# Offchain Verification Endpoint

V1. Accept requests of the form:

{
    "vk": { ... },
    "proof": { ... },
    "inputs": [ "1", "2", ... ]
}

where `vk` and `proof` are in the **upa** format. In this way, groth16 with commits is supported and we have conversion functionality from snarkjs and gnark formats.

## Existing code for endpoint (`circuits` create in upa repo):

### `Service<_>`, `HTTPServer<>`

In `prover_daemon` crate. Already has a multi-threaded server impl.

### Verifier

`upa_circuits::batch_verifier::types::UniversalBatchVerifierInput`

#[derive(Clone, Debug, Deserialize, Serialize)]
pub struct UniversalBatchVerifierInput<F = Fr> 
where                                          
    F: EccPrimeField,                          
{                                              
    pub vk: VerificationKey,                   
    pub proof: Proof,                          
    pub inputs: PublicInputs<F>,               
}                                              

A json request to the verifier service can be `UniversalBatchVerifierInput` or `Vec<UniversalBatchVerifierInput>`.

`upacircuits::batch_verifier::universal::native`

pub fn verify_universal_groth16_batch<B, I>( 
    batch: B,                                
    max_num_public_inputs: usize,            
) -> bool                                    
where                                        
    B: IntoIterator<Item = I>,               
    I: Borrow<UniversalBatchVerifierInput>,  

This handles a sequence of `UniversalBatchVerifierInput`s. If we make the endpoint accept a list of `UniversalBatchVerifierInput`s, we can use this function as-is and get batched verification for multi-proof requests.

# Client

- Initially:

  upa remote-verify --endpoint <URL> --format <snarkjs,gnark> --vk <file> --proof <file>

- Later: could create a standalone typescript package which uses upa as a dependency and implements a dedicated CLI:

  nebra-verify --endpoint <URL> --format <snarkjs,gnark> --vk <file> --proof <file>