If a 'ZK'-prover network asks for your data. don’t give it to them.

The article argues that many zero-knowledge prover networks prioritize speed and cost over privacy, so users who send them witness data in the clear may expose sensitive information. It describes the standard model of untrusted delegated SNARKs as fast but leaving witness data exposed to the prover. It presents private delegated approaches, including zkSaaS, oblivious issuance, CoSNARKs and delegated Spartan, as alternatives that trade off privacy, efficiency and trust assumptions differently. The author says NovaNet works on local client-side proving with folding schemes and has experimented with delegated Spartan, and that Remco at Worldcoin is also trying it.