Michael Merritt

Bio: Michael Merritt is an academic researcher from AT&T Labs. The author has contributed to research in topics: Shared memory & Distributed shared memory. The author has an hindex of 33, co-authored 86 publications receiving 6227 citations. Previous affiliations of Michael Merritt include Bell Labs & Lawrence Livermore National Laboratory.

Method of authenticating a terminal in a transaction execution system

Abstract: The invention provides for a method of authenticating to a user or customer a terminal, such as an automatic teller machine, in a transaction execution system. The terminal is authenticated by a central host using cryptographic techniques, and a personal security phrase is sent from the host to the terminal. A message, incorporating the personal security phrase, is communicated to the customer by the terminal, thereby indicating that the terminal is legitimate. The terminal is authenticated to the customer prior to his entering any secret or confidential information, such as a personal identification number, into the terminal.

A bounded first-in, first-enabled solution to the l-exclusion problem

Abstract: This article presents a solution to the first-come, first-enabled l-exclusion problem of Fischer et al. [1979]. Unlike their solution, this solution does not use powerful read-modify-write synchronization primitives and requires only bounded shared memory. Use of the concurrent timestamp system of Dolev and Shavir [1989] is key in solving the problem within bounded shared memory.

Disentangling multi-object operations (extended abstract)

Abstract: Afek * Michael Merrittt We consider the problem of implementing atomic operations on multiple shared memory objects, in systems which directly support only single-object atomic operations. Our motivation is to design algorithms that exhibit both low contention between concurrent operations and a high level of concurrency, by disentangling long chains of conflicting operations. That is, operations that access widely disjoint parts of a data structure, or are widely separated in time, should not interfere with each other. The algorithm reported here extends and is based on the work of Attiya and Dagan [A D96], where a nonblocking solution is presented for two-object atomic operations. For any number, k, we present a wait-free solution for atomically accessing up to k objects. Notions of local contention and local step complexity are defined, and it is shown that the solution has low local contention and local step complexity. Relations between multi-objects and the familiar resource allocation problem are explored-the algorithm presented also provides a solution to the resource allocation problem.

Secure reliable multicast protocols in a WAN

Abstract: A secure reliable multicast protocol enables a process to send a message to a group of recipients such that all honest destinations receive the same message, despite the malicious efforts of fewer than a third of them, including the sender. This has been shown to be a useful tool in building secure distributed services, albeit with a cost that typically grows linearly with the size of the system. For very large networks, for which such a cost may be too prohibitive, we present two approaches for bringing the cost down: First, we show a protocol whose cost is on the order of the number of tolerated failures. Secondly, we show how relaxing the consistency requirement to a selected probability level of guarantee can bring down the associated cost to a constant.

Computing with faulty shared memory

Abstract: This paper addresses problems which arise in the synchronization and coordination of distributed systems which employ unreliable shared memory. We present algorithms which solve the consensus problem, and which simulate reliable shared-memory objects, despite the fact that the available memory objects (e.g. read/write registers, test-and-set registers, read-modify-write registers) may be faulty.

Systems and Methods for Secure Transaction Management and Electronic Rights Protection

Abstract: PROBLEM TO BE SOLVED: To solve the problem, wherein it is impossible for an electronic content information provider to provide commercially secure and effective method, for a configurable general-purpose electronic commercial transaction/distribution control system. SOLUTION: In this system, having at least one protected processing environment for safely controlling at least one portion of decoding of digital information, a secure content distribution method comprises a process for encapsulating digital information in one or more digital containers; a process for encrypting at least a portion of digital information; a process for associating at least partially secure control information for managing interactions with encrypted digital information and/or digital container; a process for delivering one or more digital containers to a digital information user; and a process for using a protected processing environment, for safely controlling at least a portion of the decoding of the digital information. COPYRIGHT: (C)2006,JPO&NCIPI

