Worm-IT - A wormhole-based intrusion-tolerant group communication system
Journal of Systems and Software
Research note: On Byzantine generals with alternative plans
Journal of Parallel and Distributed Computing
Byzantine Consensus with Unknown Participants
OPODIS '08 Proceedings of the 12th International Conference on Principles of Distributed Systems
Proceedings of the 5th European conference on Computer systems
Asynchronous Byzantine consensus with 2f+1 processes
Proceedings of the 2010 ACM Symposium on Applied Computing
Signature-free broadcast-based intrusion tolerance: never decide a Byzantine value
OPODIS'10 Proceedings of the 14th international conference on Principles of distributed systems
Journal of Network and Computer Applications
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This paper proposes a stack of three Byzantine-resistant protocols aimed to be used in practical distributed systems: multi-valued consensus, vector consensus and atomic broadcast. These protocols are designed as successive transformations from one to another. The first protocol, multi-valued consensus, is implemented on top of a randomized binary consensus and a reliable broadcast protocol. The protocols share a set of important structural properties. First, they do not use digital signatures constructed with public-key cryptography, a well-known performance bottleneck in this kind of protocols. Second, they are time-free, i.e. they make no synchrony assumptions, since these assumptions are often vulnerable to subtle but effective attacks. Third, they are completely decentralized, thus avoiding the cost of detecting corrupt leaders. Fourth, they have optimal resilience, i.e. they tolerate the failure of f = ⌊(n-1)/3⌋ out of a total of n processes. In terms of time complexity, the multi-valued consensus protocol terminates in a constant expected number of rounds, while the vector consensus and atomic broadcast protocols have O(f) complexity. The paper also proves the equivalence between multi-valued consensus and atomic broadcast in the Byzantine failure model without signatures. A similar proof is given for the equivalence between multi-valued consensus and vector consensus. These two results have theoretical relevance since they show once more that consensus is a fundamental problem in distributed systems.