Results 1  10
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33
Fast Randomized Consensus using Shared Memory
 Journal of Algorithms
, 1988
"... We give a new randomized algorithm for achieving consensus among asynchronous processes that communicate by reading and writing shared registers. The fastest previously known algorithm has exponential expected running time. Our algorithm is polynomial, requiring an expected O(n 4 ) operations ..."
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Cited by 133 (32 self)
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We give a new randomized algorithm for achieving consensus among asynchronous processes that communicate by reading and writing shared registers. The fastest previously known algorithm has exponential expected running time. Our algorithm is polynomial, requiring an expected O(n 4 ) operations. Applications of this algorithm include the elimination of critical sections from concurrent data structures and the construction of asymptotically unbiased shared coins.
Heartbeat: A TimeoutFree Failure Detector for Quiescent Reliable Communication
, 1997
"... We study the problem of achieving reliable communication with quiescent algorithms (i.e., algorithms that eventually stop sending messages) in asynchronoussystems with process crashes and lossy links. We first show that it is impossible to solve this problem without failure detectors. We then show h ..."
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Cited by 55 (6 self)
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We study the problem of achieving reliable communication with quiescent algorithms (i.e., algorithms that eventually stop sending messages) in asynchronoussystems with process crashes and lossy links. We first show that it is impossible to solve this problem without failure detectors. We then show how to solve it using a new failure detector, called heartbeat. In contrast to previous failure detectors that have been used to circumvent impossibility results, the heartbeat failure detector is implementable, and its implementation does not use timeouts. These results have wide applicability: they can be used to transform many existing algorithms that tolerate only process crashes into quiescent algorithms that tolerate both process crashes and message losses. This can be applied to consensus, atomic broadcast, kset agreement, atomic commitment, etc. The heartbeat failure detector is novel: besides being implementable without timeouts, it does not output lists of suspects as typical failu...
Hundreds of Impossibility Results for Distributed Computing
 Distributed Computing
, 2003
"... We survey results from distributed computing that show tasks to be impossible, either outright or within given resource bounds, in various models. The parameters of the models considered include synchrony, faulttolerance, different communication media, and randomization. The resource bounds refe ..."
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Cited by 43 (5 self)
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We survey results from distributed computing that show tasks to be impossible, either outright or within given resource bounds, in various models. The parameters of the models considered include synchrony, faulttolerance, different communication media, and randomization. The resource bounds refer to time, space and message complexity. These results are useful in understanding the inherent difficulty of individual problems and in studying the power of different models of distributed computing.
On Quiescent Reliable Communication
, 1998
"... We study the problem of achieving reliable communication with quiescent algorithms (i.e., algorithms that eventually stop sending messages) in asynchronous systems with process crashes and lossy links. We first show that it is impossible to solve this problem in purely asynchronous systems (with n ..."
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Cited by 30 (1 self)
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We study the problem of achieving reliable communication with quiescent algorithms (i.e., algorithms that eventually stop sending messages) in asynchronous systems with process crashes and lossy links. We first show that it is impossible to solve this problem in purely asynchronous systems (with no failure detectors). We then show that, among failure detectors that output lists of suspects, the weakest one that can be used to solve this problem is 3P , a failure detector that cannot be implemented. To overcome this difficulty, we introduce an implementable failure detector called Heartbeat and show that it can be used to achieve quiescent reliable communication. Heartbeat is novel: in contrast to typical failure detectors, it does not output lists of suspects and it is implementable without timeouts. With Heartbeat, many existing algorithms that tolerate only process crashes can be transformed into quiescent algorithms that tolerate both process crashes and message losses. Thi...
Securing Vehicular Communications  Assumptions, Requirements, and Principles
 WORKSHOP ON EMBEDDED SECURITY IN CARS
, 2006
"... Among civilian communication systems, vehicular networks emerge as one of the most convincing and yet most challenging instantiations of the mobile ad hoc networking technology. Towards the deployment of vehicular communication systems, security and privacy are critical factors and significant chall ..."
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Cited by 23 (7 self)
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Among civilian communication systems, vehicular networks emerge as one of the most convincing and yet most challenging instantiations of the mobile ad hoc networking technology. Towards the deployment of vehicular communication systems, security and privacy are critical factors and significant challenges to be met. Thanks to the substantial research efforts carried out by the community so far, we make the following contributions in this paper: we outline security requirements for vehicular communication systems, we provide models for the system and the communication, as well as models for the adversaries, and propose a set of design principles for future security and privacy solutions for vehicular communication systems.
Failure Detection And Randomization: A Hybrid Approach To Solve Consensus
 SIAM Journal of Computing
, 1998
"... We present a consensus algorithm that combines unreliable failure detection and randomization, two wellknown techniques for solving consensus in asynchronous systems with crash failures. This hybrid algorithm combines advantages from both approaches: it guarantees deterministic termination if the f ..."
