What is Ouroboros Leios?
This website and the Ouroboros Leios project are in the early stages of research and development. Details may be added, removed, or changed over the coming weeks and months.
The Ouroboros consensus protocol lies at the heart of Cardano, driving secure and efficient transaction settlement while supporting the network's scalability and robustness.
Ouroboros Leios is the protocol version designed to increase the network's throughput by optimizing the use of available resources and enabling faster transaction processing and confirmation.
Currently, Cardano runs the Ouroboros Praos protocol, which introduced substantial security and scalability improvements to Ouroboros Classic. Leios remains in its research and development phase and will extend Praos' capabilities upon its implementation.
Leios is specifically designed to solve scalability bottlenecks in existing systems by acting as a high-throughput overlay on top of base protocols. It tackles malicious actions like protocol bursts (sudden floods of valid messages to congest the network) and equivocations (double-signing attacks), enabling near-optimal transaction processing while preserving security under real-world network constraints.
To illustrate the Leios concept, imagine a blockchain as a single-lane road prone to bottlenecks and delays – similar to how an accident on a one-lane road can block traffic, causing long tailbacks (pending transactions). Leios addresses this limitation by introducing multiple lanes, allowing multiple cars (transactions) to travel simultaneously. This approach significantly improves both speed and efficiency.
The key idea is to separate transaction ordering (which occurs on the base chain) from transaction diffusion, availability, and validation. Ultimately, these multiple lanes must merge into a single, orderly flow of vehicles – just as the blocks of the underlying main chain consolidate transactions into a final, agreed-upon sequence.
Read the following sections to learn more about the protocol’s properties and high-level architecture.