Snap-and-Chat Protocols: System Aspects
This work addresses blockchain protocol design for decentralized systems, offering incremental improvements in features like accountability and light client support.
The paper tackles the availability-finality dilemma in blockchain protocols by exploring system aspects of snap-and-chat protocols, showing they can provide accountability and support for light clients, though no concrete performance numbers are reported.
The availability-finality dilemma says that blockchain protocols cannot be both available under dynamic participation and safe under network partition. Snap-and-chat protocols have recently been proposed as a resolution to this dilemma. A snap-and-chat protocol produces an always available ledger containing a finalized prefix ledger which is always safe and catches up with the available ledger whenever network conditions permit. In contrast to existing handcrafted finality gadget based designs like Ethereum 2.0's consensus protocol Gasper, snap-and-chat protocols are constructed as a black-box composition of off-the-shelf BFT and longest chain protocols. In this paper, we consider system aspects of snap-and-chat protocols and show how they can provide two important features: 1) accountability, 2) support of light clients. Through this investigation, a deeper understanding of the strengths and challenges of snap-and-chat protocols is gained.