Fault-tolerant distributed consensus is a fundamental concept, both in cryptography as well as distributed computing. Ever since the inception of the problem by Lamport et al in 1982, the problem has been widely studied, both in cryptography as well as distributed computing community and several fundamental results have been obtained regarding the possibility, feasibility and optimality of the consensus protocols in various network models and adversarial settings. The problem has generated revived interest from several other communities over the last few years, after the advent of Blockchain protocols. Traditionally, the consensus protocols are studied either in the synchronous or in the asynchronous communication setting and very often the protocols in the former category serve as the basis for the protocols in the latter category. The focus of this book will be on the synchronous communication setting. The book presents all the seminal possibility and feasibility results in this model ever since the inception of the consensus problem, with formal security proofs. Even though the synchronous corruption model may seem weaker than the more practical asynchronous communication model, designing protocols in the synchronous model turns out to be non-trivial and demands sophisticated and highly advanced techniques. Moreover, understanding protocols in the synchronous setting often constitutes the first stepping stone to understanding the more complex asynchronous consensus protocols. The topic of synchronous consensus protocols in itself is a very vast and important topic to be covered in a single book.

Provides detailed proofs for the seminal protocols Offers self-contained presentation Supported by illustrations

Autorentext

Arpita Patra: Arpita Patra is presently an Associate Professor at the Indian Institute of Science. She previously held several industry positions, such as (a) visiting faculty at Silence Laboratories, Singapore, in the summer of 2024 and (b) visiting faculty researcher at Google Research between 2022-2023. Her area of interest is Cryptography, focusing on theoretical and practical aspects of secure multiparty computation protocols. She received her PhD from the Indian Institute of Technology (IIT), Madras and held post-doctoral positions at the University of Bristol, UK, ETH Zurich, Switzerland, and Aarhus University, Denmark. Her research has been recognized with the Prof. S. K. Chatterjee Award for Outstanding Woman Researcher or Industry Leader 2023 by IISc (2023), Google Privacy Research Faculty Award 2023, J P Morgan Chase Faculty Award 2022, SONY Faculty Innovation Award 2021, Google Research Award 2020, NASI Young Scientist Platinum Jubilee Award 2018, SERB Women Excellence award 2016, INAE Young Engineer award 2016 and associateships with various scientific bodies such as Indian Academy of Sciences (IAS), Indian National Academy of Engineering (INAE), The World Academy of Sciences (TWAS) and Indian Association for Research in Computing Science (IARCS). She has co-authored a research monogram on Multi-party Computation titled Secure Multiparty Computation against Passive Adversaries.

Ashish Choudhury: Ashish Choudhury received his PhD in Computer Science from IIT Madras, India. He held postdoctoral positions at the University of Bristol and the Indian Statistical Institute. Dr. Choudhury received the Infosys Foundation Career Development Chair Professor award and the Visvesvaraya Young Faculty Research Fellow award. He has been selected for the ACM India eminent speaker program. His research interest is in the theoretical aspect of cryptography, with a special focus on designing and analyzing multi-party computation protocols. He has offered multiple courses on cryptography and secure multiparty computation on NPTEL, a project funded by the Govt. of India, which offers free online courses in various science and engineering disciplines. He has co-authored a book titled "Secure Multi-Party Computation Against Passive Adversaries".

Klappentext

Since its inception, fault-tolerant distributed consensus has been a widely studied topic in secure distributed computing. Thanks to the advent of blockchain technology, the topic has received renewed interest from the community.

Consensus protocols are designed either in the synchronous or asynchronous communication model. The literature in each model is vast and vital enough to demand a separate monograph. Protocols and the techniques for the synchronous communication model often serve as the basis for protocols in the asynchronous model. Therefore, this work specifically focuses only on the synchronous communication model and presents all the seminal possibility and feasibility results in this model since the inception of distributed consensus protocols.

Topics and features:

• Presents protocols both against computationally bounded and computationally unbounded adversaries
• Provides detailed security proofs for the seminal protocols
• Offers freely available companion-video lectures for some of the topics
• Includes pictorial illustrations for a better understanding of the underlying concepts
• Presents state-of-the-art efficiency improvement techniques for synchronous consensus protocols
• Assumes no background in cryptography or distributed computing This monograph sets out to provide a comprehensive explanation of all the essential concepts and techniques in the domain of synchronous consensus protocols and to unfold the evolution of this topic from its inception to the present. The monograph is self-contained and can be read by those familiar with discrete mathematics and algorithms.

Arpita Patra is an associate professor at the Indian Institute of Science, Bangalore. Ashish Choudhury is an associate professor at the International Institute of Information Technology, Bangalore.

Inhalt

Introduction to fault tolerant distributed consensus.- Preliminaries.- EIG protocol for reliable broadcast.- Efficient consensus protocols.- Domain extension for consensus protocols with perfect security.- Lower Bound on the resilience of Byzantine agreement without any set up.- Byzantine broadcast with a trusted PKI set up.- Domain extension for consensus protocols with cryptographic and statistical security.- Lower bound for the number of rounds for deterministic consensus protocols.- Randomized consensus protocols.- Instantiating common-coin and leader election from scratch.- Lower Bound on the Message Complexity of Consensus/Broadcast.