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Cited by 20 (1 self)
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We present a consensus algorithm that combines unreliable failure detection and randomization, two wellknown techniques for solving consensus in asynchronous systems with crash failures. This hybrid algorithm combines advantages from both approaches: it guarantees deterministic termination if the failure detector is accurate, and probabilistic termination otherwise. In executions with no failures or failure detector mistakes, the most likely ones in practice, consensus is reached in only two asynchronous rounds.
A Tight Lower Bound for Randomized Synchronous Consensus
 In Proceedings of the 17th Annual ACM Symposium on Principles of Distributed Computing
, 1999
"... We prove tight upper and lower bounds of \Theta(t= n) on the expected number of rounds needed for randomized synchronous consensus protocols for a failstop, full information, adaptive adversary. In particular this proves that some restrictions are needed on the power of the adversary to allow ..."
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Cited by 19 (2 self)
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We prove tight upper and lower bounds of \Theta(t= n) on the expected number of rounds needed for randomized synchronous consensus protocols for a failstop, full information, adaptive adversary. In particular this proves that some restrictions are needed on the power of the adversary to allow randomized constant expected number of rounds protocols.
Randomization and Failure Detection: A Hybrid Approach to Solve Consensus
 In Proceedings of the 10th International Workshop on Distributed Algorithms, Lecture Notes on Computer Science
, 1996
"... We present a Consensus algorithm that combines randomization and unreliable failure detection, two wellknown techniques for solving Consensus in asynchronous systems with crash failures. This hybrid algorithm combines advantages from both approaches: it guarantees deterministic termination if th ..."
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Cited by 15 (2 self)
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We present a Consensus algorithm that combines randomization and unreliable failure detection, two wellknown techniques for solving Consensus in asynchronous systems with crash failures. This hybrid algorithm combines advantages from both approaches: it guarantees deterministic termination if the failure detector is accurate, and probabilistic termination otherwise. In executions with no failures or failure detector mistakes, the most likely ones in practice, Consensus is reached in only two asynchronous rounds. 1 Background It is wellknown that Consensus cannot be solved in asynchronous systems with failures, even if communication is reliable, at most one process may fail, and it can only fail by crashing. This "impossibility of Consensus", shown in a seminal paper by Fischer, Lynch and Paterson [FLP85], has been the subject of intense research seeking to "circumvent" this negative result (e.g., [Ben83, BT83, Rab83, DDS87, DLS88, CT96, CHT96]). We focus on two of the major ...
On the improbability of reaching Byzantine agreements
 In Proceedings of the 21st Annual ACM Symposium on the Theory of Computing
, 1989
"... Abstract. It is well known that for the Byzantine Generals Problem, no deterministic protocol can exist for an nprocessor system if the number t of faulty processors is allowed to be as large as ni3. In this paper we investigate the maximum achievable agreement probability p,,, in a model in which ..."
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Cited by 11 (0 self)
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Abstract. It is well known that for the Byzantine Generals Problem, no deterministic protocol can exist for an nprocessor system if the number t of faulty processors is allowed to be as large as ni3. In this paper we investigate the maximum achievable agreement probability p,,, in a model in which the faulty processors can be as devious and powerful as possible. We also discuss a restricted model with pk, denoting the corresponding maximum achievable probability. We will prove that: (i) for n =3, t=l (the first nontrivial case), & = (Gl)/2 (the reciprocal of the golden ratio); (ii) for all E with O<c<l,if’>l 1op(1E)1’2 n lo8(1(1E>“Z>
Fast asynchronous Byzantine agreement and leader election with full information
 In SODA’08
, 2008
"... We resolve two longstanding open problems in distributed computation by showing that both Byzantine agreement and Leader Election can be solved in subexponential time in the asynchronous full information model. Surprisingly, our protocols for both problems run in only polylogarithmic time. We thus ..."
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Cited by 8 (0 self)
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We resolve two longstanding open problems in distributed computation by showing that both Byzantine agreement and Leader Election can be solved in subexponential time in the asynchronous full information model. Surprisingly, our protocols for both problems run in only polylogarithmic time. We thus achieve a better than exponential speedup over previous results for asynchronous Byzantine agreement. In addition, to the best of our knowledge, ours is the first protocol for asynchronous fullinformation leader election. Our protocols work in the full information model with a nonadaptive adversary: the adversary is assumed to control up to a constant fraction of the processors, have unlimited computational power as well as access to all communications, but no access to processors ’ private random bits. The adversary is nonadaptive only in the sense that the corrupted processors must be chosen at the outset. Our protocols run in time that is polylogarithmic in the number of processors, n, and tolerate t < n 6+ɛ faulty processors for any positive constant ɛ. Our protocols are Monte Carlo, succeeding with probability 1 − o(1) for Byzantine agreement, and constant probability for leader election.