ZK and prover handoffs

ZK and prover handoff engineering

Zerynex is not a proof system or zero-knowledge verifier. Its current ZK-related value is at the interface between privacy engineering and Zcash Partially Created Transactions: developers can test disclosure rules and component structure as a transaction moves between upstream PCZT roles.

What works today

• Parse real PCZTs with the upstream Rust PCZT crate.
• Compare field presence and component counts across two stages.
• Flag newly present proprietary metadata and selected disclosure-policy fields using the canonical Rust engine.
• Run synthetic Creator/Updater/Combiner/Redactor role acceptance scenarios.
• Export sanitized results through CLI, Python, Go, CI and MCP fixtures.

A synthetic stage check:

cargo run --locked -- \
  apps/web/public/examples/clean-v6.bin \
  --compare-with apps/web/public/examples/flagged-v6.bin --json

This is an example of checking whether extra metadata appears at a handoff. The sample does not exercise ZK proof generation or verification.

Suggested workflow for prover engineers

1. Work with a disposable, synthetic or nonspendable PCZT fixture.
2. Define a role-specific privacy policy and a permitted component topology.
3. Capture a baseline fixture before a proving/signing handoff.
4. Run the same policy after the role completes, using the stage regression CLI.
5. Check separate upstream verifier/prover outcomes using their own published cryptographic APIs. Do not infer proof validity from a Zerynex report.
6. Add the deterministic, non-sensitive fixtures to a regression suite.

Not implemented yet

• Calling Sapling, Orchard, Ironwood, or Halo2 proving/verifier APIs
• Circuit constraint checks, witness analysis, proof generation, or cryptographic soundness verification
• A signer/prover authorization policy or transaction equivalence checker
• Real Zallet prover RPC compatibility and regtest lifecycle checks

We must pin upstream versions, supply positive and negative synthetic test vectors, and run the real upstream prover/verifier before describing any of those as supported.

Upstream references

• ZIP-374 PCZT
• librustzcash
• Orchard
• Halo2
• Zallet RPC

This feature is an early privacy regression guard, not an audit. Do not publish actual wallet PCZTs or ZK witnesses to public CI or LLMs.