Designing a secure permissionless distributed ledger that performs on par with centralized payment processors such as Visa is challenging. Most existing distributed ledgers are unable to "scale-out" -- growing total processing capacity with number of participants -- and those that do compromise security or decentralization. This work presents OmniLedger, the first scale-out distributed ledger that can preserve long-term security under permissionless operation. OmniLedger ensures strong correctness and security by using a bias-resistant public randomness protocol to choose large statistically representative shards to process transactions, and by introducing an efficient cross-shard commit protocol to handle transactions affecting multiple shards atomically. In addition, OmniLedger optimizes performance via scalable intra-shard parallel transaction processing, ledger pruning via collectively-signed state blocks, and optional low-latency "trust-but-verify" validation of low-value transactions. Evaluation of our working experimental prototype shows that OmniLedger's throughput scales linearly in the number of validators available, supporting Visa-level workloads and beyond, while confirming typical transactions in under two seconds.
Philipp Jovanovic is a Post-Doctoral Researcher at École Polytechnique Fédérale de Lausanne (EPFL), Switzerland. Before joining EPFL, he received his PhD in Computer Science from the University of Passau, Germany, in 2015. His research interests broadly include applied cryptography, information security, privacy, and decentralized systems. His recent work involves improving scalability, security, and privacy of distributed ledger systems. Besides this line of research, he has also worked on a wide variety of other security-related topics, including design and analysis of symmetric cryptographic primitives, side-channel attacks and countermeasures, hardware Trojans, or the security analysis of protocols deployed in the real world such as TLS or the Open Smart Grid Protocol.
Refreshments: Light lunch will be provided.