set of corrupt parties, based on the description of the protocol Π, the round r, and the transcript Trr of the protocol up to round t. We distinguish between two types of adversaries in this context. A static adversary satisfies that A0(Π, r, Trr) = A0(Π, 0, Tr0) for all rounds