For synchronous point-to-point n-node networks of undirected links, it has been previously shown that, to achieve consensus in presence of up to f Byzantine faults, the following two conditions are together necessary and sufficient: (i) n ≥ 3f + 1 and (ii) network connectivity greater than 2f . The first condition, that is, n ≥ 3f + 1, is known to be necessary for directed graphs as well. On th...

Awareness of the need for robustness in distributed systems increases as distributed systems become an integral part of day-to-day systems. Tolerating Byzantine faults and possessing self-stabilizing features are sensible and important requirements of distributed systems in general, and of a fundamental task such as clock synchronization in particular. There are efficient solutions for Byzantin...

Byzantine fault is a cumulative term given to the set of both permanent and transient faults caused in circuits which effectively present themselves as different errors at different nodes in the same circuit. Such faults have become significant with the shrinkage in node (process) technology with process variations, radiation strikes and quantummechanical effects being majorly responsible for c...

This paper outlines a flexible suite of object replication protocols that brings together Byzantine quorum systems registers and state machine replication. These protocols enable the implementation of Byzantine fault-tolerant applications that make minimal assumptions about the environment and that run in at most two more communication steps in almost all cases of non-favorable executions (in c...

We consider the problem of implementing a wait-free regular register from storage components prone to Byzantine faults. We present a simple, efficient, and self-contained construction of such a register. Our construction utilizes a novel building block, called a 1-regular register, which can be efficiently implemented from Byzantine fault-prone components.

Byzantine agreement means achieving reliable broadcast on a point-to-point network of n processors, of which up to t may be maliciously faulty. A well-known result by Pease, Shostak, and Lamport says that perfect Byzantine agreement is only possible if t < n/3. In contrast, so-called authenticated protocols achieve Byzantine agreement for any t based on computational assumptions, typically the ...

This work addresses Byzantine vector consensus (BVC), wherein the input at each process is a d-dimensional vector of reals, and each process is expected to decide on a decision vector that is in the convex hull of the input vectors at the fault-free processes [3, 8]. The input vector at each process may also be viewed as a point in the d-dimensional Euclidean space R, where d > 0 is a finite in...

This thesis describes a Byzantine Fault Tolerant Coordination framework for Web Service Atomic Transaction (WS-AT). In the framework, all core services, including transaction activation, registration, and completion & distributed commit, are replicated and protected by Byzantine fault tolerance mechanisms. The traditional Two-Phase Commit (2PC) protocol is extended by a Byzantine fault tolerant...

Information-theoretic private information retrieval (PIR) protocols, such as those described by Chor et al. [5], provide a mechanism by which users can retrieve information from a database distributed across multiple servers in such a way that neither the servers nor an outside observer can determine the contents of the data being retrieved. More recent PIR protocols also provide protection aga...

This paper explores the problem of reaching approximate consensus in synchronous point-to-point networks, where each directed link of the underlying communication graph represents a communication channel between a pair of nodes. We adopt the transient Byzantine link failure model [15, 16], where an omniscient adversary controls a subset of the directed communication links, but the nodes are ass...