Random Oracles in Constantinople: Practical Asynchronous Byzantine Agreement Using Cryptography

Abstract

Byzantine agreement requires a set of parties in a distributed system to agree on a value even if some parties are maliciously misbehaving. A new protocol for Byzantine agreement in a completely asynchronous network is presented that makes use of new cryptographic protocols, specifically protocols for threshold signatures and coin-tossing. These cryptographic protocols have practical and provably secure implementations in the random oracle model. In particular, a coin-tossing protocol based on the Diffie-Hellman problem is presented and analyzed.The resulting asynchronous Byzantine agreement protocol is both practical and theoretically optimal because it tolerates the maximum number of corrupted parties, runs in constant expected rounds, has message and communication complexity close to the optimum, and uses a trusted dealer only once in a setup phase, after which it can process a virtually unlimited number of transactions.

A Practical and Secure Coercion-Resistant Scheme for Internet Voting

“…Bulletin boards may be implemented via a Byzantine agreement, such as the proposal of Cachin et al [4].…”

Analysing Randomized Distributed Algorithms

“…For certain protocol and properties, after replacing the probabilistic behaviour with nondeterminism, one can directly use these techniques for the verification of randomized distributed algorithms. For example, using Cadence SMV [72], a proof assistant which allows the verification of large, complex, systems by reducing the verification problem to small subproblems that can be solved automatically by model checking, certain properties of the randomized consensus protocol of Aspnes and Herlihy [5] and the Byzantine agreement protocol of Cachin, Kursawe and Shoup [11] have been verified in [55] and [53] respectively. Note that, both these protocols have unboundedly many states and the proofs are for any number of processes.…”

“…In this section we describe an approach to the formal verification of Cachin, Kursawe and Shoup's randomized Asynchronous Binary Byzantine Agreement protocol (ABBA) [11], which uses techniques for the verification of non-probabilistic parameterized protocols, (finite-state) probabilistic model checking and probabilistic complexity statements. Further details concerning the models we have constructed and the proof of correctness can be found at the PRISM web page [83].…”

“…These schemes are used to prevent the adversary from forging or modifying messages. In [11,96] it has been shown that the cryptographic primitives have efficient implementations and are proved secure in the random oracle model. We therefore consider a version of the protocol which assumes the correctness of the cryptographic elements.…”

“…Since the seminal paper by Michael Rabin [85] randomized algorithms have won universal approval, basically for two reasons: simplicity and speed. Randomized distributed algorithms include a number of theoretical algorithmic schemes, for example the dining philosophers protocol and the consensus of Aspnes and Herlihy [5], as well as the practical real-world protocols for Byzantine agreement due to Kursawe et al [11] and IEEE 1394 FireWire root contention protocol [46].…”