Commissariat à l’énergie atomique et aux énergies alternatives Institut List | CEA Saclay bâtiment 565- PC 65-91191 Gif-sur-Yvette Cedex
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Établissement public à caractère industriel et commercial | RCS Paris B 775 685 019
DRT/LIST/UAF
Internship Topic
Title: Accountability in consensus based blockchains
Context:
In 2008, a white paper [1], signed under the pseudonymous of Satoshi Nakamoto, defined one of the most interesting new technologies of the past decades: the Blockchain. In fact, such technology serves as immutable, non-repudiable, public distributed ledger for the Bitcoin cryptocurrency and for other kind of applications as well. In few words, the blockchain is a chain of blocks that are continuously appended by peers and blocks contain application dependent data that peers want to write into the blockchain. In order to preserve the chain shape it should never happen that there are more than two blocks appended to the same block. To prevent this, Bitcoin uses the Proof of Work mechanism. However, even if with small probability, Proof of Work allows forks. For this reason, it is not suitable for blockchain aiming at providing strong consistency properties. Tendermint [2] is one of the BPFT Consensus [3] based blockchain and has been deeply analyzed in [4,5]. The crucial point in Tendermint is the composition of the committee (selected among the system participants) that executes the Consensus algorithm to guarantee the absence of forks, indeed everything works under the assumption that the fraction of attackers in the committee is bounded. However, this is a strong assumption on a long time running application. For this reason consensus based Blockchain solutions demand for accountability mechanisms, that is, the capability of producing unconfutable evidences of processes misbehaviors. Such mechanism aims at maintaining the number of attackers under the tolerated threshold disentivizing them to misbehave and in case they do misbehave, to detect and remove them from the system.
Objective:
The objective of this internship is to define and implement a solution to automatically derive an accountability module for a specific consensus based blockchain. At high level, such module observes the system behavior (in terms of messages exchanged) and provides evidences of misbehavior of faulty participants.
The successful candidate will join the Laboratory for Trustworthy, Smart and Self-Organizing Information Systems1 (LICIA) at CEA LIST.
Références:
[1] : https://bitcoin.org/bitcoin.pdf [2] : https://tendermint.com/
[3] : http://www.read.seas.harvard.edu/~kohler/class/cs239-w08/castro99practical.pdf [4] : http://drops.dagstuhl.de/opus/volltexte/2018/10076/
[5] : https://link.springer.com/chapter/10.1007%2F978-3-030-31277-0_11
1LICIA, https://www.researchgate.net/lab/Laboratory-for-Trustworthy-Smart-and-Self-Organizing- Information-Systems-Sara-Tucci-Piergiovanni, last access on 20/04/2018.
Methodology:
The intern will have the following responsibilities:
(1) Preparing a state-of-the art about the existing work on accountability in the blockchain context;
(2) Become confident with the Tendermint protocol and the accountability module definition define for it;
(3) Chose a formalism expressive enough to describe the accountability module;
(4) Specify a solution that taking any consensus algorithm (specified in a predetermined way) derives the specific accountability module for it;
(5) Implement such solution.
Competences:
Being Master 2 in Computer Science/Engineering.
Knowledge about distributed systems in general.
Knowledge about formal methods.
Knowledge about the blockchain technology is a plus.
Good experience in programming in any language.
Domaine de spécialité requis : Informatique
Autres domaines de spécialités, mots clés :
Moyens mis en œuvre (expériences, méthodes d’analyses, autres...): distributed systems, formal methods, programming languages, web programming, network programming.
Niveau souhaité : Bac + 4/5
Durée: 6 mois
Niveau d’habilitation défense (AS au minimum) : AS Formation souhaitée : Ingénieur/Master
Possibilité de poursuite en thèse : Oui
Lieu du stage : CEA, Centre de Saclay Nano-Innov, 91191 Gif sur Yvette Contacts :
Antonella Del Pozzo antonella.delpozzo@cea.fr +33 1 69 08 04 69
