Shades of Finality and Layer 2 Scaling
This work addresses scalability and security issues in blockchain systems, particularly for Layer 2 solutions, but appears incremental as it builds on existing concepts of finality.
The paper tackles the problem of blockchain scalability and security by distinguishing between transaction order finality and state value finality, proposing checkpoint finality to handle catastrophic failures like zero-day exploits.
Blockchains combine a distributed append-only log with a virtual machine that defines how log entries are interpreted. By viewing transactions as state transformation functions for the virtual machine, we separate the naming of a state from the computation of its value and reaching consensus on that value. This distinction allows us to separate the notion of transaction order finality from state value finality. Further consideration of how blockchain governance handles catastrophic failures such as zero day exploits leads us to the notion of checkpoint finality. Consensus on the transaction order determines the ground truth. Everything else -- computing the value of a state or handling catastrophic failures such as bugs / zero-day based attacks -- are just optimizations.