On the Divergence of Theory and Practice in Mobile ZK-Proving

The recent proliferation of mobile-first ZK rollups relies heavily on the assumption that client-side proving is feasible on consumer hardware. While theoretical models suggest that modern recursive composition (specifically Plonky2 and Nova) should render proving times negligible, our recent benchmarks paint a more nuanced picture.

In controlled environments, the math holds up. However, thermal throttling on mobile devices introduces a non-deterministic variable that most academic papers abstract away. When a device is under sustained load—common during the sync phase of a light client—the CPU governor aggressively downclocks, causing proving times to spike by factors of 3x to 5x.

We are currently exploring a hybrid approach for Nexus Grid that offloads the heavy lifting to a localized 'helper' node while keeping the witness generation strictly local. This preserves privacy while respecting the thermal constraints of mobile silicon.

Fig 1. Performance degradation of Apple A17 Pro during 120s of sustained MSM operations

As illustrated above, performance degrades rapidly after the 30-second mark. This 'thermal wall' effectively creates a hard cap on the complexity of circuits that can be proven locally without significantly degrading the user experience. A wallet app that freezes for 45 seconds while generating a proof is effectively broken, regardless of the underlying cryptographic soundness.

Beyond raw speed, the battery impact is non-trivial. Our telemetry indicates that a single complex proof generation cycle consumes roughly 2-3% of battery life on a standard iPhone 15. For a high-frequency trading use case, this is unacceptable.

We are currently exploring a hybrid approach for Nexus Grid that offloads the heavy lifting to a localized 'helper' node while keeping the witness generation strictly local. This preserves privacy while respecting the thermal constraints of mobile silicon.

This divergence serves as a reminder that cryptography does not exist in a vacuum. The physical reality of the hardware is just as much a constraint as the soundness of the proof system.