In Link We Trust: BFT at the Speed of CFT using Switches#

Lior Zeno, Naama Ben-David, Mark Silberstein (Technion)

• Why: Byzantine fault tolerance has always cost a large multiple of CFT performance; this paper erases that penalty using properties of the modern DC network itself. A genuinely novel trust model — trusting the network fabric, not cryptography — that reframes what "trusted network" means in a DC.
• What: SwitchBFT, a datacenter BFT consensus protocol matching the performance and fault tolerance of the fastest CFT protocols — attaining the speed of NOPaxos (an in-switch CFT) while tolerating Byzantine replicas.
• How: Exploits packet source authentication to eliminate cryptographic-signature overhead in the fault-free path, and switch programmability to enforce agreement decisions and verify safety, all within tight switch resource budgets. Handles packet loss and switch-crash faults as design cases.
• Where applicable: Data centers with programmable (Tofino-class) switches and source-authenticated links — the "trusted network" assumption is the constraint. For the identity-minded: this is an alternative to per-message cryptographic attestation, complementing rather than competing with workload-identity approaches like SPIFFE for different threat models.