Lecture

Decentralized Systems Engineering: Fault Tolerance & Consensus

Graph Chat

Chat with Graph Search

Ask any question about EPFL courses, lectures, exercises, research, news, etc. or try the example questions below.

DISCLAIMER: The Graph Chatbot is not programmed to provide explicit or categorical answers to your questions. Rather, it transforms your questions into API requests that are distributed across the various IT services officially administered by EPFL. Its purpose is solely to collect and recommend relevant references to content that you can explore to help you answer your questions.

In course

CS-438: Decentralized systems engineering

A decentralized system is one that works when no single party is in charge or fully trusted. This course teaches decentralized systems principles while guiding students through the engineering of their own decentralized system featuring messaging, file sha ...

Description

This lecture covers the logistics of homework, projects, and exams, revisits Paxos and introduces Multi-Paxos and Threshold Logical Clocks. It delves into fault tolerance, Byzantine faults, and the Byzantine Generals Problem, emphasizing the importance of redundancy and fault-tolerant systems. The instructor discusses the challenges of network partitions and shares a Space Shuttle story to illustrate system failures. The lecture also explores logical clocks, BFT Consensus, permissionless consensus in Bitcoin, and blockchain structure. Key concepts include fault modes analysis, consensus algorithms, and the Proof-of-Work concept in Bitcoin.

Instructors (2)

Pierluca Borsò

Expertise Teaching & PhD Courses Decentralized systems engineering CS-438 A decentralized system is one that works when no single party is in charge or fully trusted. This course teaches decentralized systems principles while guiding students through the engineering of their own decentralized system featuring messaging, file sharing, encryption, and blockchain concepts.

Bryan Alexander Ford

Links DEDIS lab home pagePersonal home page Curriculum vitae https://bford.info/cv.pdf Teaching & PhD PhD Students Shailesh Mishra Past EPFL PhD Students Eleftherios Kokoris Kogias, Kirill Nikitin, Cristina Basescu, Enis Ceyhun Alp, Simone Colombo, Pasindu Nivanthaka Tennage, Louis-Henri Manuel Jakob Merino Past EPFL PhD Students as codirector David Froelicher, Ludovic Barman, Georgia Fragkouli Courses Decentralized systems engineering CS-438 A decentralized system is one that works when n

Official source

Related concepts (32)

Proof of work

Proof of work (PoW) is a form of cryptographic proof in which one party (the prover) proves to others (the verifiers) that a certain amount of a specific computational effort has been expended. Verifiers can subsequently confirm this expenditure with minimal effort on their part. The concept was invented by Moni Naor and Cynthia Dwork in 1993 as a way to deter denial-of-service attacks and other service abuses such as spam on a network by requiring some work from a service requester, usually meaning processing time by a computer.

Blockchain

A blockchain is a distributed ledger with growing lists of records (blocks) that are securely linked together via cryptographic hashes. Each block contains a cryptographic hash of the previous block, a timestamp, and transaction data (generally represented as a Merkle tree, where data nodes are represented by leaves). Since each block contains information about the previous block, they effectively form a chain (compare linked list data structure), with each additional block linking to the ones before it.

Proof of stake

Proof-of-stake (PoS) protocols are a class of consensus mechanisms for blockchains that work by selecting validators in proportion to their quantity of holdings in the associated cryptocurrency. This is done to avoid the computational cost of proof-of-work (POW) schemes. The first functioning use of PoS for cryptocurrency was Peercoin in 2012, although the scheme, on the surface, still resembled a POW. For a blockchain transaction to be recognized, it must be appended to the blockchain.

Bitcoin network

The Bitcoin network is a peer-to-peer network of nodes which implement the Bitcoin protocol. The protocol itself implements a highly available, public, and decentralized ledger. The nodes verify that each update to the ledger follows the rules of the Bitcoin protocol. Users broadcast cryptographically signed messages to the network using Bitcoin cryptocurrency wallet software. These messages are proposed transactions, changes to be made in the ledger. Each node has a copy of the ledger's entire transaction history.

Proof of space

Proof of space (PoS) is a type of consensus algorithm achieved by demonstrating one's legitimate interest in a service (such as sending an email) by allocating a non-trivial amount of memory or disk space to solve a challenge presented by the service provider. The concept was formulated in 2013 by Dziembowski et al. and (with a different formulation) by Ateniese et al.. Proofs of space are very similar to proofs of work (PoW), except that instead of computation, storage is used to earn cryptocurrency.

Related lectures (32)

Decentralized Systems: Byzantine Consensus and Bitcoin

Explores Byzantine consensus in decentralized systems and Bitcoin's consensus mechanisms.

Blockchain Fundamentals

Explores the financial applications of blockchains, covering the definition, history, Ethereum, decentralized finance, smart contracts, tokens, assessment methods, challenges of double spending, digital signatures, and cryptographic hash functions.

Technologies for Democratic Society

Explores blockchain, smart contracts, decentralized governance, and the challenges faced by technologies like DAOs.

Blockchain Fundamentals: Overview and Use Cases

Provides an overview of blockchain technology, covering its history, key elements, use cases in different industries, and technical challenges.

Limitations of Bitcoin and Increasing TPS

Discusses the limitations of Bitcoin and ways to increase transaction processing speed.