1use algebra::PairingEngine;
 2use crate::Error;
 3use rand::Rng;
 4use groth16::{
 5    create_random_proof, generate_random_parameters, prepare_verifying_key, verify_proof,
 6    Parameters, PreparedVerifyingKey, Proof, VerifyingKey,
 7};
 8use r1cs_core::ConstraintSynthesizer;
 9
10use algebra::ToConstraintField;
11use std::marker::PhantomData;
12
13use super::NIZK;
14
15#[cfg(feature = "r1cs")]
16pub mod constraints;
17
18/// Note: V should serialize its contents to `Vec<E::Fr>` in the same order as
19/// during the constraint generation.
20pub struct Groth16<E: PairingEngine, C: ConstraintSynthesizer<E::Fr>, V: ToConstraintField<E::Fr> + ?Sized> {
21    #[doc(hidden)]
22    _engine:         PhantomData<E>,
23    #[doc(hidden)]
24    _circuit:        PhantomData<C>,
25    #[doc(hidden)]
26    _verifier_input: PhantomData<V>,
27}
28
29impl<E: PairingEngine, C: ConstraintSynthesizer<E::Fr>, V: ToConstraintField<E::Fr> + ?Sized> NIZK for Groth16<E, C, V> {
30    type Circuit = C;
31    type AssignedCircuit = C;
32    type ProvingParameters = Parameters<E>;
33    type VerificationParameters = VerifyingKey<E>;
34    type PreparedVerificationParameters = PreparedVerifyingKey<E>;
35    type VerifierInput = V;
36    type Proof = Proof<E>;
37
38    fn setup<R: Rng>(
39        circuit: Self::Circuit,
40        rng: &mut R,
41    ) -> Result<
42        (
43            Self::ProvingParameters,
44            Self::PreparedVerificationParameters,
45        ),
46        Error,
47    > {
48        let nizk_time = start_timer!(|| "{Groth-Maller 2017}::Setup");
49        let pp = generate_random_parameters::<E, Self::Circuit, R>(circuit, rng)?;
50        let vk = prepare_verifying_key(&pp.vk);
51        end_timer!(nizk_time);
52        Ok((pp, vk))
53    }
54
55    fn prove<R: Rng>(
56        pp: &Self::ProvingParameters,
57        input_and_witness: Self::AssignedCircuit,
58        rng: &mut R,
59    ) -> Result<Self::Proof, Error> {
60        let proof_time = start_timer!(|| "{Groth-Maller 2017}::Prove");
61        let result = create_random_proof::<E, _, _>(input_and_witness, pp, rng)?;
62        end_timer!(proof_time);
63        Ok(result)
64    }
65
66    fn verify(
67        vk: &Self::PreparedVerificationParameters,
68        input: &Self::VerifierInput,
69        proof: &Self::Proof,
70    ) -> Result<bool, Error> {
71        let verify_time = start_timer!(|| "{Groth-Maller 2017}::Verify");
72        let conversion_time = start_timer!(|| "Convert input to E::Fr");
73        let input = input.to_field_elements()?;
74        end_timer!(conversion_time);
75        let verification = start_timer!(|| format!("Verify proof w/ input len: {}", input.len()));
76        let result = verify_proof(&vk, proof, &input)?;
77        end_timer!(verification);
78        end_timer!(verify_time);
79        Ok(result)
80    }
81}