Impossibility of distributed consensus with one faulty process

Abstract: The consensus problem involves an asynchronous system of processes, some of which may be unreliable The problem is for the reliable processes to agree on a binary value In this paper, it is shown that every protocol for this problem has the possibility of nontermination, even with only one faulty process By way of contrast, solutions are known for the synchronous case, the “Byzantine Generals” problem

Distributed algorithms

Abstract: In Distributed Algorithms, Nancy Lynch provides a blueprint for designing, implementing, and analyzing distributed algorithms. She directs her book at a wide audience, including students, programmers, system designers, and researchers. Distributed Algorithms contains the most significant algorithms and impossibility results in the area, all in a simple automata-theoretic setting. The algorithms are proved correct, and their complexity is analyzed according to precisely defined complexity measures. The problems covered include resource allocation, communication, consensus among distributed processes, data consistency, deadlock detection, leader election, global snapshots, and many others. The material is organized according to the system model-first by the timing model and then by the interprocess communication mechanism. The material on system models is isolated in separate chapters for easy reference. The presentation is completely rigorous, yet is intuitive enough for immediate comprehension. This book familiarizes readers with important problems, algorithms, and impossibility results in the area: readers can then recognize the problems when they arise in practice, apply the algorithms to solve them, and use the impossibility results to determine whether problems are unsolvable. The book also provides readers with the basic mathematical tools for designing new algorithms and proving new impossibility results. In addition, it teaches readers how to reason carefully about distributed algorithms-to model them formally, devise precise specifications for their required behavior, prove their correctness, and evaluate their performance with realistic measures. Table of Contents 1 Introduction 2 Modelling I; Synchronous Network Model 3 Leader Election in a Synchronous Ring 4 Algorithms in General Synchronous Networks 5 Distributed Consensus with Link Failures 6 Distributed Consensus with Process Failures 7 More Consensus Problems 8 Modelling II: Asynchronous System Model 9 Modelling III: Asynchronous Shared Memory Model 10 Mutual Exclusion 11 Resource Allocation 12 Consensus 13 Atomic Objects 14 Modelling IV: Asynchronous Network Model 15 Basic Asynchronous Network Algorithms 16 Synchronizers 17 Shared Memory versus Networks 18 Logical Time 19 Global Snapshots and Stable Properties 20 Network Resource Allocation 21 Asynchronous Networks with Process Failures 22 Data Link Protocols 23 Partially Synchronous System Models 24 Mutual Exclusion with Partial Synchrony 25 Consensus with Partial Synchrony

SPINS: security protocols for sensor networks

Abstract: As sensor networks edge closer towards wide-spread deployment, security issues become a central concern. So far, much research has focused on making sensor networks feasible and useful, and has not concentrated on security.We present a suite of security building blocks optimized for resource-constrained environments and wireless communication. SPINS has two secure building blocks: SNEP and mTESLA SNEP provides the following important baseline security primitives: Data confidentiality, two-party data authentication, and data freshness. A particularly hard problem is to provide efficient broadcast authentication, which is an important mechanism for sensor networks. mTESLA is a new protocol which provides authenticated broadcast for severely resource-constrained environments. We implemented the above protocols, and show that they are practical even on minimal hardware: the performance of the protocol suite easily matches the data rate of our network. Additionally, we demonstrate that the suite can be used for building higher level protocols.

A logic of authentication

Abstract: Authentication protocols are the basis of security in many distributed systems, and it is therefore essential to ensure that these protocols function correctly. Unfortunately, their design has been extremely error prone. Most of the protocols found in the literature contain redundancies or security flaws. A simple logic has allowed us to describe the beliefs of trustworthy parties involved in authentication protocols and the evolution of these beliefs as a consequence of communication. We have been able to explain a variety of authentication protocols formally, to discover subtleties and errors in them, and to suggest improvements. In this paper we present the logic and then give the results of our analysis of four published protocols, chosen either because of their practical importance or because they serve to illustrate our method.