You Don't Need a Ledger: Lightweight Decentralized Consensus Between Mobile Web Clients

Centralized systems relying on a trusted third party are being replaced by decentralized systems using proof-of-work blockchains to reach consensus between multiple mistrusting parties. Due to the high energy usage of such systems, many solutions using a Byzantine fault-tolerant algorithm to reach consensus have emerged. While those systems solve the energy and safety concerns of proof-of-work blockchains, they still require a peer to store the full ledger and need a complex backend infrastructure to get started. This paper presents a lightweight middleware running in the browser, designed for small businesses and end-users unable to set up a complex private blockchain business network. The middleware for consensus runs entirely in the browser, with only a small server-side component used for the peer-to-peer discovery. We achieve fast confirmation times while guaranteeing safety and liveness for honest users. We also do not maintain a ledger, reducing the overall storage footprint.