WIDE Workshop on Reliable Distributed Systems and Blockchain – 17 December, 2024
📣 Programme
10:00 Opening
- 10.15 am
Vincent Gramoli (remote): From Consensus Research to Redbelly Network Pty Ltd
Abstract: In this talk, Vincent Gramoli will present his journey from a student doing research on the consensus problem, learning from the experts of the distributed computing community, to an executive director commercialising a blockchain software. Bio: Vincent Gramoli is the Founder and CTO or Redbelly Network. He received a Future Fellowship from the Australian Research Council and leads the Concurrent Systems Research Group at the University of Sydney. In the past, Gramoli has been affiliated with INRIA, Cornell, CSIRO and EPFL, and obtained his PhD degree from Université de Rennes.
- 10.45 am
Sara Tucci-Piergiovanni: Understanding the Safety, Liveness, and Incentive Compatibility of Ethereum’s Proof-of-Stake Protocol
Abstract: Ethereum’s recent upgrade, known as the Merge, transitioned the blockchain to a Proof-of-Stake model, introducing an original consensus protocol that combines elements of both Nakamoto-style and Byzantine Fault Tolerance designs. This shift led to a complex protocol that, at the time of implementation, was only partially documented. In this talk, I will present our analysis of Ethereum’s Proof-of-Stake protocol, examining its safety, liveness, and incentive compatibility across various network models. Our findings reveal that, in an eventually synchronous network without participant churn, Ethereum’s Proof-of-Stake protocol ensures safety but achieves only probabilistic liveness. Moreover, with the inclusion of the Inactivity Leak mechanism—which removes inactive validators—we identified potential safety vulnerabilities. Finally, we demonstrate that the protocol ensures incentive compatibility in a synchronous=/ setting and achieves eventual incentive compatibility in an eventually synchronous environment.
11:15am -️Coffee Break
11:45am – Distributed Algorithms
- 11.45 am
Silvia Bonomi: From traditional Byzantine to Mobile Byzantine Tolerance: Shared memories and Consensus
The Byzantine failure model allows to capture arbitrary failures during the execution of a distributed protocol. Initially born as a model to capture defects related to software bugs, it has also the capability to abstract other type of failures originated by the presence of external attackers. Recently, several extension to this model have been proposed to capture the temporal evolutution of an attack and to capture the progressive infection and sanitization of affected processes introducing the concept of Mobile Byzantine failures. We reviewed the existing Mobilie Byzantine Failure models and we investigated challenges deriving from the definition of basic distributed computing abstraction, namely consensus and shared registers, in this complex scenario highlights the main research issues and the gap currently existing between theoretical models and practical user scenarios. - 12.15 am
Alessia Milani: The Synchronization Power of Auditable Registers
Outsourcing storage capabilities to third-party distributed storage (e.g; the Cloud) is a common practice for both private and professional users. Even in secure storage systems where access control policies regulate who can access the data, an unauthorized user can access data either due to a misconfiguration of the access control system or in the occurrence of a data breach. In this talk, I will present a new distributed computing abstraction, namely the auditable register (initially proposed by Bessani and Cogo) that abstracts the need of data owners to control access to their data, tracking who read which information. An auditable register extends the classical register with an audit operation that provides information on read operations performed on the register. We consider possible formalizations of auditing. I will present a natural definition, called atomic auditing, and show that it is a powerful tool, as it can be used to solve wait-free consensus .The number of processes that can solve consensus using atomic audit depends on the number of processes that can read or audit the register. A fundamental result in distributed computing is that classical read/write registers cannot solve wait-free consensus even among two processes. Thus, augmenting the classical register with auditability augments its computability power. This means that strong synchronization primitives are needed to support atomic auditing. Joint work with Antonio Fernandez Anta, Hagit Attiya, Antonella Del Pozzo, Alexandre Rapetti, and Corentin Travers
12:45 pm Lunch
2:15 pm Untrusted Providers and Trusted Oracles
- 2.15 pm
Pascal Felber: Privacy-Preserving Data Processing at Scale: How Much Can You Trust Your Cloud Provider?
Abstract:
The processing of large amounts of data requires significant computing power and scalable architectures.
This trend makes the use of Cloud computing and off-premises data centres particularly attractive but exposes companies to the risk of data theft.
This is a key challenge toward outsourcing data processing to external Cloud providers, as data represents for many companies their most valuable asset.
In this talk, we will discuss recent and emerging mechanisms to support privacy-preserving data processing, i.e., confidential computing, on untrusted architectures. - 2.45 pm
Maria Potop-Butucaru: Byzantine tolerant distributed algorithms with trusted monotonic counters
Abstract:
We promote a new design paradigm for Byzantine tolerant distributed algorithms using trusted abstractions (oracles) specified in a functional manner. The objective here is to design distributed fundamental algorithms such as reliable broadcast and asynchronous byzantine consensus using trusted execution environments and to help designers to compare various solutions on a common ground. In this framework we revisit the Bracha’s seminal work on Asynchronous Byzantine Consensus. Our solution uses trusted monotonic counters abstraction and tolerates t Byzantine processes in a system with n processes, n ≥ 2t+1. The keystone of our construction is a novel and elegant Byzantine Reliable Broadcast algorithm resilient to t < n Byzantine processes that uses an unique trusted monotonic counter (at the initiator). Interestingly, we show that, despite common belief, when each process is equipped with a trusted component, Bracha’s algorithm still needs n>3t.Joint work with Lionel Beltrando, Yackolley Amoussou Guenou and Maurice Herlihy
3:15 pm Coffee Break
3:45 pm Trust Contracts and Agreement
- 3.45 pm
Christian Cachin: Asymmetric and Heterogeneous Trust
Abstract:
- 4.15 pm
Maurice Herlihy: Distributed Computing: the Smart Contract Model
Abstract:
The rise of decentralized finance (DeFi) and distributed ledger technology (blockchain) presents both an opportunity and a challenge to the distributed computing community. The opportunity: DiFi has become a multi-billion dollar industry, providing an ideal application for the fault-tolerant distributed algorithms and protocols the distributed computing community has studied for decades. The challenge: classical shared-memory and message-passing models do not accurately mirror the realities of blockchains and smart contracts.This talk proposes the smart contract model, a bridge between classical distributed computing and the world of blockchains and DeFi. Our focus is on cross-chain protocols, executed by a collection of active parties, some trustworthy, some not, interacting through trusted smart contracts deployed on distinct blockchains.
joint work with
Yackolley Amoussou-Guenou, Sucharita Jayanti, Maria Potop-Butucaru. and Sergio Rajsbaum - 4.45 pm
Giuliano Losa (remote): Federated Byzantine Agreement
Abstract:
The Federated Byzantine Agreement (FBA) model allows obtaining a Sybil-resilient quorum system in a permissionless environment without using proof-of-stake or proof-of-work. In this talk, we will give an overview of the FBA model, explain how to solve consensus in the FBA model, and conclude with some open problems.
✒️ Registration
Please Register by entering your name and dietary preferences at this link no later than Wednesday, November 27, 2024.
🗺 Venue
The workshop will take place in Amphitheatre P on the ground floor of ISTIC, building 12D in the Beaulieu Campus of the University of Rennes, Avenue du Général Leclerc 35042 Rennes Cedex.
