{"ID":5937204,"CreatedAt":"2026-07-07T03:14:33.014478982Z","UpdatedAt":"2026-07-09T08:25:06.104751926Z","DeletedAt":null,"paper_url":"https://arxiv.org/abs/2607.04789","arxiv_id":"2607.04789","title":"Orcaella: Hybrid Fault Tolerance with Client-Selectable Finality Latency","abstract":"Classical partially synchronous state machine replication, as in PBFT, tolerates f Byzantine replicas among n at least 3f+1 using three communication steps per request. Recent protocols such as Minimmit achieve two-message-delay decisions under stronger size assumptions, notably n at least 5f+1 when any silent replica must be counted as a potential equivocator. Hydrangea and Kudzu treat mixed Byzantine and crash faults, focusing on providing a fast-path under optimistic conditions while maintaining a fall-back commitment path similar to PBFT. In this paper, we also consider a mixed model, but focus on studying the fault tolerance of the 2-message-delay commit. For this, we prove a tight bound of n at least 5f+3c+1. Extending this result, we also show that there exists a more resilient commit path that allows an extra f_abc \u003c n-3f-2c alive-but-corrupt faults at 4-message-delays. Core liveness is claimed in executions with at most f equivocators; if this regime is violated (e.g., AbC-induced forks), the protocol enters synchronous recovery, where only the resilient-path safety guarantee is preserved. As a result, for f=16, c=6, and n=99, we obtain a commit path that tolerates 22% of replicas failing for liveness, 16% equivocating for 1-RTT safety, and 54% equivocating for 2-RTT safety.","short_abstract":"Classical partially synchronous state machine replication, as in PBFT, tolerates f Byzantine replicas among n at least 3f+1 using three communication steps per request. Recent protocols such as Minimmit achieve two-message-delay decisions under stronger size assumptions, notably n at least 5f+1 when any silent replica...","url_abs":"https://arxiv.org/abs/2607.04789","url_pdf":"https://arxiv.org/pdf/2607.04789v1","authors":"[\"Lefteris Kokoris-Kogias\",\"Alberto Sonnino\"]","published":"2026-07-06T08:25:56Z","proceeding":"cs.DC","tasks":"[\"cs.DC\",\"cs.CR\"]","methods":"[]","has_code":false}