Hierarchical Verifiable Federated Learning with Recursive Proofs

Abstract

Federated Learning enables large-scale collaborative training across distributed devices. However, in massive-scale Internet-of-Things (IoT) deployments, ensuring the trustworthy sensor-level operations remains a critical challenge. We introduce a hierarchical framework that combines a three-tier architecture (devices → gateways → server) with a high-speed recursive proof system to enforce scalable zero-knowledge proofs (ZKPs). At the device level, each proof serves as a unified cryptographic commitment, binding the device’s identity, local data integrity, and training correctness into a single attestation. These proofs are then individually verified at intermediate gateways, and compressed into a single, succinct proof using a folding scheme inspired by Nova [1] - a state-of-the-art system that can excel at this task at best. The server then verifies a small number of batched proofs before aggregation, reducing workload (∼ 571× in data load) by replacing hundreds of thousands of individual proof and model update transmissions with just one per gateway. Our fully implemented R1CS precursor demonstrates resilience against various vectors (e.g., backdoor-style attacks,) achieves a ∼ 34× verification speedup on a 105-device network, and maintains both strong security and model performance. Our prototype, evaluated on an Internet-of-Vehicles (IoV) use case, demonstrates that recursive proofs add succinct overhead while providing scalable, robust integrity guarantees against adversarial environments.