Lecture

Sybil Defenses: Artificial Costs

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 Sybil defenses focusing on artificial costs and proof-of-work mechanisms, first used as anti-spam and popularized by Bitcoin. It also explores social/trust network defenses like the 'Web of Trust' model and assumptions in social graph scenarios. The concept of Proof of Personhood is introduced, aiming to link identity to being a physical person, with approaches such as pseudonym parties and co-located physical bodies. The lecture concludes with next steps involving reviewing Paxos and implementing it, along with recommended readings on Sybil attack detection and resistance.

Instructors (2)

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

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.

Official source

Ontological neighbourhood

Computer engineering

Computer security: Blockchain

Related concepts (23)

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.

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.

Bitcoin

Bitcoin (abbreviation: BTC or XBT; sign: ₿) is a decentralized digital currency. Bitcoin transactions are verified by network nodes through cryptography and recorded in a public distributed ledger called a blockchain. The cryptocurrency was invented in 2008 by an unknown person or group of people using the name Satoshi Nakamoto. The currency began use in 2009, when its implementation was released as open-source software. The word "bitcoin" was defined in a white paper published on October 31, 2008.

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.

Computer security

Computer security, cyber security, digital security or information technology security (IT security) is the protection of computer systems and networks from attacks by malicious actors that may result in unauthorized information disclosure, theft of, or damage to hardware, software, or data, as well as from the disruption or misdirection of the services they provide. The field is significant due to the expanded reliance on computer systems, the Internet, and wireless network standards such as Bluetooth and Wi-Fi.

Related lectures (26)

Sybil Attacks and Defenses

Explores Sybil attacks, fake content creation, and defenses against online identity fraud.

Limitations of Bitcoin and Increasing TPS

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

Smart Contracts: Bitcoin and UTXO

Explores smart contracts in Bitcoin, UTXO model, authorization, validity checks, challenges, applications, and emerging trends.

Ethereum Consensus Protocols: Security and Attacks

Explores Ethereum consensus protocols, vulnerabilities, and solutions for ledger system security.

Blockchain Essentials: Decentralized Systems Engineering

Explores blockchain essentials, covering key concepts, Bitcoin transactions, Ethereum smart contracts, and future developments.