more rearranging, add edwards mod for arkworks defs

Cargo.toml

@@ -43,7 +43,7 @@ std = ["alloc", "tracing/std", "anyhow/std", "tracing-subscriber/std", "zeroize/
 parallel = ["ark-ff/parallel", "ark-ec/parallel", "ark-groth16/parallel", "ark-std/parallel", "ark-r1cs-std/parallel"]
 # TODO: eventually, feature-gate all arkworks deps behind this feature.
 arkworks = ["std", "ark-std", "ark-ec", "ark-ff", "ark-serialize", "ark-bls12-377", "ark-ed-on-bls12-377"]
-r1cs = ["ark-groth16", "ark-r1cs-std", "ark-relations", "ark-snark"]
+r1cs = ["arkworks", "ark-groth16", "ark-r1cs-std", "ark-relations", "ark-snark"]
 u32_backend = []
 
 [dev-dependencies]

src/ark_curve/edwards.rs

@@ -0,0 +1,71 @@
+use crate::Fq;
+
+#[derive(Clone, Default, PartialEq, Eq)]
+pub struct Decaf377EdwardsConfig;
+
+// These types should not be exported. They are similar to `EdwardsAffine` and
+// `EdwardsProjective` from the `ark_ed_on_bls12_377` crate, except using our own
+// `Decaf377Config` that has the cofactor set to 1. Consumers of this
+// library should use the `AffineElement` and `Element` (projective)
+// types.
+pub type EdwardsAffine = Affine<Decaf377EdwardsConfig>;
+pub type EdwardsProjective = Projective<Decaf377EdwardsConfig>;
+
+impl CurveConfig for Decaf377EdwardsConfig {
+    type BaseField = Fq;
+    type ScalarField = Fr;
+
+    const COFACTOR: &'static [u64] = &[1];
+
+    const COFACTOR_INV: Fr = Fr::one();
+}
+
+impl TECurveConfig for Decaf377EdwardsConfig {
+    /// COEFF_A = -1
+    const COEFF_A: Fq = Fq::from_montgomery_limbs_64([
+        10157024534604021774,
+        16668528035959406606,
+        5322190058819395602,
+        387181115924875961,
+    ]);
+
+    /// COEFF_D = 3021
+    const COEFF_D: Fq = Fq::from_montgomery_limbs_64([
+        15008245758212136496,
+        17341409599856531410,
+        648869460136961410,
+        719771289660577536,
+    ]);
+
+    const GENERATOR: EdwardsAffine = EdwardsAffine::new_unchecked(GENERATOR_X, GENERATOR_Y);
+
+    type MontCurveConfig = Decaf377EdwardsConfig;
+
+    /// Multiplication by `a` is just negation.
+    #[inline(always)]
+    fn mul_by_a(elem: Self::BaseField) -> Self::BaseField {
+        -elem
+    }
+
+    fn is_in_correct_subgroup_assuming_on_curve(_: &Affine<Self>) -> bool {
+        true
+    }
+}
+
+impl MontCurveConfig for Decaf377EdwardsConfig {
+    const COEFF_A: Fq = Fq::from_montgomery_limbs_64([
+        13800168384327121454,
+        6841573379969807446,
+        12529593083398462246,
+        853978956621483129,
+    ]);
+
+    const COEFF_B: Fq = Fq::from_montgomery_limbs_64([
+        7239382437352637935,
+        14509846070439283655,
+        5083066350480839936,
+        1265663645916442191,
+    ]);
+
+    type TECurveConfig = Decaf377EdwardsConfig;
+}

src/ark_curve/mod.rs

@@ -0,0 +1 @@
+mod edwards;

src/lib.rs

@@ -5,9 +5,11 @@
 use cfg_if::cfg_if;
 
 pub mod fields;
-pub mod smol_curve;
+pub mod min_curve;
 pub use fields::{fp::Fp, fq::Fq, fr::Fr};
 
+pub mod ark_curve;
+
 mod sign;
 
 mod on_curve;

src/min_curve/invsqrt.rs

@@ -2,7 +2,7 @@ use subtle::{ConditionallySelectable, ConstantTimeEq};
 
 use crate::{fields::fq::arkworks_constants::*, Fq};
 
-use crate::smol_curve::constants::ZETA;
+use crate::min_curve::constants::ZETA;
 
 impl Fq {
     /// For square elements, calculate their square root, otherwise return an undefined element.

src/min_curve/ops.rs

@@ -1,6 +1,6 @@
 use core::ops::{Add, AddAssign, Mul, MulAssign, Neg, Sub, SubAssign};
 
-use crate::{smol_curve::element::Element, Fr};
+use crate::{min_curve::element::Element, Fr};
 
 // Element addition