Gossiping with Append-Only Logs in Secure-Scuttlebutt

Anne-Marie Kermarrec, Erick Lavoie, Christian F. Tschudin

Abstract: Middlewares for building social applications, in which infrastructure is provided by participants, are currently developed by open-source communities. Among those, Secure-Scuttlebutt has pioneered the use of replicated authenticated single-writer append-only logs, i.e., chains of ordered immutable events specific to each participant, replicated by gossip algorithms that are driven by social signals, to build eventually-consistent social applications. The use of persistent append-only logs removes parameters traditionally required to be tuned for gossiping. We present two gossip models that can be used for replication: a new open model, simpler than the current SSB implementation, that works best in small and trusted groups; and the transitive-interest model practically deployed by SSB, that scales to thousands of participants and is spam- and sybil-resistant. We also present limitations of both to motivate further research.