1# Decider prove
 2
 3Two options:
 4
 5- onchain (Ethereum's EVM) mode
 6- offchain mode
 7
 8Once we have been folding our circuit instances, we can generate the *"final proof"*, the Decider proof.
 9
10
11#### Onchain Decider
12
13![](../imgs/decider-onchain-flow-diagram.png)
14
15Generating the final proof (decider), to be able to verify it in Ethereum's EVM:
16
17```rust
18type DECIDER = Decider<
19    Projective,
20    GVar,
21    Projective2,
22    GVar2,
23    CubicFCircuit<Fr>,
24    KZG<'static, Bn254>,
25    Pedersen<Projective2>,
26    Groth16<Bn254>, // here we define the Snark to use in the decider
27    NOVA,           // here we define the FoldingScheme to use
28>;
29
30// generate Groth16 setup
31let circuit = DeciderEthCircuit::<
32    Projective,
33    GVar,
34    Projective2,
35    GVar2,
36    Pedersen<Projective>,
37    Pedersen<Projective2>,
38>::from_nova::<CubicFCircuit<Fr>>(nova.clone());
39let mut rng = rand::rngs::OsRng;
40
41let start = Instant::now();
42let (pk, vk) =
43    Groth16::<Bn254>::circuit_specific_setup(circuit.clone(), &mut rng).unwrap();
44println!("Groth16 setup, {:?}", start.elapsed());
45
46// decider proof generation
47let decider_pp = (poseidon_config.clone(), g16_pk, kzg_pk);
48let proof = DECIDER::prove(decider_pp, rng, nova.clone()).unwrap();
49
50// decider proof verification
51let decider_vp = (poseidon_config, g16_vk, kzg_vk);
52let verified = DECIDER::verify(decider_vp, nova.i, nova.z_0, nova.z_i, &nova.U_i, &nova.u_i, proof).unwrap();
53assert!(verified);
54```
55
56As mentioned above, complete examples can be found at [sonobe/folding-schemes/examples](https://github.com/privacy-scaling-explorations/sonobe/tree/main/folding-schemes/examples)
57