4,648 research outputs found
Complexity of Multi-Value Byzantine Agreement
In this paper, we consider the problem of maximizing the throughput of
Byzantine agreement, given that the sum capacity of all links in between nodes
in the system is finite. We have proposed a highly efficient Byzantine
agreement algorithm on values of length l>1 bits. This algorithm uses error
detecting network codes to ensure that fault-free nodes will never disagree,
and routing scheme that is adaptive to the result of error detection. Our
algorithm has a bit complexity of n(n-1)l/(n-t), which leads to a linear cost
(O(n)) per bit agreed upon, and overcomes the quadratic lower bound
(Omega(n^2)) in the literature. Such linear per bit complexity has only been
achieved in the literature by allowing a positive probability of error. Our
algorithm achieves the linear per bit complexity while guaranteeing agreement
is achieved correctly even in the worst case. We also conjecture that our
algorithm can be used to achieve agreement throughput arbitrarily close to the
agreement capacity of a network, when the sum capacity is given
Byzantine modification detection in multicast networks using randomized network coding
Distributed randomized network coding, a robust approach to multicasting in distributed network settings, can be extended to provide Byzantine modification detection without the use of cryptographic functions is presented in this paper
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
Network error correction with unequal link capacities
This paper studies the capacity of single-source single-sink noiseless
networks under adversarial or arbitrary errors on no more than z edges. Unlike
prior papers, which assume equal capacities on all links, arbitrary link
capacities are considered. Results include new upper bounds, network error
correction coding strategies, and examples of network families where our bounds
are tight. An example is provided of a network where the capacity is 50%
greater than the best rate that can be achieved with linear coding. While
coding at the source and sink suffices in networks with equal link capacities,
in networks with unequal link capacities, it is shown that intermediate nodes
may have to do coding, nonlinear error detection, or error correction in order
to achieve the network error correction capacity
Counter Attack on Byzantine Generals: Parameterized Model Checking of Fault-tolerant Distributed Algorithms
We introduce an automated parameterized verification method for
fault-tolerant distributed algorithms (FTDA). FTDAs are parameterized by both
the number of processes and the assumed maximum number of Byzantine faulty
processes. At the center of our technique is a parametric interval abstraction
(PIA) where the interval boundaries are arithmetic expressions over parameters.
Using PIA for both data abstraction and a new form of counter abstraction, we
reduce the parameterized problem to finite-state model checking. We demonstrate
the practical feasibility of our method by verifying several variants of the
well-known distributed algorithm by Srikanth and Toueg. Our semi-decision
procedures are complemented and motivated by an undecidability proof for FTDA
verification which holds even in the absence of interprocess communication. To
the best of our knowledge, this is the first paper to achieve parameterized
automated verification of Byzantine FTDA
- …