Feature Request: Separate Verifier Generation from Proof Generation

[june-in-exile]

Currently, the Pico zkVM SDK requires developers to generate a full proof (via prove_evm) in order to obtain the Groth16Verifier.sol contract. This creates an unnecessary coupling between two conceptually distinct operations:

1. Setup/Keygen (circuit-dependent) → Generate verifier contract
2. Proving (input-dependent) → Generate proofs for specific inputs

Current Workflow Problem

To deploy a verifier contract, developers must:

// Currently required - generates BOTH proof AND verifier
client.prove_evm(stdin_builder, true, output_dir, "kb")?;

This approach has significant drawbacks:

Resource Overhead

• Time: ~30 minutes per generation
• Memory: ~32GB Docker container requirement
• Output: Generates unnecessary proof files when only verifier is needed

Use Case Mismatch

• The verifier contract only depends on the circuit structure (ELF file), not on specific input values
• In production workflows, we typically:
  1. Deploy verifier contract once (needs only Groth16Verifier.sol)
  2. Generate proofs many times with different inputs (needs proof.data + inputs.json)

Current Workaround

The only way to obtain Groth16Verifier.sol is to provide dummy inputs and run the full proving pipeline, which is wasteful:

// Dummy inputs just to generate verifier
stdin_builder.write(&0u32);
stdin_builder.write(&0u32);
// ... more dummy inputs

client.prove_evm(stdin_builder, true, output_dir, "kb")?;
// Wait 30 minutes for proof we don't need
// Just to get Groth16Verifier.sol

Proposed Solution

Add a dedicated method for verifier generation:

// Proposed API
let client = DefaultProverClient::new(&elf);
client.generate_verifier(output_dir)?;

This would:

• Accept only the ELF file (circuit definition)
• Skip witness generation, constraint solving, and proof computation
• Output only Groth16Verifier.sol and verification key (vm_vk)
• Complete in seconds instead of minutes