Here’s a proof of concept implementation of an attestation verifier written in risczero - GitHub - marlinprotocol/oyster-attestation-verifier-risczero (Warning: crappy code). It currently only implements the COSE verification step.

Takes ~2.5 hrs to run on a 8 core Ryzen 7.

Takes ~22 min on a dual socket Xeon 6544Y.

Down to ~2.5 min with a GPU! GPU is a H100, seems to utilize the GPU fully in bursts and uses a little over 10 GB VRAM.

Takes a similar amount of time (~3 min) on a RTX 4000.

Generating a groth16 receipt (which we need to verify in contracts) bumps it up to ~5.5 min.

IMO numbers look good enough for a full implementation even if it goes up to an hour.