spartan2 0.9.0

High-speed zkSNARKs without trusted setup
Documentation 
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// Copyright (c) Microsoft Corporation.
// SPDX-License-Identifier: MIT
// This file is part of the Spartan2 project.
// See the LICENSE file in the project root for full license information.
// Source repository: https://github.com/Microsoft/Spartan2

//! This module implements the Spartan traits for `pallas::Point`, `pallas::Scalar`, `vesta::Point`, `vesta::Scalar`.
use crate::{
  impl_traits,
  provider::{
    msm::{msm, msm_shared_weights, msm_small},
    traits::{DlogGroup, DlogGroupExt},
  },
  traits::{Group, PrimeFieldExt, transcript::TranscriptReprTrait},
};
use digest::{ExtendableOutput, Update};
use ff::FromUniformBytes;
use halo2curves::{
  CurveAffine, CurveExt,
  group::{Curve, Group as AnotherGroup, cofactor::CofactorCurveAffine},
  pasta::{Pallas, PallasAffine, Vesta, VestaAffine},
};
use num_bigint::BigInt;
use num_integer::Integer;
use num_traits::{Num, ToPrimitive};
use rayon::prelude::*;
use sha3::Shake256;
use std::io::Read;

/// Re-exports that give access to the standard aliases used in the code base, for pallas
pub mod pallas {
  pub use halo2curves::pasta::{Fp as Base, Fq as Scalar, Pallas as Point, PallasAffine as Affine};
}

/// Re-exports that give access to the standard aliases used in the code base, for vesta
pub mod vesta {
  pub use halo2curves::pasta::{Fp as Scalar, Fq as Base, Vesta as Point, VestaAffine as Affine};
}

impl_traits!(
  pallas,
  Pallas,
  PallasAffine,
  "40000000000000000000000000000000224698fc0994a8dd8c46eb2100000001",
  "40000000000000000000000000000000224698fc094cf91b992d30ed00000001"
);

impl_traits!(
  vesta,
  Vesta,
  VestaAffine,
  "40000000000000000000000000000000224698fc094cf91b992d30ed00000001",
  "40000000000000000000000000000000224698fc0994a8dd8c46eb2100000001"
);

// Implement big_num traits for Pasta scalar fields
// Pallas scalar = Fq, Vesta scalar = Fp
crate::impl_field_reduction_constants!(pallas::Scalar);
crate::impl_montgomery_limbs!(pallas::Scalar);
crate::impl_field_reduction_constants!(vesta::Scalar);
crate::impl_montgomery_limbs!(vesta::Scalar);

#[cfg(test)]
mod tests {
  use crate::provider::{pasta::pallas, traits::DlogGroup};
  use digest::{ExtendableOutput, Update};
  use halo2curves::{CurveExt, group::Curve};
  use sha3::Shake256;
  use std::io::Read;

  macro_rules! impl_cycle_pair_test {
    ($curve:ident) => {
      fn from_label_serial(label: &'static [u8], n: usize) -> Vec<$curve::Affine> {
        let mut shake = Shake256::default();
        shake.update(label);
        let mut reader = shake.finalize_xof();
        (0..n)
          .map(|_| {
            let mut uniform_bytes = [0u8; 32];
            reader.read_exact(&mut uniform_bytes).unwrap();
            let hash = $curve::Point::hash_to_curve("from_uniform_bytes");
            hash(&uniform_bytes).to_affine()
          })
          .collect()
      }

      let label = b"test_from_label";
      for n in [
        1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 1021,
      ] {
        let ck_par = <$curve::Point as DlogGroup>::from_label(label, n);
        let ck_ser = from_label_serial(label, n);
        assert_eq!(ck_par.len(), n);
        assert_eq!(ck_ser.len(), n);
        assert_eq!(ck_par, ck_ser);
      }
    };
  }

  #[test]
  fn test_pallas_from_label() {
    impl_cycle_pair_test!(pallas);
  }
}

#[cfg(test)]
mod big_num_tests {
  crate::test_field_reduction_constants!(pallas_frc, crate::provider::pasta::pallas::Scalar);
  crate::test_montgomery!(pallas_mont, crate::provider::pasta::pallas::Scalar);
  crate::test_delayed_reduction!(pallas_dr, crate::provider::pasta::pallas::Scalar);
  crate::test_field_reduction_constants!(vesta_frc, crate::provider::pasta::vesta::Scalar);
  crate::test_montgomery!(vesta_mont, crate::provider::pasta::vesta::Scalar);
  crate::test_delayed_reduction!(vesta_dr, crate::provider::pasta::vesta::Scalar);
}