8,462 research outputs found
Coordination-Free Byzantine Replication with Minimal Communication Costs
State-of-the-art fault-tolerant and federated data management systems rely on fully-replicated designs in which all participants have equivalent roles. Consequently, these systems have only limited scalability and are ill-suited for high-performance data management. As an alternative, we propose a hierarchical design in which a Byzantine cluster manages data, while an arbitrary number of learners can reliable learn these updates and use the corresponding data.
To realize our design, we propose the delayed-replication algorithm, an efficient solution to the Byzantine learner problem that is central to our design. The delayed-replication algorithm is coordination-free, scalable, and has minimal communication cost for all participants involved. In doing so, the delayed-broadcast algorithm opens the door to new high-performance fault-tolerant and federated data management systems. To illustrate this, we show that the delayed-replication algorithm is not only useful to support specialized learners, but can also be used to reduce the overall communication cost of permissioned blockchains and to improve their storage scalability
Tight Mobile Byzantine Tolerant Atomic Storage
This paper proposes the first implementation of an atomic storage tolerant to
mobile Byzantine agents. Our implementation is designed for the round-based
synchronous model where the set of Byzantine nodes changes from round to round.
In this model we explore the feasibility of multi-writer multi-reader atomic
register prone to various mobile Byzantine behaviors. We prove upper and lower
bounds for solving the atomic storage in all the explored models. Our results,
significantly different from the static case, advocate for a deeper study of
the main building blocks of distributed computing while the system is prone to
mobile Byzantine failures
An Improved Approximate Consensus Algorithm in the Presence of Mobile Faults
This paper explores the problem of reaching approximate consensus in
synchronous point-to-point networks, where each pair of nodes is able to
communicate with each other directly and reliably. We consider the mobile
Byzantine fault model proposed by Garay '94 -- in the model, an omniscient
adversary can corrupt up to nodes in each round, and at the beginning of
each round, faults may "move" in the system (i.e., different sets of nodes may
become faulty in different rounds). Recent work by Bonomi et al. '16 proposed a
simple iterative approximate consensus algorithm which requires at least
nodes. This paper proposes a novel technique of using "confession" (a mechanism
to allow others to ignore past behavior) and a variant of reliable broadcast to
improve the fault-tolerance level. In particular, we present an approximate
consensus algorithm that requires only nodes, an
improvement over the state-of-the-art algorithms.
Moreover, we also show that the proposed algorithm is optimal within a family
of round-based algorithms
Building Regular Registers with Rational Malicious Servers and Anonymous Clients
The paper addresses the problem of emulating a regular register in a synchronous distributed system where clients invoking and operations are anonymous while server processes maintaining the state of the register may be compromised by rational adversaries (i.e., a server might behave as rational malicious Byzantine process). We first model our problem as a Bayesian game between a client and a rational malicious server where the equilibrium depends on the decisions of the malicious server (behave correctly and not be detected by clients vs returning a wrong register value to clients with the risk of being detected and then excluded by the computation). We prove such equilibrium exists and finally we design a protocol implementing the regular register that forces the rational malicious server to behave correctly
Stabilizing Server-Based Storage in Byzantine Asynchronous Message-Passing Systems
A stabilizing Byzantine single-writer single-reader (SWSR) regular register,
which stabilizes after the first invoked write operation, is first presented.
Then, new/old ordering inversions are eliminated by the use of a (bounded)
sequence number for writes, obtaining a practically stabilizing SWSR atomic
register. A practically stabilizing Byzantine single-writer multi-reader (SWMR)
atomic register is then obtained by using several copies of SWSR atomic
registers. Finally, bounded time-stamps, with a time-stamp per writer, together
with SWMR atomic registers, are used to construct a practically stabilizing
Byzantine multi-writer multi-reader (MWMR) atomic register. In a system of
servers implementing an atomic register, and in addition to transient failures,
the constructions tolerate t<n/8 Byzantine servers if communication is
asynchronous, and t<n/3 Byzantine servers if it is synchronous. The noteworthy
feature of the proposed algorithms is that (to our knowledge) these are the
first that build an atomic read/write storage on top of asynchronous servers
prone to transient failures, and where up to t of them can be Byzantine
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