Trade-off betweew security and scalability in blockchain systems
Utilisation de Blockchain pour décentraliser les systèmes de communication et le sharding de l'historique des transactions
Résumé
The development of Blockchain has enabled the emergence of high technology in the sensitive and active sectors by allowing the reliability of information via consensus, the immutability of records, and transaction transparency. This thesis presents the design, implementation, and evaluation of techniques to scale the blockchain. The first part of this thesis consists of building a decentralized, secure peer-to-peer messaging protocol using a PKI-based blockchain, which can be an email, a website, or some other form of message. Managing users’ identities by the Blockchain eliminates the single point of failure of traditional PKIs. By using smart contracts to validate, store and revoke the certificate on a public blockchain. Security and scalability are considered two significant challenges in blockchains’ rapid and smooth deployment in businesses, enterprises, and organizations. The ability to scale up a blockchain lies mainly in improving the underlying technology rather than deploying new hardware. The second contribution of the thesis proposes SecuSca, an approach that makes a trade-off between security and scalability when designing blockchain-based systems. It designs an efficient replication model, which creates dynamic sharding wherein blocks are stored in various nodes. To maintain the required level of security, the proposed approach shows that blockchain replication over the Peer_to_Peer network is minimized as the blockchain’s length evolves. Furthermore, a sharding protocol over the network is proposed to get access to the blockchain data based on historical transactions. The protocol reduces old blocks’ replication; these blocks can be discarded from specific nodes and stored by others. The nodes willing to store the coming blocks and their data are chosen randomly. The block header of each block is kept to achieve consensus. Next, we optimize the latest approach by choosing the entering nodes following the nodes’ capacities instead of randomly.
Cette thèse propose et évalue des méthodes pour décentraliser et faire évoluer la blockchain. La première contribution de cette thèse propose un protocole d’identification décentralisé et sécurisé qui profite de la puissance et de la résilience des blockchains. La clé publique et la signature sont enregistrées dans la blockchain après validation de l’identité du signataire par des smart contracts. La deuxième contribution propose SecuSca, une approche qui fait un compromis entre sécurité et évolutivité en créant un sharding dans lequel les blocs sont stockés sur différents nœuds. La troisième contribution optimise l’approche en choisissant des nœuds selon leurs capacités. Les méthodes proposées ont été évaluées expérimentalement et ont montré leurs avantages pour la décentralisation et l’évolutivité de la blockchain.
Origine : Version validée par le jury (STAR)