GLV implementation for BLS12_377, BLS12_381 and BN254 (#158)

vesta/src/curves/mod.rs

@@ -1,9 +1,10 @@
 use crate::{fq::Fq, fr::Fr};
 use ark_ec::{
     models::CurveConfig,
+    scalar_mul::glv::GLVConfig,
     short_weierstrass::{self as sw, SWCurveConfig},
 };
-use ark_ff::{AdditiveGroup, Field, MontFp, Zero};
+use ark_ff::{AdditiveGroup, BigInt, Field, MontFp, PrimeField, Zero};
 
 #[cfg(test)]
 mod tests;
@@ -41,6 +42,40 @@ impl SWCurveConfig for VestaConfig {
     }
 }
 
+impl GLVConfig for VestaConfig {
+    const ENDO_COEFFS: &'static [Self::BaseField] = &[MontFp!(
+        "26005156700822196841419187675678338661165322343552424574062261873906994770353"
+    )];
+
+    const LAMBDA: Self::ScalarField =
+        MontFp!("20444556541222657078399132219657928148671392403212669005631716460534733845831");
+
+    const SCALAR_DECOMP_COEFFS: [(bool, <Self::ScalarField as PrimeField>::BigInt); 4] = [
+        (false, BigInt!("98231058071100081932162823354453065729")),
+        (true, BigInt!("98231058071186745657228807397848383488")),
+        (false, BigInt!("196462116142286827589391630752301449217")),
+        (false, BigInt!("98231058071100081932162823354453065729")),
+    ];
+
+    fn endomorphism(p: &Projective) -> Projective {
+        // Endomorphism of the points on the curve.
+        // endomorphism_p(x,y) = (BETA * x, y)
+        // where BETA is a non-trivial cubic root of unity in Fq.
+        let mut res = (*p).clone();
+        res.x *= Self::ENDO_COEFFS[0];
+        res
+    }
+
+    fn endomorphism_affine(p: &Affine) -> Affine {
+        // Endomorphism of the points on the curve.
+        // endomorphism_p(x,y) = (BETA * x, y)
+        // where BETA is a non-trivial cubic root of unity in Fq.
+        let mut res = (*p).clone();
+        res.x *= Self::ENDO_COEFFS[0];
+        res
+    }
+}
+
 /// G_GENERATOR_X = -1
 /// Encoded in Montgomery form, so the value here is -R mod p.
 pub const G_GENERATOR_X: Fq = MontFp!("-1");

vesta/src/curves/tests.rs

@@ -2,3 +2,4 @@ use crate::Projective;
 use ark_algebra_test_templates::*;
 
 test_group!(g1; Projective; sw);
+test_group!(g1_glv; Projective; glv);